珠江广州段微表层和次表层水中重金属分布与风险的初步评价

2009年2月至7月对珠江广州段4个站位的微表层与次表层水中As、Cd、Cr、Cu、Zn和Pb的质量浓度进行调查研究,并对健康风险作了初步评价.结果表明:珠江广州段水体均不同程度地受到6种重金属的污染;除Zn以外,微表层对其余5种重金属均具有较强的富集作用;通过饮水途径所致健康风险中,微表层平均总致癌风险为1.7×10-4.a-1,是次表层平均总致癌风险1.5×10-4.a-1的1.1倍,是国际辐射防护委员会(ICRP)推荐的最大可接受风险水平5.0×10-5.a-1的3.4倍;总致癌风险(As、Cd和Cr)约占总风险的99.8%,远高于总非致癌风险(Cu、Zn和Pb)的0.2%,控制含Cr和As废水的排放是降低该河段重金属污染物健康风险的有效途径.

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.