HR: 13:30h
AN: NB23D-01    [Abstracts]
TI: Using stable isotopes to track biomagnification of polychlorinated biphenyls (PCBs) through stream food webs
AU: * Walters, D M
EM: walters.davidm@epa.gov
AF: US EPA, Office of Research and Development, 26 W. MLK Dr. (MS-642), Cincinnati, Ohi 45268 United States
AU: Fritz, K M
EM: fritz.ken@epa.gov
AF: US EPA, Office of Research and Development, 26 W. MLK Dr. (MS-642), Cincinnati, Ohi 45268 United States
AU: Johnson, B R
EM: johnson.brent@epa.gov
AF: US EPA, Office of Research and Development, 26 W. MLK Dr. (MS-642), Cincinnati, Ohi 45268 United States
AU: Lazorchak, J M
EM: lazorchak.jim@epa.gov
AF: US EPA, Office of Research and Development, 26 W. MLK Dr. (MS-642), Cincinnati, Ohi 45268 United States
AB: Biomagnification studies of PCBs in streams are rare, even though PCBs are known to biomagnify and persist in aquatic ecosystems. We investigated PCB contamination in Twelvemile Creek (Clemson, SC, USA), a stream that received >400,000 lbs of PCBs from 1955-1978. Our goals were to determine if PCBs biomagnify in streams and to measure the relative importance of heterotrophic and autotrophic pathways for biomagnification. Sites were sampled during spring (n=6) and fall (n=4) 2003-04. Major components of the foodweb were analyzed for total PCBs, δ¹³C and δ¹⁵N. Biomagnification was apparent as mean δ¹⁵N strongly predicted PCBs (r² = 0.58), and PCBs consistently increased with trophic level. We found no consistent patterns related to carbon pathways. δ¹³C and PCBs were uncorrelated, suggesting that carbon source was unrelated to biomagnification. However, mean PCB tissue concentration in grazers were double those in shredders (Stenonema modestum, 970 ppb versus Tipula and Pteronarcys spp, 370 ppb) even though concentrations were similar for periphyton and conditioned leaves. Our results show that PCBs biomagnify and persist in streams but the importance of autotrophic and heterotrophic pathways are unclear. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.
DE: 1803 Anthropogenic effects
DE: 4817 Food chains
DE: 4870 Stable isotopes
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly