Environmentally Acceptable Endpoints for Weathered/Aged
Petroleum Hydrocarbon CCME CWS Fraction 3
Miles Tindal - Axiom Environmental Inc.
Chris Meloche – Husky Energy Inc.
Acknowledgements
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Funding
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CAPP/SEPAC
PERD
ETL (In Kind)
Technical Steering Committee
Dr. Suzanne Visser
Technical Steering Committee
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Chair: Chris Meloche, Husky Energy Inc.
Coordinator: Tannis Such, PTAC
Members:
" Gordon Dinwoodie, Alberta Environment
" Ted Johnson, Talisman Energy
" Mike Morden, Petro-Canada
" Julie Roy, Imperial Oil Research Centre
" Rick Scroggins, Environment Canada
" Rob Staniland, Talisman Energy
" Miles Tindal, Axiom Environmental
" Suzanne Visser, University of Calgary
Technical Steering Committee
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Research Providers
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Axiom Environmental Inc.
Stantec Consulting Ltd.
EnviroTest Laboratories
EBA Engineering Consultants Ltd.
Peer Review
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Dr. Doug Bright, UMA Engineering Ltd.
Introduction
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Soil Quality Guideline for F3 = 800 mg/kg
Bioremediation to this level is challenging
Several ongoing projects:
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weathered hydrocarbon field study
toxicity of PHCs in clay soil
F3a/b; invertebrate PHC uptake
Tier 2 Framework
using bioavailability to predict toxicity
Overview
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Developing an F3 guideline based on
bioavailability
Evaluating the analytical recovery of
F3 from soil
Anticipated project completion –
October 2005
PHC Canada-Wide Standard 2005
review
A Guideline for Weathered F3
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Overall objective
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identify/develop a method for bioavailable
hydrocarbon
measure the bioavailable hydrocarbon in
weathered soils
measure the toxicity of those soils
develop a relationship between the two
Sample Selection
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16 PHC-Contaminated soils collected
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F3 primary contaminant
varying degree of weathering
varying soil and hydrocarbon types
corresponding background samples collected
Indebted to Dr. Suzanne Visser for the use
of soil samples from her Turner Valley Site
Bioavailability
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What controls the bioavailable fraction
of PHCs?
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very complex issue which we make no
attempt to resolve
Our approach:
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find an analytical technique that does a
better job of predicting toxicity than the
CCME method
CCME Analytical Method
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Standard method
Aggressive solvent extraction
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(hexane acetone mix)
Likely extracts more PHC than is
bioavailable to plants and
invertebrates
Cyclodextrin
Cyclodextrin
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Cone built from 7 glucose rings
Hydrophobic interior absorbs
hydrocarbon molecules
Hydrophilic exterior makes the
complex soluble
Mimics the way fatty compounds are
solubilized by phospholipids in the
body
Cyclodextrin
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Cyclodextrin extraction selected as
technique to assess bioavailable PHC
Based on:
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some relevant research
potentially robust technique
biological analogue
Cyclodextrin methodology developed
by ETL
Assessing Toxicity
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Testing conducted by Stantec Guelph
Chronic earthworm reproduction test
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all soils
earthworm test inappropriate in subsoils
other options for testing subsoils
Chronic springtail and definitive plants
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selected soils
Using “CCME Analysis” as a
Predictor of Toxicity
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Red = Toxic Soils
Blue = Non-Toxic Soils
Current CCME
F3 Guideline
800 mg/kg
-1
0
2,000
4,000
6,000
8,000
10,000
CCME F3 Concentration (mg/kg)
12,000
14,000
16,000
Using “Cyclodextrin Analysis”
as a Predictor of Toxicity
Cyclodextrin F3 Concentration (mg/kg)
900
800
700
600
500
Blue = Non-Toxic Soils
400
300
200
100
0
-1
Red = Toxic Soils
An F3 Guideline Based on
Cyclodextrin?
Cyclodextrin F3 (mg/kg)
1,000
800
Fresh F3 in
Chernozem Soil
600
400
Potentially Toxic
Potential Guideline:
370 mg/kg Cyclodextrin F3
Non-Toxic
200
0
0
500
1,000
1,500
2,000
2,500
3,000
CCM E F3 (mg/kg)
3,500
4,000
4,500
5,000
Implications
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Possible uses of cyclodextrin
guideline:
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as a standalone Tier 2a Guideline
Tier 2a guideline supported by limited
toxicity data
Analytical Basis For The F3
Guideline
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Based on Plant and Invertebrate
Toxicity Tests
Modified by Measured Analytical
Recovery of 31%
We Investigated Analytical Recovery
Using CCME Method
Plant Toxicity Test
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Source: ESG International Inc. (2003)
Dose Response Curve
100
Shoot Length, mm
75
50
25
EC50 = 4,000 mg/kg
0
0
1,000
2,000
3,000
4,000
5,000
6,000
Concentration of F3
7,000
8,000
9,000
10,000
Guideline Derivation (Plant
and Invertebrate Data)
100%
Rank Percent
75%
50%
25%
25th Percentile = 1,300 mg/kg
0%
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10,000
20,000
30,000
40,000
F3 Concentration (mg/kg)
50,000
60,000
Materials and Methods –
Analytical Recovery Experiment
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Alberta Black Orthic Chernozem Soil
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Spiked with F3
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same soil as used by PHC CWS
at 0, 800, 2,000, and 6,000 mg/kg
Analyzed for F3 (CCME Method)
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at 1 day, 25 days, 63 days
Results – Analytical Recovery
Experiment
Recovered Concentration (mg/kg)
5,000
4,000
Day 1
Day 25
3,000
Analytical Recovery = 70%
2,000
1,000
0
0
1,000
2,000
3,000
4,000
5,000
Nominal Concentration (mg/kg)
6,000
7,000
Implications
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Analytical Recovery of F3 Used to Derive
Guideline: 31%
Analytical Recovery of F3 Using CCME
Analytical Method: 70%
Taken In Isolation, This Suggests Current
Guideline Is Over-Conservative
Summary
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Project completion: October 2005
Cyclodextrin F3 guideline developed
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Method development needed
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identify soils likely to be non-toxic
chronic invertebrate toxicity test in subsoil
Analytical recovery (31%) used in PHC
CWS may be over-conservative