Resolving sources of dissolved organic matter in the Sacramento-San Joaquin Delta by radiocarbon dating

James O. SickmanSoil and Water Science Department, University of Florida

Carol DiGiorgioCalifornia Department of Water Resources

M. Lee DavissonLawrence Livermore National Laboratory

Delores LuceroUniversity of Florida

Erin WaitesDepartment of Water Resources

Presented at:October 2004 CALFED Science Conference

Who am I?Who am I?I am an interdisciplinary scientist working in and across the fields of biogeochemistry, limnology and watershed science

My research program is focused on biogeochemical cycling of C, N and P in lakes, rivers and wetlands

In these terrestrial and aquatic ecosystems I utilize standard watershed analysis along with application of isotopes ( e.g., 15N and 18O of nitrate, 13C, 14C of dissolved organic matter) to solve environmental problems

Watersheds

Biogeochemistry

Limnology

My Research

Education and Work HistoryEducation and Work HistoryEducation:

Ph.D., Ecology, Evolution and Marine Biology (emphasis in biogeochemistry and limnology) University of California, Santa Barbara, 2001M.A., Aquatic and Population Biology University of California, Santa BarbaraB.A., Aquatic Biology, University of California, Santa Barbara

Work Experience:2004 – present: Assistant Professor. Soil and Water Science Department, University of Florida-IFAS. Biogeochemistry of rivers, lakes and wetlands

2003 – 2004: Assistant Professor. Department of Geology and Geophysics. University of New Orleans. Watershed biogeochemistry and ecosystem restoration in the Mississippi Delta and Sacramento River Delta

2001 – 2003: Senior Environmental Scientist - California Department of Water Resources, Division of Environmental Services, Sacramento, California. Carbon biogeochemistry, AMS carbon dating, aquatic ecological processes and water-quality investigations of the Sacramento-San Joaquin River Delta and State Water Project

1983 – 2001: Staff Research Associate IV. Donald Bren School of Environmental Science and Management, University of California, Santa Barbara. Global-change research on biogeochemistry, aquatic ecology and hydrology of the Sierra Nevada and Rocky Mountains.

Current Research: CaliforniaCurrent Research: CaliforniaC&N Biogeochemistry of

Montane WatershedsAquatic Ecology of Oligotrophic

Lakes

DOM Sources and Fate in Rivers and Estuaries

Effects of Seasonal Transitions on Biogeochemistry of Chaparral

Causes of macroalgae blooms in Florida springs (J. Stevenson, A. Pinowska MSU; R. Reddy UF)

Impacts of Melaleuca quinquenervia invasion on soil biogeochemical properties (M. Martin UF, P. Tipping USDA)

Sources of DOM to St Johns and Caloosahatchee Rivers (M. Fisher SJRMD, TJ Evens USDA)

Current Research: FloridaCurrent Research: Florida

Teaching: Current Courses (1)Teaching: Current Courses (1)

Spring 2005: SOS 6456 Advanced Biogeochemistry (3 credits)

TOPIC:Biogeochemical Cycles and Global Change: Sustaining Biodiversity and Ecosystem Services in Soils and Sediments

PREREQUISITES:Graduate standing, BSC 2011 and 2011L (population biology) or equivalent, AND SOS 3022 (soil chemistry ) or equivalent

COURSE DESCRIPTION:This course will present an in-depth treatment of global elemental cycles in the context of Global Change. Topics that will be covered include properties of and transfers between the key reservoirs of C, N, S & P, coupling of biogeochemical cycles and climate, and human modification of the Earth System. Discussion of ecosystem services provided by soils and sediments in terrestrial and aquatic ecosystems will be emphasized

Teaching: Current Courses (2)Teaching: Current Courses (2)

Fall 2005: SOS 4932 Environmental Biogeochemistry (3 credits)

PREREQUISITES:BSC 2010 and 2010L (general biology) or equivalent, AND CHM 2045 and 2045L (general chemistry) or equivalent

COURSE DESCRIPTION:This course will examine the biogeochemical systems of the Earth for the past 5 billion years. We will consider the effects of life on the Earth's chemistry on a global scale, emphasizing the impact of humans in altering the global biogeochemical cycles of C, N, S, and P. The course will examine several important, but complex questions regarding the Earth System: 1) How did the Earth System operate in the absence of significant human influence? 2) How can human-driven effects on global biogeochemical cycles be discerned from those due to natural variability? 3) What are the implications of changes in the Earth’s biogeochemical systems for human well-being? 4.) How robust are the Earth’s biogeochemical systems in the face of anthropogenic forcings? Topics that will be covered include element cycling, coupled biogeochemical cycles, and solutions for global change including economic valuation of natural ecosystem functions.

