Heavy Metal Accumulation and Source Apportionment in Urban River under Ecological Restoration: Relationships with Land Use and Risk Assessment Based on Monte Carlo Simulation

Abstract

The assessment of heavy metal (HM) distributions, sources, and potential risks is the first step of high-efficiency contaminant degradation and sustainable water resource utilization. In this study, the assessment of nine HMs from a typical urban river (Yongding River) in Beijing, China was implemented. Results evidence that the mean HM concentrations decreased in order: Mo > V > As > Zn > Ni > Mn > Fe > Cr > Co. The concentration of As, Zn, Mn, Fe, and Mo has a significant increase in the middle reaches, indicating agricultural and industrial pollution sources nearby. Three factors were extracted via principal component analysis, suggesting that As, Ni, Co, Mo, and V are mainly derived from anthropogenic inputs. Mn and Cr likely originated from natural sources, while Fe and Zn stemmed from mixed origins. The HM contamination levels are moderate and concentrated on As and Cr. Strong correlations among HMs and regional land use also confirmed the result. The noncarcinogenic and carcinogenic risks of HMs were evaluated based on four age groups by Monte Carlo simulation. Although the results of environmental modeling revealed a weak carcinogenic risk of As in adults (6.20 × 10–5), the risk for juveniles cannot be ignored. Target hazard quotients analysis implied relatively low noncarcinogenic risk when consuming fish tissues from rivers, and the carcinogenic risk of inorganic As in fish was acceptable. In total, this study provided powerful support for restoring HM contaminations and maintaining sustainable urban water management.