Abstract
A study of PCB concentrations and fluxes in lake sediments was conducted to test the “global fractionation” hypothesis that deposition of semivolatile organics will decline while more volatile congeners will be enriched in polar regions. Sediment cores were collected from 11 remote lakes in Canada ranging from 49° N to 82° N and were dated using excess 210Pb and 137Cs. Sediment extracts were analyzed for up to 90 PCB congeners by capillary GC-ECD with confirmation by GC/high-resolution MS. Total PCB (∑PCB) concentrations in surface slices ranged from 2.4 to 39 ng g-1 (dry wt) and showed no latitudinal trend. Fluxes (ng m-2 yr-1) and inventories of ∑PCB as well as total tetra- to octachlorobiphenyls declined with increasing north latitude while those for di/trichlorobiphenyls showed no latitudinal trend. The proportion of di/trichloro congeners of ∑PCB also increased significantly with latitude, while total octachlorobiphenyls declined. Maximum ∑PCB concentrations were observed in subsurface slices dating ...
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