Permafrost in Canada’s Subarctic Region of Northern

Ontario.

by

Andrew Tam

A thesis submitted in conformity with the requirements

for the degree of Masters of Science

Graduate Department of Geography

University of Toronto

© Copyright by Andrew Tam (2009)

ii

Abstract

An investigation of permafrost (permanently frozen soil) was conducted in

Canada‟s subarctic region of Northern Ontario. Environmental baseline conditions and

permafrost states were estimated using seasonal freezing and thawing energies based on

observed climate data and the Stefan equation. Field studies provided measurements of

the active layer depths and validated the permafrost states; laboratory studies of the soil

samples provided characterization for organic materials that have high affinity for soil

moisture. Palsas (unique dome-like formations) were observed to have enhanced

permafrost cores beneath a thermal insulating organic layer. With climate change, results

suggest the possibility of shifts from the classification of continuous to discontinuous

permafrost states in areas lacking the presence of organic materials that can have

environmental and ecological impacts. Northern infrastructures may become destabilized

with the degradation of permafrost while palsas may become lone permafrost refuges for

biodiversity that depend on cooler ecosystems, such as polar bears.

iii

Acknowledgments

Foremost, I would like express sincere gratitude to my supervisor, Prof. William

Gough, for his valuable assistance, guidance, professional knowledge, and most of all, for

his patience. I thank him for giving me the opportunity to grow as a student, to participate

in pursing a Masters degree, and to take responsibility in encompassing a research of this

scope.

I would like to recognize the assistance of Martyn Obbard and his personnel at the

Ontario Ministry of Natural Resources for this unique opportunity to study permafrost in

all of Northern Ontario.

I would like to acknowledge and express my gratitude to my fellow colleagues

Muaz Nasir and Joyce Zhang for their continuing and unwavering moral and academic

support and, in many instances, for providing me with reassurances throughout my years

at the University of Toronto at Scarborough.

I would like to recognize the contributions of Slawomir Kowal for his time in

preparing temperature data and for his assistance in the laboratory. I would like to give

special thanks to S. Das, J.W. Cowan, T.R. Beeby and A. Sarwari for their auxiliary

support in conquering the battle of proofreading my thesis.

I would like to extend special thanks to my parents for all their love, help and

support in my endeavours. I would like to show appreciation to my brother, Charles

Tam, and my sister-in-law, Angela, for all their continuing encouragements, support and

faith in my abilities. Finally, I would like to thank all my friends and supporters in

Trenton and Toronto whom continue to cheer me on in my life.

Funding from the Department of Geography at the University of Toronto

supported this research and funding by the Ontario Ministry of Natural Resources

supported the fieldwork.

iv

Table of Contents

Abstract …………………………………………………………………… ii

Acknowledgements .……...…………………………………………………… iii

Table of Contents …………………………………………………………… iv

List of Figures …………………………………………………………………… vi

List of Tables …………………………………………………………………… vii

CHAPTER 1: Introduction …………………………………………………… 1

1.1 Project Description …………………………………………… 1

1.2 Aim, Objectives and Hypotheses …………………………………… 3

CHAPTER 2: Literature Review …………………………………………… 5

2.1 Introduction …………………………………………………… 5

2.2 Surface Vegetation and Active Layer …………………………… 6

2.3 Permafrost …………………………………………………… 8

2.3.1 Defining Permafrost …………………………………… 8

2.3.2 Formation and Degradation Processes …………………… 10

2.3.3 Soil Moisture Content and Thermal Conductivity …… 12

2.3.4 Stefan Depth and Permafrost Table …………………… 15

2.3.5 „Thermal Offset‟ …………………………………… 16

2.4 Palsa …………………………………………………………… 17

2.4.1 Defining Palsa …………………………………………… 17

2.4.2 Physical Properties of Palsas …………………………… 18

2.4.3 “Palsa Lifting” …………………………………………… 20

2.4.4 The Palsa Cycle …………………………………………… 20

2.5 Soil Temperatures and Net Radiation …………………………… 22

2.6 Ground Heat Flux …………………………………………… 23

2.7 Geophysical Detection of Permafrost …………………………… 24

2.7.1 Ground Temperature Borehole Logging …………… 25

2.8 Literature Summary …………………………………………… 26

CHAPTER 3: Experimental Design and Methodology …………………… 30

3.1 Location and Study Site Descriptions …………………………… 31

3.1.1 Biogeography …………………………………………… 32

3.1.2 Climate Data and Weather Stations …………………… 34

3.2 Field Experimental Design …………………………………… 35

3.2.1 Soil Temperatures and Thermistor Probes …………… 35

3.2.2 Point-scale Geophysical Sampling …………………… 35

3.2.3 Sample Labelling and Identification …………………… 38

3.2.4 Field Soil Characterization …………………………… 39

3.3 Laboratory Analytical Methodology …………………………… 39

3.3.1 List of Materials …………………………………… 39

3.3.2 Laboratory Soil Characterization …………………… 40

3.3.3 Gravimetric Soil Moisture Content …………………… 41

v

3.3.4 Soil Acidity, Average pH Value …………………… 43

3.3.5 Soil Moisture Content Loss Test …………………… 43

3.4 Stefan Depth and Permafrost Table Calculations …………………… 45

3.5 Thawing and Freezing Degree-Days Calculations …………… 46

3.6 Geographical Information Systems …………………………… 47

CHAPTER 4: Results …………………………………………………… 48

4.1 Climate and Environmental Data …………………………………… 48

4.2 Soil Characterization (2007-2008) …………………………… 49

4.3 Laboratory Analysis Results (2007-2008) …………………… 58

4.3.1 Soil Moisture Content and Soil Acidity …………………… 58

4.3.2 Measured Depths to Permafrost …………………………… 61

4.4 Freezing and Thawing Degree-Days (1989-2007) …………… 64

4.4.1 Results from 1989 to 2002 …………………………… 64

4.4.2 Results from 2004 to 2007 …………………………… 66

4.5 Stefan Depth and Permafrost Table Results (1989-2007) …… 68

4.5.1 Porous Sandy Soils (1989 to 2007) …………………… 70

4.5.2 Non Porous Sandy Soils (1989 to 2007) …………… 72

4.5.3 Clay Soils (1989 to 2007) …………………………… 74

4.5.4 Peat and Organic Materials (1989 to 2007) …………… 77

4.6 Soil Moisture Content Loss Test (2008) …………………………… 81

CHAPTER 5: Discussion …………………………………………………… 82

5.1 Soil Characterization …………………………………………… 82

5.2 Freezing and Thawing Degree-Days …………………………… 85

5.3 Stefan Depth and Permafrost Table …………………………… 86

5.4 Permafrost Presence …………………………………………… 89

5.5 Palsa Presence …………………………………………………… 93

5.6 Addressing Research Question 1 …………………………………… 94

5.7 Addressing Research Question 2 …………………………………… 97

5.8 Sources of Error and Uncertainties …………………………… 98

5.9 Potential Research Impacts on Society …………………………… 101

CHAPTER 6: Conclusion …………………………………………………… 103

6.1 Permafrost …………………………………………………… 103

6.2 Palsas …………………………………………………………… 105

6.3 Recommendations for Further Research …………………………… 106

References …………………………………………………………………… 108

APPENDIX – Additional Figures …………………………………………… 115

vi

List of Figures

Figure 1 – “Baby” Palsa in Northern Ontario, August 2007 …………………… 18

Figure 2 – Location of settlements, weather stations and rivers

in Northern Ontario …………………………………………………… 30

Figure 3 – Terrestrial Ecozones for the Hudson Bay Lowlands by Natural

Resources Canada (Natural Resources Canada, 2007) …………… 32

Figure 4 – Forested Ecozones for the Hudson Bay Lowlands by Natural

Resources Canada (Natural Resources Canada, 2003) …………… 33

Figure 5 – Sampling Sites located in Northern Ontario Hudson Bay

divided by Three Quadrants from both 2007 and 2008 Soil

Sampling Campaigns …………………………………………………… 36

Figure 6 – Sampling Sites located in Northern Ontario - Hudson Bay for 2007

divided by Three Quadrants …………………………………………… 37

Figure 7 – Sampling Sites located in Northern Ontario - Hudson Bay for 2008

divided by Three Quadrants …………………………………………… 38

Figure 8 – Labeled sample bag with associated tin foil tray container …… 40

Figure 9 – Analysis of soil sample D5a …………………………………… 41

Figure 10 – Subsurface stratigraphy classification of Northern Ontario

and Hudson Bay by Natural Resources Canada

(Natural Resources Canada, 2006) …………………………………… 48

Figure 11 – Results: Freezing and thawing degree-days for Peawanuck,

Ontario, from 1989-2002 …………………………………………… 64

Figure 12 – Results: Freezing and thawing degree-days for Peawanuck,

Ontario, from 2004-2007 …………………………………………… 66

Figure 13 – Thermal conductivity to water content for fine-grained soils,

both frozen and thawed soils (Nixon & McRoberts, 1973) …………… 69

Figure 14 – Thermal Offset for Sand (Porosity >0.33)

Compositions 1989-2007 …………………………………………… 70

Figure 15 – Thermal Offset for Sand (Porosity <0.33)

Compositions 1989-2007 …………………………………………… 72

Figure 16 – Thermal offset for Clay Compositions 1989-2007 …………… 75

Figure 17 – Thermal Offset for Peat Compositions 1989-2007 …………… 77

Figure 18 – Thermal Offset for Palsa (Dense peat)

Compositions 1989-2007 …………………………………………… 79

Figure 19 – Excavated Palsa located in a vegetated region

in Northern Ontario …………………………………………………… 115

Figure 20 – Soil Samples baking in the oven at 105˚C for gravimetric

soil moisture content analysis …………………………………………… 115

Figure 21 – Three male polar bears in Northern Ontario, August 2007 …… 116

vii

List of Tables

Table 1 – Methodology: Environment Canada Weather Station Information

with Climate, World Meteorological Organization (WMO)

and Transport Canada (TC) ID codes …………………………………… 34

Table 2 – List of Required Materials for Laboratory Analyses: 2007 & 2008

Sampling Campaigns …………………………………………………… 40

Table 3 – Results: Elevation and Annual Temperature Ranges in Northern

Ontario communities from Environment Canada …………………… 49

Table 4 – Results: Site & Soil Characterizations from 2007 Soil Sampling Campaign with

Distances from the Shores of Hudson Bay to the Sample Sites …… 50

Table 5 – Results: Site & Soil Characterizations from 2008 Soil Sampling Campaign with

Distances from the Shores of Hudson Bay to the Sample Sites …… 53

Table 6 – Results: 2007 Laboratory Analysis for Gravimetric Soil Moisture

Content and Acidity for Northern Ontario …………………………… 58

Table 7 – Results: 2008 Laboratory Analysis for Gravimetric Soil Moisture

Content and Acidity for Sampling Sites along the Shores

of Hudson Bay …………………………………………………… 60

Table 8 – Results: 2008 Laboratory Analysis for Gravimetric Soil Moisture

Content and Acidity for Sampling Sites inland in

Northern Ontario …………………………………………………… 61

Table 9 –Results: Depths to Permafrost for 2007 Sampling Site and Classified

By Quadrants …………………………………………………………… 62

Table 10 – Results: Depths to Permafrost for 2008 Sampling Site and Classified

by Quadrants …………………………………………………………… 63

Table 11 – Results: Yearly Average Depths to Permafrost per Quadrant …… 64

Table 12 – Results: Statistical Analysis of the 1989-2002

Peawanuck Degree-Days …………………………………………… 65

Table 13 – Results: Statistical Analysis of the 2004-2007

Peawanuck Degree-Days …………………………………………… 67

Table 14 – Results: Stefan Depths for Porous Sand (Porosity >0.33)

Soil Compositions (1989-2002) …………………………………… 70

Table 15 – Results: Stefan Depths for Porous Sand (Porosity >0.33)

Soil Compositions (2004-2007) …………………………………… 71

Table 16 – Results: Stefan Depths for Non-Porous Sand (Porosity <0.33)

Soil Compositions (1989-2002) …………………………………… 73

Table 17 – Results: Stefan Depths for Non-Porous Sand (Porosity <0.33)

Soil Compositions (2004-2007) …………………………………… 74

Table 18 – Results: Stephan Depths for Clay Soil Compositions

(1989-2002) …………………………………………………………… 75

Table 19 – Results: Stefan Depths for Clay Soil Compositions

(2004-2007) …………………………………………………………… 76

Table 20 – Results: Stefan Depths for Peat Compositions (1989-2002) …… 78

Table 21 – Results: Stefan Depths for Peat Compositions (2004-2007) …… 78

Table 22 – Results: Stefan Depths for a Palsa Formation (1989-2007) …… 80

Table 23 – Results: Soil Moisture Content Loss Test (2008) …………… 81

1

CHAPTER 1: Introduction

1.1 Project Description

The formation of permafrost in the Canadian subarctic, particularly in Northern

Ontario, is not widely understood considering the complex relationships between

environmental and physical factors (Brown, 1973; Waelbroeck, 1993; Hinkel et al., 2001;

Gough & Leung, 2002; Martini, 2006; Shur & Jorgenson, 2007; Kuhry, 2008). For

continuous permafrost presence in a region, climate conditions must be favourable. The

presence of permafrost can be determined from climate conditions by calculating the

Frost Number using freezing and thawing degrees-days (Nelson & Outcalt, 1987; Hughes

& Braithwaite, 2008). Based on a hypothesis proposed by Gough and Leung (2002), the

influence of soil thermal conductivity in enhancing the penetration of freezing and

thawing energies in permafrost, the “thermal offset” phenomenon, is the primary focus of

this research. In Gough and Leung (2002), sites in southeastern Hudson Bay followed the

Frost number threshold for continuous permafrost classification. For the southwestern

sites of Hudson Bay, the Frost number showed inconsistency with the field observations

of continuous permafrost. Gough and Leung (2002) first proposed possible errors in

calculations of the thawing degree-days utilized in the Frost number equations. Results

from Gough and Leung (2002) concluded that the possible errors such as overestimations

in the thawing degree-days due to the usage of monthly means instead of daily

temperatures and the influence of snow cover could not account for the inconsistency.

Gough and Leung (2002) proposed that the inconsistency could be explained by the

asymmetric thermal properties of frozen and unfrozen soils, the 'thermal offset'

phenomenon between different thermal conductivities that are strongly dependant on soil

2

moisture content. For this research, the concept of the penetration of freezing energy into

the soil column refers to a negative heat flux of energy in the soil column resulting in the

freezing of soils. The concept of the penetration of thawing energy into the soil column

refers to a positive heat flux of energy into the soil column that results in melting of

frozen soils.

Temperature data was collected from weather stations in the study area for the

calculations of the degree-days, which provided the climatological data needed for the

Stefan equation in calculating freezing and thawing depths and thus the thermal offset for

the region. Soil samples were retrieved by fieldwork from sampling sites along the shores

of Hudson Bay and inland in Northern Ontario. Published literatures on permafrost were

reviewed to establish relationships between soil moisture content and thermal

conductivity (Gross et al., 1990; Waelbroeck, 1993; Peck & O‟Neill, 1995; Henry, 2000;

Hinkel et al., 2001; Ling & Zhang, 2004; Carey et al., 2007; Shur & Jorgenson, 2007;

Zhang et al., 2008a; Christ & Park, 2009; Duan & Naterer, 2009; Nicolsky et al., 2009;

Wang et al., 2009). Laboratory analysis of the soil samples provided gravimetric soil

moisture contents, soil characteristics, and soil acidity. Characterizations and descriptions

of the soil samples were conducted to determine the presence of soil organic matter and

soil composition. Application of geophysical methods in detecting permafrost and

monitoring changes in ground temperatures are discussed in this research (Kurfurst,

1992; Kneisel et al., 2008; Nicolsky et al., 2009).

With climate warming affecting the subarctic regions, shifts in thermal properties

can produce unfavourable environmental conditions that can shift permafrost states

(Zoltai & Witt, 1995; Hayashi et al., 2007; Shur & Jorgenson, 2007; Kuhry, 2008; Wang

3

et al., 2009). Potential impacts from shifting permafrost states are further discussed for

civil infrastructures in northern communities and on the biodiversity that rely on the

current environment (Vyalov et al., 1993; Sorochan & Tolmachev, 2006; Jin et al., 2008;

Duan & Naterer, 2009).

1.2 Aim, Objectives and Hypotheses

The aim of this research is to establish the state of permafrost and palsas in

Northern Ontario and the areas along the shores of Hudson Bay based on field

observations during the 2007 and 2008 soil sampling campaigns conducted by Gough of

the University of Toronto and Obbard of the Ontario Ministry of Natural Resources. The

two main research questions for this thesis are:

1. Can the distribution of permafrost in Northern Ontario be rationalized using the

relationship between soil moisture content and the frozen and unfrozen soil

thermal conductivities, “the thermal offset” as hypothesized by Gough and Leung

(2002)?

2. Does the presence of palsas affect the thermal conductivity of soil from the

surface cover down to the permafrost?

There are four objectives in this research:

The primary objective of this research is to examine the relationship between soil

moisture content and soil thermal conductivity through the phenomenon known as

„thermal offset‟ in determining the permafrost state in Northern Ontario and the areas

along the shores of Hudson Bay as hypothesized by Gough and Leung (2002).

4

The second objective of this research is to determine the gravimetric soil moisture

content and soil acidity in a laboratory setting of the combined 53 samples from retrieved

over a two year field sampling campaign, and on going, in Northern Ontario.

The third objective is the characterization of the active layer soil conditions based

on field observations of the soil sampling sites in Northern Ontario and the retrieved soil

samples from the 2007 and 2008 summer sampling campaigns; the results are to be

categorized spatially in quadrants and by shore and inland locations. Locations with the

presence of palsas are to be identified since the presence of palsas can affect the soil

thermal conductivity. The ecological importance of palsas is considered in relations to

polar bear (Ursus maritimus) activities at palsas.

The final and fourth objective of this research is to examine alternative methods

to traditional borehole measurements in determining the permafrost state in Canada‟s

Subarctic and Arctic regions with focus on geophysical methods & techniques such as

ground temperature borehole logging.

I hypothesize that there should be a relationship between permafrost distribution

in the study region and high soil moisture content. Higher soil moisture content increases

the soil thermal conductivity especially for frozen soils enhancing the downward freezing

effects in the active layer. I also hypothesize that the areas of high moisture content will

be in areas of high organic matter, such as peat, moss and small vegetations as this layer

is an effective insulator, thus enhancing the freezing effect. Finally, I hypothesize that

regions with high moisture content, high organic matter, and climate conditions

favourable to permafrost should be dominated with continuous permafrost formation.

5

CHAPTER 2: Literature Review

2.1 Introduction

Research has shown relationships between climatic and soil conditions, such as

surface temperature and the moisture content of soil that controls the thermal

conductivity of heat energy conducted through the soil column used to diagnose the

presence of permafrost (Waelbroeck, 1993; Hinkel et al., 2001; Gough & Leung, 2002;

Seppälä, 2003; Shur & Jorgenson, 2007; Kujala et al., 2007; Zhang et al., 2008b; Pang et

al., 2009; Wang et al., 2009).

The active layer above the permafrost is the section of soil that experiences

seasonal freezing and thawing cycles. The soil thermal conductivity has an important role

in determining the depths of freezing and thawing penetrations from the surface into the

active layer that contribute to the evolution of the permafrost. Physically based heat-

conduction models (such as the Stefan equation) have been applied using collected field

data to estimate seasonal thawing and frost depths (Nixon & McRoberts, 1973; Halliwell

& Rouse, 1987; Nelson & Outcalt, 1987; Anisimov et al., 1997; Gough & Leung, 2002;

Crepeau, 2006; Overduin et al., 2006; Hayashi et al., 2007; Guglielmin et al., 2008;

Hughes & Braithwaite, 2008; Kneisel et al., 2008; Zhang et al., 2008a).

Field sampling and surveys are conducted to monitor the presence of permafrost,

the thickness of the active layer and to determine the soil characteristics. Permafrost

presence can be determined by drilling boreholes into the subsurface until reaching the

permafrost table; this also allows for direct measurements of the active layer thickness.

Confirmation of the presence of permafrost can be accomplished by lowering thermistor

6

probes to measure soil temperatures; permafrost is deemed to be present when

temperature is at 0ºC freezing.

