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Phantom PHCs?
Francine Kelly-Hooper, Soils Scientist
Using the F2:F3b ratio to eliminate false PHC detections in clean soils
CH2M HILL Canada
Research Partners
Imperial Oil
ALS Laboratory Group
Canadian Association of Petroleum Producers, Petroleum Technology Alliance of Canada
Husky Energy
Alberta Parks and Protected Areas Division
Environment Canada Oil Spills Research Centre
Natural Sciences and Engineering Research Council
Natural Resources Canada
Orphan Well Association
Geological Survey of Canada
2007: Crude Oil Spiked Peat Experiment
Spiked peat with crude oil to study biogenic vs petrogenic carbon patterns over a 300 day period.
2008: Diesel Spiked Manure Experiment
Spiked composted manure and sand with diesel oil and studied biogenic vs petrogenic carbon patterns over a 300 day period.
2009: Background PHC survey of 34 sites located in Alberta, BC and Newfoundland
Canadian Geologic Survey collected soils samples and shipped them to ALS Laboratories in Waterloo for PHC, PAH and grain size analysis.
What are biogenic organic compounds?
BOCs are carbon-based compounds that are naturally biosynthesized by living organisms. BOCs are ubiquitous throughout the environment.
BOC groups containing C, H and O include: lipids, carbohydrates, proteins and nucleic acids.
BOC hydrocarbon groups containing only C and H include n-alkanes.
Why are BOCs confused as PHCs?
Canadian Council of Ministers of the Environment (CCME) Reference Method for the Canada-Wide Standard (CWS) for
Petroleum Hydrocarbons (PHC) in Soil
Methods can produce false positives in uncontaminated organic materials (e.g. peat, manure, etc.).
The goal is to “catch” petroleum hydrocarbons. However, background biogenic organic compounds are inadvertently “caught” as well.
The problem is that the hexane and acetone solvents indiscriminately extract all carbon from petroleum and biological sources.
Source: thedatingangle.com
Extract injection
F2, F3, F4 concentrations quantified by chromatogram integrations
) ) ) ) ) ) ) )
ion flow flame detector
capillary column
carrier gas line
Vaporizer Oven
Flame Ionization Detector
electronic signal
GC-FID Analysis of Sample Extract
Retention Time (minutes)
0
100
200
300
pA
4 5 6 7 8 9 10 11
F4 >C34
F3 C16-C34
F2 C10-C16
UCM
Diesel F3 2000 mg/kg
Reported F3 3000 mg/kg Peat
F3 1000 mg/kg
Diesel-Spiked Peat GC-FID Chromatogram
Carbon Numbers
F1 F2 F4
C10 C16 C6 C34 >C34
F4 C34
F1 F2 C10-C16
> F3
C16-C34 C6-C10
Biogenic Organic Compounds
(e.g. fatty acids, sterols, waxes, etc. ) Gasoline
Diesel/No. 2 Fuel Oil
Crude Oil
No. 6 Oil/Lube Oil/Heavy fuels, Tar, Asphalts
Classification of Petroleum Hydrocarbon Sources by Carbon Number Range
CCME Fractions F1 to F4
Carbon Numbers
F2
C10 C19 C6 C32
LEPH C10-C19
HEPH C19-C32
Biogenic Organic Compounds
(e.g. fatty acids, sterols, waxes, etc. ) Gasoline
Diesel/No. 2 Fuel Oil
Crude Oil
No. 6 Oil/Lube Oil/Heavy fuels, Tar, Asphalts
Classification of Petroleum Hydrocarbon Sources by Carbon Number Range
LEPH and HEPH Ranges
Comparison of Background Soil Survey Results to Alberta Tier 1 Soil and Groundwater Remediation Guidelines
Alberta Tier 1 Soil and Groundwater Remediation Guidelines – March 18, 2014
“Coarse textured soil and groundwater remediation guidelines may be used for organic contaminants in organic soils”
34 Background Soil Samples: AB, BC, NL
0
400
800
1200
1600
F3
(mg
/kg
) Comparisons of F2, F3, F4 Concentrations to AB Tier 1 Soil Remediation Guidelines
Surface Soils Natural/Agr/Resid/Parkland Guidelines
16 samples (47%) exceeded F3 coarse soil standard 300 mg/kg
0
50
100
150
200
F2
(mg
/kg
)
0 samples exceeded F2 course soil standards 150 mg/kg
%TOC
0
1000
2000
3000
0% 10% 20% 30% 40%
F4
(mg
/kg
)
0 samples exceeded F4 course soil standards
2800 mg/kg
Only F3 exceeded the Guidelines
• All soils with >28% TOC exceeded the F3 coarse soil standards
• Peat soils have >40% TOC
source: Peatland Resources of Canada
Peat soils cover 11% of Canada
0-1%
2-8% 6-25% 26-75% 76-100%
source: Alberta Geological Survey
Peat soils cover 18% of Alberta
But there is a light at the end of the tunnel!
