Phytoremediation of Salt (& PHC) Impacted Soils Using Biochar … · 2016-05-20 ·...
Transcript of Phytoremediation of Salt (& PHC) Impacted Soils Using Biochar … · 2016-05-20 ·...
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
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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 -‐
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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