Vegetation and peat cover over the active layer is known to have a significant

influence on both soil thermal conductivity and soil moisture content. The presence of

this top layer allows further protection of the permafrost from climatic extremes

(Seppälä, 1986). Brown (1973), Seppälä (1986), Weidong & Allard (1995), Kujala, et al

(2007), Vallée & Payette (2007), and Kuhry (2008) have linked the influence of peat and

vegetation on enhancing the soil thermal conductivity with moisture content in the

formation of unique geologic mounds on the permafrost, known as palsas. The presences

of palsas were analyzed for the relationships between soil moisture content and the

thermal conductivity that governs the rate of permafrost thawing based on field

measurements (Seppälä, 1986; Kujala et al., 2007; Kuhry, 2008). While complimenting

traditional point-scale borehole samplings on determining permafrost, geophysical

methods can be applied to detect frozen soil, ice structures and sediment layers

(Moorman et al., 2003; Kneisel et al., 2008).

2.2 Surface Vegetation and Active Layer

Zoltai & Witt (1995) determined general trends of pH for bogs, fens and peat

wetlands in Northern Ontario. Fens are wetlands, region of saturated lands, that are

hydrologically influenced by mineral soil deposits (Zoltai & Witt, 1995; Price &

Waddington, 2001). The pH of wet rich fens is above 7.0, basic conditions, while the pH

of moderate-rich fens is acidic between pH 5.5 and 7.0 (Zoltai & Witt, 1995). Poor fens

and bogs are acidic with pH generally less than 5.5 from humic acid generated by

7

decomposition of the dominant Sphagnum species (Zoltai & Witt, 1995). The surface

vegetated layer above the soil column is composed of moss and lichen species, and when

partially decomposed over time in bogs, peat is produced (Dunne & Leopold, 1978;

Gross et al., 1990; Zoltai & Witt, 1995; Price & Waddington, 2001). Results from the

study of soil moisture content in Sphagnum species conducted by Yoshikawa et al.

(2004) suggested that soil thermal conductivity is sensitive to volumetric soil moisture

content. Volumetric soil moisture content is the volume of water per unit volume of soil;

this is also reflected as the in situ field capacity (Yoshikawa et al., 2004). Field capacity

is the amount of water held in soil after gravitational drainage. Thermal conductivity is a

measure of the ability for a medium to transfer heat energy by a gradient (Yoshikawa et

al., 2004). The difference in thermal conductivity of dry and moist moss condition is

about 1.5 folds; this allows moss on top of permafrost, specifically palsa features, to have

a significant impact in the freezing process (Yoshikawa et al., 2004). During the freezing

process, formations of ice lenses contribute to frost heaving (Guglielmin et al., 2008).

The process of frost heaving is favourable in ground material with high soil moisture

content with organic content (Guglielmin et al., 2008). Water conductive porosity,

interconnected pores in soils, contributes to increased soil water content that suggests

organic soils can store greater volumes of soil water (Carey et al., 2007). Typical organic

soils have 40 to 60% active pore space capable to hold water where active pore spaces

have diameters greater than 1x10-5

metres (Carey et al., 2007). Carey et al (2007) noted

that larger porosity does not imply greater hydraulic conductivity and the effects of

interconnected pores can contribute to soil moisture flow. Organic matter possess greater

affinity for water that increase the soil moisture content which in turn enhances the soil

8

thermal conductivity in allowing a greater freezing penetration, i.e. frost depth, and, at the

same time, insulation against climatic changes in the environment (Waelbroeck, 1993;

Zoltai & Witt, 1995).

2.3 Permafrost

2.3.1 Defining Permafrost

Permafrost is defined as ground material that remains below 0ºC for at least two

consecutive years, a definition based solely on temperature (Gough & Leung, 2002;

Smith & Burgess, 2002; Shur & Jorgenson, 2007). Permafrost is found below the active

layer, in the cryotic layer, as the soil in a perennial frozen state (Smith & Burgess, 2002;

Gough & Leung, 2002; Shur & Jorgenson, 2007; Muller, 2008). The surface energy

balance, soil moisture content and organic top layer determines the active layer depth

(Gough & Leung, 2002; Muller, 2008). The active layer depth varies throughout the

season due to the freeze-thaw cycle, as a response to the thermal gradient between the

atmosphere and permafrost (Hinkel et al., 2001; Smith & Burgess, 2002; Muller, 2008).

Climate factors affecting the active layer includes air temperature, annual surface

temperatures, extended periods of warming, thickness of overlying organic layer and the

presence of snow (Pang et al., 2009). Permafrost is classified under the Cryosol and

Gelisol soil orders due to the presence of cryogenic process such as cryoturbation and ice

segregation (Bockheim et al., 2006; Juma 2006).

Shur & Jorgenson (2007) have defined permafrost in a broad sense encompassing

time and climatic variation, where three conditions have been developed: the climate

favourable to permafrost, climate neutral to permafrost, and climate unfavourable to

9

permafrost. Permafrost is always present where climate is favourable to permafrost and is

characterized with the continuous permafrost zonation (Shur & Jorgenson, 2007).

Permafrost is present or absent in the climate neutral condition and is characterized with

the discontinuous permafrost zonation (Shur & Jorgenson, 2007). There is no permafrost

in regions where there is unfavourable climate condition for permafrost (Shur &

Jorgenson, 2007). Relict permafrost distributions can be observed in unfavourable

climate condition where special classification zones can be characterized such as subsea

and mountain permafrost (Natural Resources Canada, 2006).

Permafrost classification by Natural Resources Canada (NRCAN) is generalized

into continuous, extensive discontinuous, sporadic discontinuous, isolated patches and no

permafrost zones based on land surveys, borehole observations and temperature

isotherms (French, 1999; Natural Resources Canada, 2006). Continuous permafrost is

classified in areas dominated by 90 to 100% permafrost presence, and typically

characterized in areas with mean annual temperatures less than –6 ºC (French, 1999;

Natural Resources Canada, 2006). Extensive continuous permafrost is classified in areas

containing 50 to 90% permafrost presence (Natural Resources Canada, 2006). Between

the 10 to 50% permafrost presence range is classified as sporadic discontinuous

permafrost, and typically characterized in areas with mean annual temperatures less than

–1ºC (French, 1999; Natural Resources Canada, 2006). Less than 10% permafrost

presence in an area is classified as isolated patches of permafrost with mean annual

temperatures less than 0 ºC (French, 1999; Natural Resources Canada, 2006). No

permafrost is classified where there is no observed presence of permafrost.

10

In order to calculate and distinguish zones of continuous and discontinuous

permafrost, the Frost number (F) using only climatological data can be employed.

Continuous permafrost was calculated to have a Frost number threshold of greater than

0.67. Discontinuous permafrost would be expected at regions with Frost numbers less

than 0.67 (Nelson & Outcalt, 1987). The Frost number was defined by Nelson & Outcalt

(1987) as a dimensionless ratio of freezing and thawing degree-day sums:

F = [(FDD0.5

) / (FDD0.5

+ TDD0.5

)], (1)

where FDD is the freezing degree-days and TDD is the thawing degree-days, both

in Celsius. Degree-days provide a non-linear relationship between accumulation and

annual mean temperatures used in periglacial proxies for permafrost distribution (Hughes

& Braithwaite, 2008). Freezing degree-days are calculated by summing the degrees of the

number of days below a threshold temperature, such as 0 degrees Celsius. For thawing

degree-days, the similar approach in freezing degree-day calculation is applied with a

threshold of days with temperatures greater than 0 degree Celsius. However, the

definition of the Frost number threshold does not produce consistent results in the

Hudson Bay region, as seen in Gough & Leung (2002), where as the eastern sites of

Hudson Bay follows the Frost Number threshold and the western and southwestern sites

of Hudson Bay do not. The Frost number in the latter instance is below the continuous

permafrost threshold at odds with observations.

2.3.2 Formation and Degradation Processes

Permafrost formation occurs on all exposed surfaces in continuous permafrost

zones that are controlled by climate (Shur & Jorgenson, 2007). This is known as climate-

11

driven permafrost (Shur & Jorgenson, 2007). The climate driven permafrost can be

modified by the ecosystem, this is known as the climate driven, ecosystem-modified

permafrost (Shur & Jorgenson, 2007). This complex formation also relies on energy

balance, soil thermal properties, evapotranspiration, microclimates and incorporating

spatial variation in topography and time (Shur & Jorgenson, 2007). As vegetation

develops and peat accumulates, the depth of the active layer becomes saturated with

water, enhancing the soil moisture content (Hinkel et al., 2001; Shur & Jorgenson, 2007).

Frost is then allowed to penetrate further into the active layer, reducing the depth (Hinkel

et al., 2001; Shur & Jorgenson, 2007). At the same time, the initial active layer base

above the permafrost incorporates to the cryotic layer (Hinkel et al., 2001; Shur &

Jorgenson, 2007). The freezing process from the top of the active layer down to the

permafrost and up from the permafrost table in autumn is referred by Hinkel et al. (2001)

as the “zero curtain regime.”

As Shur & Jorgenson (2007) suggested, permafrost degradation is pronounced in

discontinuous permafrost zones due to climate change and disturbances on the surface.

Shur & Jorgenson (2007) discussed four mechanisms of degradation. First, vertical

degradation can arise due to a lack of protection from the surface ecosystem, an organic

insulating layer, with warmer climate and a positive ground heat flux. The second

mechanism of degradation can occur by the removal of protective insulating vegetation

above the active soil layer to expose the permafrost to a warmer environment (Shur &

Jorgenson, 2007). The third mechanism includes the lateral degradation of permafrost

that can occur from warming and influx of heat from adjacent lakes and groundwater

hydrology (Shur & Jorgenson, 2007). Finally, the degradation-aggradation of permafrost

12

adjustments can occur from shifts to the current environmental condition over the

landscape that results in an overall net change in the ground heat energy balance, such as

changes in snow and organic covers (Hayashi et al., 2007; Shur and Jorgenson, 2007;

Muller 2008).

2.3.3 Soil Moisture Content and Thermal Conductivity

Shur & Jorgenson (2007) suggested that permafrost without a surface organic

layer is the least thermally stable. Results from Karunaratne & Burn (2004) suggested

that the underlying soil thermal properties have greater influence than the influence of the

surface ecosystems. Hinkel et al. (2001) noted that arctic soils, in general, possess a layer

of organic material that has large porosity and high hydraulic conductivity. Soil thermal

properties can be altered by the soil texture and rates of evapotranspiration by plant life

that can influence the soil moisture content (Spielvogel et al., 2004). Evapotranspiration

is the transfer of moisture to the atmosphere by photorespiration of vegetation and

evaporation process that dominates soil moisture content (Dunne and Leopold, 1978). To

calculate thermal conductivity (λ) for the upper peat and organic layers, Hayashi et al.

(2007) suggested applying the de Vries Equation:

λ = (xwλw + kaxaλa + ksxsλs) / (xw+kaxa+ksxs), (2)

where: x is the volume fraction of water (w), air (a) & solid (s),

λ is the thermal conductivity (Wm-1

ºC-1

), & k is a weighing factor of porosity. The de

Vries Equation accounts for the soil moisture content and porosity that heavily influences

the soil thermal conductivity (Zhang et al., 2008a). The de Vries Equation allows the

partitioning of the three interfaces of water, air and solid (Hayashi et al., 2007, Zhang et

13

al., 2008a). Shur & Jorgenson (2007) suggests that with thermal conductivity properties

of the soil, permafrost would be expected in regions of silty and clayey soils, and seldom

in regions with gravely soils.

Conduction of heat energy through the soil column and permafrost can be

enhanced by an increase in water content resulting in a greater loss of heat during the

winter and greater heat retention in the summer (Shur & Jorgenson, 2007). Hinkel et al.

(2001) found that increased air temperatures does not directly increase the thermal heat

flux towards the permafrost through the active layer, but is a surrogate measure of the

overall net energy balance entering the ground. Hinkel et al. (2001) mentioned that

thermal energies, both freezing and thawing, entering the active layer can be dissipated

by near-surface evapotranspiration, as a function of the soil moisture content, initially

protecting the permafrost from thawing or degradation in the early spring and fall seasons

allowing for a time-lag in the freezing and melting process. With warming temperatures,

the increase in runoff and melt water can modify the topography through erosion and

affect the underlying permafrost by increasing the soil moisture content (Thie, 1974;

Cline, 1997; Hinkel et al., 2001; Spielvogel et al., 2004; Martini, 2006; Eyles, 2006;

Wang et al., 2009). Soil moisture content can be enhanced over time by the development

of drainage networks, increase in precipitation rates, decrease in evaporation rates, and

changes in the soil composition (Thie, 1974; Hinkel et al., 2001; Spielvogel et al., 2004;

Martini, 2006; Wang et al., 2009). The soil moisture content is associated with the

underlying soil texture as silty and clayey soils will have a higher water content yielding

higher thermal conductivities, and gravel soils will have lower water content, yielding

lower thermal conductivities (Peck & O‟Neill, 1995; Hinkel et al., 2001; Spielvogel et

14

al., 2004). Shur & Jorgenson (2007) observed that landscape regions of wet organic soils

typically had permafrost and landscape with gravely soils had discontinuous permafrost.

The evaporative cooling effect from high moisture content serves as a buffer against

temperature variation (Hinkel et al., 2001; Spielvogel et al., 2004). Over prolonged

periods of time in moist conditions, insulating peat can develop to provide further

buffering against temperature variation by increasing the thermal resistance, inverse of

the thermal conductivity (Thie, 1974; Hinkel et al., 2001; Cheng et al., 2004; Spielvogel

et al., 2004; Martini, 2006; Zhang et al., 2008b; Pang et al., 2009). Other environmental

factors such as snow cover can increase thermal resistance and insulate against warming

temperatures (Cline, 1997; Cheng et al., 2004; Osterkamp, 2005; Zhang et al., 2008b).

These complex thermal properties between the peat and snow layers can act to protect the

permafrost, keep the permafrost table stable and contribute to permafrost aggradation

(Cheng et al., 2004; Martini, 2006; Zhang et al., 2008b; Pang et al., 2009)

Field soil moisture content and thermal conductivity can be determined using

thermistor probes in soil pits (Halliwell & Rouse, 1987; Overduin et al., 2006; Hayashi et

al., 2007; Shur & Jorgenson, 2007; Nicolsky et al., 2009). For soil moisture content,

another common method is to employ a Time-Domain Reflectometry (TDR) probe at

specific depth intervals of the active layer (Halliwell & Rouse, 1987; Pilon et al., 1989;

Hayashi et al., 2007). Neutron probes and gravimetric soil moisture content methods can

be used to determine reference field values (Pilon et al., 1989; Hinkel et al., 2001;

Hayashi et al., 2007). Thermal conductivity can be determined using needle probes

buried at specific intervals of the active layer and record changes as the active layer

15

thaws (Halliwell & Rouse, 1987; Overduin et al., 2006; Hayashi et al., 2007; Nicolsky et

al., 2009).

2.3.4 Stefan Depth and Permafrost Table

Nixon & McRoberts (1973) derived the Frost depth calculation for estimating the

depth of active layer thawing and freezing with the thermal conductivities and

temperatures. The Frost depth (D) in metres, is represented by the general heat

conduction (flux) equation:

D = [(2nλtTave)/(ρƒL)]0.5

, (3)

where, λ, the thermal conductivity can be represented as λf, frozen thermal conductivity

in the winter season, and λu, the unfrozen thermal conductivity in the summer seasons, n

is the n-factor ratio between ground-surface to air temperature (dimensionless), t is the

elapsed time since thawing (s), Tave is the mean temperature (ºC), ρ is density of ice

(kgm-3

), ƒ is volumetric fraction of ice (dimensionless), and L is the latent heat of fusion

of ice (Jkg-1

; Nixon & McRoberts, 1973; Nelson, 1986; Broadridge & Pincombe, 1995;

Rees, 2006; Hayashi et al., 2007; Hughes & Braithwaite, 2008). This equation is also

known as the Stefan equation (Crepeau, 2006; Hughes & Braithwaite, 2008). A

simplified version of the Stefan Equation using degree-days is given as:

D = (2 λ DD/L)0.5

, (4)

where DD is the Degree-days, for freezing days in the winter, freezing degree-days

(FDD), and for thawing days in the summer, thawing degree-days (TDD).

To represent the summer Stefan thawing layer depth, the equation:

Du = (2 λu TDD/L)0.5

, is applied (5).

16

For Stefan freezing layer depth, the equation:

Df = (2 λf FDD/L)0.5

, is applied (6).

Criteria for a stable permafrost state, based on the Stefan depth calculations, occurs when

depths of freezing (Df) is greater than the experienced depths of thawing (Du) in a soil

column (Nixon & McRoberts, 1973).

2.3.5 „Thermal Offset‟

„Thermal Offset‟ is a phenomenon as arising from the difference in frozen and

unfrozen soil thermal conductivities in units Watts per meter degrees Celsius (Burns &

Smith, 1987). Burns & Smith (1987) characterized „thermal offset” as when a mean

annual temperature difference exists between the upper active layer and the permafrost

layer. Thermal offset is determined by soil thermal conductivity that in turn is associated

with soil moisture (Burns & Smith, 1987). Frozen soils as compared to unfrozen soils

have greater thermal conductivities (Kujala et al., 2007). In winter, frozen soils with high

soil moisture content allow for a deep downward penetration of cold energies that freezes

the soil (Burns & Smith, 1987; Anisimov et al., 1997). In summer, unfrozen soils with

low soil moisture content have reduced warming penetrations energies (Burns & Smith,

1987; Anisimov et al., 1997). For cold energy penetration, mean seasonal winter

temperatures are applied to the Temperature of Seasonal Depth of Thawing/Freezing

(Thermal Offset) equation:

Df = Du + ΔDλ (7),

where ΔDλ in metres is the thermal offset, difference in the thermal properties of the

frozen, winter, Df, and thawed, summer, Du, soils from Equations 5 and 6 (Nixon &

17

McRoberts, 1973; Burns & Smith, 1987; Anisimov et al., 1997). The application of the

thermal offset calculations provides a more robust method for determining permafrost

thickening and degradation over time due to the inclusion of the thermal conductivity

factor in the Stefan equation, Equations 3 to 6 (Anisimov et al., 1997).

2.4 Palsa

2.4.1 Defining Palsa

Palsas are geologic formations on continuous and discontinuous permafrost zones

in the subarctic regions possessing a permafrost core and alternating layers of segregated

ice that form lenses (Seppälä, 1986; Weidong & Allard, 1995; Kujala, et al., 2007).

Palsas have been observed in Canada, Finland, Iceland, Alaska and Siberia (Seppälä,

1986; Weidong & Allard, 1995; Kujala, et al., 2007; Vallée & Payette, 2007; Kuhry,

2008). In Canada, palsas have been documented in Northern Québec, Northern Ontario

and Northern Manitoba (Brown, 1973; Weidong & Allard, 1995; Vallée & Payette,

2007). Palsas appear as thick mounds or circular-domed elevation of terrain (Brown,

1973; Seppälä, 1986; Kujala, et al., 2007; Kuhry, 2008; Figure 1). These mounds can

have a height up to a few metres and diameters from tens to hundreds of metres and are

carbon pools due to the vast amount of organic materials (Brown, 1973; Seppälä, 1986;

Kujala, et al., 2007; Kuhry, 2008). Luoto & Seppälä (2002) classified palsas to be

typically present in flat areas adjacent to water bodies with the presence of organic

materials.

18

Figure 1 – “Baby” Palsa in Northern Ontario, August 2007. Photo by:

William Gough.

The internal core of the palsa is composed of frozen peat, silt and layers of frozen ice

(Seppälä, 1986). It should be mentioned that palsa research is limited to a few selected

authors (Brown, 1973; Seppälä, 1986; Weidong & Allard, 1995; Kujala, et al., 2007;

Vallée & Payette, 2007; Kuhry, 2008).

