Wet deposition of polychlorinated biphenyls in the eastern Mediterranean

TitleWet deposition of polychlorinated biphenyls in the eastern Mediterranean
Publication TypeJournal Article
Year of Publication2004
AuthorsMandalakis, M, Stephanou EG
JournalEnvironmental Science and Technology
Pages3011 - 3018

The concentrations of polychlorinated biphenyls (PCBs) were measured in rain samples collected from a semi-urban and a marine background site of the eastern Mediterranean. The concentration of ΣPCB (sum of 54 PCB congeners) in the city of Heraklion (2.9 ± 1.9 ng L-1) was not significantly higher than the corresponding concentration measured at the background sampling station of Finokalia (1.9 ± 0.9 ng L-1). In both sites, the sum of tri- and tetrachlorinated congeners accounted for more than 55% of ΣPCB in rainwater. For all samples, the percentage of particle-bound PCBs ranged between 6.6% and 63.8%, providing an average value of 31 ± 18%. The washout ratios of particulate PCBs (Wp) were constant for individual congeners regardless the degree of chlorination. Average W P values ranged between 1.9 × 105 and 5.2 × 105 while a value of 2.7(±1.3) × 105 was deduced for ΣPCB. The corresponding washout ratios for gaseous PCBs were substantially lower and ranged between 7 × 103 (PCB 99) and 1. 3 × 105 (PCB 180). Washout ratios of gaseous PCBs were also calculated based on Henry's law, and they were found to be 30-920 times lower than those obtained from field measurements. On the basis of our data, the wet deposition flux of ΣPCB in the eastern Mediterranean should approach 820 ng m-2 yr-1. This flux is similar with the values recently reported for several background sites of the United States and Europe, but it is 1 order of magnitude lower than the flux of PCBs measured in the western Mediterranean 16 yr ago.


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