Spatio-temporal variations, fugacity fractions and air-soil exchanges of PCBs in industrial, urban and semi-rural sites

Abstract

This study investigated the spatiotemporal variations in the occurrence of polychlorinated biphenyl (PCB) congeners both in soil and ambient air. Soil and air samples were taken simultaneously for three seasons (spring, summer, and autumn) from industrial, urban, and semi-rural areas in Bursa, Turkey. Light and medium PCB homologous groups were dominant in all samples.Total PCB ( n-ary sumation (25) PCBs) concentrations in the air were 0.12 +/- 0.13, 0.06 +/- 0.07, and 0.08 +/- 0.11 ng/m(3) and in soil were 4.01.+/- 2.38, 5.44 +/- 3.14, and 3.66 +/- 1.56 ng/g DM for summer, spring, and winter, respectively. Moreover, the samples were taken from different sites to determine the spatial fluctuations. The average n-ary sumation (25) PCBs in the air were 0.22 +/- 0.06, 0.03 +/- 0.01, and 0.03 +/- 0.02 ng/m(3) and in soil were 7.08 +/- 1.84, 2.98 +/- 0.52, and 3.06 +/- 0.70 ng/g DM for industrial, urban and semi-rural sites, respectively. Maximum air and soil PCB concentrations were determined in the industrial region. The spatiotemporal changes in the fugacity fractions and net fluxes were also examined. The direction of the PCB movement was assessed and the results indicated that soil was a diffusive source for PCBs. The calculated fugacity fractions (ff) were above 0.7 while average flux values were calculated as 0.65 +/- 0.33 ng/m(2)-d, 0.21 +/- 0.19 ng/m(2)-d, and 0.26 +/- 0.27 ng/m(2)-day for industrial, urban and semi-rural regions, respectively.