Biogeochemical Cycling of PCBs in Lakes of Variable Trophic Status: A Paired-Lake Experiment

• Published in: Limnology and oceanography Vol. 44; no. 3; pp. 889 - 902
• Main Authors: Jeremiason, Jeff D., Eisenreich, Steven J., Paterson, Michael J., Beaty, Ken G., Hecky, Robert, Elser, James J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Waco, TX American Society of Limnology and Oceanography 01-05-1999
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Congeners; Ecotoxicology, biological effects of pollution; Fresh water environment; Freshwater; Fundamental and applied biological sciences. Psychology; Lakes; Marine; Particulate matter; PCBs; Polychlorinated biphenyls; Sediments; Stormwater; Surface areas; Surface runoff; Vaporizing; Watersheds; Canada, Ontario, Experimental Lakes Area; Organic carbon; Flux; Trophic status; Biogeochemical cycle; Sediments; Polychlorobiphenyl; Freshwater environment; Pollutant; Seasonal variation; Chlorocarbon; Lakes; Water pollution; Comparative study
• ISSN: 0024-3590; 1939-5590
• DOI: 10.4319/lo.1999.44.3_part_2.0889

A paired whole-lake experiment was conducted on two remote, atmospherically driven lakes in the Experimental Lakes Area (ELA) to examine the stresses of trophic condition on air-water exchange and settling fluxes of polychlorinated biphenyls (PCBs). Lake 227 (L227) and Lake 110 (L110) are similar in volume, surface area, and watershed area but differ significantly in trophic status. The two lakes have similar access to atmospheric PCBs but eutrophic L227 may exhibit enhanced air to water exchange due to greater biotic uptake of dissolved PCBs. Settling fluxes of PCB were significantly greater in eutrophic L227 (40 ng m-2d-1in 1993; 29 ng m-2d-1in 1994) than in oligotrophic L110 (22 ng m- 2d-1in 1993 and 17 ng m-2d-1in 1994). Dissolved ΣPCB concentrations were not significantly different in the two lakes (∼0.3 ng liter-1). Greater ΣPCB settling fluxes in L227 vs. L110 coupled with similar dissolved concentrations after June supports the hypothesis that air-water exchange supports the water column PCB concentrations. Surprisingly, ΣPCB fugacity gradients in both lakes indicated that net volatilization dominated during the entire ice-free period, requiring another source. A ΣPCB mass budget in the epilimnion of each lake over the stratified period showed that the major PCB losses were due to settling and volatilization. ΣPCB settling losses were 2.4 times greater in L227 than in L110 due to higher settling particle fluxes. The mass budgets suggest that the major PCB input to these remote lakes is from the watershed. Our results indicate the intimate environmental linkage between atmospheric, land, and aquatic PCB reservoirs.