Source apportionment and health risk assessment of heavy metals in groundwater from a typical coal mining area in Hunan Province, China

This paper is the result of geological survey engineering.

Objective This study addresses groundwater heavy metal contamination and associated health risks in a typical coal mining area. Using a small watershed in a coal mining region of Hunan Province as the study area, this study aimed to characterize groundwater heavy metal pollution, quantify source contributions, and assess health risks for different receptor populations, so as to support water environment management in mining areas.

Methods Twenty groundwater samples were collected and analyzed using the Positive Matrix Factorization (PMF) model and human health risk assessment methods to identify heavy metal sources and potential health risks.

Results (1) groundwater in the study area is heavily polluted by Fe and Mn, with mean concentrations exceeding the Class III limits of the Chinese groundwater quality standard (GB/T 14848-2017); comprehensive evaluation indicates pollution ranging from mild to severe; (2) PMF source apportionment identified three main sources—natural geogenic sources (52.85%), agricultural activities (22.98%), and mining activities (24.17%); (3) health risk assessment indicated that drinking water ingestion is the main exposure pathway; Fe and Mn contribute most to the risk, but the hazard index (HI) for both adults and children is below the safe threshold of 1.

Conclusions Groundwater heavy metals in the study area are influenced by both natural geochemical background and human activities (mining and agriculture). Although overall health risks are currently acceptable, the cumulative effects of geogenic factors and certain metals warrant continued attention.