Accumulation of Atmospheric and Sedimentary PCBs in a Lake Michigan Food WebEPA Grant Number: U915564
Title: Accumulation of Atmospheric and Sedimentary PCBs in a Lake Michigan Food Web
Investigators: Stapleton, Heather M.
Institution: University of Maryland Center for Environmental Science
EPA Project Officer: Lee, Sonja
Project Period: August 1, 1999 through August 1, 2002
Project Amount: $84,174
RFA: STAR Graduate Fellowships (1999) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Chemistry
The Great Lakes region is well known for its polychlorinated biphenyl (PCB) contamination. We have discovered elevated PCB concentrations among the region?s apex predators, such as lake trout and salmon. These apex predators are commercially and recreationally important to the region. Since the curtailment on PCB use in the 1970s, concentrations have shown a relative decrease in the environment. In the late 1980s, however, a stabilization in PCB concentrations, just above the FDA advisory level (2 micrograms/g) was observed in Great Lakes lake trout, and appear to be remaining steady. The reason for this stabilization is unclear, but plausible hypotheses include large-scale atmospheric exchange, internal recycling of historically contaminated sediments, and alterations in food web dynamics. The objective of this research project is to assess the relative influence of atmospheric exchange, internal recycling within the water column and sediment, and food web dynamics on PCB assimilation within the fisheries of Lake Michigan.
Field work began on this project in April 1997 and will be completed in September 1999. A temporal sampling strategy was designed to collect samples from the air, water, sediment, and representative biota to assess the impact of seasonal dynamics on PCB burdens within abiotic and biotic compartments. This strategy also determined the primary route through which PCBs are currently being supplied to the fisheries. Representative food web members include: buld plankton, benthic amphipods (Diporeia hoyi), opossum shrimp (Mysis relicta), deepwater sculpin (Myoxocephalus thompsoni), alewife (Alsoa pseudoharegnus), bloater chub (Coregonus hoyi), rainbow smelt (Osmerus mordex), lake trout (Salvelius namaycush), burbot (Lota lota), and salmon (Oncorhynchus sp.). Isotopic signatures of food web members will be analyzed to determine their trophic status as estimated by the nitrogen and carbon isotope values. In addition, diet analyses will be conducted on fish species to determine their major prey items.
These parameters will aid in establishing a trophic model of the food web and will be useful in determining the dynamics of PCB transfer through bioaccumulation.