Temporal variations of PCBs and their estimated air-soil exchange fluxes measured in seven sites in Bursa-Turkey

Abstract

Polychlorinated biphenyls (PCBs) can travel in ambient air for long distances and exchange between different environments. Soil and ambient air samples were simultaneously gathered during the winter and summer months in 7 regions in Bursa, Turkey, to study spatio-temporal fluctuations and soil-air exchange of PCBs. sigma(25) PCB concentrations for the winter and summer seasons were 0.007-0.04 ng/m(3) and 0.03-0.24 ng/m(3) in air, also 4.09-10.00 ng/g DM and 1.65-10.01 ng/g DM in soil, respectively. PCB concentrations showed spatial variations in air and soil samples. The lowest total PCB levels were measured both in air and soil samples in the R (rural) site. The highest sigma(25) PCB concentrations were measured in the SR3 site in soil samples, while the I1 site was the most polluted in air samples. Ambient air concentrations of PCBs in the summer months were greater than those in winter. In SR1, SR2, SR3, and I1 sites, soil PCB levels in the summer were higher than in the winter. The opposite was observed in the other sites (R, U, I2). Net flux values and fugacity fraction (ff) values for all regions indicated that PCBs represented a transfer from soil to air. The air-soil net gas phase flux values changed between 0.04 - 1.01 ng/m(2)-day and 0.02-0.83 ng/m(2)-day in the summer and winter, respectively. The PCB homologous distributions of mean flux values differed depending on the regions and seasons. PCBs with 4- and 5-CBs were dominant in both seasons.