Partitioning and Bioavailability Assessment for Sediments from South Wilmington Wetlands Huan Xia and Upal Ghosh Department of Chemical, Biochemical, and Environmental Engineering University of Maryland, Baltimore County

Location 27-acre degraded wetland Contaminants detected in marsh soil: Metals (e.g. As, Pb, Cr) PAHs (e.g. Benzo(a)pyrene, Benzo(k)fluoranthene) PCBs such as Arochlor-1248 (Hendershot and Asreen Jr. 2005)

Introduction Hydrophobic organic compounds (HOCs) like PCBs and PAHs strongly bound to sediment geochemical components Some carbonaceous particles (e.g. soot and charcoal) exhibit greater sorption capacity than organic matter, resulting in reduced exposure Traditional risk assessment uses default values from generic organic matter Site specific values can be orders of magnitude different from default values EPA recommends using site specific measurement of partition constants to refine the risk assessment

Study Objectives: Methods Evaluate site specific bioavailability of PAHs and PCBs in South Wilmington Wetland sediment and refine risk assessment. Methods Sediment samples collected from 12 locations of wetland. Measurement of PAH and PCB concentrations in sediment samples. Laboratory partitioning study to measure PAH and PCB porewater concentrations using Polyethylene (PE) as passive sampler 5 PRCs used to correct for equilibrium porewater concentration Laboratory bioaccumulation study for PCBs using Lumbriculus variegatus

Results: Total PAH and PCB concentrations in sediments Total PAH range from 0-40 mg/kg , mean value: 12 mg/kg Total PCB range from 0-4.6 mg/kg , mean value :0.7 mg/kg

Total Equilibrium porewater concentrations of PAHs & PCBs The highest PAH porewater concentration was measured in Sed01. Sed02 and Sed03 were amended with 5% activated carbon to evaluate the effect of the carbon treatment, named as Sed02T and Sed03T. “U” refers to “untreated”. 70% to 90% reduction in PAH porewater concentration observed in treated samples

Total Equilibrium porewater concentrations of PAHs & PCBs The highest total PCB porewater concentration was measured in Sed02U, Sed03U and 1330. 80% to 90% reduction in PCB porewater concentration also observed in treated samples Site specific organic partition constants : Koc= Cs/Cw/foc

Bioaccumulation of PCBs in Lumbriculus variegatus Worm recovery ranges from 50- 70%. The highest bioaccumulations in worms were in samples 1330, Sed03 and Sed02, which also had the highest PCB levels in sediment. Reduction in PCB bioaccumulation was 97-98% in treated samples

partition constants for PAHs and PCBs Measured Koc values for both PAHs and PCBs were 1-2 orders of magnitude higher than the generic values used in preliminary risk assessments Median value of BC/OC ratio : 9%, n=300 (Cornelissen et al. 2005) Measured BC/OC ratio: 17-36% Human Health Risk Assessment Protocol, 2012 Karickoff 1981, Werner et al 2010

PCB Bioaccumulation Factors (BCF) in worms log BCF= 0.819 log Kow- 1.146 BCF calculated as: BCF= Clipid/Cporewater Measured BCF (blue diamonds) are consistent with the generic values (green dash), but nearly 1 order of magnitude higher than those in initial PRG (red dash) EPA. (1999). Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities

PRGsediment = Toxicity Value × foc × Koc Calculation for Preliminary Remediation Goals (PRGs) Benthic organism-based PRGs (Equilibrium Partitioning Approach): PRGsediment = Toxicity Value × foc × Koc PRG, concentration in sediment (mg/kg DW sediment) Toxicity Value , Aquatic community-based toxicity value (μg/L) foc, Organic carbon fraction (2 % default used in initial calculation, average of 4% TOC was detected in sediments ) Koc, Organic carbon partition constants (default value from HHRAP used in initial calculation, measured specific Koc used in revised version) Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: PAH Mixtures (EPA, 2003e)

Revised Benthic Organism-based PRGs using site specific Koc Human Health Risk Assessment Protocol, 2012

Calculation for Preliminary Remediation Goals (PRGs) PRGs based on invertebrate –based food web modeling: (bioamagnification and trophic transfer through dietary exposure) PRGsediment= 𝑇𝐻𝑄 ∗𝑇𝑅𝑉 𝐹𝑇 ∗(𝐹𝐼𝑅∗ 𝐵𝐶𝐹 𝑓 𝑜𝑐 𝐾 𝑜𝑐 +𝑆𝐼𝑅) Local receptors: American robin, Raccoon, Spotted sandpiper, etc. Spotted sandpiper was selected due to its most rigid sediment concentration criteria. (Ecological Sediment Screening Level, EPA 2007a, 1999, 1993)

