Danny Reible, X Lu, A Skwarski, B Drake and D Lampert University of Texas Presented by Andrew Jackson, Texas Tech University Research supported by

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1 Danny Reible, X Lu, A Skwarski, B Drake and D Lampert University of Texas Presented by Andrew Jackson, Texas Tech University Research supported by EPA, DOD ESTCP/SERDP, NIH & Industrial Sources 1

2 Traditional Indicator Bulk sediment concentration Relatively easy to measure If equilibrium partitioning applies, bulk sediment measure also indicates porewater/mobile phase concentrations Absent direct partitioning data: Ws K = = K f C d oc oc pw Reality: porewater concentration is typically << predicted by this equation, due to desorption resistant phenomena 2

3 Bulk sediment concentration is less useful as indicator of exposure risk Porewater concentration is better indicator (even for active benthic uptake by ingestion) Porewater is difficult to measure, but possible with solid phase micro extraction (SPME) Field deployable SPME, capable of measuring porewater with vertical resolution 3

4 Direct in situ measurement (PE, POM, SPME) Solid phase microextraction (SPME) Sorbent polymer PDMS (poly dimethylsiloxane) 30 µm fiber on 110 µm core (13.6 (3 µl PDMS/m of fiber) 10 µm on 230 µm core (7 µl /m) 30 µm on 1 mm core (94 µl /m) ng/l detection with 1 cm resolution Profiling field deployable system May require 7 30 days to equilibrate x

5 Equilibrium K f PCB factor of two PAH +/ 45% Fiber Volume 7 94 µl/m Log Kf PAHs/PCBs Log Kf = Log Kow R² = PAHs PCBs Log Kow 5

6 600 PAH Kinetics in Sampling Rod External MT control Key Area /Volume PAHs relatively quick 4 6 days High molecular weight Fiber conc (μg/l) Phen B[b]F Chrysene B[a]P Time(d) PCBs much slower days Field Confirmation Different exposure times Different fiber thickness Add tracers Fiber conc c (μg/l) PCB Kinetics in Field Sampling Rod PCB52 PCB153 PCB28 PCB Time(d) 6

7 Extraction and Analysis PAHs HPLC w/fluorescent detection Extraction with µl ACN directly in autosampling vials with inserts PCBs GC w/ecd Extraction with µl hexane directly in autosampling vials with inserts Thermal ldesorption with splitless l injection Potential for co elution of congeners Dt Detection ti limits it (1 cm 170/110 PDMS fiber) 10 pg/l (High MW PCBs) to 10 ng/l (Low MW PAHs) 7

8 Bioaccumulation studies Ilyodilus (freshwater oligochaete) Anacostia River sediments New Bedford Harbor/Brown Lake sequentially diluted sediments e (3, 6, 12, 25% NBH) Neanthes (marine polychaete) Hunter s Point sediments Cross comparison of direct porewater measurements (Hunter s Point) Thin Layer Capping (Anacostia River) 8

9 log BCF BCF = f C t lipid C pw Freshwater oligochaetes PAHs and PCBs Anacostia River sediments R 2 = log K ow In sediments and in deposit-feeding organism (porewater not route of exposure) 9

10 lo og BCF BCF = f C t lipid C pw Freshwater oligochaetes PAHs and PCBs Sequential Dilution sediments R 2 = log K ow 10

11 t/flipid)/cpw w) Log( (C BCF = f C t lipid C pw y = 1.103x R² = Marine polychaetes PCBs Hunter s Point sediments R 2 = Log K ow 11

12 Log ((C Ct/flipid)/Cp pw) BCF = f C t lipid C pw y = 1.071x R² = Marine and freshwater PAHs and PCBs R 2 =0.845 Log BCF=1.07 Log Kow Log K ow 12

13 PCB SPME POM PE** Air Bridge Extracted Extracted Predicted Congener (UT) (EERC) (MIT) (MIT) Porewater pg/l pg/l pg/l pg/l Raw pg/l Porewater TOC corr. pg/l*** Porewater Kd=Kocfoc pg/l < NR NR NR NR * NR NR NR NR NR NR NR NR < * *

14 Avoids concerns about contaminant dynamics associated with porewater extraction Provides in situ profile with up to 1 cm vertical resolution depending on detection limits Profiles provide rate/mechanism information Disadvantages Deployment time Analytical l requirements complexity Depth Concentration Advection Bioturbation Diffusion 14

15 Cap Performance Anacostia Active Capping Demonstration Benthic Accumulation Field Studies Anacostia Active Capping Demonstration Preliminary measurements 6/07 Second Round (poor organism recovery) 10/07 San Diego Bay/Pennsacola, FL In cooperation with Sediment Ecosystem Assessment Protocol SERDP ER

16 Percent Sediment and Phen C/C0versus Depth Clean Sand Cap Phenanthrene % Sediment Cap-sediment Intermixing Zone Sediment (cm) Depth 29 0% 50% 100% 150% C/C 0 and Percent Passing 27

17 Profiling SPME to indicate cap performance B[a]A Pore Water Concentrations -4 Pore Water Concentration (ng/l) Overlying Water -2 Depth (cm) ACS 0cm 2cm 4cm 6cm

18 /f l (ppb) C t / Phenanthrene Chrysene B(a)A B(b)F B(k)F B(a)P C pw K ow (ppb) Unit slope is BCF estimated by K ow 18

19 Depth /cm Pyrene Concentration /(ng/l) Average in sediment Caps Sand Coke Breeze

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21 PAHs B(b)F, B(k)F, BaP in Muscalista Tissue Conce entration (ug/kg) PAH Tissue Correlation with Pore Water Concentration (0-7 cm) R² = Pore Water Concentration (ng/l) Tissue Conce entration (ug/kg) PAH Tissue Correlation with TOC NormalizedSediment Concentration R² = Sediment Concentration (ng/g) Single correlation with porewater concentrations works well for all three compounds

22 Total PAHs 28% deviation bt between Utexas and TestAmerica 22

23 Test Am merica Phenanthrene y = 1.04x R² = UT Value Most of 28% difference associated with pyrene Test America Pyrene y = 1.72x Poorest duplicate R² = 0.84 correlation with low UT Value concentration, high molecular weight Benzo[a]Pyrene 2.0 compounds like BaP 1.0 All concentrations within y = 1.09x R² = 0.30 factor of two 0.0 t America Test UT Value 23

24 Direct passive measurement of porewater concentrations provides good indication of potential bioaccumulation of PAHs and PCBs in benthic deposit feeders Bulk solid and extracted porewater measurements are not as well correlated with ih bioaccumulation In situ profiling fl with SPME provides useful information on contaminant migration rates and mechanisms and can be used, e.g., to evaluate cap performance 24