Bulk Humin - CLU-IN
Bulk Humin - CLU-IN
Bulk Humin - CLU-IN
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Tools to Assess Plant C and PAH C Cycling in PAH-<br />
Contaminated Sediments.<br />
S.T. Gregory and Elizabeth Guthrie-Nichols<br />
Environmental Technology Program<br />
Department of Environmental and Molecular Toxicology
Acknowledgements and Collaborators<br />
Thorne Gregory, NCSU - Poster<br />
Jeremy Bell, NCSU<br />
Chris Swanston, LLNL<br />
Laura Hainsworth, LLNL<br />
John Vogel, LLNL<br />
Evelyn Drake<br />
Steve Rock, US EPA<br />
Brad Atkinson, NC DENR<br />
National Science Foundation, BES-0337453
Rhizosphere mechanisms that alter organic matter<br />
Microbial exudates Plant exudates<br />
Stabilize organic matter<br />
or<br />
Destabilize organic matter<br />
Labile and Refractory Carbon Pools<br />
Plant uptake<br />
of HOC<br />
Biogenic Carbon Cycling<br />
Contaminant bioaccessibility<br />
Microbial Degradation<br />
of HOC
Tools to Relate changes to SOM by plants to PAH attenuation<br />
Different Sites<br />
Ecologies<br />
Contaminants<br />
“Are we there yet?” or<br />
“Heading in the right direction”<br />
Phragmites<br />
Photos courtesy of Steve Rock<br />
Phragmites from field
Tools for OM Characterization<br />
• Changes to SOM composition as vegetation develops<br />
% TOC<br />
13 C NMR<br />
(carbon composition)<br />
Labile and Refractory OM<br />
Humic materials<br />
Light and Heavy Density<br />
δ 13 C IRMS<br />
14 C Radiocarbon Dating<br />
Plant Carbon<br />
PAH
Tools for to Characterize PAH Attenuation<br />
• PAH Attenuation as SOM changes with plant C inputs<br />
PAH Concentrations<br />
- Histograms<br />
- Compound ratios Plant Carbon<br />
Labile and Refractory OM<br />
Humic materials<br />
Density Fractions<br />
δ 13 C IRMS<br />
14 C Radiocarbon Dating<br />
PAH
Modern Plant Carbon and Petroleum Carbon<br />
Radiocarbon Signatures<br />
14 CO2<br />
14 C<br />
PMC for plants = 100% (modern)<br />
• High Abundance of 14C from 14 Plants<br />
CO2 in atmosphere<br />
N 2<br />
petroleum<br />
PMC for petroleum = 0% (dead)<br />
• Low Abundance of 14C due 14C decay over time
Modern Plant C and Petroleum Radiocarbon Signatures<br />
14 CO2<br />
Plants<br />
14 C<br />
Modern C (high PMC)<br />
Petroleum products<br />
Dead C (low PMC)<br />
N 2
Fractionation Methods to Improve C Cycling Sensitivity<br />
Humic Chemical Fractionation Density Separation<br />
<strong>Bulk</strong> Sediment<br />
2x Solvent Extraction<br />
Alkaline<br />
<strong>Bulk</strong> <strong>Humin</strong> Humic Materials<br />
HF/HCl -Treated <strong>Humin</strong><br />
<strong>Bulk</strong> Sediment<br />
CsCl<br />
Light Fraction Heavy Fraction<br />
Occluded Light<br />
Fraction<br />
Sonication<br />
Heavy<br />
Fraction<br />
Represent functionally different C pools<br />
that are simple enough to link to<br />
ecosystem models
Results<br />
Characterization of OM (Gasoline Distillate Waste)<br />
Non- Phragmites<br />
Vegetated Mixed Grass<br />
<strong>Bulk</strong> Sediment<br />