Teaching: Planned Course (3)Teaching: Planned Course (3)

SOS 4XXX/5XXX: Watershed Science and Analysis

COURSE DESCRIPTION:Given the interconnectedness of watersheds and the integrating influence of

hydrology, watersheds are a fundamental scale at which to study and manage ecosystems. Watershed science is an interdisciplinary field that incorporates fundamental and applied knowledge of natural sciences (hydrology, geomorphology, chemistry, biology, geology) and social sciences (law, environmental policy and resource economics). This course will provide advanced training in concepts, tools and methods for solving watershed-scale problems. It will consist of a combination of lecture, field work and laboratory analyses. A local watershed will be used as the focus of the course.

Topics to be covered:1. Introduction to watershed science2. Field/lab methods in watershed analysis3. Remote sensing and GIS4. Geomorphology5. Hydrologic and hydrochemical modeling 6. Biogeochemistry of watersheds7. Use of environmental isotopes in watershed science8. Watersheds in environmental policy and regulation9. Environmental monitoring, databases and analysis

John Wesley Powell, renowned explorer of the Grand Canyon defines a watershed as "that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of a community”

Isotopes of Carbon and Their Abundance

Isotope Protons Neutrons Proportion Half life

12C 6 6 99%

stable13C 6 7 1%

14C 6 8 0.0000000001% 5568 years

Radiocarbon Basics

http://www.rlaha.ox.ac.uk/orau/calibration.html

History of Radiocarbon Dating

Invented by Willard F. Libby of the University of Chicago after the end of World War 2.

Libby later received the Nobel Prize in Chemistry in 1960 for the radiocarbon discovery

http://www.c14dating.com/k12.html

Shroud of Turin(AD 1260-1390)

Flow in and through the Delta:

Comprises 70% of annual California runoff

Supplies drinking water to 23 million people

Maintains agricultural vitality of California economy

Evolving concerns over past 50 years:

Primary conduit for state water project flows

Expanding role for environmental flows

Increasing degradation of water quality

Principal quality problems related to:

Salinity, agricultural wastes, local land use, and conflicting flow management strategies

California’s Delta region exhibits elements common to agricultural/urban areas of Florida

Managing water quality and the ecological Managing water quality and the ecological health of the Delta affects all of Californiahealth of the Delta affects all of California

How do we restore habitat, without:

high organic loads leading to carcinogenic by-products formed during drinking water treatment

carcinogen levels increase proportionally with organic matter content natural wetlands have 5-10X more organic matter than Delta today EPA STAGE 1 D/DBP RULE ON THE HORIZON

bioaccumulating toxic metals that impact fish: wetland chemistry promotes bioavailability of mercury and selenium

Increasing salinity in municipal and agricultural supplies 2-5X increase in bromide renders chlorinated water undrinkable

Promoting land subsidence

The CALFED Restoration mission is to balance ecological, agricultural, and urban demands, but

Carbon runoff from agricultural practices is a growing concern for water quality

Restoration of Delta may have unwanted Restoration of Delta may have unwanted consequences for water qualityconsequences for water quality

Wetland

Forest

Agricultural

Grasses

Historic

Today

Urban

Organic-rich soilsWetland

DOM is a precursor to disinfection byproducts in finished drinking water

DOM likely originates from modern and historical sources

Relative proportions of different sources will vary during water year

The Dynamic Delta Landscape Presents Unique Challenges for Drinking Water Quality

BanksPumping Plant

COCO22 DOCDOC

Determination of Delta Island DOM Influence at Banks

Can Isotopic fingerprinting determine if:

Delta island peat is a significant source of C loading to the State WaterProject?

C inputs from Delta island peat vary through time depending on seasonal and hydrologic conditions?

Simple Conceptual Model for DOM Sources to the State Water Project

Riverine DOM Peat-derived DOM

State Water Project

Sampling and Analysis

Monthly sampling: Rivers Ag drains

Periodic sampling: Urban runoff

DOM Fractionation

Measurements: AMS carbon dating C, N and S isotopes SUVA THMFP

Water fingerprinting using DSM2 model

Emphasis to date has been on DOM fractionation and radiocarbon measurements

DOM Fractionation Procedure

After Aiken et al. (1992)

Fractionation favors isolation of hydrophobic compounds (humics) which tend to be more refractory

Longer environmental persistence of these hydrophobic compounds may correlate to radiocarbon age.

