Spatial and temporal trends in short-chain chlorinated paraffins in Lake Ontario sediments

Short-chain chlorinated paraffins (polychlorinated-[C-10-C-13]-n-alkanes) were measured in Lake Ontario sediments collected during a lake-wide survey to characterize spatial and temporal trends in contamination. The Lake Ontario average SUP sediment concentration was 49 ng/g (dry wt), which was somewhat higher than the lake-wide average for SigmaDDT (32 ng/g). Individual stations in each of the depositional basins exhibited the highest concentrations, ranging from 147 ng/g (dry wt) to 410 ng/g at an index station in the Niagara (western) basin. Relative average contributions of the carbon chain groups to total SCCPs on a lake-wide basis were as follows: SigmaC(10) = 24%, SigmaC(11) = 35%, SigmaC(12) = 34%, SigmaC(13) = 6.6%. Assessment of core profiles and estimates of SUP fluxes indicated that an area of the western end of Lake Ontario is heavily impacted (SCCP flux of 170 mug/m(2) yr) and potentially influenced by local industrial sources of SUPS. Maximum accumulation of SCCPs in this area of the western basin occurred in the mid-1970s. In contrast, SUP concentrations in a core from a site in the central area of the lake (SCCP flux of 8.0 mug/m(2) yr) were more similar to levels characteristic of remote locations primarily impacted by atmospheric sources.