Toxic Metal Pollution and Ecological Risk Assessment in Sediments of Water Reservoirs in Southeast China

Abstract

ABSTRACTThe concentration, distribution and pollution status caused by toxic metals, i.e. (Hg, Cd, Cr, Cu, Mn, Pb, Cd and Zn) were measured in sediments from two water reservoir (Tong reservoir and Yang reservoir) in southeast coastal area in China by using enrichment factor (EF), potential ecological risk index , total potential ecological risk (PER) and principal component analysis. Results showed that most of the sediment samples collected from both water reservoirs were moderately to heavily polluted by Cu, Cr, Cd, Hg, Pb and Zn. In Tong reservoir mean concentrations of the various toxic metals, i.e. (Hg, Cd, Cr, Cu, Mn, Pb and Zn) were 0.26, 1.64, 81.04, 46.68, 208.81, 88.43 and 165.27 mg kg−1, respectively while in Yang reservoir mean concentrations of the various toxic metals, i.e. (Hg, Cd, Cr, Cu, Mn, Pb and Zn) were 0.28, 0.51, 21.38, 24.44, 322.37, 47.72 and 70.84 mg kg−1, respectively. Results of EF showed that in Tong reservoir Cu, Hg and Pb ranged from moderately enrichment to moderately severe enrichment while Cr and Zn were in the range of moderately enrichment. Similarly, cadmium (Cd) was found in the range of severe enrichment. While in Yang reservoir; Cu, Cr, Pb and Zn has no enrichment but Cd and Hg were characterised as moderately enriched. Moreover, PER in Tong reservoir was ranged, 142.71–415.07 with an average of 234.67 in all the core sediments, which showed that PER of Tong reservoir is in the range of considerable risk. While total PER of Yang reservoir was in the range of moderate risk to considerable risk. Among both water reservoirs, sediments samples collected from the Tong reservoir were more contaminated than Yang reservoir. The extent of pollution caused by toxic metals in both water reservoirs indicates that condition is much alarming for biota and for residents in surrounding area of both reservoirs. Sediments samples of both reservoirs were extensively polluted by mainly two toxic metals, i.e. (Cd and Hg) while moderately less polluted by other toxic metals. Accumulation of Cd and Hg in both reservoirs was predominantly influenced by agricultural practices, human activities, residential run-off and soil erosion.