Distribution, source, and pollution assessment of heavy metals in Sanya offshore area, south Hainan Island of China.

Forty-four surface sediments from Sanya offshore area are analyzed for assessing heavy metals (Cu, Pb, Zn, Cr, Cd, Hg, and As) pollution. High metal values except for As are located in the southern areas which have fine-particle presence. However, high values of the metal As appear at a depth of 15-30 m in the Yazhou Bay. As and Pb show moderate contamination, and other metals show low contamination. The metals (except for As) are confirmed not to be enriched to slightly enriched, which are controlled by the grain size and mainly derived of the natural weathering products. The moderately severe to severe enrichment of As occurs in the Yazhou Bay and the nearshore area of the Sanya Bay. The reason is due in part to the excessive use of agricultural fertilizers. Further, it is also likely to be related to the high background value of As in the sea area.