Revised PRGs based on exposure to Spotted Sandpiper

Conclusions Observed site specific Koc values were higher than generic values derived from organic matter, mainly due to elevated black carbon in sediment BCF measures in good agreement with literature values PCB bioaccumulation is explained well by porewater data Site specific measurements provided realistic parameters to refine the remediation goals

Acknowledgements City of Wilmington, Delaware Brightfields Inc Acknowledgements City of Wilmington, Delaware Brightfields Inc. Labmates for worm retrieval

Methods Correction based on different properties: diffusivity, partitioning coefficient, molar volume Molar volume adjustment Calculate residual PRC in PE: 𝐶 𝑝𝑟𝑐,𝑓 𝐶 𝑝𝑟𝑐,𝑖 Exchange rate (for PRC) : 𝐾 𝑒,𝑝𝑟𝑐 =− ln⁡( 𝐶 𝑝𝑟𝑐,𝑓 𝐶 𝑝𝑟𝑐,𝑖 ) 𝑡 Sampling rate (for PRC) : 𝑅 𝑠,𝑝𝑟𝑐 = 𝐾 𝑒,𝑝𝑟𝑐 𝐾 𝑝𝑒𝑤,𝑝𝑟𝑐 𝑀 𝑝𝑒 𝑅 𝑠,𝑡𝑎𝑟𝑔𝑒𝑡 = 𝑅 𝑠,𝑝𝑟𝑐 ( 𝑉 𝑚,𝑝𝑟𝑐 𝑉 𝑚,𝑡𝑎𝑟𝑔𝑒𝑡 ) 0.39 𝐾 𝑒,𝑡𝑎𝑟𝑔𝑒𝑡 = 𝑅 𝑠,𝑡𝑎𝑟𝑔𝑒𝑡 𝐾 𝑝𝑒𝑤,𝑡𝑎𝑟𝑔𝑒𝑡 𝑀 𝑝𝑒 𝐶 𝑤,𝑡𝑎𝑟𝑔𝑒𝑡 = 𝐶 𝑝𝑒,𝑡𝑎𝑟𝑔𝑒𝑡 𝐾 𝑝𝑒𝑤,𝑡𝑎𝑟𝑔𝑒𝑡 [1− exp − 𝐾 𝑒,𝑡𝑎𝑟𝑔𝑒𝑡 𝑡 ] 𝐾 𝑝𝑒𝑤 , PE sampler partition coefficient; 𝑀 𝑝𝑒 , mass of PE sampler; 𝑉 𝑚 , molar volume; t, exposure time (28days) (Huckins et al 2006)

partition constants for PAHs and PCBs Elevated Koc (3-4 orders of magnitude range) for PAHs previously observed from industrially impacted sites (n=117) Hawthorne et al. 2006

Methods Impregnate PE sampler with PRCs Measured CW may not be at equilibrium CW corrected using Performance Reference Compounds (PRCs) Assume absorption = desorption Assume PRCs have similar properties as HOCs PRCs: PCB 29 (mono, di, tri), 69 (tetra, penta), 155 (hexa), 192 (hepta, octa, nona and deca groups) for PCB correction and d-10 pyrene for PAH. Preload PE sampler with PRCs for two week and measure initial concentration in sampler (CPRC,i) Add PE sampler into sediment

Methods Laboratory worm bioaccumulation study for PCBs Species: Lumbriculus variegatus Daily water exchange and water quality monitoring 28 days bioaccumulation Worm collection Analyzed worm tissue for PCBs

Revised Benthic Organism-based PRGs using site specific Koc

Revised PRGs based on exposure to Spotted Sandpiper SVOCs 2,4-Dinitrophenol NA PAHs 2-Methylnaphthalene 6280 356 Acenaphthene 6010 167 Acenaphthylene 1570 346 Anthracene 7270 256 Benzo(a)anthracene 5050 360 Benzo(a)pyrene 4850 477 Carbazole 37 Chrysene 3500 367 Dibenz(a,h)anthracene 4120 255 Fluoranthene 8110 209 Indeno(1,2,3-cd)pyrene 3820 521 Phenanthrene 5860 288 Pyrene 7570 347 Pesticides 4,4'-DDE 0.017 0.00092 4,4'-DDT 0.0036 Dieldrin 0.005 0.0014 Endrin 0.013 0.0097 Endrin aldehyde 0.0047 Endrin ketone 0.014 0.0045 gamma-Chlordane 1.61 Heptachlor epoxide 0.030 0.0087 PCBs PCBs,total 0.40 0.09 Dioxins/Furans 2,3,7,8-TCDD 0.000011 0.000036 PRG C sed (mg COPEC/kg DW sediment) NOAEL Based using site BCF NOAEL Based from initial report COPEC

Revised PRGs : Bentho-based Vs. Exposure to Spotted Sandpiper

Revised PRGs : Bentho-based Vs. Exposure to Spotted Sandpiper