Heavy metals of sediment cores in Dachan Bay and their responses to human activities

The grain-size distributions and heavy metal content in two sediment cores from Dachan Bay were analyzed, and the vertical distribution, provenance, and ecological risk of heavy metal were evaluated. The concentrations (mu g g(-1)) of Cu, Pb, Zn, Cd, Cr, Hg, As, and Ni in the sediment samples were 14.8-408, 33.0-130, 78.6-256, 0.193-1.79, 47.5-192, 0.052-1.39, 8.94-25.2, and 26.0-89.6, respectively. Most heavy metal concentrations increased from the bottom to the upper layers. On the basis of two sediment cores, the potential ecological risk of heavy metals was determined to be low, and the degree of potential ecological harm of heavy metals was in the order of Hg > Cd > As > Cu > Pb > Cr > Zn. Principal component analysis and correlation analysis yielded similar results, which indicated that heavy metals were closely related to the input of anthropogenic pollution (i.e., industrial pollutants and sewage discharge).