Atmospheric concentrations, distributions and air-soil exchange tendencies of PAHs and PCBs in a heavily industrialized area in Kocaeli, Turkey.

Dilovasi is one of the heavily industrialized areas in Turkey with serious environmental problems. In this study, the atmospheric concentration of PAHs and PCBs were measured for a whole year at 23 sites. The average ambient air Σ15PAH and Σ41PCB concentrations were found as 285 ± 431 ng m-3 and 4152 ± 6072 pg m-3, respectively. PAH concentrations increased with decreasing temperature especially in urban areas, indicating the impact of residential heating. However, PCB concentrations mostly increased with temperature probably due to enhanced volatilization from their sources. The gradient obtained for PCBs, rural < suburban < urban < industrial/urban, is more clear than those obtained for PAHs. The average Σ15PAH and Σ41PCB soil concentrations were found as 992 ± 1323 and 18.8 ± 32.0 μg kg-1, respectively. PCB soil concentrations did not show significant temporal variations while PAH concentrations were variable especially for urban areas. The volatilization tendencies of low and medium molecular weight PAHs from soil to air were higher in industrial-urban areas than rural sites, showing that soil was a secondary source for PAHs. Fugacity ratios of PCBs were mostly <1.0 for the whole sampling period. Although the source/sink tendency of soil for some PCBs depends on their volatility, considering the whole data, PCBs were generally deposited to soil.