Phytoremediation of Salt (& PHC) Impacted Soils Using Biochar Augmentation; Implications of Salt Tolerance Mechanisms Dr. Barbara A. Zeeb Canada Research Chair – Biotechnologies & Environment Dept. Chemistry & Chemical Engineering Royal Military College of Canada Kingston, ON CANADA

RPIC Federal Contaminated Sites National Workshop Stream C - Remediation 26 April, 2016; 10:30-11 am

Salinization

Causes︎•  Natural processes︎

•  Landfilling of high salt content wastes︎

Consequences︎•  Land degradation •  Reduction in plant

growth & yield •  Reduction water

quality •  Toxic to aquatic,

microbial, veg communities

︎

︎

Weathering

Agricultural Practices

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Landfilling Waste

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http://blogs.oregonstate.edu

Currently estimated that Canada has >7.2 million ha of salinized soils

Phytotechnologies

the application of plants to engineering and science problems

•  remediating environmental contaminants (phytoremediation)

•  ecorestoration & habitat creation •  carbon sequestration

Mechanisms of Phytoremediation

1.  Accumulate 2.  Excrete

Biochar carbon rich by-product of pyrolysis

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Phytotechnologies

6

Phytoextraction !  Use vegetation to

mobilize salts into above ground tissues

Biochar︎!  Improve soil structure ︎!  Improve seed germination︎!  Improve plant growth︎

︎

Uptake ︎

Accumulation︎

Halophytes

vv

2. Accumulation

1. Exclusion

3. Excretion

Na+    Cl  -­‐  

h"p://imgkid.com/plant-­‐roots-­‐vector.shtml  

Adapted from Yensen & Biel 2006

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Cement Kiln Dust (CKD) Landfill !  Operating Cement Plant in Bath, ON

!  30 min west of Kingston

!  CKD landfilled from 1973 – 2009 !  Saline sodic material, slightly alkaline, low TOC

!  Project Objectives: i) improve aesthetics & ii) reduce [salt]︎

CKD Site Characterization Electrical

Conductivity (dS/m)

Sodium Absorption

Ratio

Chloride (µg/g)

MOE Guideline <0.7 5 -- Soil Characterization

Saline: >4 Sodic: >13 Average: ~100

CKD Site 11-20 15.4 5800-13500

Objectives

1.  Compare the phytoextraction efficiency of 3 halophytes –  P. australis –  P. nuttalliana –  S. pectinata

2.  Investigate different salt tolerance mechanisms & their ability to remove salt from soil

3.  Role of biochar augmentation

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Phytoextraction of Chloride with Phragmites australis

Phytoextraction Phragmites australis = accumulator species︎•  large, perennial grass︎•  growth prolifically︎•  effectively extracts Cl- from soils︎

July 2013︎Oct 2013︎

July 2014︎

Temporal Study

3 - 9 years︎

•  Total chloride in top 10 cm of soil:︎•  464 ± 193 kg︎

•  Based on yearly extractions of 72-82 kg︎

Remediation Timeframe

McSorley, K., Rutter, A. Cumming, R., and Zeeb, B.A. 2015. Phytoextraction of chloride from a cement kiln dust (CKD) contaminated landfill with Phragmites australis. J. Waste Management (accepted Oct 2015).

Addition of 60 lbs of biochar (5% w/w)︎

Planted 36 seedlings per plot︎

Field Trial

S. pectinata︎

A. elongatum︎

P. nuttalliana ︎

A. elongatum & ︎P. nuttalliana

seeds︎

5% Biochar︎ Buffer Zone︎ Control︎

5% Biochar︎ Control︎

Biochar Effects ︎

• Significant ↓ in uptake of Na+ in P. nuttalliana & K+ and Cl- in S. pectinata︎• No ↓uptake of divalent cations︎• Improved germination of P. nuttalliana by 67%︎

Accumulation

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•  Conventional phytoextraction calculation ︎

i.e. [shoot ion] x biomass at harvest︎

P. australis has highest phytoextraction potential︎

S. pectinata growing in RMC lab

Implications of Salt Tolerance Mechanisms on Extraction Efficiency

82X mag

2200X mag

excreted salts

salt glands

!  EDS for identification of salts excreted on stem & leaf surfaces of S. pectinata !  Cl- and K+ main ions excreted

!  Mean weekly excretion !  Cl- 8500 ± 1200 µg/g !  K+ 5800 ± 940 µg/g

Characterization of Excreted Salts

When considering excretion in lieu of accumulation: •  Cl- removal increased 160% •  K+ removal increased 30%

Salt Excretion

S. pectinata ︎•  highest salt phytoextraction potential︎•  native to Ontario︎

McSorley, K., Rutter, A. Cumming, R., and Zeeb, B.A. Chloride Accumulation vs Excretion: Variations in phytoextraction potential of three halophytic grass species growing in a salinized landfill. J. Waste Management (submitted April 2016).

!  Potential for wind dispersion and dilution !  haloconduction theory !  micro (Cl-) and macro (K+) nutrients released by

S. pectinata & wind dispersed !  potential beneficial effects

!  Further research needed to determine extent of redistribution

Fate of Salts

Summary •  P. australis can extract 65 ± 4 kg/km2 Cl-/season

!  remediate site in 3-9 years

•  Biochar can be used for assisted re-vegetation at the CKD landfill –  ↑ germination of P. nuttalliana by 67%

•  Salt tolerance mechanisms affect phytoextraction efficiency –  Salt excretion with S. pectinata most efficient

Acknowledgements Co-Authors: • Dr. Allison Rutter, Queen’s University • Kaitlin McSorley, Pinchin Envt. • Rob Cumming, Lafarge, Canada