%TOC 21 + 1.9 27 + 0.4<br />
14C PMC 2.0 + 0.1 24 + 0.16<br />
<strong>Bulk</strong> <strong>Humin</strong><br />
%TOC 7.5 + 0.2 13 + 0.1<br />
14C PMC 6.1 + 0.1 44 + 0.3<br />
HF/HCl <strong>Humin</strong><br />
%TOC 10 + 1.8 28 + 1.0<br />
14C PMC 2.1 + 0.1 33 + 0.2<br />
14 C abundance increases due to Plant C inputs<br />
into Distillate Waste Sediment<br />
estuary<br />
8-10 ft<br />
Asphalt-like waste<br />
18% TPH
Changes to OM Composition<br />
Characterization of Gasoline Distillate Waste<br />
Non- Phragmites<br />
Vegetated Mixed Grass<br />
<strong>Bulk</strong> Sediment<br />
%TOC 21 + 1.9 27 + 0.4<br />
14C PMC 2.0 + 0.1 24 + 0.16<br />
<strong>Bulk</strong> <strong>Humin</strong><br />
%TOC 7.5 + 0.2 13 + 0.1<br />
14C PMC 6.1 + 0.1 44 + 0.3<br />
HF/HCl <strong>Humin</strong><br />
%TOC 10 + 1.8 28 + 1.0<br />
14C PMC 2.1 + 0.1 33 + 0.2<br />
14 C abundance increases for Labile and<br />
Refractory OM fractions; <strong>Humin</strong> has more…<br />
Sediment (n=4)<br />
Trees, shrubs<br />
Phrag/<br />
Grasses<br />
Phrag/Colonization<br />
No vegetation<br />
Plant Carbon<br />
Phragmites δ 13 C<br />
PAH<br />
-27.50 -27.00 -26.50 -26.00 -25.50 -25.00 -24.50<br />
δ 13 C<br />
<strong>Bulk</strong> Sediment<br />
<strong>Bulk</strong> <strong>Bulk</strong> <strong>Humin</strong><br />
<strong>Humin</strong><br />
HF <strong>Humin</strong>
[PAH] relative to OM changes Plant Carbon<br />
Non- Phragmites<br />
Vegetated Mixed Grass<br />
<strong>Bulk</strong> Sediment<br />
%TOC 21 + 1.9 27 + 0.4<br />
14C PMCa 2.0 + 0.1 24 + 0.16<br />
TPAH (μg/g soil) 161 + 11.8 69 + 2.9<br />
<strong>Bulk</strong> <strong>Humin</strong><br />
%TOC 7.5 + 0.2 13 + 0.1<br />
14C PMC 6.1 + 0.1 44 + 0.3<br />
TPAH (μg/g soil) 14 + 1.9 11 + 1.2<br />
HF/HCl <strong>Humin</strong><br />
%TOC 10 + 1.8 28 + 1.0<br />
14C PMC 2.1 + 0.1 33 + 0.2<br />
TPAH (μg/g soil) 6.0 + 1.0 2.8 + 0.3<br />
a Analyses by NOAA/WHOI AMS facility<br />
estuary<br />
PAH<br />
8-10 ft<br />
Asphalt-like waste<br />
18% TPH
[PAH] relative to OM changes Plant Carbon<br />
Non- Phragmites<br />
Vegetated Mixed Grass<br />
<strong>Bulk</strong> Sediment<br />
%TOC 21 + 1.9 27 + 0.4<br />
14C PMCa 2.0 + 0.1 24 + 0.16<br />
TPAH (μg/g soil) 161 + 11.8 69 + 2.9<br />
TPAH (μg/g OC) 767 + 125 254 + 14.4<br />
<strong>Bulk</strong> <strong>Humin</strong><br />
%TOC 7.5 + 0.2 13 + 0.1<br />
14C PMC 6.1 + 0.1 44 + 0.3<br />
TPAH (μg/g soil) 14 + 1.9 11 + 1.2<br />
TPAH (μg/g OC) 181 + 29.3 81 + 9.5<br />
HF/HCl <strong>Humin</strong><br />
%TOC 10 + 1.8 28 + 1.0<br />
14C PMC 2.1 + 0.1 33 + 0.2<br />
TPAH (μg/g soil) 6.0 + 1.0 2.8 + 0.3<br />
TPAH (μg/g OC) 60 + 21 10 + 1.4<br />
a Analyses by NOAA/WHOI AMS facility<br />
PAH<br />
Inputs of Plant C related to<br />
decreased [PAH]
[PAH] relative to OM changes Plant Carbon<br />
Non- Phragmites<br />
Vegetated Mixed Grass<br />
<strong>Bulk</strong> Sediment<br />
%TOC 21 + 1.9 27 + 0.4<br />
14C PMCa 2.0 + 0.1 24 + 0.16<br />
TPAH (μg/g soil) 161 + 11.8 69 + 2.9<br />
TPAH (μg/g OC) 767 + 125 254 + 14.4<br />
