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1 2009

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Sources and distribution of polychlorinated dibenzo-para-dioxins and dibenzofurans in sediments from urban cascade reservoirs, central Poland

Urbaniak M., Zieliński M., Wesołowski W., Zalewski M.

Environment Protection Engineering

2009

Vol. 35, nr 3

93-103

The transport pattern of the organochlorine pollutants along the river-bed is an important issue due to their accumulation in reservoir bottom sediments and bioaccumulation in the food chain. In this study, seventeen most toxic 2,3,7,8-substituted dibenzo-para-dioxins (PCDDs) and dibenzofurans (PCDFs) were selected to determine sediment contamination in a cascade of five urban reservoirs. The total concentrations of PCDD/Fs ranged from 22.98 to 254.56 ng kg-1 d.w. with the minimum in the first reservoir, maximum in the middle reservoir, and decline at the end of the reservoirs' cascade. Concentrations of 2, 3, 7, 8-tetrachlorinated dibenzo-para-dioxin (TeCDD) equivalents (TEQs) estimated based on WHO-TEFs decreased along the reservoir cascade (4.94; 3.02; 1.51 and 0.52 ng kg-1 of d.w., respectively), excluding the first one (0.80 ng kg-1 of d.w.). This situation can be related to the hydraulic transport and deposition of PCDD/Fs along the cascade system. The PCDD/PCDF ratio showed a different pattern with the pre-dominance of PCDFs in the first two cascade reservoirs (61.01% and 88.75%, respectively) and PCDDs in the last three reservoirs (86.16%, 87.83% and 91.41%, respectively).