丹江口水库沉积物重金属背景值的确定及潜在生态风险评估

Determination of Background Value and Potential Ecological Risk Assessment of Heavy Metals in Sediments of the Danjiangkou Reservoir

为研究丹江口水库表层沉积物中重金属的污染水平及潜在的生态风险,利用参考元素法,对丹江口水库表层沉积物重金属的背景值进行了确定,结果显示Cr、Ni、Cu、Zn、As、Cd、Hg和Pb的背景值分别为41.18、34、32.13、76.84、10.46、0.70、0.07和27.11 mg·kg^(-1).利用Hakanson潜在生态危害指数法对丹江口沉积物中重金属进行生态风险评估,结果表明,丹江口表层沉积物中8种重金属的潜在生态风险指数(RI)值在29.49~214.11,平均值为118.91,总体处于低风险水平;8种重金属污染系数排序为:Cd>Hg>Zn>Cr>Pb>Ni>As=Cu,污染系数变化范围在0.22~2.96之间,平均值在1.05~1.31之间,处于中等偏低的污染状态,其中,Cd和Hg这两种危害性极大的元素污染系数稍高,平均值分别为1.31和1.24,值得进一步关注.

The aim of this study was to explore the pollution level and potential ecological risk of heavy metals in sediments of the Danjiangkou Reservoir, and the study obtained the background value of heavy metals of the surface sediments using reference element and statistical methods. The results indicated that the background values of Cr, Ni, Cu, Zn, As, Cd, Hg and Pb were 41. 18, 34, 32. 13, 76. 84, 10. 46, 0. 70, 0. 07 and 27. 11 mg-kg - 1 , respectively. In addition, the potential ecological risks of the eight heavy metals in sediments were assessed using the Hakanson ecological risk index method. The values of RI for these eight metals in surface sediments ranged from 29. 49 to 214. 11, with the mean value of 118. 91, and the pollution level was low. Furthermore, the Cif value was in the order of Cd ﹥ Hg ﹥ Zn ﹥ Cr ﹥ Pb ﹥ Ni ﹥ As = Cu with the mean value of 1. 05- 1. 31, and the pollution level varied from low to intermediate. The Cif values of Cd and Hg were higher than those of other heavy metals with the mean values of 1. 31 and 1. 24, respectively, which should be paid more attentions.