Contaminant Characteristics and Ecological Risk Assessments of Heavy Metals from River Networks in the Western Area of the Wangyu River

Abstract

To study the pollution characteristics and ecological risks of heavy metals in the western area of the Wangyu River, water and surface sediment samples of five rivers were investigated. The concentration and chemical fractions of eight heavy metals (Ni, Cu, Cr, Zn, As, Cd, Pb, and Hg) were analyzed, the pollution sources of heavy metals were studied using multivariate statistical analysis, and various ecological risk assessments were applied to identify the level of heavy metal contaminants. The results showed that the concentration of heavy metals in water was low, except for Hg, which was lower than the Class I standard of Surface Water Environmental Quality Standard. The content of heavy metals in surface sediments was high, except for Hg, which was significantly higher than the environmental background values. The partition coefficient of heavy metals in water-sediments showed that Cd, As, and Hg had strong re-emission potential. The Igeo indicated that Cu, Zn, and Cd were in a high pollution state as a whole. The RI showed that Cd was the main ecological risk factor in the study area. The RRSP indicated that the degree of pollution by Ni, Zn, and As was low because of its high residual fraction ratio, which was difficult to release under natural conditions. However, the degree of pollution by Cd was high because it had the highest content of weak acid extractable fraction among all the heavy metals. Therefore, it is necessary to pay more attention to Cd contamination. The source analysis of heavy metals showed that the western area of the Wangyu River was mainly affected by the pollution emissions from the surrounding machinery factories.