Distribution of polycyclic aromatic hydrocarbons (PAHs) in pore water and sediment of a small aquatic ecosystem

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured both in pore water and solid sediment isolated from the Teufelsweiher pond, a small aquatic ecosystem in Upper Bavaria (Germany) from 1992 to 1994. All 16 EPA priority compounds were present with mean total concentrations from 501 to 663 ng/l in the pore water and 976-1600 mu g/kg (dry weight) in the solid sediment. Fluoranthene and pyrene were the dominant compounds and accounted for 21-28% of the total PAHs, the ratios of fluoranthene/pyrene and phenanthrene/anthracene ranging from 1.61-2.86 and 0.86-1.57, respectively. These results suggest that the main sources of PAHs are incomplete combustion processes of fossil fuel; the compounds are then transported into the Teufelsweiher by deposition and runoff. The distribution of PAH concentrations exhibit a pronounced dependence on both particle size and organic matter content of the sediment: two fractions (<6.3 mu m and 63-200 mu m), containing higher contents of organic matter, trapped more PAHs compared with other fractions. The dissolved organic carbon (DOC) in the pore water is mostly responsible for lower K-OC' in situ measured compared with the estimated K-OC. The spatial and temporal variations of PAH concentrations are also discussed.