Contamination and ecological-health risks of heavy metals in groundwater of a typical agricultural area in Northwest China

Heavy metal pollution in groundwater has become a widespread issue worldwide. However, information on heavy metal pollution in groundwater of inland river basins in Northwest China remains limited. This study evaluated pollution and ecological-health risks of heavy metals in groundwater of the Zhangye Basin that is a typical inland river basin in Northwest China. The concentrations of heavy metals in groundwater were relatively low. Heavy metals in groundwater of the northeastern edge and western regions of the study area showed higher concentration than those of the remaining parts. Iron was the dominant heavy metal in groundwater with a maximum concentration of 1270 μg/L. Results of heavy metal pollution index calculations showed that approximately 3.5% of groundwater samples are classified into a moderate or high pollution level. The ecological risks of heavy metals in groundwater were relatively low with several metal(loid)s including As, Ni, and Cd serving as the dominant risk contributors. Ingestion pathway contributed to 97.2%/93.6% of non-cancer risks and 97.5%/97.5% of cancer risks for children/adults. Ingestion was the main health risk contributor. Total hazard quotients and cancer risks for children were 3.5 and 9.7 times higher than those for adults, suggesting that children are much more susceptible to potential harm caused by heavy metals in groundwater. Therefore, more effective control strategies should be taken in the study area as soon as possible.