F2:F3b presence vs absence ratio
Ratio >0.10 = PHC presence (contaminated)
Ratio <0.10 = PHC absence (clean)
Nil F2
High F2
High F2
F3a (C16-C22) and F3b (C22-C34) Distributions in Diesel and Clean Peat
F3a
F2 Total F3 F4
Carbon Number C16 C10 C22 C34
Clean Peat
7% F3a 93% F3b
11% F3b
89% F3a
F3b 63%
F3a 37%
Diesel
Diesel Contaminated
Peat
F3b (C16-C22) (C22-C34)
F3a (C16-C22) and F3b (C22-C34) Distributions in Crude Oil and Clean Peat
F2 Total F3 F4
Crude + Peat
Carbon Number
C16 C10 C22 C34
Peat
69% F3b
31% F3a
F3a F3b (C16-C22) (C22-C34)
FederatedCrude Oil
50% F3b
50% F3a
7% F3a 93%
F3b
Nil F2
High F2
High F2
13 Crude Oil Samples
% o
f T
ota
l F3
Co
nce
ntr
atio
n
0
25
50
75
100
13 Fresh Crude Oil Samples 34 Background Soil Samples
34 Soil Samples
0
25
50
75
100
% o
f T
ota
l F3
Co
nce
ntr
atio
n
F3a (C16-C22) F3b (C23-C34) F3a (C16-C22) F3b (C23-C34)
Median
F3b 93% F3a 7%
F3b 51%
F3a 49%
Median
1 2 3 4 5 6 7 8 9 10 11 12 13
Heavy PHC sources such as engine oil and tar have high F3b percentages as do clean soils, manure and biosolids
F3a F3b
F2 F3 F4
Tar
Engine Oil
Crude Oil
Diesel Fuel
Peat 7% F3a 93%
F3b
F3a 89%
F3b 11%
53% F3b
47% F3a
6% F3a
94% F3b
14% F3a
86% F3b
High F3a
High F3a
Low F3a
Low F3a
Low F3a
Carbon Number C16 C10 C22 C34
Clean Peat
Diesel
Diesel Spiked
Peat
F2:F3b Ratio
= 2.22
= 0.79
= 0.01
F2
F2 = 823 mg/kg
F3b = 371 mg/kg
F2 = 613 mg/kg F3b = 2,816 mg/kg
F2 = 10 mg/kg F3b = 1,395 mg/kg
F3b
ABSENT
PRESENT
PRESENT
F2:F3b Ratio Diesel PHC Presence Value is >0.10
F2
Total F3
Carbon Number C16 C10 C22 C34
Clean Peat
F2 = 10 mg/kg
F3b = 1,000 mg/kg
F2:F3b Ratio
= 0.01
Crude Oil Spiked
Peat
F2 = 1,000 mg/kg
F3b = 2,000 mg/kg
= 0.50
F3b
Crude Oil
F2 = 1,000 mg/kg
F3b = 1,200 mg/kg = 0.83
ABSENT
PRESENT
PRESENT
F2:F3b Ratio Crude Oil PHC Presence Value is >0.10
10
100
1000
10000
100000
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.600.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.600.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
300
300 mg/kg F3 coarse soil guideline
F2:F3b Ratio
Mea
sure
d F
3 (m
g/kg
) (l
og s
cale
)
PHC presence
clean soils/compost contaminated soil/compost
contaminated sand
0.10
PHC absence 0.10
Manure Compost, Peat and Sand Spiked with Diesel and Crude OIl – Day 0 & Day 300 Samples
F2:F3b Ratios and F3 Concentrations Clean Manure Compost and Background Soil Survey Samples
Contaminated samples >300 mg/kg F3 also had >0.10 F2:F3b ratio
Does the contamination source have an F2:F3b ratio of >0.10?
No Do not proceed with evaluation
Management required
Do the F2 and/or F4 concentrations in the soil sample exceed soil standards?
Yes No
Does the F3 concentration in the soil sample exceed the soil standard?
Does the GC-FID pattern in the peat sample match the GC-FID pattern(s) in the contamination source and/or background soil?
No Yes Exclude sample from evaluation
No Yes
Management not required
No
Pre-screening requires
chromatogram interpretation
expertise
Yes
Tie
r 1
Eva
luat
ion
Pre
-scr
eeni
ng
Is the F2:F3b ratio in the soil sample >0.10?
Yes
Does the soil sample biomarker and/or PAH analysis indicate PHC presence?
No
Management not required
Yes
Management required
No
Management not required
Tie
r 2
Eva
luat
ion
Biogenic vs Petrogenic Decision Tree
Rules of Thumb for Practical Applications
• Cannot be used to assess soils contaminated by heavy PHC products (e.g. motor oil, tar, asphalt, etc.)
• PHC contamination source must have an F2:F3b ratio of greater than or equal to 0.10
• Chromatograms must be studied for every soil sample to ensure that all contaminated samples have the same PHC source.
• Clean samples are identified by non-detectable F2 concentrations combined with the absence of PHC UCMs.
