Polychlorodibenzo-p-dioxin and polychlorodibenzofuran concentrations in lake sediments and fish after a ground water pollution with chlorophenols

Two sediment cores from Lake Valkjärvi, one from the deepest place in the middle of the lake and the other from the estuary, earlier found to be highly contaminated by chlorophenols at least from the nineteen seventies, were analyzed for their polychlorodibenzo-p-dioxin and polychlorodibenzofuran (PCDD/F) concentrations to resolve whether or not the chlorophenol pollution in the lake was also accompanied by PCDD/Fs. Also fish samples caught from Lake Valkjärvi, were analyzed. The total levels of PCDD/Fs and PCBs in Lake Valkjärvi, seem to be at the same level as rural areas in Finland and somewhat lower than in rural areas in other countries. The concentrations of PCBs and PCDD/Fs correlated with one another at different depths and they most probably represent atmospheric inputs. However, very low traces of the impurities of KY-5 can be seen in the isomer patterns of both PCBs and PCDD/Fs. Also fish results indicate that there is no major pollution of the lake with PCDD/Fs. This supports the view presented previously that chlorophenols entered the lake almost exclusively via the ground water reservoir, and were not accompanied by PCDD/Fs which were trapped due to their adsorption to soil particles.