Health risk assessment of heavy metals in the water of surface and subsurface microlayers from Guangzhou section of Pearl River

Concentrations distribution of the As、Cd、Cr、Cu、Zn and Pb in the water of surface and subsurface microlayers of 4 locations from Guangzhou section of Pearl River from February 2009 to July were examined in this study.The health risks associated with these heavy metals in water were also assessed primarily.The results showed that the water in Guangzhou section of Pearl River was polluted by 6 kinds of heavy metals in different degree.The surface microlayer has definite enrichment of these heavy metals except Zn.Among the health risks caused by drinking of water with heavy metals,the average total health risk caused by the carcinogens in the surface microlayer was 1.7×10-4·a-1,which was 1.1 times of the subsurface microlayer(1.5×10-4·a-1) and 3.4 times of the maximum allowance levels recommended by ICRP(5×10-5·a-1).The health risk of carcinogenesis caused by As,Cd and Cr accounted for about 99.8% of the total risk,which was significantly higher than that of the noncarcinogens(Cu、Zn and Pb)(0.2%).Therefore,it is an effective way to reduce the environmental health risk by controlling the discharge of Cr and As into the Guangzhou section of Pearl River.