Characteristics of nutrients pollution and ecological risk assessment of heavy metal in sediments of Fenhe River, Taiyuan section, China

This study aimed to reveal the characteristics of nutrients and heavy metals associated with ecological risks in the sediments of Fenhe River, Taiyuan section. The concentrations of nutrients (total nitrogen, total phosphorus, total organic matter) and heavy metals (As, Cu, Zn, Pb, Cr, Ni, Hg, Cd) were investigated. Spatial distribution, correlation analysis and source identification were facilitated to indicate nutrient and heavy metal pollution characteristics. Evaluations of heavy metals’ contamination degree were achieved by comprehensive ecological risk indexes including Igeo, Iin, Cf, pollution load index and risk index. The results showed that nutrients accumulated in the middle region and were mainly from embryophyte, zooplankton and phytoplankton or algae, based on C/N values. Large spatial variabilities existed in heavy metal distribution patterns; source identification for heavy metals revealed they were from natural sources and anthropogenic activities based on a principal component analysis model. Results of different ecological risk indexes showed that pollution associated with Hg was rated as a moderate ecological risk but was significant contamination, higher ecological risks mainly existed in the middle region.