2.4.2 Physical Properties of Palsas

Palsas are usually found in regions of high acidic peat formation typically a bog

wetland (Brown, 1973; Seppälä, 2003). Kujala et al. (2007) determined physical

properties of the palsa mounds, peat was collected and the pH was determined to be 3.4

and the water content was 79% of the total mass by weight. Studies on palsa formation

and height by Seppälä (1986) suggested that during the summer season, the peat layer is

dryer and has a lower thermal conductivity. During the fall season, peat thermal

19

conductivity increases as freezing and water content increases in the peat (Brown, 1973;

Seppälä, 1986; Kujala, et al., 2007). This increase in peat thermal conductivity allows the

frost and cold to penetrate deeply into the palsa to enhance freezing of the ice lenses

(Kujala, et al., 2007; Kuhry, 2008). The presence of snowfall in the winter season tends

to decrease the thermal conductivity preventing the cold penetration effect (Kuhry, 2008).

Frost heave contributes to the dome-like feature of palsa from the freezing of soil

moisture in establishing the ice lenses (Seppälä, 1986; Henry, 2000; Kujala, et al., 2007;

Guglielmin et al., 2008; Kuhry, 2008). Kuhry (2008) suggest that landforms associated

with permafrost include palsa hummocks, peat plateaus and polygonal peat plateaus.

These landforms contribute to modifying the topography that may further influence soil

moisture by altering the local hydrology, water drainage pathways (Martini, 2006; Kuhry,

2008; Wang et al., 2009). Luoto & Seppälä (2002) suggests a complex spatial and

temporal interaction where palsas should mostly occur in areas that have undergone

periods of warm temperatures that provided significant soil moisture followed by

seasonal freezing. Kujala et al (2007) demonstrated that the thermal conductivity could

be enhanced with high moisture content (65%) for both frozen (1.5 Wkm-1

) and unfrozen

(0.5 Wkm-1

) soils when compared to low moisture content (56%) for frozen (0.6 Wkm-1

)

and unfrozen (0.2 Wkm-1

) soils. Since water has a higher energy transfer rate as solid ice

than in the liquid phase, the overall conductivity is greater at 1.5 Wkm-1

for frozen

compared to 0.5 Wkm-1

for unfrozen soils (Kujala, et al., 2007. The frozen peat layer acts

as an insulating layer during the next summer seasons to prevent thawing or heat

penetration promoting growth (Kujala, et al., 2007).

20

2.4.3 “Palsa Lifting”

Palsa growth in height is referred to as „lifting of the palsa‟ by Seppälä (1986) due

to the buoyancy properties of the ice core on wet peat where water is collected and stored

into the core, thus increasing its volume. The height of a palsa determines the extent in

which thawing can penetrate the mound. As freezing occurs downward, capillary water is

collected beneath the freezing layer, this process contributes to the formation of ice lenses

that segregate frozen peat layers (Brown, 1973; Seppälä, 1986; Kujala, et al., 2007;

Kuhry, 2008). The ice lens formation is also an extension of the permafrost, thus results

in the reduction of the base of the active layer. Experiments in man-made palsas by

Seppälä in 1982 illustrated this effect as frost was able to penetrate 70 cm downward into

the core of the palsas, and after two summers, 15-30 cm of the frost was still detectable in

October 1985 (Seppälä, 1986).

2.4.4 The Palsa Cycle

Seppälä (2003) noted the presence of Lycopodium annutinum, Huperzia selego,

Polytricum mosses and Cladonia lichens on newly developed palsas in the Finnish

Lapland. Depending on the region, palsa formation is observed in poorly drained areas

such as fens and bogs are dominated by Sphagnum species (Zoltai & Witt, 1995; Seppälä,

2003). Peat formation in bogs occurs over time as partial degradation of vegetation, such

as moss, into carbon organic matter (Zoltai & Witt, 1995). Seppälä (1986) suggests that

in order for palsa to begin the formation process, it would need a 50 cm thick insulating

layer of peat to develop first. The top layer cover then acts as an insulating layer and with

21

high moisture content, the thermal conductivity increases allowing deep frost penetration

(Seppälä, 1986).

The edges of the palsas are characterized as sharp steep edges that collect drifting

snow, however, since palsa freezing occurs from above towards the core, the edges

remain warmer and unfrozen (Seppälä, 1986). The collection of drifting snow by wind is

also a driver for palsa formation by acting as an insulating layer (Seppälä, 1986). Thin

layers of snow cover in the winter allow frost and cold to penetrate deeper into the peat

than with thick layers of snow. As the wind carries away the snow layer, the frost

penetration is enhanced, thus increasing the freezing of the peat. The growth of palsas is

not continuous, after a maximum height (about 7m to 12m), usually characterized by

formation of the sharp edges for snow drift collection and a top plateau, the frost layer

can no longer increase in thickness (Seppälä, 1986). In the summer, instead of snowdrift,

blowouts of sand dunes and glaciofluvial deposits of fine sands can become layered in the

palsa (Seppälä, 2003).

Seppälä (2003) acknowledged that blockside erosion due to rise in height allow

the formation of cracks. Enhanced by wind interactions, the edges of the palsas begin to

collapse, which signifies the degradation stages, and pools of water surrounding the palsa

form (Seppälä, 1986; Seppälä, 2003). Intense wind speeds above 50 m s-1

can enhance

erosion and degradation of the palsa (Seppälä, 1986; Seppälä, 2003). Internally, the ice

core may begin to melt causing an internal collapse of the palsa as a pond forms in its

place. The formation of a circular pit in the topography usually signifies a „dead‟ palsa

formation (Seppälä, 1986). However, this formation and degradation process was

suggested to be cyclic as new peat can develop in the ponds and pits created by remnant

22

palsas, and over time, provide the foundation for a new palsa core for development

(Seppälä, 1986). The degradation of a particular palsa may not necessarily be attributed

to climate change as suggested by Seppälä (1986) since the mechanism may be due to

this cyclic process over time.

2.5 Soil Temperatures and Net Radiation

A standard method for determining the presence of permafrost is to measure the

soil temperatures (Pilon et al., 1989; Mühll et al., 2002; Smith & Burgess, 2002; Kneisel

et al., 2008; Nicolsky, 2009). To measure soil temperatures, thermistors are deployed in

the active layer at set intervals (Pilon et al., 1989; Nicolsky, 2009). Thermistors are

defined as semi-conductor probes that measure electrical resistance in relation to

temperature (Pilon et al., 1989; Mühll et al., 2002; Nicolsky, 2009). Thermistors record

continuous time series of temperature data onto data loggers. The data loggers record and

allow the data to be downloaded later. Thermistors connected in series form a thermistor

cable (Pilon et al., 1989).

Surface temperature can be determined by using an infrared thermocouple sensor

or calculated by applying the Stefan-Boltzmann Equation:

εσTs4 = Qlw↑ + (1-ε)Qlw↓, (8)

where ε is the emissivity, σ is the Stefan-Boltzmann Constant (5.67x10-8

Wm-2

K-4

), Ts is

the surface temperature (Kelvin), Qlw↑ is the reflected longwave radiation (Wm-2

), Qlw↓ is

the sky longwave radiation (Wm-2

; Crepeau, 2006). Incoming and outgoing shortwave

and longwave radiations can be measured using a four-component radiometer (Hayashi et

al., 2007).

23

2.6 Ground Heat Flux

Halliwell & Rouse (1987) stated that buried soil heat flux plates are the standard

method in measuring ground heat flux. A soil heat flux plate is composed of a

thermopile, encased in an electrically insulating material that is placed between two

metallic plates (Halliwell & Rouse, 1987; Wen et al., 2008). When buried in the soil

layer, the heat flux passing through the plate results in a temperature difference across the

thermopile that is proportional to the flux density where a voltage output from the

thermopile can be measured and continuously recorded on data loggers (Halliwell &

Rouse, 1987).

Hayashi et al (2007) suggested that ground heat flux (Qg) for the energy balance

of the active layer consists of three components and can be calculated from the

calorimetric method:

Qg = Qi + Qs + Qp, in Watts per square metre (Wm-2

). (9)

Qi is the latent heat used to melt ice in the active layer represented by the

equation: Qi = ρƒLΔz, (10)

where ρ is density of ice (kgm-3

), ƒ is volumetric fraction of ice (unit less), L is the latent

heat of fusion (Jkg-1

), Δz is rate of frost table depth change (m).

Qs is the heat that warms the active layer represented by the equation:

Qs = Σi CidiΔTi, (11)

where „i‟ represents the location of soil thermistor of the thermistor cable, Ci is

volumetric heat capacity (MJm-3

ºC-1

), di is thickness (m), ΔTi is rate of daily

temperature change (ºC).

Finally, Qp is heat conducted into the permafrost layer from the upper active layer.

24

2.7 Geophysical Detection of Permafrost

With warming temperatures in polar regions, concerns of warming-induced

permafrost degradation, northern expansion of infrastructures, and the movement of

contaminants in the once frozen subsurface have driven the need for geophysical methods

to be applied in determining the extent of permafrost (Delaney et al., 2001; Tsuji et al.,

2001; Smith & Burgess, 2002; Sorochan & Tolmachev, 2006; Kalinovich et al., 2008;

Kneisel et al., 2008; Wang et al., 2009). Geophysical methods are applied to investigate

and characterize subsurface conditions over large areas. It should be noted that there is no

set standard geophysical method in determining permafrost (Pilon et al., 1989; Kurfurst,

1992; Hinkel et al., 2001; Nieto & Stewart, 2002; Smith & Burgess, 2002; Mühll et al.,

2002; Moorman et al., 2003; Kneisel et al., 2008). Kneisel et al. (2008) stated that most

geophysical methods for permafrost were derived from application of geophysical

methods from geological survey methods and petroleum exploration techniques since the

1970s. Certain methods have advantages in determining permafrost, such as detecting

boundary transitions, structures and sediment layers, but the same method will have

limitations, such as depth, resolution, misidentification of ice and rock, and the scale of

application. Since drilling borehole operations in permafrost is often expensive, time

consuming and logistically demanding, this is one of the main reasons in employing

geophysical methods (Tsuji et al., 2001; Mühll et al., 2002; Moorman et al., 2003; Saito

& Yoshikawa, 2007; Kneisel et al., 2008; Nicolsky, 2009).

25

2.7.1 Ground Temperature Borehole Logging

A classical method to determining the presence of permafrost is to measure the

ground temperatures (Pilon et al., 1989; Mühll et al., 2002; Smith & Burgess, 2002;

Kneisel et al., 2008; Nicolsky et al., 2009). To measure temperatures, thermistors are

deployed vertically in the subsurface usually in boreholes (Pilon et al., 1989; Kurfurst,

1992; Mühll et al., 2002; Nicolsky et al., 2009). Thermistors are semi-conductor probes

that measure electrical resistance in relation to temperature (Pilon et al., 1989; Mühll et

al., 2002; Nicolsky et al., 2009). Thermistors record continuous time series of

temperature data onto data loggers. The data loggers sort and allow the data to be

downloaded later. Thermistors can be connected in series to a Thermistor cable (Pilon et

al., 1989). Installation of thermistor cables occurs as an opportunistic operation following

excavation and borehole drilling operations (Mühll et al., 2002; Nicolsky et al., 2009).

This approach allows the collection of more data and reduces the expense in separate

borehole drillings (Mühll et al., 2002; Nicolsky et al., 2009). Permafrost is determined to

be present when ground temperatures are below 0ºC (Smith & Burgess, 2002). The

boreholes are typically encased using porous polyvinyl chloride (PVC) pipes where the

thermistor cable can be lowered into the subsurface (Kurfurst, 1992). However, the

protective PVC pipe can act as thermal contaminator and insulator that affects the

temperature measurements, this occurrence is referred to as “leaky cables” (Pilon et al.,

1989).

Borehole logging requires drilling into the subsurface (Saito & Yoshikawa, 2007;

Nicolsky et al., 2009). Three main types of drilling used in determining permafrost

depths are percussion, rotary and auger drillings. Percussion drilling requires the use of

26

heavy equipment and gasoline-powered machinery at the study site, and utilizes a weight

to create an impact force that bores through the subsurface material (Saito & Yoshikawa,

2007). Rotary drills utilize torque and axial forces with various drilling bits to create a

borehole that displace ground material by helical flighting along the axis of rotation of

the drill bit (Saito & Yoshikawa, 2007). Once the borehole is created, probes connected

to loggers by a wire are placed down the boreholes. However, not all boreholes can be

used due to the diameter of the hole, the presence of frozen fluids, and the stability of the

borehole walls (Saito & Yoshikawa, 2007). The presences of frozen fluids act as a barrier

against the probe from being lowered to the depth of the borehole. The stability of

borehole walls can be reinforced by inserting wall casings (Saito & Yoshikawa, 2007).

2.8 Literature Summary

Arctic soils are characterized by an upper organic layer, followed by an active

layer that varies in depth by season and underlain by permafrost that is ground material

frozen for at least two years (Waelbroeck, 1993; Gough & Leung, 2002). The high

moisture content of the peat and organic layer was determined to have a soil moisture

range of 16 to 65% by volume and indicated that the increase of moisture content allows

for greater dielectric conductance (Yoshikawa et al., 2004). Continuous permafrost is

present in climate favourable conditions and in regions dominated by a negative ground

heat energy balance. Gough & Leung (2002) determined inconsistencies with the Frost

number thresholds for characterizing permafrost presence along the western shores of

Hudson Bay and in Northern Ontario and suggested a greater role in the thermal

conductivity properties. Shur & Jorgenson (2007) suggested that freezing penetration

27

downwards into the active layer of the soil is enhanced by increased moisture content that

enhanced the thermal conductivity of energy transfer. Moisture content and insulation

provided by overlying vegetation and organic layers enhance the soil thermal

conductivity properties that allows for greater freezing penetration (Karunaratne and

Burn, 2004; Shur and Jorgenson, 2007; Wang et al., 2009). Removal of the vegetation

and organic layers reduces the insulation effect allowing for various degradation methods

of permafrost to occur (Karunaratne & Burn, 2004; Shur & Jorgenson, 2007; Zhang et

al., 2008b; Pang et al., 2009). Karunaratne & Burn (2004) and Shur & Jorgenson (2007)

suggested that the composition of the soil could determine the presence of permafrost, as

presence would be expected in regions of silty and clayey soils, and seldom in regions

with gravely soils due to the textures ability to retain moisture content. Soil moisture

content heavily influences the soil thermal conductivity that allows the conduction of the

thermal freezing and thawing energies into the soil column (Wang et al., 2009). A

thermal offset phenomenon favourable to permafrost presence occurs when freezing

energies in the winter season exceeds the summer thawing energy penetration, positive

heat flux, in the soil column resulting in a thickened frozen soil layer (Burns & Smith,

1987). Enhanced freezing can occur in highly saturated active layers above the

permafrost, the formation of palsas can result from the development of an ice lens that

cause a volumetric expansion of the soil to produce mounds (Brown, 1973; Seppälä,

1986; Kujala, et al., 2007; Kuhry, 2008). This cyclic process is influenced by vegetation,

atmospheric conditions, and soil thermal conductivity, that can be enhanced by the soil

moisture content, that enables downward freezing penetration into the soil, negative heat

flux (Seppälä, 1986; Kujala, et al., 2007). Hayashi et al (2007) suggested that the heat

28

and mass transfer equation can be coupled to simulate the thawing and freezing depths by

applying the Stefan equation based on the soil thermal conductivity, soil moisture content

and atmospheric forcing.

With northern climates predicted to continue on a warming trend, the increased

likelihood for environmental disturbances, such as permafrost and palsa degradation, are

expected and the changes will affect local wildlife and northern communities (Seppälä,

1986; Vyalov et al., 1993; Anisimov & Nelson, 1996; Sorochan & Tolmachev, 2006;

Kujala et al., 2007; Dyck et al., 2007; Callaghan, 2008; Crompton et al., 2008). Polar

bear (Ursus maritimus) habitats have been identified in Northern Ontario that is

dominated by permafrost and palsas (Callaghan, 2008; Crompton et al., 2008). In spring,

female polar bears display site fidelity behaviour by returning to dens that were

established in the previous year (Crompton et al., 2008). This site fidelity behaviour is

even prominent over feeding needs suggesting that shifts in permafrost may affect the

ecology of the region causing disturbances to the site fidelity behaviour, reducing the

survival fitness of cubs (Crompton et al., 2008; Dyck et al., 2008). Changes in the

ecology from shifts in permafrost may affect local food sources for polar bears affecting

the den locations and survival (Dyck et al., 2008).

Permafrost distribution and active layer monitoring involves high quality

atmospheric, soil, and hydrological data that can be collected using the standard borehole,

soil temperature and atmospheric measurements that can be complimented for larger

spatial scale with modern geophysical tools. Shifts in the permafrost will pose a greater

threat for engineering designs on infrastructures in aboriginal communities infrastructures

and for the industrial pipelines that traverse Canada‟s North. The phase change of water

29

to ice increases the soil strength by the process of cementation, however, the degradation

of permafrost can significantly weaken the strength of soil and reduce the load bearing

that can prove hazardous to human infrastructures and transportation networks (Christ &

Park, 2009). With warming temperatures and seasonal frost heaving processes, the

expansion and melting of the ice in frozen ground can result in both sudden and gradual

changes to infrastructure foundations that can compromise the structural stability and

safety of buildings (Ling & Zhang, 2004; Kim et al., 2008; Larsen et al., 2008; Christ &

Park, 2009; Duan & Naterer, 2009). Understanding and predicting the permafrost state is

important in engineering protocols in order to minimize risks to human safety and for the

environment (Vyalov et al., 1993; Sorochan & Tolmachev, 2006; Dyck et al., 2007;

Callaghan, 2008; Crompton et al., 2008; Kim et al., 2008; Larsen et al., 2008; Christ &

Park, 2009; Duan & Naterer, 2009).

30

CHAPTER 3: Experimental Design and Methodology

Two field-sampling campaigns were completed in mid-August of 2007 and 2008

along the shores of Hudson Bay and inland Northern Ontario. Gough and personnel from

the Ontario Ministry of Natural Resources conducted sampling and fieldwork. The study

area is located between 54º28.909 north to 56º47.759 north and from 83º36.585 west to

89º30.534 west from the shores of Hudson Bay to within 100 kilometres inland of

Northern Ontario (Figure 2).

Figure 2 – Location of settlements, weather stations and rivers in Northern Ontario. Map

produced with Manifold V.7 GIS software with UTM projection 16

31

3.1 Location and Study Site Descriptions

The communities of Peawanuck, Ontario, and Fort Severn 89, Ontario, are located

within the study area. The Indian Settlement of Peawanuck (55°00.500 N, 85°25.333 W)

is located in the Kenora District; governed by the Weenusk First Nation Band,

provincially by the Government of Ontario, and federally by the Government of Canada

(Figure 2). According to the 2001 Census conducted by Statistics Canada, the permanent

population count for Peawanuck is 193 (Statistics Canada, 2007). An updated count by

the Weenusk First Nation in 2007 showed a population of 300 (Weenusk First Nation,

2007a). The Peawanuck community is bilingual in Cree and English. Peawanuck is

bordered by Polar Bear Provincial Park and located near the Winisk River.

The First Nation Reserve of Fort Severn 89 (56°00.000 N, 87°21.000 W) is

located near the Severn River. Fort Severn is governed by the Cree First Nation,

provincially by the Government of Ontario, and federally by the Government of Canada

(Figure 2). The permanent population for Fort Severn is 639 as reported by the Indian and

Northern Affairs Canada registration (Indian and Northern Affairs Canada, 2008). Both

Fort Severn and Peawanuck are accessible by boat in the summer season and by air

service all year round. Ice roads connect the two First Nation communities during the

winter season.

It should be referenced that the ghost town of Winisk (55°15.402 N, 85°12.396

W), referred as Weenusk in Cree, Ontario, was the original Indian Settlement location

before the establishment of Peawanuck, Ontario (Figure 2). Winisk is located along the

Winisk River. The Winisk Flood of 1986 destroyed the settlement and resulted in the

relocation and establishment of Peawanuck, Ontario, about 35 kilometres to the south.

32

Winisk is a historical military radar site. The Royal Canadian Air Force (RCAF) Station

Winisk and airfield were established in the late 1950‟s as part of the Mid-Canada Line to

provide early warning radar detection against intercontinental ballistic missiles (Tsuji et

al., 2001). The Department of National Defence, in the mid-1960s, decommissioned the

station; however, there remain environmental concerns at this site (Tsuji et al., 2001).

3.1.1 Biogeography

The terrestrial ecozone for Fort Severn and Peawanuck, Ontario, is classified as

the Hudson Plains, located north of the Boreal Plains, in between the Taiga Shield, and

south of the Southern Arctic ecozone (Figure 3; Natural Resources Canada, 2007).

