PARENT SESSION
WP1 - Bioavailability
Chair: Ranville, Jim1, 1 Colorado School of Mines, Golden, CO
2:10 PM to 5:30 PM - Wednesday, 20 November 2002
Room Ballroom G-I
(575) Effects of Carbon Substrate on the Bioavailability of Organic Contaminants.
McLeod, Pamela*,1, van den Heuvel-Greve, Martine1, Allen-King, Richelle2, Luoma, Samuel3, Luthy, Richard1, 1 Stanford University, Palo Alto, CA, USA2 Washington State University, Pullman, WA, USA3 US Geological Survey, Menlo Park, CA, USA
ABSTRACT- Sediments comprise a reservoir from which benthic organisms can acquire toxic compounds that bioaccumulate in higher predators. Our work investigates the sediment organic geochemical processes that influence the bioavailability and bioaccumulation of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). We focus on the assimilation of PCBs and PAHs from sediment by marine organisms at the base of the food chain. Sediments contain various types of sorbent organic matter, and we hypothesize that the bioavailability of hydrophobic organic compounds like PCBs and PAHs depends on the nature of the organic matter in sediments to which the PCBs and PAHs are bound. We conducted laboratory investigations of the relationship between carbonaceous sorbents in sediment and the bioavailability of a PCB and PAH bound to these particles. Clams (Macoma balthica) were simultaneously fed particle-bound 3H-benzo(a)pyrene (BaP) and 14C-2,2′,5,5′-tetrachlorobiphenyl (TCBP) in pulse-chase feeding studies and absorption efficiencies were measured as a proxy for bioavailability. We observed significantly lower absorption efficiencies for the PCB and PAH off hard carbons (i.e., activated carbon, coke) versus diatoms and wood. These results support the hypothesis that differential bioavailability can result from different substrates in sediment. Our findings suggest that adding a sorbent like activated carbon or coke to impacted sediment could sequester PCBs and PAHs and reduce their availability to biota.
Key words: bioavailability, sediment, polychlorinated biphenyls, polycyclic aromatic hydrocarbons