Source apportionment of soil heavy metals based on APCR/MLR and the PMF model: a case study of the Henan section of the Yellow River

The occurrence characteristics of heavy metals (HMs) in aquatic environments have garnered widespread attention. Industrial wastewater, agricultural runoff, and domestic sewage discharged along the Yellow River in Henan Province pose potential threats to both the river ecosystem and human health. Consequently, the present study elucidated HM sources in the Henan section of the Yellow River via field investigations and model validation. The total concentrations of seven heavy metals (Cu, Pb, Zn, Cr, Ni, Cd, As) in riverbank soils of the studied area ranged from 0.28 (Cd)-798.55 (Mn) mg/kg.. HM levels were generally higher in tributaries than in the main stream, with significant inter-tributary variation (P < 0.05). The spatial distribution of potential ecological risk showed a pyramidal structure, dominated by medium-risk zones (61.50%), followed by high-risk and low-risk areas. Health risk assessment indicated elevated risks for children compared to adults, with oral ingestion identified as the primary exposure pathway (> 90%). Correlation analysis revealed Zn was significantly correlated with other HMs (P < 0.05). Source apportionment via Principal Component Analysis (PCA) combined with the Positive Matrix Factorization (PMF) model quantified contributions as: industrial emissions (28.50%) > agricultural non-point sources (21.70%) > geological background (15.30%) > industrial wastewater (12.80%) > transportation emissions (10.50%) > mining activities (7.00%). Industrial sources were identified as the primary contributor to both ecological and health risks. This study provides a reference and a basis for formulating effective measures to prevent and control HMs enrichment in agricultural soils.