Figure 3 – Terrestrial Ecozones for the Hudson Bay Lowlands by Natural Resources

Canada (Natural Resources Canada, 2007)

33

Fort Severn and Peawanuck are dominated by subarctic vegetation that includes open

trees, shrubs, and wildflowers; this region is located in the Transitional Forest ecozone

and north of the Boreal Coniferous ecozone (Figure 4; Natural Resources Canada, 2003).

Figure 4 – Forested Ecozones for the Hudson Bay Lowlands by Natural Resources Canada

(Natural Resources Canada, 2003)

Peawanuck is located in the Hudson Bay Lowlands along the Winisk River,

where swamps, bogs and muskeg areas are found in adjacent wet areas (Figure 2). Fort

Severn is located to the west of Peawanuck near the mouth of the Severn River (Figure

2). The wildlife in the Fort Severn and Peawanuck regions are briefly listed as: Beaver,

Black Bear, Polar Bear, Caribou, Ermine, Arctic Fox, Red Fox, Snowshoe Hares, Lynx,

Moose, Otter, Mink, Muskrats, Snowy Owl, Crow and Wolf. Water Fowl included:

34

Canada Geese, Snow Geese, Swans, Sand Hill Crane, Loons and Ducks. Along the

Hudson Bay shores, it is typical to see: Walrus, Beluga Whales, and Seal (Weenusk First

Nation, 2007b). During the 2008 summer sampling campaign, the following were

observed in the study area: Caribou, Polar Bear, Eagle, Snow Geese, Loons, Whale, and

Sand Hill Crane.

3.1.2 Climate Data and Weather Stations

Weather stations located in the study area within the Hudson Bay watershed as

listed in use by Environment Canada Weather Office: Fort Severn (A) and Peawanuck

(AUT; Environment Canada, 2009a; Environment Canada, 2009b). Weather station

descriptions are shown in Table 1 and Figure 2.

Table 1 – Methodology: Environment Canada Weather Station Information with Climate, World

Meteorological Organization (WMO) and Transport Canada (TC) ID codes. (Environment Canada,

2009a; Environment Canada, 2009b)

Location Latitude Longitude Climate ID WMO ID TC ID

Fort Severn (A) 56°1.200' N 87°40.800' W 6012500 71099 YER

Peawanuck

(AUT)

54°58.800' N 85°25.800' W 6016295 71434 WWN

Average snow depths in centimetres, mean annual precipitation in millimetres,

soil and air temperatures in degrees Celsius, and permafrost zones were collected from

Environment Canada Weather Office stations in Peawanuck and Fort Severn, Ontario,

and from the Atlas of Canada of the Natural Resources of Canada, respectively

(Environment Canada, 2009a; Environment Canada, 2009b; Natural Resources Canada,

2006). Weather stations were installed in the 2008 summer campaign at the 2007

sampling-site of G5a/8E3 (Shagamu) (55°41.102 N, 86°51.325 W) and near 8A1 Burnt

Point (55°14.507 N, 84°19.032 W) by the Ontario Ministry of Natural Resources to

35

provide snow depth, air and soil temperature data and wind speed. This site is situated

between Fort Severn and Peawanuck, Ontario (Figure 2).

3.2 Field Experimental Design

3.2.1 Soil Temperatures and Thermistor Probes

Soil temperatures were determined using thermistor probes that were lowered into

a borehole created by the hand auger. The depths to the permafrost were measured by

using a graded rod. Permafrost presence was determined when soil temperature was at

freezing, 0ºC; the temperatures were recorded in the field notes.

3.2.2 Point-scale Geophysical Sampling

A total of 53 soil samples were collected in the two-year sampling campaign; 20

and 33 soil samples retrieved in August of 2007 and 2008, respectively (Figure 5). Within

the study area, observations were made at over 500 sites.

36

Figure 5 – Sampling Sites located in Northern Ontario Hudson Bay divided by Three Quadrants

from both 2007 and 2008 Soil Sampling Campaigns. Map produced with Manifold V.7 GIS

software with UTM projection 16

A hand auger was used to produce a borehole where soil samples from the surface, 30

and 120-centimeter depths were extracted and collected in plastic containers and double

plastic Ziploc bags (Table 2). Upon reaching the permafrost, the solid state of ground

prevented further auguring deeper into the subsurface, which can be confirmed by

lowering and striking a graded rod in the borehole. The soil samples were transported

back to the University of Toronto Scarborough campus. Helicopter support was used for

transportation to the sampling locations. The depths to the permafrost were determined

by lowering the graded rod into augured boreholes for measurements in centimetres.

Using Figure 2, the study area was divided into three quadrants (Figure 5).

Quadrant 1 included all the sampling sites in 2007 and 2008 that were located between

37

the provincial boundary line of Ontario and Manitoba and the western portion of the

Severn River (Figure 5; Tables 9 and 10). Quadrant 2 was divided to include all the

sampling sites in 2007 and 2008 that were located between the eastern portion of the

Severn River and the western portion of the Winisk Rivers (Figure 5; Tables 9 and 10).

Quadrant 3 included all the sampling sites in 2007 and 2008 that were located between

the eastern portion of the Winisk River and to the shores of James Bay (Figure 5; Tables

9 and 10). Figure 6 was produced to show the 2007 sampling campaign.

Figure 6 – Sampling Sites located in Northern Ontario - Hudson Bay for 2007 divided by Three

Quadrants. Map produced with Manifold V.7 GIS software with UTM projection 16

Figure 7 was produced to show the 2008 sampling campaign.

38

Figure 7 – Sampling Sites located in Northern Ontario - Hudson Bay for 2008 by Three

Quadrants. Map produced with Manifold V.7 GIS software with UTM projection 16

3.2.3 Sample Labelling and Identification

Each soil-sampling site from the study site was geo-referenced using a hand-held

global positioning satellite (GPS) system. Soil samples retrieved from the 2007 sampling

campaign were labelled with a unique identification key that corresponded with the

recorded field data in the field notes. For example, Sample “B1” represented a sample

from site „B‟ made on the „first‟ day of the campaign. This was conducted for all 20

samples in 2007. For the 2008 soil sampling campaign, the samples were labelled with a

second identification key that corresponded to the field notes. For example, Sample

“8A1”, „8‟ represents the „month of August‟ for sampling at site „A‟ on the „first‟ day.

This was conducted for all 33 samples in 2008 (Figure 8). The labelled soil samples, site

39

coordinates, temperature data, and the depths to permafrost measurements were recorded

in the field notes. Additional field data were recorded in picture documentation.

3.2.4 Field Soil Characterization

The soil properties in the field were characterized based on visual and physical

observations of colour, texture, and soil moisture that were recorded in the field notes.

The presence of organic areas, such as peat layers, bogs, fens, and the lack of organics

were noted in the field notes. Additional field data were recorded in picture

documentation. Soil samples were collected at the point-scale resolution into containers

and labelled appropriately before being transported to the University of Toronto

Scarborough campus for further in-depth analysis.

3.3 Laboratory Analytical Methodology

The soil samples retrieved from the 2007 sampling campaign were analyzed on October

4th

of 2007. The samples from the 2008 soil-sampling campaign were analyzed on

October 27th

of 2008. Both laboratory analyses were conducted at the University of

Toronto Scarborough campus. Laboratory methodology for soil moisture and acidity

analyses was adapted from the GLOBE (2005) protocol soil techniques.

3.3.1 List of Materials

The materials required for the soil sampling campaign and laboratory analysis in

2007 and 2008 are listed in Table 2.

40

Table 2 – Methodology List of Required Materials for Laboratory Analyses: 2007 & 2008 Sampling

Campaigns.

2007 Campaign 2008 Campaign

20 soil samples containers

20 200 ml Erlenmeyer beakers,

20 tin foil baking trays,

2 glass stir rods,

2 metal tablespoons,

2 Litres distilled water,

1 graduated 100mL cylinder

1 TDS pH meter,

1 25mL pH 7 buffer solution,

Baking oven, mass balance, and

paper towels.

80 Ziploc Bags

33 200 ml Erlenmeyer beakers,

33 tin foil trays,

2 glass stir rods,

2 metal tablespoons,

5 Litres distilled water,

1 graduated 100 mL cylinder

1 Symphony SB70P pH meter,

1 25 mL pH 7 buffer solution,

1 25 mL pH 10 buffer solution,

Baking oven, mass balance (Denver

Instrument MXX-2001), and paper towels

3.3.2 Laboratory Soil Characterization

In depth soil characterization of the retrieved soil samples were conducted at the

University of Toronto Scarborough campus soil laboratory. The labelled samples were

transferred from the sample containers into corresponding labelled tinfoil trays (Figure

8).

Figure 8 – Labeled sample bag with associated tin foil tray container: Sample

8A1a with sandy & rocky materials. Picture was taken on 4 OCT 08 by A. Tam

41

By using a glass stir rod, the sample could be dispersed (Figure 9).

Figure 9 – Analysis of soil sample D5a: Presence of fungus and partially

decomposing organic material. Picture was taken on 4 OCT 07 by A. Tam.

Observations were noted based on colour, texture, moisture content, the presence of

partially decomposed vegetation, presence of rocks and pebbles, aggregation, and any

unique characteristics such as fungus and moulds (Figure 9).

3.3.3 Gravimetric Soil Moisture Content

The gravimetric soil moisture content, θm, in percentage was determined using

the outlined principles and procedures outlined by Juma (2006), supported by the

GLOBE (2005) protocol. The mass of the tin trays, Tm, plastic sample container, Cm, and

bag, Bm, were determined and recorded using an electronic mass balance in units of

grams, g. The tinfoil trays containing the soil samples were placed onto a mass balance to

determine the Initial Total Mass, ITm. The initial total mass of the soil samples included

42

both the masses of the plastic sample container, Cm, and bag, Bm. To determine the soil

moisture mass, Wm, the mass of the plastic container and bag were subtracted from the

initial total mass (Equations 12 & 12a). In 2007 laboratory analysis, the Wm was

determined using the following equation:

(ITm) - [(Cm) + (Bm)] = (Wm). (12)

For the 2008 laboratory analysis, Equation 15 was modified to determine the Wm:

(ITm) - [(Bm)] = (Wm) (12a)

The tinfoil trays were then placed into the baking oven at the University of Toronto at

Scarborough Soil Lab at 105˚C for 24 hours (1 day) before being removed from the oven

(Figure 20), the tinfoil trays and soil samples were cooled down to ambient room

temperature (22°C) for 15 minutes, and the Final total mass, FTm, was recorded by the

mass balance.

To determine the mass of the oven-dried soil, ODSm, the final mass of the sample and

tray after drying, FTm, was subtracted by the mass of the tin tray, Tm:

(FTm) - (Tm) = (ODSm) (13)

To determine the soil moisture (Ws), the mass of the oven-dried soil was subtracted from

the soil moisture mass:

[(Wm) - (ODSm)] = (Ws) (14)

To determine the water content in percentage, θm, Ws was divided by Wm then multiplied

by 100:

(θm in %) = [(Ws) / (Wm)] * 100 (15)

This was repeated for all samples. The dried oven soil was collected back into the

containers for storage.

43

3.3.4 Soil Acidity, Average pH Value

To calibrate the pH probe, the probe tip was washed with distilled water and

immersed in a pH7 buffer solution for calibration as directed by the manufacturer‟s

specifications in calibration. To determine the acidity of the soil sample, 50 grams of

oven dried soil was measured and placed in a 200 ml Erlenmeyer beaker and 100 ml of

distilled water was added. The solution was manually stirred with a glass-stirring rod for

5 minutes before being left to settle for 15 minutes. After 15 minutes, the pH probe was

lowered into the solution for two minutes, and the pH value was recorded. Three trials

were conducted per each soil sample. The pH values were converted to the concentration

of Hydrogen, [H+]:

pH = -log[H+] , [H+] = [1/(10^pH)]. (16)

The arithmetic average of the concentration of Hydrogen of each 3 trials (Trial1,

Trial2, Trial3) per sample was calculated and recorded:

{[([H+] Trial1) + … + ([H+] Trial3)] / 3} = (mean [H+]). (17)

Finally, using Equation 16, the mean concentration of Hydrogen was converted back to

the mean pH value. This was repeated for all samples. The solutions were safely disposed

in the soil laboratory waste bins.

3.3.5 Soil Moisture Content Loss Test

A control test for water content loss by evaporation of the soil samples in the

plastic bag containment was conducted for 35 days (5 weeks) from March 4th

to April 8th

,

2008 using 9 control samples where plastic bags were filled with water and placed at

various locations around the University of Toronto Scarborough campus.

44

A mass water balance approach was applied for the soil moisture content control

test. The mass of the plastic containment bag, Mbag, was determined using an electronic

mass balance. Using a graduated 100 mL cylinder, 50 mL of ordinary water from the

laboratory was poured and sealed in the plastic bags then placed on the mass balance to

determine the total mass, Mbw. The mass of water, Mw, in grams was determined by the

equation:

[(Mbw) – (Mbag)] = (Mw). (18)

To convert Mw, in grams, to a volume in millilitres, Vw, the density of water at

23ºCelsius (0.9975 g/mL) can be used:

[(Mw) (g) / (0.9975 g/mL)] = (Vw). (19)

This process was repeated nine times for 9 control samples. The 9 control samples were

labelled with a unique identification key that corresponded with the laboratory notes. For

example, Sample “T1”, „T‟ represents the “Test” sample designation while „1‟ refers to

„Location #1‟. Initial leak test of the test samples were conducted and recorded to

determine if the containment was compromised. Three test samples had one-level of

containment, a seal single layer plastic bag with 50 mL of water. The next three test

samples had a two-level containment, a sealed single plastic bag with 50 mL of water

within a sealed outer plastic bag. The last three test samples were given three-level

containment, a sealed single plastic bag with 50 mL of water within a sealed inner plastic

bag sealed in an outer plastic bag. One test sample of each level of containment was

placed around the University of Toronto Scarborough campus for 5 weeks. Test samples

T1, T4 and T5 were placed in the University of Toronto Scarborough campus soil

laboratory, Science Wing Room 313, to simulate water loss over the given period. Test

45

samples T2, T6 and T9 were placed in Science Wing Room 653, to simulate water loss

over the given period in a faculty office setting. Test samples T3, T7 and T8 were placed

in University of Toronto Scarborough Foley Hall Residence, to simulate water loss over

the given period in a storage setting. After the 5 weeks, the mass of the test samples,

M5wks, were determined using the electronic mass balance.

The change in mass water, ΔMw, difference could be calculated from:

[(M5wks)-(Mbw)] = (ΔMw), (20)

To convert the change in mass water, in grams, to a volume loss, Vloss, in millilitres, the

density of water at 23ºCelsius (0.9975 g/mL) can be used:

[(ΔMw) (g)/ (0.9975 g/mL)] = (Vloss). (21)

To finally determine the percentage of water lost, WL%, after five weeks, the following

can be applied:

[(Vloss)/(Vw)]*100 = (WL%). (22)

3.4 Stefan Depths and Permafrost Table Calculations

The Stefan depths were determined using Equation 3. The depth to permafrost, d,

were extracted from field notes and data provided by Gough. Average depths to

permafrost were calculated using the collected field data on permafrost depth with an

arithmetic average approach. When the calculated seasonal Stefan depth of freezing

exceeds the seasonal Stefan depth of thawing (Du < Df), the resulting positive thermal

offset represents the theoretical thickness of a frozen layer of soil that has persisted over

the summer thawing season, and has survived into the next freezing cycle (Burns &

46

Smith, 1987; Duan & Naterer, 2009). When the thermal offset conditions of Df < Du,

there is a loss of frozen ground at the frost table (Burns & Smith, 1987).

3.5 Thawing and Freezing Degree-Days Calculations

Thawing and freezing degree-days (TDD, FDD, respectively) were calculated

using temperature data collected from the weather station in Peawanuck, Ontario. The

temperature data prior to 1986 were collected from the Winisk, Ontario weather station.

Following the destruction of Winisk and the relocation of the community to Peawanuck

in 1986, all temperature data after 1986 were obtained from the present day weather

station Peawanuck (AUT). In calculating thawing degree-days, the cumulative number of

days above 0ºC was counted for a single year record. For the freezing degree-days, the

cumulative count of the number of days below 0ºC was counted for a single year interval.

For a one-year interval, this calculation requires 12 months of temperature data. Twelve

month was chosen from the beginning of July from the previous year to the end of June

of the next year. A thawing degree-day calculation example for the year of 1992 would

be to count the number of days above 0ºC starting from July 1st of 1991 ending on June

30th

of 1992 and then determine the sum of the number of count of days above 0ºC. This

was repeated for calculating freezing degree-days.

47

3.6 Geographical Information Systems

Geographical Information Systems (GIS) was used to produce a geographical map

of the sampling area based on degree-decimal location coordinates. The location

coordinated were geo-reference using hand held Global Positioning Satellite (GPS)

device conducted by personnel from the Ontario Ministry of Natural Resources. A map of

the Hudson Bay region was also produced in GIS Manifold System software version 8

and drawings from ESRI Data and Maps Volume One. The Universal Transverse

Mercator (UTM) coordinate system was applied as the map projection. UTM zones 16

and 17 were utilized for the GIS map projection. GIS was used to extract distances from

the sample sites to the nearest shore of Hudson Bay using the query function and the

software reported distances in units of metres.

48

CHAPTER 4: Results

4.1 Climate and Environmental Data

Both climate and environmental data were collected for the Fort Severn and

Peawanuck, Ontario, sites. The mean annual precipitation for the Hudson Bay lowlands

was determined to range from 401 to 600 millimeters (Natural Resources Canada, 2006).

The mean maximum snow depth in the Hudson Bay lowlands was determined to range

from 30-49 centimetres (Natural Resources Canada, 2006). The subsurface stratigraphy

of Fort Severn and Peawanuck is continuous permafrost (Figure 10; Natural Resources

Canada, 2006).

Figure 10 – Subsurface stratigraphy classification of Northern Ontario and Hudson

Bay by Natural Resources Canada (Natural Resources Canada, 2006)

49

A summary of the minimum and maximum winter (January) and summer (July) daily

temperatures for Fort Severn and Peawanuck are shown in Table 3.

Table 3 – Results: Elevation and Annual Temperature Ranges in Northern Ontario communities

from Environment Canada. (Environment Canada, 2009a; Environment Canada, 2009b).

Location Relief

Elevation

(metre)

Minimum

Daily

January

Temperature

– Winter

(ºC)

Maximum

January

Daily

Temperature

– Winter (ºC)

Minimum

Daily July

Temperature

– Summer

(ºC)

Maximum

Daily July

Temperat

ure –

Summer

(ºC)

Fort Severn 15.80 m -34 to -30 -24 to -20 6 to 10 16 to 20

Peawanuck 52.70 m -29 to -25 -24 to -20 6 to 10 16 to 20

4.2 Soil Characterization (2007-2008)

Using GIS software and GPS coordinates for the sample sites recorded in the field

notes, Figures 5 to 7 were produced to include sample site locations from the shore of

Hudson Bay to approximately 100 kilometers inland.

Soil characteristics of the retrieved soil samples and over 500 site observations

revealed soils of the Cryosols and Histosols orders which typically have permafrost

presence within the first two-metres in depth (Juma, 2006). Site descriptions from the

field notes revealed extensive peat formations and organic matter content in the poorly

drained soils. Further laboratory analyses of the soil samples are shown in Table 6.

Distances from the sampled sites to the nearest shore of Hudson Bay were extracted to

Tables 4 and 5. The results of soil characterizations from August 2007 and 2008 are

shown in Tables 4 and 5, respectively. There were 20 sites and soil characterizations for

2007 and 33 for 2008 totaling 53 characterizations during the two-year sampling

campaign (Tables 4 and 5).

50

Table 4 – Results: Site & Soil Characterizations from 2007 Soil Sampling Campaign with Distances

from the Shores of Hudson Bay to the Sample Sites.

Sample

ID Latitude Longitude

Distance to

Hudson Bay

(m) Site & Soil Characteristics

B1 55°15.405 -85°12.394 10000

Site was heavily vegetated. Soil sample was

aggregated with the presence of organic

matter (woody stems, roots and moss).

Sample appeared light brown/gray colour

and a gritty clay texture. No detectable

odour.

