Distribution characteristics and its ecological risk assessment of heavy metals in river sediments from Yanhe river

Abstract

In order to evaluate the distribution characteristics and pollution risk of heavy metals in sediments of Yanhe river, we investigated the contents of the heavy metals in the sediments from 9 representative sections of the river. The index of potential ecological risk and the index of geo-accumulation were used to assess the pollution degree and the ecological risk of heavy metals in the sediment, and the Pearson correlation was used to determine the pollution sources. The results showed that the average contents of Cr, Pb, Cu, Zn, Ni, As, Cd, Hg and As in the sediments were 124.56, 98.21, 66.00, 46.20, 22.64, 4.45, 0.14 and 0.11 mg·kg-1, respectively. Among them, the average contents of Pb, Hg, Cu, Cr and Cd exceeded the environmental background values of Shaanxi Province by 5.8, 4.4, 3.2, 1.8 and 1.4 times, respectively, and the average contents of Ni, As and Zn were lower than the environmental background values of Shaanxi Province. The average of heavy metals in the sediment of Yanhe river is 303.14, with the potential ecological risk index arranged from high to low as S8>S1>S5>S7>S2>S3>S6>S9>S4, and the proportions of medium potential ecological risk and strong ecological risk is 11.1% and 88.9%, mainly caused by Hg. Meanwhile, the geo-accumulation index of Cr, Pb, Hg and Cu in the sediments is greater than 0, which is mild-moderate pollution; the geo-accumulation index of the Cd is between -0.37 and 0.11, which is no-mild pollution; and the geo-accumulation index of Ni, Zn and As are less than 0, which is no pollution. Ni, Cd and Cu in the sediments of Yanhe river have a high similarity, and industrial layout, road traffic and geological activities may be the primary sources of pollution.

Keywords

• yanhe river
• heavy metals
• pollution distribution
• geo-accumulation index
• potential ecological risks index