<strong>Bulk</strong> <strong>Humin</strong><br />
%TOC 7.5 + 0.2 13 + 0.1<br />
14C PMC 6.1 + 0.1 44 + 0.3<br />
TPAH (μg/g soil) 14 + 1.9 11 + 1.2<br />
TPAH (μg/g OC) 181 + 29.3 81 + 9.5<br />
HF/HCl <strong>Humin</strong><br />
%TOC 10 + 1.8 28 + 1.0<br />
14C PMC 2.1 + 0.1 33 + 0.2<br />
TPAH (μg/g soil) 6.0 + 1.0 2.8 + 0.3<br />
TPAH (μg/g OC) 60 + 21 10 + 1.4<br />
a Analyses by NOAA/WHOI AMS facility<br />
HUM<strong>IN</strong><br />
Nonvegetated<br />
Phragmites<br />
colonization<br />
Carbonyl C<br />
Phragmites/Grass<br />
PAH<br />
Carboxyl<br />
Ester C<br />
Amide C<br />
Aromatic C<br />
Phenols<br />
C-O C-N<br />
Alkyl-O<br />
Aliphatic C<br />
72 ppm 33 ppm
Other Indices for PAH Attenuation…<br />
PAH Concentrations (Alkylated and Non-alkylated PAHs)<br />
• PAH Distribution Histograms<br />
PAH Families (i.e., Phenanthrene)<br />
P0 Phenanthrene<br />
P1 Methyl Phenanthrene<br />
P2 Di-methyl Phenanthrene<br />
• Compound Specific PAH Ratios<br />
Ratios of particular alkylated or parent PAHs
PAH Attenuation<br />
mg PAH / kg sediment<br />
Weathering Indices (Petroleum Distillate Waste)<br />
2 1<br />
1 8<br />
1 5<br />
1 2<br />
9<br />
6<br />
3<br />
0<br />
2 1<br />
1 8<br />
1 5<br />
1 2<br />
1 . 2<br />
1 . 0<br />
0 . 8<br />
0 . 6<br />
0 . 4<br />
0 . 2<br />
0 . 0<br />
1 . 2<br />
1 . 0<br />
0 . 8<br />
0 . 6<br />
0 . 4<br />
0 . 2<br />
0 . 0<br />
9<br />
6<br />
3<br />
0<br />
<strong>Bulk</strong> Sediment - No vegetation<br />
N 0 B P A C L A C E D f u N 1 N 2 N 3 N 4 F 0 F 1 F 2 F 3 D 0 D 1 D 2 D 3 A N P 0 P 1 P 2 P 3 P 4 F L P Y F P 1 R e B a A C 0 C 1 C 2 C 3 C 4 B b F B k F B e F B a F P r y l IO P D A B g P C o<br />
N1 N2 N3 N4 F0 F1 F2 F3 D0 D1 D2 D3 P0 P1 P2 P3 P4 C0 C1 C2 C3 C4<br />
<strong>Bulk</strong> Sediment – Phragmites/Grass<br />
Phragmites/Grass<br />
A<br />
N 0 B P A C L A C E D f u N 1 N 2 N 3 N 4 F 0 F 1 F 2 F 3 D 0 D 1 D 2 D 3 A N P 0 P 1 P 2 P 3 P 4 F L P Y F P 1 R e B a A C 0 C 1 C 2 C 3 C 4 B b F B k F B e F B a F P r y l IO P D A B g P C o<br />
N1 N2 N3 N4 F0 F1 F2 F3 D0 D1 D2 D3 P0 P1 P2 P3 P4 C0 C1 C2 C3 C4<br />
HF/HCl <strong>Humin</strong> - No vegetation<br />
f r l I N 0 B P A C L A C E D u N 1 N 2 N 3 N 4 F 0 F 1 F 2 F 3 D 0 D 1 D 2 D 3 A N P 0 P 1 P 2 P 3 P 4 F L P Y F P 1 R e B a A C 0 C 1 C 2 C 3 C 4 B b F B k F B e F B a F P y O P D A B g P C o<br />
N1 N2 N3 N4 F0 F1 F2 F3 D0 D1 D2 D3 P0 P1 P2 P3 P4 C0 C1 C2 C3 C4<br />
HF/HCl <strong>Humin</strong> – Phragmites/Grass<br />
Phragmites/Grass<br />
N 0 B P A C L A C E D f u N 1 N 2 N 3 N 4 F 0 F 1 F 2 F 3 D 0 D 1 D 2 D 3 A N P 0 P 1 P 2 P 3 P 4 F L P Y F P 1 R e B a A C 0 C 1 C 2 C 3 C 4 B b F B k F B e F B a F P r y l I O P D A B g P C o<br />
N0 Bp Acl Ace Dfu N1 N2 N3 N4 F0 F1 F2 F3 D0 D1 D2 D3 An P0 P1 P2 P3 P4 Fl Py Fp1 Re BaA C0 C1 C2 C3 C4 BbF BkF BeP BaP Pryl Iop DA BgP Co<br />
B
PAH Attenuation<br />
Weathering Indices – Compound Ratios<br />
N3/P2 Weathering Ratio<br />
1.0<br />
0.9<br />
0.8<br />
0.7<br />
0.6<br />
0.5<br />
0.4<br />
0.3<br />