B2 55°20.032 -85°27.129 9341

Situated in grassy vegetation. Some

aggregation present in soil sample. Presence

of organic matter (fine roots). Sample

appeared light brown in colour, clayey

texture with moderate moisture. Gravel was

present at 100 cm depth. No detectable

odour.

B3 55°20.032 -85°25.673 8134

Soil sample was not well aggregated.

Presence of organic matter (fine roots) with

high moisture content. Soil appeared dark-

brown colour. Presence of gravel. Strong

musky odour.

B4 55°11.745 -85°39.212 29136

Sample site located on a palsa. Hummocky

Tundra terrain with the presence of a "baby

palsa." Presence of organic matter (partial

decaying grasses and fibrous roots). Soil

sample was well aggregated and dry. No

detectable odour.

B5 55°02.865 -85°51.121 49826

Presence of organic matter (twigs). Mostly

decomposing plant organic material. Soil

appeared dark and very moist. No

detectable odour. Soil contained presence of

three miniscule worm-like organisms.

B6 54°56.772 -86°06.884 69600

Site was situated on a palsa adjacent to a

pond. Other ponds were observed in the

area. Sample was well aggregated with high

organic matter content. Soil sample had

presence of organic matter (fine roots). No

detectable odour.

51

C2c 55°04.860 -84°15.321 21258

Site was located in a vegetated fen near a

palsa (15-20 metres wide). A dried mudflat

south of the palsa was observed adjacent to

the sampling site. An area with trees is

located 20 metres to the north of the palsa.

Presence of organic matter (decomposing

leaves, stems, and pod husks). Husks

appeared white internally and dark brown

externally. Soil colour appeared dark brown

with organic matter and very moist

conditions. Presence of fine sediments. No

detectable odour.

C3 54°54.146 -84°10.322 41836

Sample site was located on a steep terrain

adjacent to a palsa and ponds with adjacent

trees. Soil colour appeared light brown.

Presence of organic matter (peat, fungus,

molds, and roots). The soil sample was dry.

No detectable odour.

C8 55°16.289 -83°50.593 500

Sample site was located on the coast of

Hudson Bay in a fen at the north aspect of a

coastal ridge. Willows were observed at the

site. There was presence of organic matter

(moss and fibrous roots with a spongy

texture). Sample appeared dark brown in

colour and dry. Presence of fine particulate

matter with weathered and rounded pebbles

that appeared white & black. Gravel was

observed at a depth of 10 cm. No detectable

odour.

D1 54°56.873 -83°46.804 31719

Sample site was located at the centre of a

palsa plateau. Adjacent area to the east was

relatively treeless. Palsa fens are located to

the south, west and north of the sample site.

Palsa centre was 90 cm in height. A new

palsa formation was observed (3 m wide by

20 m long) and dark in appearance to the

north. Presence of organic matter (dense

fibrous roots, decaying leaves, fungus, moss

and mold). Sample had a clayey texture. No

detectable odour

52

D2 55°06.382 -83°48.716 15233

Sample site was located at the centre of a

palsa surrounded by a moat. Standing water

was present to the east, west and northern

edges. Soil samples showed presence of

organic matter (woody stems, roots, leaf

litter, and dark-brown coloured peat).

Moderate moisture content. No detectable

odour.

D4l 55°00.503 -83°12.043 21606

Sample site was located 3 m into a fen. Soil

sample showed presence of organic matter

(fibrous roots, decaying plant matter, leaf

litter, and fungus with a spongy texture).

The sample was moist. No detectable odour.

D5a 54°50.442 -83°03.364 31420

Sample site was located on a coastal plain

with the presence of trees. Samples were

retrieved from a central palsa. Presence of

organic matter (white moss, fungi, partial

decaying grass, twigs, woody stems, and

roots). The sample appeared light brown in

colour. There was presence of weathered

and rounded pebbles. No detectable odour.

E1 56°21.871 -89°30.534 64315

Sample site was located at the centre of a

palsa. Standing water was observed to the

northern edge of the palsa. A 1-metre

depression with standing water in the palsa

was speculated as a thaw slump. Presence

of organic matter (long fibrous roots, plant

stems, peat and decomposing organic

matter). No detectable odour.

E2 56°30.401 -89°18.550 44307

Sample site was located 25 m in a fen and

on a 0.5 m tall palsa. Presence of organic

matter (decaying bark and twigs). Soil

sample appeared to have a sandy and grainy

texture that had a light reddish-orange

colour. No detectable odour.

E2a 56°30.401 -89°18.550 44307

Sample site was located 1 m from the

southern edge of a fen. Presence of organic

matter (roots, grasses, decaying bark, leaves

and twigs). Soil sample appeared light

brown in colour. No detectable odour.

53

E6 56°26.585 -88°36.857 21074

Sample site was located in hummocky

lichen woodland with a large palsa plateau.

Forested area was well developed. Presence

of soil organic matter (roots, stems, and

peat). Presence of weathered and rounded

black pebbles. The soil appeared light

brownish-yellow colour with an orange

horizon. The soil had a sandy texture. No

detectable odour.

E10 56°22.395 -87°54.609 500

Sample site was located in a dried fen with

gravel edges. Samples were taken 2.5, 5 and

10 metres into the fen. Soil samples showed

presence of organic matter (dense root

networks with a spongy characteristic,

grasses, leaves, and woody stems). Soil had

an overall dark-brown colour. Sample had a

presence of fine sediments. Clayey soil was

observed in the sample site. Strong foul

odour was present.

F8 55°13.126 -84°41.726 2046

Sample site was located 2 km from the

Hudson Bay coast on a beach ridge.

Presence of organic matter (decaying thick

root systems). Sample contained rocks and

pebbles. Soil colour appeared to have a

mixture of dark & light shades of brown.

Sample was dry and had a sandy texture.

No detectable odour.

G5a 55°41.102 -86°51.325 21289

The sample site was in a fen field at the

centre of an emerging palsa. Soil sample

contained presence of organic matter (dense

roots, white mold, decaying twigs and

grasses). Soil was primarily organic matter.

No detectable odour.

Table 5 – Results: Site & Soil Characterizations from 2008 Soil Sampling Campaign with Distances

from the Shores of Hudson Bay to the Sample Sites.

Sample

ID Latitude Longitude Location

Distance to

Coast (m) Soil & Site Characteristics

8A1 55°14.507 -84°19.002 Coastal 2842

Sampling at Burnt Point near a

fence post in a fen. Presence of

sand with round weathered

gravel. Gravel had white and

black colours. No organic matter

content was observed. Sandy and

silty soil texture. No detectable

54

odour. Whales were observed in

Hudson Bay from this location.

8A2 55°36.618 -85°48.648 Coastal 367

Sample site was located to the

north of a grass area on a beach

ridge near a fen along the coast.

Site had high moisture content.

Sandy and clayey soils were

observed with weathered pebbles.

No organic matter content was

observed. No detectable odour.

8A3 55°27.630 -85°58.379 Inland 19329

Sample site was dominated by a

hummocky palsa with an

emerging palsa to the west. Peat

and moss were observed at the

site. No detectable odour.

8B1 55°28.982 -85°59.529 Inland 18421

Sample site was located on a

beach ridge. High soil moisture

content. Gravelly soil texture.

Rounded and weathered gravel

stones with black and white

colours. No organic matter

content was observed. No

detectable odour. A polar bear

was observed.

8B2 55°52.162 -86°47.037 Coastal 90

Sample site was located on a

beach ridge near the coast. Site

had high moisture content. Sandy

soil was observed in the upper 10

cm with weathered pebbles.

Gravelly soil was observed at a

depth of 2 m. No organic matter

content was observed. No

detectable odour.

8B3 55°55.436 -87°11.034 Coastal 940

Sample site was located on a

beach ridge near the coast and a

fen. Sandy and clayey soil

textures were noted. Site had high

moisture content. No organic

matter content was observed. No

detectable odour.

55

8B4 56°22.281 -87°54.601 Coastal 500

Adjacent to 2007 site “E10”.

Sample site was located on a

beach ridge and near a fen. A few

trees were noted in the area. Soil

from the beach ridge was sandy

and gravelly with weathered

pebbles. Soil from the beach ridge

had high soil moisture content.

Soil from the fen was dominantly

clayey. Whales and a mink were

observed in the area. No

detectable odour.

8C1 55°16.296 -83°50.592 Coastal 655

Adjacent to 2007 site “C8”.

Sample site was located on a

beach ridge near the south of a

fen. High soil moisture content.

Soil in the beach ridge had a

gravelly soil texture. Soil in the

fen was dominantly clayey. No

detectable odour.

8C2 55°11.730 -83°17.420 Coastal 1468

The site had shrub vegetation

without any tall trees and located

on a beach ridge. Site had high

moisture content with ponds and

large puddles. Clay soil was

detected under an upper peat

layer. Below the clay soil, sandy

soil was observed. No detectable

odour. A Greater Yellow Leg was

observed in the area.

8C3 55°12.499 -82°57.808 Coastal 1339

Sample site was located on a

beach ridge dominated with

grasses and shrubs. No trees were

in the area. Surface soils had a

gravelly and sandy texture with

black and white pebbles. Site had

high soil moisture content. No

detectable odour.

8C4 55°02.715 -82°51.658 Coastal 8765

Site was located on a beach ridge

dominated by gravelly and sandy

soils. No presence of organic

matter. Site had high soil

moisture content. No odour

detected.

8C5 54°48.174 -82°12.008 Coastal 85

Site was located at the shores of

James Bay on sandy dunes and

56

beach known as Hook Point. Site

was moderately vegetated

dominated in sandy soils. Site had

high soil moisture content. No

detectable odour.

8D1 55°43.908 -86°29.256 Coastal 6388

Site was located on a beach ridge

near a palsa and fen. The surface

was dominated in peat.

Weathered and rounded gravel

were observed at the surface. Soil

below the gravel was clayey. Site

had high soil moisture content.

No detectable odour. An eagle

nest was observed in the area.

8D2 56°25.104 -88°09.957 Coastal 7631

Site was located on a beach ridge

near a fen. Trees were observed in

the fen. Surface soil was

dominantly sandy and clayey.

Wet gravel was observed at

greater depths.

8D3 56°35.560 -88°25.510 Coastal 560

Sample site was located on a

beach ridge near a fen. Clayey

and sandy soils were observed

near the fen with pebbles. No

detectable odour.

8D4 56°47.266 -88°57.621 Coastal 5680

Site was located on a beach ridge

dominated by sandy and clayey

soils. Site had high soil moisture

content. No detectable odour.

8D5 56°26.550 -88°36.048 Inland 21074

Adjacent to 2007 site “E6”. Site

was located in lichen woodland.

8E1 55°37.780 -87°33.988 Inland 37800

Site was located on a palsa

plateau dominated in peat. Some

trees were observed in the area

and remnants of a fen. The site

had high soil moisture content

with the presence of bogs. Clayey

soil was observed below the peat

layer. No detectable odour.

8E2 55°31.322 -86°58.361 Inland 39841

Site was located in lichen

woodland with a pond to the

southwest. Low trees and shrubs

were observed in the area. Site

had high moisture content. No

detectable odour.

8E3 55°41.111 -86°51.326 Inland 21289 Adjacent to 2007 site “G5a”. Site

57

was located on a palsa with an

emerging palsa nearby and

surrounded by a fen. The site has

low vegetations and no trees. Site

had high soil moisture content.

Nearby fuel barrel cache was

damaged due to vandalism.

8E4 55°15.623 -85°12.639 Coastal 50

Site was located near Winisk,

Ontario, near the coast. Site was

well vegetated by grass. Surface

soil layer was dominated by

organic material underlain by

clay. No detectable odour.

8F1 55°46.94 -87°22.559 Inland 17663

Site was located in a fen

dominated by lichen. Presence of

an old palsa was observed. Soil

had high moisture content.

8F2 55°30.075 -86°36.199 Inland 30768

Site located in lichen wooden.

Site was observed to have been a

burned area with some surviving

trees. Gravel was observed at a

depth of 45 cm.

8G1 55°13.124 -84°41.727 Coastal 2040

Adjacent to 2007 site “F8”. Site

was located on a beach ridge

dominated by sandy and clayey

soils. Gravelly soils were

observed below the surface layer.

Site had high soil moisture

content. No detectable odour.

8G2 55°02.797 -83°06.238 Inland 12407

Site was located in a shallow

Polar Bear den on a ridge of

hummocky organic material.

Sedges and low growth vegetable

was observed in the area.

8G3 55°02.541 -83°04.724 Inland 11151

Site was located in a Polar Bear

den and 20 metres from a beach

ridge and fen. Sandy soil was

observed at the site. Standing

water was observed at the fen. A

Boreal Chorus Frog (Pseudacris

maculata) was identified at the

site.

8G4 54°38.784 -83°03.361 Inland 53321

Hummocky surface soil was

dominated by sphagnum. Clayey

soil was observed below the

organic layer. Soil had high

58

moisture content.

8H1 54°42.897 -84°06.587 Inland 58298

Site was located in lichen

woodland on a ridge. Clayey soil

was observed at the site. Bird nest

was observed to the south of the

ridge. Polar Bear tracks and a

hole possibly excavated by a

Polar Bear were observed. Soil

had moderate moisture content.

4.3 Laboratory Analysis Results (2007-2008)

4.3.1 Soil Moisture Content and Soil Acidity

The results from the laboratory analysis work were completed on October 4th

of

2007 for the gravimetric soil moisture content and soil acidity from the samples retrieved

from Northern Ontario and Hudson Bay (Figure 6). The gravimetric soil moisture content

and soil acidity results are summarized in Table 6.

Table 6 – Results: 2007 Laboratory Analysis for Gravimetric Soil Moisture Content and Acidity for

Northern Ontario

Results: Northern Ontario - August 2007

Sample

Identification

Gravimetric

Soil Moisture

Content Soil Acidity

SID θm (%) pH Average

B1 31.9 7.09

B2 63.2 6.90

B3 93.9 6.02

B4 72.0 5.75

B5 94.0 5.95

B6 73.2 3.71

C2c 92.7 5.40

C3 71.9 4.16

C8 22.9 6.06

D1 81.6 4.24

D2 78.8 4.75

D4l 92.5 6.06

D5a 81.1 3.99

E1 31.1 3.50

59

E10 94.2 6.06

E2 10.2 6.84

E2a 56.1 5.47

E6 5.6 5.79

F8 28.6 5.79

G5a 76.9 5.34

The majority of the samples was composed of organic material such as peat or

soils with fibrous roots and partially decomposed moss. The overall results showed high

soil moisture condition in which eighteen (18) of the twenty (20) samples had gravimetric

soil moisture content, θm, greater than 20% (Table 6). Fourteen (14) of the 20 samples

had gravimetric soil moisture content, θm, greater than 50% soil moisture content (Table

6). The samples were acidic overall with a mean pH of 4.41 (STD = 1.06; Table 6).

Average pH was calculated using the methodology outlined in 3.3.4 Soil Acidity,

Average pH Value.

The samples from the 2008 soil-sampling campaign were analyzed on October

27th

of 2008 for the gravimetric soil moisture content and soil acidity from the samples

retrieved from Northern Ontario and Hudson Bay (Tables 7 & 8). The analysis and

results were divided based on coastal and inland regions of the sample area (Figure 7).

The results are shown in Tables 7 & 8.

The results from the analysis of the twenty-three (23) coastal samples along

Hudson Bay showed drier gravimetric soil moisture, θm, conditions in which twenty-two

(22) of the 23 samples were less than 30% soil moisture content (Table 7). Fourteen (14)

of the 23 samples had soil moisture contents greater than 10% soil moisture content and

only three (3) of the 23 samples had soil moisture contents greater than 20% soil moisture

content (Table 7). The highest coastal soil moisture content was 37.5% at site 8C2 in

60

2008 (Table 7). The mean pH for the coastal samples was 7.14, slightly basic (STD =

0.05; Table 7).

Table 7 – Results: 2008 Laboratory Analysis for Gravimetric Soil Moisture Content and Acidity for

Sampling Sites along the Shores of Hudson Bay.

Results: Shores of Hudson Bay - August

2008

Sample

Identification

Gravimetric

Soil Moisture

Content Soil Acidity

SID θm (%) pH Average

8A1 15 7.1 7.11

8A1 30 5.7 7.10

8A1 65 5.5 7.15

8A1 120 14.2 7.14

8A2 9.3 7.12

8A2 18 25.7 7.18

8B1 6.6 7.17

8B2 8.6 7.07

8B3 12.6 7.13

8B4 10 10.0 7.17

8B4 PF 15.6 7.18

8C1 12.6 7.08

8C2 37.5 7.09

8C3 9.7 7.09

8C4 10.1 7.08

8C4 137 15.4 7.18

8C5 7.6 7.33

8D2 15.9 7.12

8D3 10.8 7.08

8D4 20.1 7.17

8G1 0 9.4 7.15

8G1 116 16.4 7.15

8G1 PF 14.9 7.17

Results from the analysis of the ten (10) inland soil samples from Northern

Ontario showed higher soil moisture content, θm, conditions in which six (6) of the 10

soil samples were greater than 20% soil moisture content and only two (2) of 10 samples

with less than 15% soil moisture content (Table 8).

61

Table 8 – Results: 2008 Laboratory Analysis for Gravimetric Soil Moisture Content and Acidity for

Sampling Sites inland in Northern Ontario.

Results: Inland Northern Ontario - August

2008

Sample

Identification

Gravimetric

Soil Moisture

Content Soil Acidity

SID θm (%) pH Average

8D5 6.5 7.02

8E1d 21.5 7.39

8E2a 91.0 6.00

8F1a 92.1 6.76

8F2a 12.5 7.14

8F4a 47.4 7.09

8G4a160 19.4 7.50

8G4asfc 95.4 5.37

8H1a10 77.1 6.00

8H1a100 18.5 7.48

The mean pH for the inland samples was 6.17, therefore slightly acidic (Table 8). The

highest inland soil moisture content value was 95.4% at site 8G4 in 2008 (Table 8).

4.3.2 Measured Depths to Permafrost

Point-scale depths to permafrost were measured at twenty (20) sites along the

shores of Hudson Bay and inland in Northern Ontario using a graded rod (Figure 6). This

was conducted in August of 2007; the results for the depths to permafrost and the

location of each sample site in the designated quadrants are shown in Table 9.

62

Table 9 – Results: Depths to Permafrost for 2007 Sampling Site and Classified by Quadrants

Sample

ID

Average

Depths to

Permafrost

(cm) Quadrant on Map

B1 68 2

B2 N/A 2

B3 N/A 2

B4 35 2

B5 N/A 2

B6 37.5 2

C2c 39 3

C3 47 3

C8 10 3

D1 52 3

D2 42 3

D4l 86 3

D5a 37 3

E1 49 1

E10 58 1

E2 33 1

E2a 40 1

E6 N/A 1

F8 52 3

G5a 48 2

In August of 2008, point-scale depths to permafrost were measured at twenty-eight (28)

sites along the shores of Hudson Bay and inland in Northern Ontario using a graded rod

(Figure 7). Depth to permafrost was confirmed using a thermistor probe to determine the

minimum and mean soil temperatures. The results of the mean depths to permafrost, soil

temperatures and the location of each sample site in the designated quadrants are shown

in Table 10.

63

Table 10 – Results: Depths to Permafrost for 2008 Sampling Site and Classified by Quadrants

Sample

ID

Average Site Depth to

permafrost (cm)

Average Site

Soil

Temperature

(ºC)

Site Soil

Temperature

(min ºC)

Quadrant

on Map

8A1 119.67 5.27 1.82 3

8A2 125.5 3.56 1.58 2

8A3 48.17 1.1 0.14 2

8B1 108 1.9 1.9 2

8B2 85 1.83 1.58 2

8B3 114.5 0.9 0.9 2

8B4 96.25 1.47 1.47 1

8C1 110.75 2.07 1.26 3

8C2 95 8.2 8.2 3

8C3 93 5.58 4.96 3

8C4 99 4.31 3.19 3

8C5 182 1.77 1.77 3

8D1 39 0 0 2

8D2 149.5 3.98 2.01 1

8D3 99 0.46 0 1

8D4 142 0.09 0.09 1

8D5 175 10.5 10.5 1

8E1 140.8 1.11 0.29 2

8E2 256 2.6 2.6 2

8E3 83.82 0.96 0.18 2

8E4 193.5 5.38 5.17 2

8F1 145.67 6.6 4.86 2

8F2 175 10.87 10.87 2

8G1 140.5 0.72 0.48 3

8G2 49.89 0.65 0.23 3

8G3 53.71 2.87 0.87 3

8G4 147.67 2.62 2.36 3

8H1 166 2.96 2.39 3

The mean depths to permafrost were calculated from Tables 9 & 10 according to the map

quadrants where each site was located and the results are shown in Table 11.

