Ecological risk assessment of potentially toxic elements (PTEs) in the soil-plant system after reclamation of dredged sediment

Abstract

The Shayinghe River is an important tributary of the Huaihe River in China. The concentrations of potential toxic elements (PTEs), such as As, Hg, Pb, Cu, Zn, Cr, and Cd in soils and dominant vegetation from mud-dumping areas reclaimed with dredged sediments, and areas without mud-dumping (non-mud-dumping areas) adjacent to the Shayinghe River were investigated. The potential ecological risk index (ERI) and transfer coefficient (TC) were calculated and evaluated. The results showed that the potential toxic element concentrations in all sampling areas decreased in the order of (Zn, Cr) > (Cu, Pb) > As>Cd > Hg. Additionally, the total concentrations of the PTEs significantly increased from mud-dumping to the non-mud-dumping areas. Ecological risk assessment of soils showed that all the elements did not exhibit apparent ecological risks (except for As). This element exhibited a moderate ecological risk, implying that the dredging of sediments could increase the potential ecological risk of individual PTEs. Additionally, the PTEs in some of dominant plants in mud-dumping areas did not increase, indicating no apparent accumulation. The principal component analysis (PCA) showed that the principal components of the PTEs in plants from dredged sediments were different from those in the agricultural soil, indicating the influence of dredging on PTEs. Finally, Cd, Zn, and Hg had higher transfer coefficients (up to 6), even if their concentrations were relatively low, suggesting potential ecological risks to the plants.

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