Source Apportionment and Health Risk Assessment of Heavy Metals in Hongjiannao Lake Based on the APCS-MLR Model

• • Industrial sources dominate heavy metal contamination in Hongjiannao Lake, contributing 35.44% of total load, with Hg, Cr, Zn, and Cu as primary factors; agricultural sources contribute 24.67%, natural 23.65%, and traffic 16.23%. • • Total heavy metal concentration dropped from 112.51 μg/L (2013–2016) to 58.80 μg/L (2017–2024), a 47.7% reduction, following the 2016 closure of small coal mines and ecological restoration, demonstrating policy effectiveness. • • Carcinogenic risk exceeded the alert threshold (1×10⁻⁴) at all sampling points for As (100% exceedance) and 16.67% for Cd, with adults facing 1.97–5.24 times higher risk than children, necessitating targeted remediation. • • Non-carcinogenic health risks (HI) were below 1 for all age groups, with the highest HI of 5.82×10⁻¹ for Pb in adult males, indicating negligible non-carcinogenic effects but underscoring Pb's relative contribution.