0.2<br />
0.1<br />
0.0<br />
Increased Weathering<br />
Increased weathering<br />
<strong>Bulk</strong> Sediment Fractions<br />
Non Vegetated<br />
Phragmites/Grass<br />
Phragmites Colonization<br />
Trees/Shrubs<br />
0.0 0.2 0.4 0.6 0.8<br />
D3/C3 Weathering Ratio
PAH Attenuation<br />
Compound Ratio to %TOC<br />
HF/HCl <strong>Humin</strong> Fractions<br />
N3/P2 Weathering Ratio<br />
1.4<br />
1.2<br />
1.0<br />
0.8<br />
0.6<br />
0.4<br />
0.2<br />
0.0<br />
Increased Weathering<br />
Non Vegetated<br />
Phragmites Colonization<br />
5 15 25 35 45<br />
% Organic Carbon<br />
Phragmites/Grass<br />
Trees/Shrubs<br />
Plant Carbon<br />
PAH
For Humic Fractionations…<br />
• Plant-derived C inputs present in bulk sediment and humin<br />
– Greater inputs to humin<br />
• Reduced [PAH] related to inputs of Plant C and 14 C PMC<br />
– For labile and refractory distillate waste OM<br />
– Percent loss (PAH C norm) greater for humin (83% to 67%)<br />
• More weathered PAH compound ratios related to Plant C and<br />
14 C PMC
Density Fractionation of SOM<br />
Simplifying SOM Fractionation<br />
Density Separation<br />
Light Fraction Heavy Fraction<br />
Labile C<br />
Fast C cycling<br />
<strong>Bulk</strong> Sediment<br />
CsCl<br />
Occluded Light<br />
Fraction<br />
More degraded;<br />
recalcitrant due to<br />
microbial degradation of<br />
Light Fraction<br />
Sonication<br />
Heavy<br />
Fraction<br />
Fast C cycling pools<br />
Slow C cycling pools<br />
Plant Carbon<br />
PAH<br />
(Swanston et al., 2004)
Density Fractionation of SOM<br />
Fractions that are more ecologically-relevant<br />
Density Separation<br />
<strong>Bulk</strong> Sediment<br />
Light Fraction Heavy Fraction<br />
Younger ( 14 C); Fast C turnover<br />
CsCl<br />
Occluded Light<br />
Fraction<br />
Sonication<br />
Heavy<br />
Fraction<br />
Older ( 14C) Slower C turnover<br />
C sequestration<br />
Plant Carbon<br />
PAH
Density Fractions and SOM Composition<br />
Characterization of Gasoline Distillate Waste<br />
Density Fraction %TOC 14 C PMC<br />
Non-vegetated<br />
Light Free 46 + 1.5 1.9<br />
Occluded Light 30 + 1.2 3.2<br />
Heavy 10 + 0.2 5.3<br />
Phragmites/Grass<br />
Light Free 34 + 0.9 57 younger, biogenic C from plants<br />
Occluded Light 28 + 0.1 30 biogenic inputs but cycles slower<br />
Heavy 12 + 0.5 31 biogenic inputs but cycles slower<br />
Plant C is present in all fractions with vegetation, but greatest for Light Fraction<br />
a Analyses by LLNL AMS facility.<br />
estuary<br />
8-10 ft<br />
Asphalt-like waste<br />
18% TPH
OM Changes in Density Fractions<br />
Gasoline Distillate Waste – Density Fractions<br />
Fraction %TOC 14 Non-vegetated<br />
C PMC [PAH]<br />
μg/g soil<br />
Light Free 46 + 1.5 1.9 504<br />
Occluded Light 30 + 1.2 3.2 361<br />
Heavy 10 + 0.2 5.3 62<br />
Phragmites/Grass<br />
Light Free 34 + 0.9 57 181<br />
Occluded Light 28 + 0.1 30 56<br />
Heavy 12 + 0.5 31 37<br />
a Analyses by LLNL AMS facility.<br />
More Plant C in Vegetated Light Fraction<br />
