乌梁素海表层沉积物中营养盐和重金属分布特征以及风险评价

Distribution and Risk Assessment on the Nutrients and Heavy Metals in Surface Sediments of Wuliangsuhai Lake

为了解乌梁素海表层沉积物中营养盐和重金属污染情况,于2021年7月对乌梁素海16个采样点位表层沉积物中总氮、总磷和9种重金属的含量进行了测定分析.结果表明,表层沉积物中ω(TN)和ω(TP)均值为7.91 g·kg^(-1)和1.89 g·kg^(-1),变异系数分别达到了27.96%和43.51%,具有一定的空间差异;营养盐污染指数表明,乌梁素海表层沉积物中TN和TP均处于严重污染程度.表层沉积物中Cr、Ni、Cu、Zn、Cd和Hg等重金属均已超过了背景值,其中Cd和Hg超标最严重,重金属地累积指数(I_(geo))也显示Cd和Hg生态风险严重.乌梁素海表层沉积物中重金属潜在生态风险指数值RI值介于337.82~681.88之间,均值为504.39,处于强的潜在生态风险,其中Cd和Hg两种重金属对RI贡献最高,贡献率分别达到了47.83%和43.99%.

To understand the pollution condition of nutrients and heavy metals in surface sediments from Wuliangsuhai Lake,the contents of total nitrogen,total phosphorus,and nine heavy metals in the surface sediments from 16 sampling sites were measured and analyzed in July 2021.The results showed that the average values ofω(TN)andω(TP)in the surface sediments were 7.91 g·kg^(-1) and 1.89 g·kg^(-1),and the coefficients of variation were 27.96%and 43.51%,respectively.There were spatial variations in the nutrient content over the study regions.The results of the nutrient pollution index indicated that TN and TP were at a heavy pollution level in the surface sediments of Wuliangsuhai Lake.The average concentrations of heavy metals(Cr,Ni,Cu,Zn,Cd,and Hg)in the surface sediments were higher than the background contents,and Cd and Hg were the highest-risk elements.The results of Igeo also showed that Cd and Hg had the higher ecological risk.A potential ecological risk assessment indicated that the potential ecological risk index(RI)of the investigated heavy metals ranged from 337.82 to 681.88,with an average value of 504.39.This indicated that heavy metals of surface sediments from Wuliangsuhai Lake were at high ecological risk.The results of Er showed that Cd and Hg had become the main rates for the contribution of potential ecological risk,reaching 47.83%and 43.99%,respectively.