Pollution characteristics and health risk assessment of heavy metals of a certain river in headwater stream of Xiangjiang River

To investigate the distribution characteristics of heavy metal elements in a river section in headwater stream of Xiangjiang River and assess their health risks to coastal residents, five heavy metal elements (As, Cu, Pb, Zn and Cd) in 13 surface water samples of the river were collected and monitored at three periods (wet, dry and normal). The Nemero comprehensive pollution index method and the health risk assessment model were employed to study the pollution levels, distribution characteristics and potential health risks of these heavy metals. The results showed that the average metal concentrations in the surface water samples in the river followed the order of Zn > As > Pb > Cd > Cu. The pollution levels of these heavy metals were arranged as follows: normal period ≈ dry period > wet period, and upstream ≈ midstream > downstream. The results of Nemero comprehensive pollution index method showed that 86.1% of the sampling sites in the river were heavily polluted by heavy metals throughout the year. The result of health risk assessment indicated that the environmental health risks in the surface water in the study area were mainly caused by As and Cd. The health risk level of these heavy metals in study area followed the order of upstream > midstream > downstream and dry period > normal period > wet period. And the children were nearly 2.1 times more susceptible to health effects than adults.