Plant C inputs directly linked to PAH loss in all three fractions<br />
Plant Carbon<br />
PAH
OM Changes relative to [PAH]<br />
Gasoline Distillate Waste – Density Fraction<br />
Fraction %TOC 14C PMC [PAH] [PAH]<br />
Non-vegetated<br />
μg/g soil μg/g OC<br />
Light Free 46 + 1.5 1.9 504 554<br />
Occluded Light 30 + 1.2 3.2 361 1205<br />
Heavy 10 + 0.2 5.3 62 608<br />
Phragmites/Grass<br />
Light Free 34 + 0.9 57 181 523 no change % loss PAH<br />
Occluded Light 28 + 0.1 30 56 200 greatest % loss PAH<br />
Heavy 12 + 0.5 31 37 306 greatest % loss PAH<br />
a Analyses by LLNL AMS facility.<br />
More Plant C in Vegetated Light Fraction<br />
Plant C inputs directly linked to PAH loss in all three fractions<br />
Plant Carbon<br />
PAH
N0 N0 N0<br />
BP BP BP<br />
ACL ACL ACL<br />
ACE ACE ACE<br />
Dfu Dfu Dfu<br />
N1 N1 N1<br />
N2 N2 N2<br />
N3 N3 N3<br />
N4 N4 N4<br />
F0 F0 F0<br />
F1 F1 F1<br />
N0 N0<br />
F2 F2 F2<br />
BP BP<br />
F3 F3 F3<br />
ACL ACL<br />
D0 D0 D0<br />
ACE ACE<br />
D1 D1 D1<br />
Dfu Dfu<br />
D2 D2 D2<br />
N1 N1<br />
D3 D3 D3<br />
N2 N2<br />
AN AN AN<br />
N3 N3<br />
P0 P0 P0<br />
N4 N4<br />
P1 P1 P1<br />
F0 F0<br />
P2 P2 P2<br />
N0<br />
F1 F1<br />
P3 P3 P3<br />
N0 N0<br />
F2 F2<br />
P4 P4 P4<br />
BP BP BP<br />
F3 F3<br />
FL FL FL<br />
ACL ACL ACL<br />
ACE<br />
D0 D0<br />
PY PY PY<br />
ACE ACE<br />
D1 D1<br />
FP1 FP1 FP1<br />
Dfu Dfu Dfu<br />
D2 D2<br />
Re Re Re<br />
N1 N1 N1<br />
D3 D3<br />
BaA BaA BaA<br />
N2 N2 N2<br />
AN AN<br />
C0 C0 C0<br />
N3 N3 N3<br />
P0 P0<br />
C1 C1 C1<br />
N4 N4 N4<br />
P1 P1<br />
C2 C2 C2<br />
F0 F0 F0<br />
P2 P2<br />
C3 C3 C3<br />
F1 F1 F1<br />
P3 P3<br />
C4 C4 C4<br />
F2 F2 F2<br />
P4 P4<br />
BbF BbF BbF<br />
F3 F3 F3<br />
FL FL<br />
BkF BkF BkF<br />
D0 D0 D0<br />
PY PY<br />
BeP BeP BeP<br />
D1 D1 D1<br />
FP1 FP1<br />
BaP BaP BaP<br />
D2 D2 D2<br />
Re Re<br />
Pryl Pryl Pryl<br />
D3 D3 D3<br />
BaA BaA<br />
IOP IOP IOP<br />
AN AN AN<br />
C0 C0<br />
DA DA DA<br />
P0 P0 P0<br />
C1 C1<br />
BgP BgP BgP<br />
P1 P1 P1<br />
C2 C2<br />
Co Co Co<br />
P2 P2 P2<br />
C3 C3<br />
P3 P3 P3<br />
C4 C4<br />
P4 P4 P4<br />
BbF BbF<br />
FL FL FL<br />
BkF BkF<br />
PY PY PY<br />
BeP BeP<br />
FP1 FP1 FP1<br />
BaP BaP<br />
Re Re Re<br />
Pryl Pryl<br />
BaA BaA BaA<br />
IOP IOP<br />
C0 C0 C0<br />
DA DA<br />
C1 C1 C1<br />
BgP BgP<br />
C2 C2 C2<br />
Co Co<br />
C3 C3 C3<br />
C4 C4 C4<br />
BbF BbF BbF<br />
BkF BkF BkF<br />
BeP BeP BeP<br />
BaP BaP BaP<br />
Pryl Pryl Pryl<br />
IOP IOP IOP<br />
DA DA DA<br />
BgP BgP BgP<br />
Co Co Co<br />
Results<br />
Weathering Indices for Density Fractions (Petrogenic)<br />
mg/kg PAH/soil mass<br />
mg/kg PAH/soil mass<br />
mg/kg PAH/soil mass<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<br />
14<br />
12<br />
10<br />
8<br />
6<br />
4<br />
2<br />
0<br />
6<br />
5<br />
4<br />
3<br />
2<br />
1<br />
0<br />
Refinery Waste Pit – No Plants<br />
Light Density Fraction<br />
Refinery Waste Pit – with Phragmites<br />
Light Density Fraction<br />