Isolation Columns

Combustion/Extraction

isotopesmeasured

Whole Water Sample

HClpH 2

XAD 8

NaOHpH 13

XAD- 8 Eluate:Hydrophobic Acids (humic and fulvicacids)

Hydrophilic and transphilic acids and neutrals(fraction and radiocarbon computed from mass balance)

Whole Water Sample

HClpH 2

XAD 8

NaOHpH 13

XAD- 8 Eluate:Hydrophobic Acids (humic and fulvicacids)

Hydrophilic and transphilic acids and neutrals(fraction and radiocarbon computed from mass balance)

Fractionation Data

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

SacramentoRiver

San JoaquinRiver

BaconIsland

BouldinIsland

TwitchellIsland

BanksPumping

Plant

DO

M F

ract

iona

tion

%

Hydrophilic + Transphilic

Hydrophobic Acids (XAD 8)

Radiocarbon Comparison of Surface DOM and Soil Organic Matter

Accelerator Mass Spectrometry

fraction modern carbonSource DOC XAD-8Sacramento R 1.07, 1.10San Joaquin R 1.09, 1.10Old R 1.08, 1.53Cache Cr 0.89Missouri R 0.94-1.14 0.87-0.99Mississippi R 1.06-1.09*Hudson R 0.84-0.96Others 1.06-1.11 0.77-1.40Delta Island Soil Organic Matter 0.38-0.89

from Davisson (2002)

* from Raymond and Bauer (2000)

2.00

1.90

1.80

1.70

1.60

1.50

1.40

1.30

1.20

1.10

1.00

Fra

ctio

n M

od

ern

Ca

rbo

n (

fmc)

(Fraction Modern Carbon)

standard

C

C

C

C

12

14

12

14

samplefmc

River XAD-8 Fractions Are Younger Than Ag Drain Water

April-Oct 2003

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.401

4C

(fm

c)

Banks Hood Vernalis Bacon Bouldin Twitchell

Whole WaterXAD 8

Calculated 14C abundance in non-XAD-8 DOC fractions indicate old or possibly fossil carbon sources

8

814

814

814

1

XAD

XADXADWWXADnon fDOC

CfDOCCC

0.00

0.40

0.80

1.20

10 20 30 40

April-Oct 2003

Ca

lcu

late

d 1

4C

of

no

n-X

AD

-8 D

OC

(fm

c)

Maximum Daily Air Temperature ( oC)

HoodVernalis

Sac. River and Aqueduct 14C abundance of XAD-8 fraction closely track each other

Jones Tract Breach June 2003

y = 1.072x - 0.0724R2 = 0.858

0.80

0.85

0.90

0.95

1.00

0.80 0.85 0.90 0.95 1.00

Hood 14C XAD-8 (fmc)

Ban

ks 1

4C

XA

D-8

(f

mc)

Sac. River

Aqu

educ

t

Simple Mass Balance Mixing Model Tends to Under-Predict 14C abundance of XAD-8 DOC Fraction

* Based on DSM2 daily mass flow estimates for all major Delta inflows

ii

mixCX

CCXCCXC

...214

22114

1114

*Input Flows

Sac. River

SJ River

Ag Drains

Other Streams

linear mixing model

0.7

0.8

0.9

1.0

1.1

1.2

Apr-03 May-03 Jun-03 Jul-03 Aug-03

14C

XA

D-8

(fm

c)

Ag DrainsRiversBanks Pumping PlantPredicted Banks

Implications from Simple Mass Balance Modeling

Delta Island agricultural drainage has minimum influence on DOC at Banks

Increasing flow contributions from eastside of Delta or San Joaquin River cannot account for 14C discrepancy

Modern-aged carbon is added to the XAD-8 fraction between Hood and Banks

SUVA (L/mg-m) THMFP (µmol/mmol C)Sac. River 2.13 7.45

Aqueduct 2.83 9.08

For Sacramento and San Joaquin rivers, whole water DOM predominantly has lower radiocarbon content than corresponding XAD-8 fractions

The non-XAD-8 portion of DOM in these river waters suggest old or fossil carbon inputs

Sacramento River and San Joaquin River have younger XAD-8 fractions than Delta Island agricultural drain waters

A conservative mixing model for DOM at Banks predicts older carbon than is observed for most samples thus far

Results suggest young carbon is added between Hood and Banks, which may explain increases in SUVA and THMFP

Conclusions

Funding provided by the CALFED Bay Delta Program, State Water Project Contractors and Department of Water Resources

Acknowledgements

Twitchell Island

Banks Pumping Plant