Heavy Metal Pollution and Ecological Risk Assessment of Rice Fields on the Northwest Bank of the Lower Yangtze River in HeXian County

To investigate the contamination status, sources, spatial distribution, and health risks of heavy metals in paddy soils of Hexian County, 63 surface soil samples were analyzed for eight metals. Multiple pollution indices and multivariate statistical methods were applied to evaluate contamination levels and identify potential sources. Source apportionment was conducted using principal component analysis (PCA) combined with correlation analysis and spatial distribution characteristics. Results showed variable concentrations of heavy metals, with arsenic, copper, and lead exhibiting relatively higher single-factor pollution indices. The Nemerow pollution index (PN) ranged from 0.86 to 3.05 (mean = 1.16), indicating overall slight to moderate pollution, with localized areas showing higher pollution levels. The potential ecological risk index (RI) ranged from 28.06 to 66.45 (mean = 35.66), which was well below the threshold of 150, indicating a low ecological risk. Health risk assessment indicated negligible non-carcinogenic risks for both children and adults. Although carcinogenic risks remained within acceptable limits, children exhibited higher susceptibility, suggesting potential long-term concerns. Overall, these findings provide scientific evidence for targeted pollution control and risk-based agricultural management in Hexian County, and offer practical implications for mitigating heavy metal contamination and protecting agricultural sustainability in regions along the lower Yangtze River.