Refinery Waste Pit – with Phragmites<br />
Light Occluded Density Fraction<br />
Plant Carbon<br />
PAH
PAH Attenuation in Density Fractions<br />
• Specific PAH Ratios<br />
N3/P2 weathering ratio<br />
1<br />
0.75<br />
0.5<br />
0.25<br />
0<br />
Increased Weathering<br />
Heavy No Plants<br />
Heavy Phragmites<br />
Occluded Light<br />
No Plants<br />
Increased weathering<br />
Light No Plants<br />
Occluded Light Phragmites<br />
0.01 0.11 0.21 0.31 0.41 0.51 0.61<br />
D3/C3 weathering ratio<br />
Light<br />
Phragmites<br />
Plant Carbon<br />
PAH
PAH Attenuation in Density Fractions<br />
Specific PAH Ratios to %TOC<br />
N3/P2 weathering ratio<br />
1<br />
0.75<br />
0.5<br />
0.25<br />
0<br />
Increased Weathering<br />
Heavy No Plants<br />
Heavy Phragmites<br />
Occluded Light No Plants<br />
5 15 25 35 45<br />
%TOC<br />
Light No Plants<br />
Occluded Light Phragmites<br />
Light Phragmites<br />
Plant Carbon<br />
PAH
PAH Attenuation relative to 14 C PMC<br />
• Specific PAH Ratios to Percent Modern Carbon<br />
N3/P2 weathering ratio<br />
Increased Weathering<br />
1<br />
0.9<br />
0.8<br />
0.7<br />
0.6<br />
0.5<br />
0.4<br />
0.3<br />
0.2<br />
0.1<br />
0<br />
Heavy No Plants<br />
Light Phragmites<br />
Occluded Light<br />
No Plants<br />
Occluded Light Phragmites<br />
Heavy Phragmites<br />
1 11 21 31 41 51<br />
% 14 C PMC<br />
Light<br />
No Plants<br />
Plant Carbon<br />
PAH
For Density Fractions…<br />
• Plant-derived C present in all vegetated density fractions<br />
• Light fraction contained most Plant C<br />
• Reduced [PAH] were related to inputs of Plant C<br />
– Mass loss of PAH for all vegetated density<br />
fractions<br />
– Mass loss greater for occluded and heavy<br />
fractions<br />
• Increased 14 C PMC values related to more<br />
weathered N3/P3 ratios
Potential Application to PAH Cycling Among Trophic Levels<br />
Higher Trophic Organisms<br />
Plant C compounds Benthic Organisms<br />
Microbial lipids<br />
Modern C (high PMC)<br />
Petroleum products<br />
Carbon Cycling Dead C (low PMC)<br />
Labile and Refractory SOM fractions
Future Directions…<br />
• Can 14C PMC be used to assess PAH attenuation in relation to other<br />
weathering indices<br />
– Desorption isotherms, toxicity assays<br />
– Biological inventory data (indices for eco-restoration)<br />
• Use 14 C PMC and fractions to evaluate PAH C cycling from<br />
petrogenic and pyrogenic sources<br />
• Use 14C radiocarbon analyses and IRMS to evaluate PAH C cycling<br />
among trophic levels at field sites<br />
– Other petroleum-derived contaminants
Results<br />
• PAH Attenuation via Weathering Indices<br />
D3/C3 weathering ratio<br />
1<br />
0.75<br />
0.5<br />
0.25<br />
0<br />
Increased Weathering<br />
Heavy Phragmites<br />
Heavy No Plants<br />
5 15 25 35 45<br />
%TOC<br />
Occluded Light<br />
No Plants<br />
Occluded Light<br />
Phragmites<br />
Light Phragmites<br />
Light<br />
No Plants<br />
Plant Carbon<br />
PAH
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