Source analysis of groundwater chemical components and health risk assessment in the eastern Sichuan hilly region

This paper is the result of hydrogeological survey engineering.

Objective In order to understand the water quality of shallow groundwater in Guangan area, identify the main sources of pollutants and possible health risks, improve the level of water resources management and ensure water safety for residents.

Methods This paper takes the shallow groundwater widely exploited and utilized in Guang 'an area as the research object. Through field investigation and interview, 74 groups of shallow groundwater analysis results are collected, and hydrochemical analysis, ion ratio and positive definite matrix subfactorization (PMF) model are comprehensively applied to the source analysis of groundwater chemical components. Finally, based on the health risk assessment model (HRA), Monte Carlo simulation (MCS) was used to evaluate the potential health risks existing among adults and children in the study area.

Results The results show that the PMF model identified four main controlling factors: high geological background value (F1), dissolution effect (F2), cation exchange and redox reaction (F3), and anthropogenic pollution (F4). The major exceedance substances in the regional groundwater are nitrate ions, fluoride ions, manganese ions, etc. The average contribution of these four factors to the groundwater quality is in the following order: F2 > F3 > F1 > F4; The results of the health risk assessment model showed that the health risk of a single pollutant exceeding the standard in the study area was low for adults and children, and the risk order of the main exceedant was NO₃⁻ > F⁻ > Mn, but the mean value of the total non-carcinogenic risk was high, and the total non-carcinogenic risk of children was about 1.49 times that of adults. Factor 2 and factor 3 are major sources of human health risk.

Conclusion The results of this study can provide reference for regional groundwater quality management, development and utilization, and suggest that the main substances exceeding the standard should be monitored to prevent the safety of groundwater drinking water.