Heavy Metal Pollution of the Drinking Water Sources in the Liujiang River Basin, and Related Health Risk Assessments

Abstract

The characteristics of heavy metal pollution in drinking water in the Liujiang river basin and its potential hazards on human health were investigated. In this study, the regular water-quality indices and the contents of metal elements Cd, As, Cr, Hg, Zn, Cu, Pb, Fe, and Mn in the Liujiang river and its main tributaries were detected from January to December of 2016. The health risks of drinking contaminated water were evaluated by the health risk assessment model recommended by the US EPA. The results showed that the concentrations of all of the aforementioned metal elements, except Hg, did not exceed the limits recommended by China's surface water environmental quality standard (GB 3838-2002). Pearson correlation analysis of the concentrations of metal elements indicated that Cd, Pb, As, and Fe may have similar sources, and Cu, Cr, Hg, and Zn may have source of diversity, while there was no significant correlation between the concentrations of metal elements and the pH value. The carcinogenic health risks posed by heavy metal elements in the Liujiang river basin in adults and children were 4.52E-04 a-1 and 5.91E-04 a-1, respectively, while the non-carcinogenic health risks were 8.96E-09 a-1 and 1.14E-08 a-1, respectively. The heavy metal elements in drinking water, on the basis of their average carcinogenic health risks, were ranked as Cr > As > Cd, and the risk levels ranged from 3.58E-06 to 1.21E-04 a-1; the risk values of Cr and As were higher than the maximum allowance levels recommended by ICRP (5.0×10-5 a-1). Simultaneously, the risk levels of the average non-carcinogenic health risks ranged from 3.53E-12 to 2.87E-09 a-1, and the range was lower than the maximum allowance levels recommended by EPA. Carcinogens, especially Cr and As, are the main causes of health risks in the aquatic environment of the Liujiang river basin, and should be prioritized as the main objects of aquatic environmental risk management in the Liujiang river basin.