Source analysis and health risk assessment of heavy metals in groundwater in the northeast of Changde City

This paper is the result of environmental geological survey engineering.

Objective Heavy metal pollution of groundwater is a major challenge for ensuring safe water supply in the world. The source analysis and health risk assessment will provide scientific basis for the targeted control of heavy metal pollution in groundwater and health management of populations.

Methods In this study, 121 groundwater samples were collected in the northeast of Changde city. The PMF model and health risk assessment model were applied to analyze and evaluate the pollution sources and health risks of heavy metals in the groundwater.

Results (1) The mean concentration of heavy metals in groundwater followed the order of Fe>Zn>As>Cu>Pb>Cr>Cd. Among them, Fe and As exceeded the limits of groundwater quality standard Ⅲ water to varying degrees, and the exceeding rates were 36.37% and 14.05%, respectively, and the spatial distribution of the two elements was significantly different. (2) The PMF model identified four major sources of heavy metals: natural sources, waste incineration, agricultural activities and traffic emissions, with contribution rates of 85.46%, 8.26%, 4.36% and 1.92%, respectively. (3) The results of health risk assessment showed that As was the main element that contributing to both non-carcinogenic and carcinogenic risks. The non-carcinogenic risk index (HI) of adults and children were 0.90 and 1.14, respectively, and the proportion of non-carcinogenic risk exceeding the control value in adults and children were 36.35% and 42.55%, respectively. The carcinogenic risk index (TCR) of adults and children was 1.97×10⁻⁴ and 8.27×10⁻⁵, respectively, and the proportion of carcinogenic risk exceeding the control value in adults and children was 52.9% and 34.15%, respectively.

Conclusions For drinking water safety, more attention should be paid to the impact of As exposure in groundwater. It is essential to focus on the protection of shallow groundwater by promoting the control of agricultural non-point source pollution, regulating pesticide use, and strengthening water quality monitoring in areas with concentrated shallow wells or gradually advancing alternative water source solutions, so as to achieve more targeted risk prevention and control.