Polycyclic aromatic hydrocarbons in remote mountain lake waters.

Polycyclic aromatic hydrocarbons (PAH), including alkylated and sulfur derivatives, were identified and measured in the waters from three European remote mountain lakes during both ice-free and ice covered periods. The measured concentrations were in the same order in all three lakes (700-1100 pg/l). The PAH patterns in both dissolved and particulate water phases were dominated by the low molecular weight compounds (i.e. phenanthrene, fluoranthene and pyrene) in Lakes Redó (Pyrenees) and Gossenkölle (Alps). In contrast, the high molecular weight (HMW) compounds (i.e. chrysene+triphenylene, benzofluoranthenes, benzo[e]pyrene) were very significant in lake Ovre Neådalsvatn (Caledonian). These HMW PAH correspond to mixtures originating from high temperature combustion processes which have been photodegraded during long range atmospheric transport and parallel the PAH mixtures encountered in the underlying lake sediments. In contrast, dissolved PAH exhibit temperature dependence with higher concentrations found at water temperatures below 6-7 degrees C reflecting higher condensation from the atmospheric gas phase reservoir.