Spatial distribution characteristics and risk assessment of polychlorinated biphenyls (PCBs) in sediments and soils from the Dishui Lake and its river system

In order to investigate the pollution levels of PCBs in urban artificial lake, fourteen PCB congeners in sediments and soils of Dishui Lake and its river system were quantified by GC/MS, and then the distributions, sources and ecological risk of PCBs were discussed. The results showed that the concentrations of ∑₁₄PCBs in sediments and soils ranged from 0.65-16.41 ng·g^-1(dry weight, dw) and 0.47-1.27 ng·g^-1, respectively, which were at a low level in general. Higher concentrations of PCBs were found in surface sediments from the river system of Dishui Lake than those in surface and core sediments from Dishui Lake, which indicated that the sediments in Dishui Lake would be polluted by the river system in the process of diversion. The concentrations of PCBs in core sediments decreased with depth, which showed that the sediments of Dishui Lake had been polluted by PCBs since its completion. In all samples, Tetra-CBs and Penta-CBs accounted for 20.65% and 67.12% of ∑₁₄PCBs, respectively, and PCB105, PCB118 and PCB77 were the dominant compounds. The results of source apportionment by principal component analysis (PCA) indicated that PCBs in sediments and soils from Dishui Lake and its river system were influenced by the historical cumulative emissions of 2#, 1# PCBs used in China and municipal solid waste incineration and combustion sources. The toxic equivalents (TEQs) of 12 (DL-PCBs) ranged from 0.01-79.40 pg·g^-1, and the TEQs in 7 samples of surface sediments from Dishui Lake and its river system were beyond the interim sediments quality guidelines (ISQGs) suggested by USEPA, which would result in potential eco-toxicological risks for aquatic organisms.