Daniel Bouchard Sanexen Environmental Services Inc. What Additional Value Can Compound Specific Isotope Analysis (CSIA) Bring to the Assessment of Organic Contaminants in Groundwater? www.vertexenvironmental.ca SMART Remediation OƩawa, ON │ February 7, 2019 SMART is Powered by:
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Daniel BouchardSanexen Environmental Services Inc.
What Additional Value Can Compound Specific Isotope Analysis (CSIA) Bring to the Assessment of Organic Contaminants in Groundwater?
www.vertexenvironmental.ca
SMART RemediationO awa, ON │ February 7, 2019
SMART isPowered by:
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What additional value canCompound Specific Isotope Analysis (CSIA)bring to the conventional assessment oforganic contaminants in groundwater?
D a n i e l B o u c h a r d , P h . D . ( S a n e x e n )R am o n A r a v e n a , Em e r i t u s P r o f . ( U o f Wa t e r l o o )D a n i e l H u n k e l e r , P r o f . ( U o f N e u c h â t e l )
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In contaminated aquifers, dissolved VOCs migrate with GW flow, and concentrations can decrease over distance due to destructive and non‐destructive processes:• Biodegradation vs dilution
Remediation technologies usually aim at stimulating a specific contaminant removal process: • Destructive (chemical and biological) and non‐destructive (physical)
• Co‐occurring processes
• Is our contaminant of concern being removed by the process?
Context
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• Need for a tool that can assess the destructive (chemical, biological) and non‐destructive (physical) processes
o that is compound‐specific
o while 2 or more processes occur simultaneously
• Stable isotopes is a promising tool
Context
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• Present the common applications and current development of Compound‐Specific Isotope analysis (CSIA)
1. Introduction
I. Principles and Mechanisms
2. Applications in Hydrogeology
I. In situ Biodegradation
II. In situ Remediation Treatment
III. Source Identification
Context
Aim of the Presentation
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Introduction
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Carbon 14
Unstable atom
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14N + cosmic neutron
0
Carbon 12
Stable atom
Carbon 13
Stable atom
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Introduction
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Carbon 12
Stable atom
Carbon 13
Stable atom
12C : 98,89 %
13C : 1,11 %
Natural Abundance
1 : 88
1H: 99,985 %
2H : 0,0155 %
35Cl: 75,7 %
37Cl : 24,3 %
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Introduction
Implicationfor Molecules
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≠ ≠13
2
TCE
≠ ≠
13 2
Toluene
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IntroductionBIODEGRADATION
• Leads to 13C enrichmentin the remaining substrate
Toluène
Bouchard et al. 2008. Organic Geochem
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CSIAApplicationin MNA
BTEX in GW
Adapted from Richnow et al. 2003. JCH
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CSIAApplicationin MNA
Results for 13C
Adapted from Richnow et al. 2003. JCH
toluene o‐xylene
concentration
Ratio 13C/12C
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CSIAApplicationin MNA
Results for13C and 2H(dual isotope plot)
Adapted from Fisher et al. 2007. ESnT
Benzene
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CSIAApplicationduring In situ Remediation Treatment
Applying a dual isotope plot todestructive and non‐destructive processes
Anaerobicbiodegradation
Aerobicbiodegradation
ISCO
Air‐waterpartitioning
NAPLVolatilization
Physical removal volatilization
Biodegradation Aerobic/Anaerobic
Chemical oxidation
Dilution
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CSIAApplicationduring In situ Remediation Treatment
Treatment: Air Sparging
Source: PHC including BTX
Aquifer: Anaerobic
Duration: 284 days(with a winter pause from December to March)
Bouchard et al, 2018 GWMR
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CSIAApplicationduring In situ Remediation Treatment
Treatment: Air Sparging
Bouchard et al, 2018 GWMR
Overall interpretation:1‐ biodegradation > volatilization2‐ Limitations in air distribution?
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CSIAApplicationduring In situ Remediation Treatment
Treatment: ISCO
Shayan et al, 2018 GWMR
Source: BTEX
Injection: Na‐persulfate
Duration: 391 days
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Injection
source
sampling
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CSIAApplicationduring In situ Remediation Treatment
Treatment: ISCO
Shayan et al, 2018 GWMR
Day 156:Na‐persulfate injectionin the source zone
From day 156 to 208: Evidence of chemicaloxidation
> 293 days:Anaerobicbiodegradation
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CSIAApplicationduring In situ Remediation Treatment