64

Table 11 – Results: Yearly Average Depths to Permafrost per Quadrant

Average Depths to Permafrost (cm)

Year Quadrant on Map

--- 1 2 3

2007 45.0 47.13 45.63

2008 132.35 126.25 114.29

4.4 Freezing and Thawing Degree-Days (1989-2007)

4.4.1 Results from 1989 to 2002

The freezing and thawing degree-days from 1989 to 2002 were calculated from

temperature data collected from the northern community weather station at Peawanuck,

Ontario. The results are shown in Figures 11 and 12 and the statistical data were shown in

Tables 12 and 13.

Results: Peawanuck Degree Days (1989 - 2002)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

Year

Degre

e D

ays

Thawing Degree Days Freezing Degree Days

Figure 11 – Results: Freezing and thawing degree-days for Peawanuck, Ontario, from 1989-2002

65

The thawing degree-days appear to have generally increased between the years of

1989 to 2002 with slight decreases in 1992, 1995, 2000 and 2002; test of significance

using regression analysis with a 95% confidence interval was performed, and the p-value

of 0.106 suggests that the observed trend is not statistically significant (R2 = 0.216; r =

0.465; Figure 11; Table 12).

Table 12 – Results: Statistical Analysis of the 1989 – 2002 Peawanuck Degree-Days

Peawanuck Degree Days

1989 - 2002

Thawing

Degree Days

Freezing

Degree Days

STD 164 297

MEAN 1433 1192

R2 0.216 0.660

p-value

(95% CI) 0.106 0.000

The peak thawing degree occurred in 2001 at 1798 thawing degree-days. The freezing

degree-days appear to have generally decreased between the years of 1989 to 2002; test

of significance using regression analysis with a 95% confidence interval was performed,

and the p-value of 0.000 suggests that the observed trend is statistically significant (R2 =

0.660, r = -0.812; Figure 11; Table 12). From 1989 to 2000, the number of freezing

degree days decreased from 1614 to 557 freezing degree-days (Figure 11). There was an

increase in freezing degree-day from 2000 to 2001, 557 to 1105 freezing degree-days

respectively (Figure 11). As shown in Figure 11, the number of freezing degree days per

year in the late 1980s and early 1990s exceeded the number of thawing degree-days for

the same year. From 1993 onwards, the thawing degree-days per year exceed the freezing

degree-days per year. As the thawing degree-days in Peawanuck increased, there was a

decrease in the freezing degree-days.

66

4.4.2 Results from 2004 to 2007

The freezing and thawing degree-days from 2004 to 2007 were calculated from

temperature data collected from the Peawanuck weather station (Figure 12).

Results: Peawanuck Degree Days (2004 - 2007)

1025

1751 17181659

1054

1439

722

1232

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2004 2005 2006 2007

Year

Deg

ree D

ays

Thawing Degree Days Freezing Degree Days

Figure 12 – Results: Freezing and thawing degree-days for Peawanuck, Ontario, from 2004-2007

The thawing degree-days appear to have generally increased between the years of

2004 (1025 thawing degree days) to 2007 (1659 thawing degree days) with a peak

increase in 2005 at 1751 thawing degree-days; test of significance using regression

analysis with a 95% confidence interval was performed, and the p-value of 0.301

suggests that the observed trend is not statistically significant (R2 = 0.491; r = 0.701;

Figure 12; Table 13).

67

Table 13 – Results: Statistical Analysis of the 2004 - 2007 Peawanuck Degree-Days

Peawanuck Degree Days

2004 - 2007

Thawing

Degree Days

Freezing

Degree Days

STD 345 303

MEAN 1538 1112

R2 0.491 0.006

p-value

(95% CI) 0.301 0.920

The freezing degree-days appear to have slightly increased between the years of

2004 (1054 freezing degree day) to 2007 (1232 freezing degree days) with a peak

decrease in 2006 at 722 freezing degree-days; test of significance using regression

analysis with a 95% confidence interval was performed, and the p-value of 0.920

suggests that the observed trend is not statistically significant (R2 = 0.006, r = 0.077;

Figure 12; Table 13). As shown in Figure 12, in 2004, freezing degree-days per year

exceeded the thawing degree-days per year, and, by 2005, the thawing degree-days per

year had exceeded the freezing degree-days.

Statistical regression analysis, using 95% confidence interval, was performed for

the entire 1987 to 2007 (excluding 2003) degree-days. Regression analysis for the

thawing degree-days from 1989 to 2007 (excluding 2003) had a p-value of 0.101

suggesting the trend was not statistically significant, with standard deviation of 195.552

and R2

value of 0.173. Regression analysis using 95% confidence interval showed that

freezing degree-days from 1989 to 2007 (excluding 2003) had a p-value of 0.014

suggesting that the trend is statistically significant, with standard deviation of 248.453

and R2

value of 0.314. Overall, the number of thawing degree days did not change

68

significantly between 1987 and 2007 whereas there was a significant decrease in the

number of freezing degree days over the same period.

4.5 Stefan Depth and Permafrost Table Results (1989-2007)

The Stefan depth to the permafrost table and thermal offset were calculated using

the degree-days from Figures 11 & 12 with Equations 4, 5, 6 and 7 for the periods

between 1989 to 2002 and 2004 to 2007. The Stefan depth for freezing, Df, and thawing,

Du, layers were used to calculate the thermal offset in determining the permafrost state.

Various soil thermal conductivity (λ) values for various substrates dominating Arctic

soils were considered in calculating the results, such as sand (porous, non-porous), clay

and peat soils. The soil thermal conductivities of Du (λu) reflect dry theoretical summer

conditions of 0% soil moisture content, representing a lesser thermal offset effect (Figure

13; Nixon & McRoberts, 1973). The soil thermal conductivities of Df (λf) were adjusted

by 1.5 times the values of Du to represent the thermal offset effect of moist soils of 20%

soil moisture content (Figure 13; Nixon & McRoberts, 1973; Kujala et al., 2007).

69

Figure 13 - Thermal conductivity to water content for fine-grained soils, both frozen and

thawed soils (Nixon & McRoberts, 1973).

Since palsas have more organic matter and higher soil moisture content (30% soil

moisture content), the soil thermal conductivity was adjusted by 1.75 times the dry value

to represent an enhanced thermal offset effect (Figure 13; Nixon & McRoberts, 1973;

Kujala et al., 2007).

70

4.5.1 Porous Sandy Soils (1989 to 2007)

For Arctic soils dominated by porous sand (porosity >0.33) and given the degree-

day conditions from Figures 11 and 12 from 1989 to 2007, the thermal offset results were

calculated from the Stefan depths using Equations 4, 5, 6 and 7 (Figure 14 & Table 14).

Thermal Offset in Sand (Porosity >0.33) 1989 - 2007

-0.400

-0.300

-0.200

-0.100

0.000

0.100

0.200

0.300

0.400

0.500

1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008

Year

Th

erm

al

Off

set

Df

- D

u (

m)

Thermal Offset Df - Du (m)

Figure 14 – Thermal Offset for Sand (Porosity >0.33) Compositions 1989-2007

Table 14 – Results: Stefan Depths for Porous Sand (Porosity >0.33) Soil Compositions (1989-2002)

Stefan Depth - Permafrost Table (1989 - 2002)

Sand (Porosity >0.33) λ(F) = 1.99x1.5, λ(U) = 1.99

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

1989 1.579 1.157 0.422

1990 1.551 1.184 0.368

1991 1.486 1.231 0.255

1992 1.438 1.091 0.347

1993 1.419 1.198 0.221

1994 1.434 1.239 0.194

1995 1.354 1.147 0.207

1996 1.461 1.217 0.244

1997 1.328 1.243 0.085

1998 1.109 1.309 -0.200

1999 1.166 1.258 -0.092

71

2000 0.927 1.176 -0.249

2001 1.306 1.360 -0.054

2002 1.277 1.171 0.106

From 1989 to 1997, the depth of annual freezing of Arctic soils dominated by

porous sand generally exceeded the depth of annual thawing leading to a positive thermal

offset value (Table 14). This favoured permafrost conditions to freezing, interannual

accumulation, by a mean of 0.260 metres (STD = 0.103) over the 9-year span (Table 14).

After 1998, the depth of annual thawing exceeded the depth of annual freezing

leading to a negative thermal offset value, permafrost unfavorable conditions, by a

maximum of 0.249 metres of thawing in 2000 in arctic soils dominated by porous sand

(Table 14).

For Arctic soils dominated by porous sand from 2004 to 2007 and given the

degree-day conditions from Figure 12, the thermal offset results showed depth of annual

freezing of Arctic soils dominated by porous sand generally exceeded the depth of annual

thawing leading to a positive thermal offset value (Table 15).

Table 15 - Results: Stefan Depths for Porous Sand (Porosity >0.33) Soil Compositions (2004-2007)

Stefan Depth - Permafrost Table (2004 - 2007)

Sand (Porosity >0.33) λ(F) = 1.99x1.5, λ(U) = 1.99

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

2004 1.276 1.027 0.249

2005 1.490 1.343 0.148

2006 1.056 1.330 -0.274

2007 1.379 1.307 0.072

This favoured permafrost conditions for freezing by a mean of 0.49 metres (STD

= 0.227) over 4 years from 2004 (Table 15). In 2006 and onwards, the depth of annual

72

thawing exceeded the depth of annual freezing leading to a negative thermal offset value,

loss of permafrost, of 0.274 meters of thawing in porous sandy arctic soils (Table 15).

4.5.2 Non Porous Sandy Soils (1989 to 2007)

In Arctic soils dominated by non-porous sand (porosity <0.33) and given the

degree-day conditions from Figures 11 and 12 from 1989 to 2007, the thermal offset

results were calculated using Stefan depths and Equations 4, 5, 6 and 7 (Figure 15; Table

16).

Thermal Offset in Sand (Porosity <0.33) 1989 - 2007

-0.300

-0.200

-0.100

0.000

0.100

0.200

0.300

0.400

1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008

Year

Th

erm

al

Off

se

t D

f -

Du

(m

)

Thermal Offset Df - Du (m)

Figure 15 – Thermal Offset for Sand (Porosity <0.33) Compositions 1989-2007

73

Table 16 – Results: Stefan Depths for Non-Porous Sand (Porosity <0.33) Soil Compositions (1989-

2002)

Stefan Depth - Permafrost Table (1989 - 2002)

Sand (Porosity <0.33) λ(F) = 0.787x1.5, λ(U) = 0.787

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

1989 0.993 0.728 0.265

1990 0.976 0.744 0.231

1991 0.934 0.774 0.160

1992 0.905 0.686 0.218

1993 0.892 0.753 0.139

1994 0.902 0.779 0.122

1995 0.852 0.721 0.130

1996 0.919 0.765 0.153

1997 0.835 0.781 0.054

1998 0.697 0.823 -0.126

1999 0.733 0.791 -0.058

2000 0.583 0.740 -0.157

2001 0.821 0.856 -0.034

2002 0.803 0.737 0.067

From 1989 to 1997, the depth of annual freezing of non-porous sandy arctic soils

generally exceeded the depth of annual thawing leading to a positive thermal offset value

(Table 16). This favoured permafrost conditions to freezing, interannual accumulation, by

a mean of 0.164 metres (STD = 0.065) over the 9-year span (Table 16).

After 1998, the depth of annual thawing exceeded the depth of annual freezing

leading to a negative thermal offset value, permafrost unfavorable conditions, by a

maximum of 0.157 metres of thawing in 2000 in non-porous sandy soils (Table 16).

For arctic non-porous sandy soils and given the degree-day conditions from

Figure 12 from 2004 to 2007, the thermal offset results showed depth of annual freezing

generally exceeded the depth of annual thawing leading to a positive thermal offset value

(Table 17).

74

Table 17 – Results: Stefan Depths for Non-Porous Sand (Porosity >0.33) Soil Compositions (2004-

2007)

Stefan Depth - Permafrost Table (2004 - 2007)

Sand (Porosity <0.33) λ(F) = 0.787x1.5, λ(U) = 0.787

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

2004 0.802 0.646 0.157

2005 0.937 0.844 0.093

2006 0.664 0.836 -0.172

2007 0.867 0.822 0.045

This favoured permafrost condition to freezing by a mean of 0.031 metres (STD = 0.143)

over the four years (Table 17).

In 2006, the depth of annual thawing of Arctic soils dominated by non-porous

sand exceeded the depth of annual freezing led to a negative thermal offset value, loss of

permafrost, of 0.172 meters of thawing (Table 17).

4.5.3 Clay Soils (1989 to 2007)

For Arctic soils dominated by clay and given the degree day conditions from

Figure 11 from 1989 to 2002, the thermal offset results were calculated using Equations

4, 5, 6 and 7 (Figure 16; Table 18).

75

Thermal Offset in Clay 1989 - 2007

-0.200

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0.300

1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008

Year

Th

erm

al

Off

se

t D

f -

Du

(m

)

Thermal Offset Df - Du (m)

Figure 16 – Thermal offset for Clay Compositions 1989-2007

Table 18 – Results: Stephan Depths for Clay Soil Compositions (1989-2002)

Stefan Depth - Permafrost Table (1989 - 2002)

Clay λ(F) = 0.755x1.5, λ(U) = 0.755

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

1989 0.972 0.713 0.260

1990 0.956 0.729 0.226

1991 0.915 0.758 0.157

1992 0.886 0.672 0.214

1993 0.874 0.738 0.136

1994 0.883 0.763 0.120

1995 0.834 0.707 0.128

1996 0.900 0.750 0.150

1997 0.818 0.765 0.053

1998 0.683 0.806 -0.123

1999 0.718 0.775 -0.057

2000 0.571 0.725 -0.154

2001 0.805 0.838 -0.033

2002 0.787 0.721 0.065

76

From 1989 to 1997, the depth of annual freezing of clay soils generally exceeded

the depth of annual thawing leading to a positive thermal offset value (Table 18). This

favoured permafrost conditions to freezing, interannual accumulation, by a mean of 0.160

metres (STD = 0.063) over the 9-year span (Table 18).

After 1998, the depth of annual thawing exceeded the depth of annual freezing for

clay soils leading to a maximum negative thermal offset value, permafrost unfavorable

condition, of 0.154 metres of thawing in 2000 (Table 18).

For clayey soils and given the degree-day conditions from Figure 12 from 2004 to

2007, the thermal offset results showed depth of annual freezing of clay soils generally

exceeded the depth of annual thawing leading to a positive thermal offset value (Table

19).

Table 19 – Results: Stefan Depths for Clay Soil Compositions (2004-2007)

Stefan Depth - Permafrost Table (2004 - 2007)

Clay λ(F) = 0.755x1.5, λ(U) = 0.755

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

2004 0.786 0.633 0.153

2005 0.918 0.827 0.091

2006 0.651 0.819 -0.169

2007 0.849 0.805 0.044

This favoured permafrost condition to freezing by a mean of 0.030 metres (STD = 0.140)

since 2004 (Table 19).

In 2006, the depth of annual thawing for Arctic soils dominated by clay soils

exceeded the depth of annual freezing, leading to a negative thermal offset value, loss of

permafrost, of 0.169 meters of thawing (Table 19).

77

4.5.4 Peat and Organic Materials (1989 to 2007)

In Arctic soils dominated by peat with other organic matter and given the degree-

day conditions from Figure 11 from 1989 to 2002, the thermal offset results were

calculated using Equations 4, 5, 6 and 7 (Figure 17; Table 20).

Thermal Offset in Peat 1989 - 2007

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008

Year

Th

erm

al

Off

se

t D

f -

Du

(m

)

Thermal Offset Df - Du (m)

Figure 17 – Thermal Offset for Peat Compositions 1989-2007

From 1989 to 1997, the depth of annual freezing of peat generally exceeded the

depth of annual thawing leading to a positive thermal offset value (Table 20). This

favoured permafrost conditions to freezing, interannual accumulation, by a mean of 0.109

metres (STD = 0.043) over the 9-year span (Table 20).

78

Table 20 – Results: Stefan Depths for Peat Compositions (1989-2002)

Stefan Depth - Permafrost Table (1989 - 2002)

Peat λ(F) = 0.352x1.5, λ(U) = 0.352

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

1989 0.664 0.487 0.177

1990 0.652 0.498 0.155

1991 0.625 0.518 0.107

1992 0.605 0.459 0.146

1993 0.597 0.504 0.093

1994 0.603 0.521 0.082

1995 0.570 0.482 0.087

1996 0.614 0.512 0.103

1997 0.558 0.523 0.036

1998 0.466 0.551 -0.084

1999 0.491 0.529 -0.039

2000 0.390 0.495 -0.105

2001 0.549 0.572 -0.023

2002 0.537 0.493 0.045

After 1998, the depth of annual thawing exceeded the depth of annual freezing for

Arctic soils dominated by peat leading to a maximum negative thermal offset value,

permafrost unfavorable condition of 0.105 metres of thawing in 2000 (Table 20). In

Figure 12 from 2004 to 2007, the thermal offset results were calculated using Equations

4, 5, 6 and 7 (Table 21).

Table 21 – Results: Stefan Depths for Peat Compositions (2004-2007)

Stefan Depth - Permafrost Table (2004 - 2007)

Peat λ(F) = 0.352x1.5, λ(U) = 0.352

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

2004 0.537 0.432 0.105

2005 0.627 0.565 0.062

2006 0.444 0.559 -0.115

2007 0.580 0.550 0.030

79

The depth of annual freezing of Arctic soils dominated by peat generally

exceeded the depth of annual thawing leading to a positive thermal offset value by a

mean of 0.021 metres (STD = 0.095) since 2004 (Table 21). In 2006, the depth of annual

thawing for Arctic soils dominated by clay soils exceeded the depth of annual freezing

leading to a negative thermal offset value, loss of permafrost, of 0.115 meters of thawing

(Table 21).

In palsa areas dominated in peat material with high soil moisture content and

given the degree-day conditions from Figures 11 and 12 from 1989 to 2007, the thermal

offset results were calculated using Equations 5, 6, 7 and 8 (Figure 18; Table 22).

Thermal Offset in Palsas (Dense Peat) 1989 - 2007

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0.300

1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008

Year

Th

erm

al

Off

se

t D

f -

Du

(m

)

Thermal Offset Df - Du (m)

Figure 18 – Thermal Offset for Palsa (Dense peat) Compositions 1989-2007

80

Table 22 – Results: Stefan Depths for a Palsa Formation (1989 – 2007)

Stefan Depth - Permafrost Table (1989 - 2007)

Peat λ(F) = 0.352x1.75, λ(U) = 0.352

Year Df (m) Du (m)

Thermal Offset

Df - Du (m)

1989 0.717 0.487 0.230

1990 0.705 0.498 0.207

1991 0.675 0.518 0.157

1992 0.653 0.459 0.194

1993 0.644 0.504 0.141

1994 0.651 0.521 0.130

1995 0.615 0.482 0.133

1996 0.664 0.512 0.152

1997 0.603 0.523 0.081

1998 0.504 0.551 -0.047

1999 0.530 0.529 0.001

2000 0.421 0.495 -0.074

2001 0.593 0.572 0.021

2002 0.580 0.493 0.088

2004 0.580 0.432 0.148

2005 0.677 0.565 0.112

2006 0.480 0.559 -0.080

2007 0.626 0.550 0.077

From 1989 to 2002, the depth of annual freezing of peat generally exceeded the

depth of annual thawing leading to a positive thermal offset value (Table 22). This

favoured permafrost conditions to freezing by a mean of 0.101 metres (STD = 0.094)

over the 14-year span (Table 22). In 1998 and 2000, the depth of annual thawing

exceeded the depth of annual freezing for Arctic soils dominated by peat leading to a

negative thermal offset value, permafrost loss of 0.047 and 0.074 metres, respectively,

from thawing (Table 22).

81

4.6 Soil Moisture Content Loss Test (2008)

The results from a soil moisture control loss test using nine (9) control soil

containment samples were accomplished to simulate the loss of soil moisture over a five

(5) week period was conducted for the 2008 sampling campaign from March to April

2009.

