American Chemical Society, Environmental Science and Technology, 16(48), p. 9315-9324
DOI: 10.1021/es501686a
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Polyethylene passive samplers were deployed during summer and fall 2011 in the lower Great Lakes to assess the spatial distribution and sources of gaseous and freely dissolved organochlorine pesticides (OCPs), and their air-water exchange. Average gaseous OCP concentrations ranged from non-detect to 133 pg/m3. Gaseous concentrations of hexachlorobenzene, dieldrin and chlordanes were significantly greater (Mann-Whitney test, p < 0.05) at Lake Erie than Lake Ontario. A multiple linear regression implied that both cropland and urban areas within 50 km and 10 km buffer zones respectively were critical parameters to explain the total variability in atmospheric concentrations. Freely dissolved OCP concentrations (non-detect to 114 pg/L) were lower than previously reported. Aqueous half lives generally ranged from 1.7 - 6.7 years. Nonetheless, concentrations of p,p'-DDE and chlordanes were higher than New York State Ambient Water Quality Standards for the protection of human health from the consumption of fish. Spatial distributions of freely dissolved OCPs in both lakes were influenced by loadings from areas of concern and the water circulation patterns. Flux calculations indicated net deposition of γ-hexachlorocyclohexane, heptachlor-epoxide, α- and β-endosulfan (-0.02 to -33 ng/m2/day) and net volatilization of heptachlor, aldrin, trans-chlordane and trans-nonachlor (0.0 to 9.0 ng/m2/day) in most samples.