Concentrations of porewater heavy metals, their benthic fluxes and the potential ecological risks in Daya Bay, South China.

Heavy metal (Cr, Mn, Fe, Ni, Cu, Zn, Cd, Pb) concentrations in surface sediment porewater and their benthic fluxes were investigated in Daya Bay, South China, to study their accumulation and transfer at the sediment-water interface, as well as the impact of human activities on heavy metals. Heavy metals in porewater displayed different patterns in three partitions (top, center and inlet), which was mainly attributed to the difference in the biogeochemical conditions, hydrodynamic force inner the bay and the human activities along the bay. Ecological risk assessment results showed that heavy metals in porewater dramatically exceeded the background values. The average release of heavy metals from sediment were (6.1 ± 3.3) × 104-(2.7 ± 1.6) × 108 g a-1 in the bay, so they had potential risks to the water environment, and sediment should be paid more attention to as the endogenesis of contamination.