The results showed an mean loss of 4.4 millilitres of moisture from samples in

double and triple containment (Table 23). All samples showed decreasing results in water

volume, the least being from T5 with a loss of -2.8 millilitres and the most with T6 at -6.9

millilitres over 5 weeks (Table 23).

Table 23 – Results: Soil Moisture Content Loss Test (2008)

Control

ID

Initial Water

Mass Mbw

(Total) (g)

After-5

Weeks

Water mass

M5wks (g)

Change in

Water

Mass (g)

Water

Density at

23C (g/mL)

Volume

Loss

(mL)

T1 54.2 50.9 -3.3 0.9976 -3.3

T2 54.2 50.8 -3.4 0.9976 -3.4

T3 54.0 48.5 -5.5 0.9976 -5.5

T4 54.1 50.4 -3.7 0.9976 -3.7

T5 63.8 61.0 -2.8 0.9976 -2.8

T6 53.5 46.6 -6.9 0.9976 -6.9

T7 54.1 48.0 -6.1 0.9976 -6.1

T8 53.9 49.9 -4.0 0.9976 -4.0

T9 63.8 60.0 -3.8 0.9976 -3.8

MEAN 56.2 51.8 -4.4 --- -4.4

STD 4.3 5.1 1.4 --- 1.4

82

CHAPTER 5: Discussion

5.1 Soil Characterization

The soil samples retrieved from the study sites were visually analyzed and

described based on visible characteristics of the soil, the composition, presence of soil

organic matter, and with analyses on acidity and the gravimetric soil moisture content.

Acidity and soil moisture content (SMC) measurements from 2007 and 2008 have

revealed acidic to neutral conditions (pH ~ 4 to 7) and variation in soil moisture content

(SMC ranged between 20 to 60%). Characterization of the accompanying soil sampling

sites revealed the presence of soil organic matter, living and decomposing plant residues,

and various moss and lichen compositions. Inland samples had low acidic pH values, the

presence of soil organic matter, and the soil was dominantly clayey. Soil samples near the

shores of Hudson Bay contained sandy soil and were slightly basic having a higher pH

value.

The majority of the analyzed samples collected from the inland sampling sites in

Northern Ontario from 2007 and 2008 contained high contents of organic matter (Tables

4 and 5). Sphagnum and partially decomposed plant material was the major composition

of the samples. Plant materials discovered included decomposing stems, roots, and

leaves. Inorganic materials found in the samples were rocks and mineral sediments

(Tables 4 and 5). Samples found with high organic matter content, based on the site

descriptions, had a lower pH value (pH of 4.41 from the 2007 campaign and pH of 6.17

from the 2008 campaign); suggesting acidic conditions (Tables 6, 7 and 8). Decomposing

organic materials can release organic acids in moist conditions (Zoltai & Witt, 1995).

Gravimetric soil moisture content was higher for samples and sites with abundant organic

83

material located in clayey and silty soils. High gravimetric soil moisture content

(SMC~60%) conformed to high moisture conditions observed in the wet Hudson Bay

lowland area, as there were abundant vegetation and organic material that can lead to a

greater affinity for water in soils (Tables 6 and 8). The presence of peat formations,

Sphagnum, grasses and ideal soil compositions provide favourable conditions for the

inland soils to retain soil moisture content. A relatively high soil moisture conditions for

an inland site was observed at B5 with a gravimetric soil moisture content of 94% and

pH~6 being ~50 km inland from the nearest Hudson Bay shore (Tables 5 and 7). Site B5

was highly organic which can withhold water molecules in the soil pore space (Seppälä,

2003). Based on the field notes provided from Gough, most of the samples with acidic

conditions were extracted from sites situated in fens and bogs (Tables 4 and 5). Zoltai &

Witt (1995) suggested that fens and bogs have relatively low pH due to high degradation

rates of organic matter contents in which supports the findings of the site soil

characterizations.

The majority of the analyzed soil samples collected along the Hudson Bay coastal

sites in Northern Ontario were dominated by sandy and gravelly soils (Tables 4 and 5).

There were little traces of soil organic matter. The observed organic material was

observed from samples retrieved near the soil surface composed of primarily partially

decomposed plant matter. The plant materials discovered included decomposing stems,

roots, and peat. The dominant inorganic materials found in the samples were rocks and

sediments ranging from sizes of pebbles (~ 10 mm in diameters) to gravel (~30 mm). The

observed rocks were rounded and smoothed due to the processes of weathering and

erosion from the shore and atmospheric actions. This area also experiences seasonal

84

freezing and thawing cycles. The sediments were unsorted resulting in conglomerate of

different sizes, shapes and colours. The low gravimetric soil moisture content (~20%) for

the coastal samples, in comparison to the inland gravimetric soil moisture content, can be

attributed to the poor water retaining ability of sand and gravel with the lack of abundant

organic material and clay minerals (Eyles & Miall, 2007; Tables 6 and 7). Without

decomposing soil organic matter to produce humic acids, the coastal samples resulted in a

higher mean pH value of 7.14 then compared to the inland pH of 6.17; basic conditions

(Tables 6 and 8). Weathering and chemical erosion of rocks, parent material and glacial

sediments can produce a moderate base (Eyles & Miall, 2007).

Highly organic soils with high soil moisture contents can undergo considerable

frost heaving by the formation of ice lenses that expand the soil volume (Guglielmin et

al., 2008; Kuhry, 2008). The observation of palsas in the Hudson Bay Lowlands provides

direct evidence to support frost heaving and the formation of ice lenses. However the

presence of excess soil moisture content for palsa development suggests warmer

conditions in the area followed by sufficient seasonal cooling to provide freezing, this

imply significant changes per season in the thickness of soils due to heaving and melting

that can modify the topography (Thie, 1974; Gross et al., 1990; French, 1999; Henry,

2000; Spielvogel et al., 2004; Kim et al., 2008; Larsen et al., 2008; Wang et al., 2009).

85

5.2 Freezing and Thawing Degree-Days

The freezing and thawing degree-days were determined using actual weather data

from Peawanuck weather station in Northern Ontario. The threshold in determining

freezing and thawing was set at 0ºC. As shown in Figure 11, in the span of 14 years from

1989 to 2002 the number of freezing degree-days had decreased with statistical

significance (r = -0.812, R2 = 0.660; p-value = 0.000; Table 12). The lowest number of

freezing degree-days was calculated at 557 for the year of 2000 (Figure 11). For the

thawing degree-days with minor variation was observed over the 14-year span (p-value =

0.106; STD = 163.93; Table 12). The thawing degree-days increased to a peak number of

days of 1,798 calculated for the year of 2001 before decreasing near the mean thawing

degree-days for 2002 (Figure 11 & Table 12).

The freezing and thawing degree-days was calculated for a second interval of 4

years from 2004 to 2007, this was due to the incomplete temperature data provided by the

Peawanuck weather station during 2003 (Figure 12); this is further discussed in Section

5.8 Sources of Error & Uncertainties. As shown in Figure 12, in the span of 4 years from

2004 to 2007 the number of freezing degree-days had slightly increased, however this

was not statistically significant (r = 0.077, R2 = 0.006; p-value = 0.920; Table 13). The

lowest number of freezing degree-days was calculated at 722 for the year of 2006 (Figure

12). A sharp increasing trend was observed for the thawing degree-days from the years

2004 to 2005 with minor variation afterwards, however this was not statistically

significant (p-value = 0.105; Figure 12). The thawing degree-days had increased to a

peak number of days of 1,751 calculated for the year of 2005 before slightly decreasing

to 1,659 thawing degrees days for year of 2002 (Figure 12 & Table 12).

86

An analysis of the degree-day trends for Peawanuck, Northern Ontario has shown

that since 1993, the numbers of thawing degree-days have exceeded the numbers of

freezing degree-days, suggesting a warming trend in the region (Figure 11). With

increased number of thawing degree-days and decreased number of freezing degree-days

(T-test two-tailed p-value = 0.002; Figures 11 and 12), climatic and environmental

conditions have become unfavourable for permafrost presence. As this region is located

in the southern portion of the Arctic and parts in the Subarctic, the permafrost state in the

region is likely and most susceptible to be in decline. This degradation of permafrost

would be amplified in surface areas without vegetation and organic layers that could

provide insulation against thawing energies.

5.3 Stefan Depth and Permafrost Table

The Stefan depth of freezing (Df) and thawing (Du) were used to calculate the

thermal offset (Df - Du) to provide an estimate of the thickness of the active layer and

permafrost with projections of the permafrost table (Tables 14 to 21). In the winter

season, dominated by negative ground heat flux, the freezing energies can penetrate down

the soil column represented by the Stefan depth of freezing derived from freezing degree-

day with temperatures less than 0°C. This provided a seasonal estimate of the depth of

soil susceptible to freezing. In the spring-summer seasons, thawing of the active layer

begins when sufficient incoming solar radiation and geothermal heats allows for a

positive ground heat flux state (Ling & Zhang, 2004; Carey et al., 2007; Hayashi et al.,

2007). The geothermal heating at the permafrost base is not discussed in this thesis.

Heating from the atmosphere will first remove the insulating snow cover from the surface

87

before thawing the active layer (Muller, 2008; Zhang et al., 2008b). The depth of thawing

is determined with the Stefan depth of thawing calculation.

In areas south of the subarctic, it is typical to have a negative thermal offset (Du >

Df) condition (Burns & Smith, 1987; Duan & Naterer, 2009). This represents seasonal

freezing during the winter season followed by a complete thawing of the soils in the

summer season. When the seasonal Stefan depth of thawing does not exceed the seasonal

Stefan depth of freezing (Du < Df), the resulting positive thermal offset represents the

theoretical thickness of a frozen layer of soil that has persisted over the summer thawing

season, and has survived into the next freezing cycle (Burns & Smith, 1987; Duan &

Naterer, 2009). Since permafrost is defined as permanently frozen soils that remain

frozen for at least two consecutive years, this layer of frozen soil must persist through a

second summer-thawing cycle (Gough & Leung, 2002; Shur & Jorgenson, 2007; Muller,

2008). If the positive thermal offset (Du < Df) condition persists over two warming

seasons, the soil state would be classified as the development of permafrost or permafrost

present (Burns & Smith, 1987; Duan & Naterer, 2009). In regions with continuous

permafrost zones, such as in the Arctic, positive thermal offset conditions will lead to the

thickening of the permafrost layer (Burns & Smith, 1987; Duan & Naterer, 2009).

Negative thermal offset conditions in the Arctic will lead thinning of the permafrost layer

and the development of thicker summer active layers; the permafrost table represents the

interface at which the extent of the depth of thawing ends and meets the permafrost layer

(Burns & Smith, 1987; Muller, 2008; Duan & Naterer, 2009). In discontinuous

permafrost zones such as in the Subarctic, negative thermal offset conditions can result in

the disappearance of permafrost.

88

The Stefan depths calculation, using Equation 4 required the soil thermal

conductivity (λ). Soil thermal conductivity is strongly influenced by the soil moisture

content and the type of soils. Calculations of Stefan depths were categorized based on the

typical composition of Cryosols that dominated by sand (porous and non porous), clay,

and an organic top layer, peat. Theoretical dry soil conductivities (0% soil moisture

content) were assigned to the four categories as follows: porous sand (λ = 1.99), non-

porous sand (λ = 0.787), clay (λ = 0.755) and peat (λ = 0.352). The thermal conductivities

for moist (20% soil moisture content) and frozen soils were increased by a factor of 1.5 to

the dry soil conductivities (Nixon & McRoberts, 1973; Kujala et al., 2007). The dry soil

thermal conductivities, representing warm summer soil conditions, were applied in the

Stefan Equation to calculate depth of thawing (Du) (Equation 5). The enhanced thermal

conductivities for moist and frozen soils represented the winter conditions in calculating

the Stefan depth of freezing (Df) equation (Equation 6). The generalized soil

conductivities were applied, as there were no accessible previous soil investigations

conducted in study area. Peat was identified as a thermal insulator resulting as having the

least conductivity. The greatest conductivity was assigned to porous sand due to the large

porosity (typically 33%) and high soil water capacity (Dunne & Leopold, 1978; Price &

Waddington, 2000).

The study area is located in the continuous permafrost zone (along the shores of

Hudson Bay) and in the region of discontinuous permafrost (further inland in Northern

Ontario). The thermal offset values can be applied as an annual change to permafrost

thickness (Burns & Smith, 1987; Natural Resources Canada, 2006). In general, the

results of the thermal offsets showed positive thermal offset conditions favourable to

89

permafrost in the years from 1989 to 1997, 2002 to 2005 and 2007; the remaining years

(excluding 2003) showed negative thermal offset values (Tables 14 to 22). The greatest

thermal offset was experienced in the porous sandy soils due to the high soil conductivity

value (Tables 14 and 15). The least thermal offset was experienced by organic peat layer

due to the low soil conductivity value and thermal insulating properties (Tables 20 and

21).

5.4 Permafrost Presence

Using the Stefan depth calculations for permafrost (Equation 4) and the degree-

days, extracted from weather station data, from 1989 to 2007 (Figures 11 and 12), the

thermal offset was calculated to determine the change in permafrost thickness. Actual

depths to permafrost were measured during the 2007 and 2008 field sampling campaigns

(Figure 5). Mechanically in 2007 field campaign, permafrost was deemed present when a

graded metal rod could no longer be drilled into the subsurface (Figure 6). Difficulties

can arise in differentiating the impact of the rod on the permafrost table or with a buried

obstruction, such as a rock or an ice lens (Mühll et al., 2002). The presence of permafrost

in 2008 was determined using thermistor probes that were lowered into an augured

borehole (Figure 7). The thermistor measured ground soil temperature and recorded the

temperature range on a data logger. When the soil temperature was reported near or at

0°C, the sample site was deemed to be permafrost present (Smith & Burgess, 2002;

Nicolsky et al., 2009).

Annual depth to permafrost measurements provides monitoring information of the

active layer thickness and the state of the permafrost at the study sites (Nicolsky et al.,

90

2009). Using this information, trends can be used to assessment the future state of

permafrost for the region such as estimating the mean reduction of permafrost and the

extension of the active layer (Anisimov & Nelson, 1996; Nicolsky et al., 2009; Pang et

al., 2009). Averaged depths to permafrost were calculated from the measured sampling

points located in each of the three quadrants in Table 11 to represent the western, central

and eastern portion of Northern Ontario and the shores of Hudson Bay (Tables 10-12). A

significant annual variation between the mean depth to permafrost of August 2007 and

2008 was observed (Figure 5; Table 11). In 2007, the depth to permafrost ranged between

40 to 50 centimetres while in 2008 the depth to permafrost ranged between 110 to 140

centimetres from the surface (Table 11; Figures 11 and 12). The results of 2008 were

roughly three times greater than the depths measured in 2007 which could be explained

due to different sampling strategies as there was a focus in the coastal regions for 2008

and inland for 2007; the coastal sites were dominated by sandy soils and the inland sites

contained greater organic material content. As observed in the 2008 results of the three

quadrants in Table 11 and Figure 7, there was a decrease in the depths to permafrost from

west to east, Quadrants 1 to 3, suggesting asymmetrical thawing of the active layer and

permafrost. The depth to permafrost measurements suggests thicker active layer

developments were experienced in Quadrant 1, an enhanced thawing event. In Quadrant

3, the influence of the peat and organic material may have insulated and reduced the

thawing energies on the active layer and permafrost. In comparison to the 2007 mean

depth to permafrost results in Table 11, Quadrant 3 experienced less thawing than

compared to Quadrant 2. A direct explanation of these trends for Quadrant 3 was not

investigated for this thesis and further research in area should be conducted.

91

Based on the descriptions listed in Table 4 and 5, highly vegetated areas and high

organic matter in the soil composition was documented as distance progressed inland

with the sample sites. The highly organic layer of peat and vegetation above the active

layer could provide thermal insulating benefits (Thie, 1974; Hinkel et al., 2001; Cheng et

al., 2004; Spielvogel et al., 2004; Martini, 2006; Zhang et al., 2008b; Pang et al., 2009).

Based on the results in Table 8, the high organic composition observed at the sample sites

could provide thermal insulation for permafrost against heat energy penetrations through

the active layer and reduced the severity of thawing in the summer. In the winter, an

upper snow layer above the soil provides an additional thermal insulation that can prevent

freezing energies, increase thermal resistance, from entering the soil column to enhance

the permafrost (Cline, 1997; Cheng et al., 2004; Osterkamp, 2005; Zhang et al., 2008b).

Lowland areas in bogs and fens have significant organic matter and soil moisture that

allowed well-aggregated conditions to further retention of soil water in the soil pores

(Juma, 2006; Carey et al., 2007; Kim et al., 2008; Kuhry, 2008). However, as

established with Shur & Jorgenson (2007), an increase in soil moisture content could

result in an increase in thermal conductance of energy with respect to different soil

compositions.

Near the shores of Hudson Bay, active layer thawing depth were seen to be higher

than inland, this can be attributed to the low organic matter content, sandy soil

composition with moderate moisture conditions near the body of water (Table 7 and

Figure 5). Without the high organic matter composition, a thermal insulating layer cannot

be effectively established over the active layer. Sandy and moist soils enhance the soil

92

conductivity and allow further penetration of heat energy into the soil column resulting in

a greater Stefan depth of thawing (Tables 14 to 17).

Acidity in the inland soils ranges from pH of 5 to 7 and remains acidic conditions

of the soil samples in Tables 6 & 8 could be attributed to the organic matter content in

Tables 4 & 5 possibly due to the production of organic and humic acids. Since the study

area is located on the Canadian Shield as the parent bedrock material, there is little

capacity for chemical dissolution to provide buffer conditions for the soils (Eyles &

Miall, 2007).

Thermal offset calculations from the degree-days observed at Peawanuck revealed

permafrost to be in a fluctuating state of freezing and degradation with high degradation

rates to have occurred from 1998 to 2001 before recovering to a positive thermal offset.

In the summer months, permafrost unfavourable conditions exist as air temperatures are

above freezing allowing the growth of the active layer (Shur & Jorgenson, 2007). Over

winter, permafrost growth by incorporation of the active layer base can occur when

conditions favour permafrost development (Shur & Jorgenson, 2007). Overall, there was

a negative thermal offset in 2006, resulting in a reduction of permafrost thickness by a

minimum of 0.115 metres in peaty soil and a maximum of 0.274 metres in sandy soils

(Tables 16 and 21). With further studies on thermal offset in this region, prediction of the

permafrost fate along the shores of Hudson Bay and in the Northern Ontario region can

be projected.

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5.5 Palsa Presence

Shallow active layers above the permafrost were observed in palsas with highly

acidic and moist characteristics due to the organic matter content (Figure 19). In moist

conditions, thermal conductance can be enhanced for heat transfers to the soil column.

For the palsas observed in July and August of 2007 and 2008, the organic top layer of

Sphagnum species and peat formations served as an insulating layer that prevented

further energy penetration from the atmosphere to the soil. Based on the field notes,

palsas were situated in fens, bogs and peat lands that are high in moisture and organic

matter (Tables 4 and 5). Soil samples collected from palsas contained higher soil

moisture contents. The thick organic layers did protect against permafrost degradation by

reducing the severity of heat energy penetration (Figure 19; Tables 6 & 21). The layer of

organic material can enhance freezing of soil moisture in the winter causing the

expansion and raised soil column to form the circular mounds (Kujala et al., 2007;

Kuhry, 2008). Palsa acidity ranges more broadly from a pH of near 3 to a pH of 7 (Tables

4 and 6). The analysis of the freezing and thawing degree-days showed a change in the

1990s where the number of thawing degree-days has exceeded the freezing degree-days

suggesting unfavourable climatic conditions for permafrost and palsas. However, even in

the summer, palsas are able to remain intact and present in the landscape possibly due to

the enhanced organic peat layer protection.

Due to limitation on literature surrounding the interactions of palsas in nature, the

exact purposes of these features remain understudied and not well understood. Palsas

may have an ecological role in the habitat of Polar bears. Field notes from both 2007 and

2008 have reported disturbed palsa, possibly due to polar bear activity in the region in

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search of den locations or for cooling purposes near the permafrost (Figures 19 & 21).

