Quantifying source-specific human and ecological risks of heavy metals in riparian wetlands using integrated chemical...

Riparian wetlands act as critical sinks for heavy metals in urbanized basins; however, how distinct pollution sources influence heavy metal risks through different chemical forms to generate divergent human and ecological risks remains poorly quantified. This study established an integrated framework combining BCR chemical speciation, spatial statistics, GeoDetector analysis, and APCS-MLR receptor modeling to mechanistically decouple source-risk pathways in the Jingwei Wetland Nature Reserve. The results showed that Cd exhibited the highest mobility factor (MF: 0.55) compared to the stable residual fractions (>80.0%) of Zn and Cr. Source apportionment identified three primary drivers: traffic emissions (PC1), industrial discharges (PC2), and mixed combustion-agricultural inputs (PC3). Crucially, a distinct risk dichotomy was revealed: industrial sources (PC2) contributed >54.0% of carcinogenic risks for humans, whereas mixed sources (PC3) drove ecological risks, predominantly through high-mobility Cd. This divergence highlights that bioavailable fractions, rather than total concentrations, dictate ecological vulnerability, particularly for Cd, where diffuse, non-point pathways contributed significantly (38.0%) to its accumulation, distinct from anthropogenic point sources. The results demonstrate that bioavailable fractions, rather than total concentrations, control ecological vulnerability, whereas toxicity-weighted industrial metals dominate carcinogenic risk. These findings support a pathway-differentiated management strategy targeting industrial point sources for health protection and diffuse agricultural inputs for ecological integrity, advancing precision remediation in riparian ecosystems.