XU Shuanggui, YANG Sha, QIN Xiwei, REN Erfeng, YANG Qipeng
（Department of Geological Engineering, Qinghai University, Xining 810016, China）

Abstract: In order to evaluate the pollution status, spatial distribution characteristics, potential ecological risk and possible sources of heavy metals (Hg, Cr, Zn, Cu, Cd), 16 surface sediments were collected from Xining section of the Huangshui River Basin. The concentrations of heavy metals were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Mercury Analyzer. Pollution load index (Pij and PLI), H？kanson potential ecological risk index (Ei and RI) and sediment quality guideline (SQGs) were calculated to evaluate the pollution degree of heavy metals in sediments. Pearson correlation analysis (PCA) and cluster analysis (CA) were used to deduce the potential sources of these elements. The PLI results showed that Xining section of the Huangshui River Basin were significantly contaminated by Hg and Cd. Hg increased firstly and then decreased from upstream to downstream, and Cd generally increased from upstream to downstream. The ecological hazards (Ei) for each heavy metals in a descending order were Hg> Cd> Cu> Cr> Zn. The comprehensive index of potential ecological risks (RI) for heavy metals indicated that 87.5% of the 16 sediments samples had more than moderate ecological risks, and the site with high RIs were generally located in Beichuan River and the midstream and downstream of the Huangshui River, which were heavily polluted by industrial, agricultural and transportation sources. In addition, the Ei of Hg and Cd were predominant components of RI, indicating that Xining section of the Huangshui River Basin is an area with extremely high potential ecological risk of Hg and Cd．The SQGs results indicated the toxic effects of these five heavy metals were low in the sediments, and Cr had a higher possibility of toxic effects on benthos. The PCA and CA results showed that Cr, Cu and Zn were mainly affected by natural sources. The major source of Hg and Cd was human activities (e.g., industrial activities).

Key word: Xining section of the Huangshui River Basin; surface sediments; heavy metals; spatial distribution; ecological risk

EARTH AND ENVIRONMENT Vol.49, No.5, Tot No.343, 2021, Page 561-569