PRINCIPAL COMPONENTS-ANALYSIS OF POLYCHLORINATED DIBENZO-P-DIOXINS AND POLYCHLORINATED DIBENZOFURANS IN SEDIMENTS FROM LAKE CHAMPLAIN AND LAKE GEORGE, NEW-YORK, USA

Principal-components analysis (PCA) was used to compare concentrations of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenz ofuran (PCDF) compounds in sediments collected from two interconnected lakes, Lake Champlain and Lake George, New York, USA. Two different P CDD/PCDF congener profiles were present in surface sediment samples fr om Lake George. Samples collected near residential areas and power-boa t marinas had elevated hepta- and octa-CDDs (1 +/- 0.3 ng/g) and tetra -octa-CDFs compared with samples collected in other areas of the lake. The PCDD/PCDF pattern in the high-level samples was similar to the PC DD/PCDF pattern in sediments from Green Lake, NY, a small lake in whic h atmospheric deposition is the only route for PCDD/PCDF contamination , either from local sources or from long range transportation from mul tiple sources in the midwest. The samples containing the higher PCDD/P CDF concentrations also contained higher lead concentrations (173 +/- 33 mu g/g) compared to the low-level PCDD/PCDF samples (52 +/- 25 mu g /g). However, the increase in lead concentrations was accompanied by i ncreased concentrations of other trace metals. Consequently, it can be concluded that emissions from power boats are not responsible for the PCDD/PCDF contamination in Lake George. Concentrations of PCDDs/PCDFs in the low-level samples were similar to PCDD/PCDF concentrations in sediments from remote midwestern lakes where long range atmospheric de position was the only plausible route of entry for the PCDD/PCDF compo unds. However, other studies have shown that offshore sediments in Lak e George have lower concentrations of organic carbon than inshore samp les and, therefore, the low-level PCDD/PCDF pattern may be an artifact related to a reduced PCDD/PCDF concentration in sediments with a low organic carbon content. Surface and core sediments from Lake Champlain also partitioned into two groups, which both had PCDD/PCDF patterns d iffering from the high-level surface sediments collected form Lake Geo rge. The largest group of samples was characterized by the presence of high octa-CDD concentrations (3.5-18 ng/g). The second group of sampl es was four sections from a single core sample collected near a bleach ed kraft pulp and paper mill, which closed in 1970. These samples had high concentrations of tetra-CDFs (0.5-1.4 ng/g), primarily 2,3,7,8-te tra-CDF, accompanied by comparable concentrations of octa-CDD (0.9-4.4 ng/g). The presence of 2,3,7,8-tetra-CDF is consistent with results f rom several studies where PCDDs/PCDFs were analyzed in samples taken f rom various stages of the bleached kraft process. These samples were g rouped in the same quadrant on a PCA plot as coal soot and pulp and pa per mill sludge. However, the grouping was not close, and the PCDD/PCD F contamination in these sediments cannot be associated with either so urce. Five sections of a core collected near a currently operating ble ached kraft pulp and paper mill also had elevated 2,3,7,8-tetra-CDF co ncentrations (0.3 +/- 0.05 ng/g), but these 2,3,7,8-tetra-CDF concentr ations were accompanied by considerably higher octa-CDD concentrations (7.5 +/- 0.5 ng/g). Therefore, they could not be distinguished by PCA from the majority of the Lake Champlain samples.