Female polar bears are known to exhibit site-fidelity behaviour for dens in Northern

Ontario (Crompton et al., 2008). With climate change and shifts in the terrain with

melting permafrost, the impact on inland polar bear food sources may lead to changes in

feed behaviour (Dyck et al., 2007; Callaghan, 2008). Dyck et al (2007) cautions that

impacts on polar bears from climate change is still not well understood as there are many

interconnected factors that can affect distribution, feeding behaviour, body mass and

survival; however, it should be noted that early breakup of sea ice experienced in Hudson

Bay may be a major factor in polar bear survival (Gagnon & Gough, 2005; Stirling et al.,

2008).

5.6 Addressing Research Question 1

• 1. Can the distribution of permafrost in Northern Ontario be rationalized using the

relationship between soil moisture content and the frozen and unfrozen soil

thermal conductivities, “the thermal offset” as hypothesized by Gough and Leung

(2002)?

By establishing relationships of soil thermal conductivity with soil moisture

content and thermal offset trends over time, using the Equation 7 from Burns & Smith

(1987), the presence of permafrost can be predicted. The presence of permafrost will

ultimately depend on the climate conditions that are favourable for permafrost formation

(Shur & Jorgenson, 2007). Continuous and discontinuous permafrost zonation can be

determined using the Frost number calculation from Equation 1 as suggested by Nelson

& Outcalt (1987); however, as shown in Gough & Leung (2002), there were

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discrepancies between calculated Frost Numbers with field observations in the Hudson

Bay Lowlands. The application of the thermal offset approach includes the soil moisture

effect that has shown support to the field observations (Tables 14 to 21; Gough & Leung,

2002). This research furthers the understanding of the presence of continuous permafrost

in Canada‟s subarctic region of Northern Ontario due to the thermal offset phenomenon

while calculations of Frost numbers and observations in southeastern Hudson Bay show

discontinuous permafrost. By using degree-days in this research in establishing the Stefan

depths of thawing and freezing, this allows the thermal offset to be calculated. Unlike the

Frost number, which aids in permafrost zone classification, the thermal offset allows

estimations on the direct changes to permafrost thickness. With available permafrost

thickness measurements and the thermal offset, a timeframe could be estimated using

projected climate scenarios to predict the fate of permafrost for a region. Since freeze-

thaw degree-days requires temperature data collected at weather stations, issues

pertaining to data quality arise from the use of transposed data from neighboring

locations to remote sites that lack a permanent weather station. This remains an academic

issue, as these temporal and spatial variations in temperature can lead to

misrepresentations in theoretical calculations that may not be represented with real world

observations, as seen in the application of the Frost number by Gough & Leung (2002).

Based on this research and the data provided, the thermal offset was calculated for

the Peawanuck region using various values of soil thermal conductivities based on

dominant arctic soil compositions. Temperature data was provided from a pre-existing

weather station at Peawanuck, Ontario, for this undertaking. Temperature data allowed

the calculations of the degree-days required for the Stefan depths equation that ultimately

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allows for assessing the presence of permafrost through the thermal offset approach. To

determine the fate of permafrost and its future presence in this subarctic region both

climatological and environmental factors must be considered in order to represent the

complexities of natural system. Long-term monitoring of permafrost is necessary since

the behaviour of permafrost is seasonally and temporally dynamic, permafrost can

thicken over one winter, so that variation can lead to new depths to permafrost in the

following summer or completely melt. Important environmental factors that should be

considered are thermal insulation by organic matter and vegetation that can enhance and

protect permafrost thickness, prolonging permafrost presence. Biological activity is an

important factor that is difficult to assess, such as polar bears disturbances of the upper

and active layers that can have impacts on permafrost insulation (Figure 19). Inorganic

factors will have strong influences on the energy conductance of the soils above the

permafrost, such as soil composition, moisture content, and acidity. The resulting

complexity of the question proposed for this research has shown that with simplification

of nature, estimations and trends of permafrost presence and extent can be determined for

a region. The trend of the calculated thermal offset for Peawanuck, Ontario, suggested a

weak negative trend from the shores of Hudson Bay and inland into Northern Ontario;

this suggests greater permafrost shifts are likely to occur near the shores of Hudson Bay

where soils are dominant porous with sands and gravel, and where vegetation and organic

insulation and protection is weaker; less soil moisture also weakens the thermal offset

effect. Further inland in peaty and clayey soils, the thermal offset of permafrost showed a

weak negative trend suggesting events favourable to thawing however, the severity is

reduced due to the protective insulation layers of organic material and peat. For accurate

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results, long-term monitoring, installation of weather stations in remote areas, and

geophysical methods in surveying permafrost should be adapted to provide better

resolution and include variables from all the physical factors influencing the permafrost.

5.7 Addressing Research Question 2

• Does the presence of palsas affect the thermal conductivity of soil from the

surface cover down to the permafrost?

The presence of palsas can affect the thermal conductivity of soil, from the

surface cover down to the permafrost, due to the high organic matter presence that has

affinity for soil moisture and provides a thermal insulation effect. The formation of palsas

resulted from the enhancement of the permafrost core from favourable conditions, such

as the insulating properties of vegetation and organic matter layers. Peat and mosses

prevent thermal conductance of heat energy in the summer air to the permafrost and

prevents permafrost degradation. The same process can enhance the cold penetration into

the palsa, via thermal offset, in the fall and winter seasons. If there is no insulating snow

cover, the enhanced cold penetration can freeze additional soil moisture and strengthen

the palsa formation. Based on the reviewed studies and the site characteristics conducted

from soil samples of palsas, there is evidence that suggests that the characteristics of the

thick organic layers above the active layer in a palsa does decrease thermal conductivity

of heat energy from the surface to the permafrost. In comparison of thermal offset results

for 2006 in Table 20, peat soil (-0.115 m), and Table 22, palsa formation (-0.080 m), the

additional organic material and soil moisture enhances the soil thermal conductivity by a

factor 1.75 (thermal offset effect) for the Stefan freezing depth allowing for a greater cold

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penetration (0.480 m for palsa in comparison to 0.444 for peat soils) that reduces the

impact of the summer thawing penetration. Since only a few authors dominate the

scientific literature on palsas in general, further studies are crucial and necessary to

determine the role and thermal dynamics of palsas in the arctic. It should be noted that

from the field study, palsas may have a significant ecological role for polar bears as

evidence have suggested that polar bears have be attempting to construct habitats and

dens near and on palsas (Figure 19).

5.8 Sources of Error and Uncertainties

Traditional permafrost delineation methods involved drilling boreholes. Since

subsurface materials, such as the organic layer and unconsolidated sediment layers, are

not homogenous in nature, it is difficult to auger boreholes in moist soil conditions as the

integrity of the borehole walls may collapse. Utilizing an auger can generate heat in the

borehole along the walls and this may thermally contaminate the thermistor readings

leading to inaccurate soil temperature results. With this important error, soil temperatures

close 0ºC, up to 4ºC, were accepted as permafrost present.

The data collected from boreholes in the study area provided point-scale

resolution specific to the sampling site. The combination of multi-borehole data in this

analysis for the quadrants extrapolated the results between boreholes to produce data on a

regional scale. Since permafrost presence is site specific, up scaling to a larger scale

reduces the resolution of site-specific characteristics, and this up scaling technique

assumes a homogenous subsurface approach.

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Sources of error for laboratory analytical methodology could be due to a time

difference between soil collection and laboratory analysis work in which there was a

month disjunction from August to October. A soil moisture control loss test of 9 control

samples was accomplished to simulate the loss of soil moisture through the sampling

containments over a one month period was conducted for the 2008 sampling campaign.

The results showed a mean loss of 4 millilitres of moisture from samples in single, double

and triple containment (Table 23). To rectify this error, an addition of a correction factor

of 7% was added to the measured gravimetric soil moisture values, also in millilitres, and

then converted to gravimetric soil moisture content in unit percentage.

Observation of the soil characteristics was extremely difficult to visually identify

as soil or peat due to partial decomposition; vegetation and fungus species proved

difficult to identify due to partial fragments and decomposition.

The gravimetric soil moisture content was conducted since this accepted method

allows for simple and direct measurements without bulk density information. Few soil

sample containments did leak and this may have altered the gravimetric soil moisture

content. Since the soil samples were not filled to the volume of the sample containers and

with the time difference, the bulk density of the soil could not be determined to convert

gravimetric soil moisture content to the volumetric soil moisture content.

In calculating the degree-days of freezing and thawing, temperature data from

1986 to 2007 was acquired from weather stations in the study area (Figure 2). Incomplete

yearly temperature data sets were examined and years with extreme gaps in data, greater

than 30 missing days, were omitted from the calculation. Temperature data sets from

1986 to mid-1988 and 2003 were incomplete and omitted (Figures 11 and 12). To ensure

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full data sets, missing days up to five consecutive days were corrected using linear

regression from the beginning and the end of the month. Individual missing days were

corrected using an arithmetic mean value of the temperature on the day before and after.

While determining the Stefan depths and thermal offset, the quality of degree-day

data was limited to the quality of the extracted temperature data. Uncertainty in the

temperature data could influence the final results of the thermal offset calculations. The

thermal offset calculation required values for soil conductivity, which could not be

determined at the time of soil sampling. Generalized soil thermal conductivities were

applied based on the literature review for Arctic soils and peat. With additional field data

on the soil composition and site characteristics, an accurate soil thermal conductivity

could be achieved by applying the de Vries Equation (Equation 2) that could be utilized

in the thermal offset estimations.

Using Geographical Information Systems (GIS), errors of significant digits may

have led to some inaccuracies in determining distances between the sample sites and the

Hudson Bay shore based on the map produced (Figures 5, 6 and 7). Electronic maps of

the Northern Ontario region used for this study were was geo-referenced from 1984 and

compiled in 1992. The study area and sampling region spanned over two Universal

Transverse Mercator coordinate systems, the UTM 16 and 17. UTM 16 was selected as

the projection in generating the map figures. Slight geographical shifts to the actual

sampling locations may have occurred with this selected projection.

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5.9 Potential Research Impacts on Society

The results from this undertaking established data for permafrost presence to be

estimate based on soil moisture content, temperature data and soil thermal conductivity

properties. Incorporating the results of this research in establishing physical relationships

of soil thermal conductivity in the development and degradation of permafrost can allow

models and predictions in the fate of permafrost. The region of Northern Ontario along

Hudson Bay is situated at the southern edge of the sub-Arctic zone. With climate

warming, this region is at the frontline of environmental change as shift in physical

properties of the permafrost can result in destabilizing structures erected on the

permafrost and palsa formation and degradation which is a significant safety risk for

northern communities of Canada (Vyalov et al., 1993; Sorochan & Tolmachev, 2006).

An ongoing concern in Arctic regions and northern communities pertains to

delineating and predicting the movement of contaminants in contaminated sites located in

continuous and discontinuous permafrost states (Delaney et al., 2001; Tsuji et al., 2001;

Kalinovich et al., 2008). With changes to the underlying permafrost, sites such as the

relic radar station at Winisk still possess potential subsurface contamination concerns

(Tsuji et al., 2001). The transitional layers between the active layer and permafrost table

forms finger-like grooves and channels (Eyles & Miall, 2007; Kalinovich et al., 2008).

With thawing of the active layer, the permafrost table becomes asymmetric (Delaney et

al., 2001; Kalinovich et al., 2008). Since permafrost is considered impermeable, these

finger-like grooves and asymmetric topography will influence the flow paths for

contaminants resulting in difficulties in delineating contaminated sites, especially, since

the permafrost table can have considerable temporal and spatial variability within one

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freezing and thawing cycle of a year (Delaney et al., 2001; Tsuji et al., 2001; Eyles &

Miall, 2007; Kalinovich et al., 2008).

As Canada continues to develop northwards with the sub-Arctic being the

forefront of climate change, permafrost research can provide predictions and assessments

in determining the impacts of shifting ground. The processes of frost heaving and the

degradation of permafrost are continuing concerns to existing and future building

foundations and transportation infrastructures, which can be destabilized and cause risks

to human health and safety (Sorochan & Tolmachev, 2006; Eyles & Miall, 2007; Pang et

al., 2009). In the physical process of freezing soil water into ice, volumetric expansion

occurs in the soil with an increase in mechanical strength that can be compromised by

melting, and further exacerbated by resulting melt water (Eyles, 2006; Duan & Kim et

al., 2008; Duan & Naterer, 2009; Pang et al., 2009). Impacts can lead to ground

subsidence, settlement and infrastructure foundation failures that can cost significant

amount of damages and expenses for constructions, repairs, renovations and planning

(Ling & Zhang, 2004; Eyles, 2006; Sorochan & Tolmachev, 2006; Duan & Kim et al.,

2008; Jin et al., 2008; Larsen et al., 2008; Naterer, 2009). Permafrost predictions and

models have economical importance for civil construction and engineering of oil and gas

pipelines, for military infrastructure developments in Canada‟s Arctic regions, and for

transportation networks. Continuing permafrost research can further develop adaptation

methods by planners and engineers to improve the quality of life, reduce risks, and

improve safety for Canada‟s First Nation peoples and northern communities.

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CHAPTER 6: Conclusion

6.1 Permafrost

The dominant physical processes governing permafrost presence were identified

as: climate and environmental conditions, ground heat flux, and soil thermal conductivity

properties (Nixon & McRoberts, 1973; Burns & Smith, 1987; Halliwell & Rouse, 1987;

Nelson & Outcalt, 1987; Hinkel et al., 2001; Gough & Leung, 2002; Mühll et al., 2002;

Smith & Burgess, 2002; Cheng et al., 2004; Yoshikawa et al., 2004; Overduin et al.,

2006; Carey et al., 2007; Hayashi et al., 2007; Shur & Jorgenson, 2007; Kujala et al.,

2007; Kneisel et al., 2008; Muller, 2008; Zhang et al., 2008a; Duan & Naterer, 2009;

Nicolsky et al., 2009; Wang et al., 2009). Changes in these processes can either favour

permafrost formation, aggradation, or degradation. This supports the hypothesis

presented by Gough & Leung (2002), the analyses of the soil samples provided and the

literature reviewed suggest evidence that soil thermal conductivity has shown to play a

substantial role in permafrost presence in the Hudson Bay region. Both evidence from the

laboratory analyses and site descriptions in support of Shur & Jorgenson (2007) suggests

that soil moisture content can influence and enhance the conduction of energy through

the soil column. Since soil thermal conductivity is not a factor in the Frost number and

the rate of permafrost thawing equations, the use of Stefan Equation in determining the

thermal offset is appropriate for determining the state of permafrost (Burns & Smith,

1987). The Stefan depths utilize the number of freezing and thawing degree-days and

include the soil thermal conductivity that can be influenced by soil moisture content and

by soil compositions (Nixon & McRoberts, 1973; Nelson, 1986; Hayashi et al., 2007;

Hughes & Braithwaite, 2008). The complex interactions of soil organic matter enhances

104

soil moisture and acidic conditions, and that the layers of organic matter can provide

unique insulating effects that can protect and favour permafrost presence (Zoltai & Witt,

1995; Yoshikawa et al., 2004; Carey et al., 2007). Since 1993, there has been a shift in

Northern Ontario favouring a decreasing trend in freezing degree-days (p-value = 0.000;

Table 12).

This research concludes that permafrost is present in the Northern Ontario areas

dominated by organic materials such as peat with clayey soils. The organic material and

clayey soils provides high soil moisture content that enhances the soil thermal

conductivities during the winter to favour the freezing process while the organic layer in

the summer provides insulation against the thawing energies. At the shoreline of Hudson

Bay, the thin layer of organic material with sandy soils provide an enhanced soil thermal

conductivity that allows greater extents of thawing in the summer and freezing in the

winter; however, since the shore areas are located further north and experiences a cooler

climate than in the southern lands allowing for permafrost favourable conditions. Overall,

permafrost in the Hudson Bay Lowlands and shores are expected to remain present. With

continuing warming trends, it is not unreasonable to conclude the possibility that there

may be a future shift at the southern extent of the subarctic in Northern Ontario to be

reclassified from being a continuous permafrost zone to the discontinuous permafrost

state, and a further shift of the current discontinuous permafrost zone in the south to the

sporadic permafrost state. Future studies in the southern extent of the subarctic should

monitor for indicators of permafrost degradation as referenced in French (1999) for: (1)

increase in active layer thickness, (2) increases in permafrost degradation, and (3)

evidence of slope and active layer failures.

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6.2 Palsas

Based on observations in the field, this research has incorporated palsas into this

research. Thermal offset results have shown that soils high in organic matter content can

reduce the soil thermal conductivities to provide a layer of insulation for the permafrost

below; this process has permitted the formation of palsa features on the arctic terrain

(Table 23; Seppälä, 2003; Kuhry, 2008). The exact role and characteristics of palsas have

not been widely studied in Northern Ontario; however, observations of these unique

formations have shown ecological and habitat significances for Polar Bears in the region

(Brown, 1973). The dominant physical processes governing the presence of palsas were

identified as thermal conductivity of peat, snow cover and wind speed (Brown, 1973;

Seppälä, 1986; Seppälä, 2003; Kujala, et al., 2007; Vallée & Payette, 2007; Kuhry,

2008). The results from this research concluded that peat layers have the least soil

thermal conductivity in comparison to sand and clay soil compositions allowing the peat

layer to provide insulation against thawing energies in the summer. The presence of snow

cover in the winter and winds proves detrimental to the presence of palsas as snow cover

insulates against freezing energies in the winter from thickening the underlying

permafrost (Seppälä, 1986). Wind actions deposits snow against the palsas and can

provide additional erosion actions against the palsas reducing the structural stability

favouring degradation (Brown, 1973; Seppälä, 1986; Kuhry, 2008; Zhang et al., 2008b).

Since Polar Bears tend to establish dens or utilize palsas for cooling purposes in the

summer, it is possible for Polar Bears to assist in the degradation process by the removal

of the insulating peat layer and by exposing the permafrost to the atmosphere. Changes in

the permafrost can alter the landscape and drainage network affecting food sources for

106

biota and change population distributions (Dyck et al., 2007; Callaghan, 2008; Crompton

et al., 2008). With continuing warming trends, it is not unreasonable to conclude that in

discontinuous and sporadic permafrost zones, the most likely location to observe

permafrost would be in areas dominated in organic material and sites beneath palsas

(Brown, 1973).

6.3 Recommendations for Further Research

Further research on the physical properties of permafrost in the Arctic region will

allow accurate models to predict the presence and potential degradation of permafrost.

With the aforementioned statement, continuous research as part of a long term climate

and permafrost monitoring program and network is recommended to establishing a

continuous and accessible database of permafrost measurements for Northern Ontario.

Long term monitoring of the climate conditions can be accomplished by the deployment

and installation of portable weather stations within the study area that are connected to

data loggers to record continuous air and soil temperature measurements. A second

recommendation for further research is the application of geophysical methods and tools

to compliment field investigations and soil sampling campaigns to provide better

resolution of the active layer thickness, depths to permafrost, soil moisture contents and

actual permafrost thickness data. The use of geophysical methods and tools allow

measuring physical properties on a broad spatial scale and the collected data can be

applied to Geographical Information Systems (GIS) to produce maps, regional

distributions and models of permafrost. This can provide a better understanding of the

permafrost state for civil engineering projects in the northern First Nation communities.

107

Finally, a third recommendation for further research is to focus on the dynamic ecological

and environmental importance of palsas in Northern Ontario and to map the distribution

of palsa features with GIS. Since palsa-polar bear interactions have been observed at

palsas, possibly in search of a den or for cooling purposes, detailed assessments and

research should be conducted to provide better knowledge of the impacts of climate

change on polar bears in this region (Figures 19 & 21). Further research in permafrost

and palsas will not only benefit the academic community but also for those currently

residing in Canada‟s Arctic and Subarctic regions where transportation, resources, and

infrastructures depends on understanding the state of permafrost.

108

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APPENDIX – Additional Figures

Figure 19 – Excavated Palsa located in a vegetated region in Northern Ontario. Digital

photo taken by William Gough, July-August, 2007. Note: Exposed internal core of the

palsa, possibly due to Polar Bear activity in the region

Figure 20 – Soil Samples baking in the oven at 105˚C for gravimetric soil moisture

content analysis: oven drying in the Science Wing Room 313 Laboratory. Picture was taken

on 4 OCT 08 by A. Tam.

116

Figure 21 – Three male polar bears in Northern Ontario, August 2007. Digital photo was

taken by William Gough.