Source Apportionment of Inorganic Pollutants and Health Risk Assessment in Rivers of Resource-Based Cities: A Case Study of Ma'anshan City

Anthropogenic activities such as mining operations have significantly increased the input of inorganic pollutants (e.g., heavy metals) into aquatic environments, exacerbating surface water quality degradation in downstream cities. This has led to regional water environmental issues and poses potential risks to ecological livability and human health in beautiful city construction, particularly in metal-mining areas. Taking the typical resource-based city of Ma'anshan as a case study, this research analyzed the distribution, sources and potential health risks of inorganic pollutants in Caishi River and Cihu River, and evaluated the uncertainty of potential health risks using Monte Carlo simulation. The results indicate relatively low overall pollution levels in both rivers. The average exceedance rates for total nitrogen (TN) and sulfate were 35% and 74%, respectively. The maximum detected concentrations of heavy metals Cu, As and Ni were below the class Ⅲ water quality standards (GB 3838-2002), except for Hg, which exceeded the standards in 90% of samples and became the main contributor to heavy metal pollution indices. The Positive Matrix Factorization (PMF) model identified five sources: smelting activities (19.8%), regional geological environment (16.5%), mixed agricultural activities and urban sewage (24.3%), water-rock interactions from geological strata (19.4%), and agricultural activities (20.0%). For controlling human health risks from surface water, priority should be given to the control of the sources from agricultural activities and urban sewage rather than from mining activities. Non-carcinogenic health risks from surface water exposure were negligible. However, carcinogenic heavy metal As was the main contributor to carcinogenic health risks, which were not negligible. Carcinogenic Risk (CR) values for 23%-28% of adults and and 50%-55% of children exceeded the acceptable threshold of 0.0001 indicating relatively high probabilistic risks. Exposure duration and As concentration were the largest positive contributors to the CR. It is recommended that As and Hg be prioritized as key indicators for monitoring dissolved heavy metals in surface water, with additional attention paid to regulating and managing exposure duration and As concentration for health risks mitigation.