Statistical characteristics, source apportionment, and health risk assessment of heavy metals in shallow groundwater: a typical agricultural area of China.

Heavy metal pollution in groundwater poses global environmental and public health risks, particularly in agricultural regions relying on groundwater for irrigation and drinking. Here we quantify 11 heavy metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Cd, Ba) in the Fengpei Plain, China, and apportion their sources and health impacts using the APCS-MLR receptor model coupled with health risk assessment. Mean concentrations ranked as: Sr (521.5 μg/L) > Ba (50.45 μg/L) > Fe (15.37 μg/L) > As (1.080 μg/L) > Zn (0.887 μg/L) > Cu (0.294 μg/L) > Cr (0.083 μg/L) > Ni (0.064 μg/L) > Co (0.032 μg/L) > Mn (0.027 μg/L) > Cd (0.011 μg/L). Source apportionment using the APCS-MLR model revealed five major sources of heavy metals in the study area, with their respective contributions as follows: iron ore mining (22.8%), traffic emissions (24.4%), agricultural activities (18.9%), industrial activities (6.4%), and unidentified sources (27.5%). The health risks associated with heavy metals in groundwater were mainly attributed to As ingestion through drinking water. At approximately 6.7% of sampling sites, the non-carcinogenic hazard index (HI) for children exceeded 1 (maximum 1.31), while adult carcinogenic risk (TCR) exceeded the acceptable threshold, reaching 1.39 × 10⁻4 for females and 1.13 × 10⁻4 for males. This study provides a comprehensive understanding of the distribution, sources, and health risks of groundwater heavy metals, offering valuable guidance for groundwater management and contributing to the protection of drinking water safety for residents in agriculture-dominated regions.