Spatial distribution and health risk assessment of dissolved heavy metals in groundwater of eastern China coastal zone

Abstract

Environmental changes and human activities have deteriorated the quality of groundwater, which is an important source of freshwater in coastal areas. The Jiangsu Coastal Zone (JCZ), which is a typical area of the eastern China coastal zone (ECCZ), has a great demand for clean water resources due to its dense population. The groundwater in the JCZ is affected by both human activities and seawater intrusion. However, research on heavy metals in the groundwater of the JCZ is limited. This study investigated the spatial distribution characteristics and influencing factors of heavy metals in coastal groundwater of Jiangsu Province and conducted a health risk assessment (HRA). Relatively high concentrations of Cu, Cd, Pb, Co, Zn, and Ba existed in the northern JCZ, while As and B predominated in the central JCZ. The main heavy metal pollutants in the groundwater are B and As, with mean values at 0.61 mg/L and 0.02 mg/L, exceeding the standard rate reaching 48.28% and 18.07% respectively. The HRA results showed that B had the largest hazard quotient (HQ), accounting for 50.22% of the total HQs, and As was attributed to the pollutant with the largest cancer risk (CR), accounting for 99.74% of the total CRs. According to the results of the correlation analysis, heavy metals in the groundwater of JCZ mainly originated from industrial pollution, seawater intrusion, and mineral dissolution. Seawater intrusion increases the content of As and B in groundwater, leading to higher health risks. Therefore, the government should strengthen the supervision of seawater intrusion by implementing more effective water resource management policies, or adopting engineering measures such as installing subsurface physical barriers to prevent and control seawater intrusion.