Distribution, source, and ecological risk assessment of potentially toxic elements in surface sediments from Qingfeng River, Hunan, China

Abstract

The spatial distribution and potential ecological risks of potentially toxic elements (PTEs) such as Sb, As, Cu, Zn, Pb, and Cr in sediment samples from the Qingfeng River were evaluated. This study aims to reveal the current status of sediment quality in the Qingfeng River and provide a scientific basis for its remediation and further comprehensive management. Descriptive analysis and inverse distance weighted method were used to investigate the concentration and spatial distribution of PTEs in sediments. The geoaccumulation index evaluation (Igeo), Nemerow index (NI), and potential ecological risk index (RI) were used to evaluate the pollution degree of PTEs. Multivariate statistical techniques, such as cluster analysis, correlation analysis, and principal component analysis, were used to identify the sources of PTEs. The results showed that the river sediments were mainly polluted by Sb (concentration range: 69–11,900 mg kg−1) and As (concentration range: 8–607 mg kg−1) and that the average concentrations were 4.3 and 553 times those of the background values, respectively. Based on the spatial distribution and pollution risks of PTEs, the study area was divided into three river sections, and the pollution risks were decreased in the order of upstream > midstream > downstream. The geoaccumulation index evaluation showed that the hierarchy of PTE pollutant concentration was as follows: Sb > As > Cu > Zn > Cr > Pb. The Nemerow indexes and potential ecological risk indexes all indicated that a very high potential risk exhibited in the study area, while the potential ecological risk of Sb was significantly higher than that of the other PTEs. Correlation analysis and principal component analysis indicated that Pb, As, and Sb were mainly derived from industrial activities, and Cu, Cr, and Zn were mainly derived from agricultural activities. The results showed that a very high potential risk existed in the study area. Sb was the main pollution factor of the surface sediments of the Qingfeng River and posed a very high potential ecological risk, while Cu, Cr, Zn, and Pb had low ecological risks. The results also determined that the sources of PTEs in the sediments could be mainly attributed to human activities. Substantial measures should be taken to control and resolve the PTE pollution in the Qingfeng River at the source.