Characterization of Heavy Metal Pollution in Urban Wetland Sediments and Evaluation of Human Health Risk

Urban wetlands are transitional sub-ecosystems, which have an important part in connecting the city sources of heavy metal pollution with freshwater ecosystems, and numerous studies have studied the nature of heavy metal pollution, though only several have investigated the consequences of heavy metals on the health of city dwellers residing in urban wetlands. The Monte Carlo simulation-based method of assessing health risks was employed to calculate the health risks related to the population residing within the study site as one of the measures taken within the framework of the present research to identify the health risks faced by the population when using the sediments of Huixian Wetland Mudong Lake, Guilin City, to evaluate health outcomes. The results showed that Cd and As had the highest geoaccumulation index values and were the most seriously polluted metals. The northeastern and northwestern areas of the lake exhibited a strong level of ecological risk, likely due to their proximity to anthropogenic pollution sources and slower water exchange rates. Non-carcinogenic risk indices (HI) for both adults and children were below 1, with children facing higher risk than adults. For carcinogenic risk, As, Cd, Cr, and Pb posed greater risks to children than adults, with 99.96% of the total carcinogenic risk (TCR) values exceeding the USEPA threshold of 1.00 × 10−4, indicating an unacceptable risk to children. Sensitivity analysis revealed that the hand–oral intake rate (IRing), As, and Cr were the main factors affecting the human health risk. These findings provide clear guidance for targeted risk control; priority should be given to pollution control of Cd and As, as well as protective measures in high-risk zones, to reduce children’s exposure. The results of this study provide a scientific basis for precise risk control and remediation measures in the region.