Toxicological Risk Assessment and Source Identification of Groundwater Pollution: A Case of Sheep Herd Damage in a Pastoral Area

Improper emissions from industrial activities pose toxicological risks to groundwater safety. Based on an environmental forensic identification case involving livestock (sheep) damage caused by groundwater pollution in a pastoral area, we comprehensively evaluated groundwater quality risks, toxicological risks, and pollution sources using multivariate statistical methods, the Nemerow index method, and a non-carcinogenic health risk model. The potential specific pollutants in the region mainly included calcium, potassium, sodium, magnesium, manganese, fluoride, chloride, sulfate, ammonia nitrogen, total dissolved solids, and nitrate. An evaluation of the groundwater health risk factors showed that fluoride, nitrate, and manganese pose higher health risks (HQ > 1), as fluoride > nitrate > manganese. This suggests that these three pollutants were the primary causes of livestock damage. Identification of pollution sources using multivariate statistical analysis revealed that the main pollutants in the groundwater originate from two rare earth enterprises in the surrounding industrial park, followed by the emissions from animal husbandry. This study provides guidelines into comprehensive regional toxicological risk assessment and source tracing, offering an identification method for similar forensic environmental damage cases.