Polychlorinated biphenyl (PCB) concentrations and air-soil exchange in olive lands in Bursa

In the first stage of the study, it was aimed to investigate the regional and seasonal variations of PCB concentrations from olive groves in Bursa. In this context, soil samples (0-5 cm) were collected between April 2016 and December 2016 and polychlorinated biphenyls (PCBs) were analyzed. Concentration values of a total of 59 (PCB59) PCB species were determined and the concentrations ranged from 3 to 21.6 ng/g DM (Dry Matter). The average concentration values determined in soil samples were 13.8 ± 5.8 ng/g DM, 5.7 ± 2.6 ng/g DM and 5.3 ± 2.3 ng/g DM for industrial, urban and semi-rural regions, respectively. At all sampling points, 5CB (31%) was the most dominant homologous group. Following were 6-CBs (14.7%) and 7CB (14.3%). PCB concentrations were compared with the current regulation values. As a result, the PCB concentrations measured in Bursa olive groves were lower than the limit values. It was determined that the highest PCB pollution was obtained in olive soils in the industrial zone. All regions were evaluated according to season and temperature, but there was no significant correlation between PCB levels and temperature. In addition, the concentration of 8 PCBs (PCB 81, 126, 169, 114, 118, 123, 156, 167) which were accepted for dioxin-like toxicity were between 1.5-3.7 ng/g DM. In the second stage of the study, PCB changes in soil-air interface were investigated and it was aimed to determine the direction of transition of PCBs using net deposition fluxes and fugacity fractions. In this context, air and soil samples were also taken from 3 sampling points simultaneously. The mean PCB concentration values determined in outdoor air samples were 0.6 ± 0.5 ng/m3, 0.07 ± 0.03 ng/m3 and 0.08 ± 0.05 ng/m3 for industrial, urban and semi-rural regions, respectively. As in soil samples, the highest air PCB concentrations was obtained in the industrial sampling region. Average net gas phase fluxes were 3.5 ± 1.5 ng/m2-day, 0.6 ± 0.5 ng/m2-day and 2 ± 1.2 ng/m2-day for industrial, urban and semi-rural areas, respectively. In this study, the mean fluxes of all homologous groups were positive and the ff values were higher than 0,5 (>0,5) in all regions. The transition direction of PCBs were from soil to air during the sampling period.