Levels and Origin of PAHs in Some Big Lakes

This study was designed to assess the contamination of a very special lake, Lake Baikal in Siberia, and two big lakes, Ladoga and Onega in the European part of Russia, by polycyclic aromatic hydrocarbons (PAHs). PAH compounds were analyzed by HPLC and the target PAH, benzo[ a ]pyrene (B a P), by using the spectral-luminescence (Shpol'skii) method. Elevated levels (to 96 w g kg m 1 ) of B a P in sediments of Lake Baikal reflected proximity to potential sources of emission, situated either on shore (a paper and pulp mill in Baikalsk) or upstream river systems. The concentration of B a P in sediments decreased with the distance from outlet and the depth. The sediment samples contained several representatives of PAHs. The total content of identified compounds reached 873 w g kg m 1 (less than four nuclear representatives not included). Dominating heavy PAHs were dibenz[ a,j ]anthracene, dibenz[ a,h ]anthracene, dibenzo[ a,e ]pyrene, and dibenzo[ a,l ]pyrene. The concentration of B a P in sediments of northeastern Baikal was more than two times less than that for the southern part of the lake and corresponds to the background level. The B a P levels estimated for sediments close to paper and pulp mills of the Lake Ladoga exceeded 160 w g kg m 1 , being two orders of magnitude higher than that for other areas of these lakes. The contamination of sediments of Lake Onega by PAHs is affected by pulp and paper mills as well as other sources. Our results clearly demonstrate the contribution of specific industrial sources like paper and pulp mills to the content of PAHs in the Baikal, Ladoga, and Onega water ecosystem.