黑河重金属空间分布及与大型底栖动物的关系

为探究河流水体和表层沉积物重金属分布特征及其与大型底栖动物的响应关系，于2019年8月在黑河上、中游不同区域采集底栖动物、水体及表层沉积物样品，测定了8种重金属（Cr、Cu、Ni、Pb、Zn、Cd、Hg、As）的含量，利用多元统计法分析了底栖动物、水体及表层沉积物重金属空间分布特征，并运用综合污染指数、潜在生态风险指数法对河流水体及表层沉积物重金属的污染风险进行评价，最后运用相关性分析了大型底栖动物与河流水体及表层沉积物的关系.结果表明，水体重金属含量整体较低，空间变化不显著.表层沉积物中w（Mn），w（Zn），w（Cr），w（Ni），w（Cu），w（Pb），w（As），w（Cd）均高于水体和土壤背景值，其均值分别为背景值的1.36，2.26，2.66，2.10，1.98，1.85，1.89和3.33倍，且空间差异显著.表层沉积物中Cu、Cr、Ni可能来源于农药化肥的施用和工业废水排放；Cd、Pb、Mn可能来源于矿渣及其渗滤液和自然背景的叠加影响；As和Zn可能与生活及工业污水排放有关.水体重金属污染水平极低；表层沉积物重金属污染主要由Cd、Cr、Zn、Ni引起；空间变化趋势为上游支流>上游干流﹥中游.表层沉积物中Mn、Cd的RI值分别为17.20和12.30，属高风险水平，其他元素均为低度风险水平.大型底栖动物现存量及多样性呈空间差异性分布，基眼目密度与水体中As呈正相关；鞘翅目、半翅目和基眼目密度及3种生物多样性指数均与表层沉积物重金属含量呈显著性相关，其可作为黑河上、中游水体及表层沉积物重金属污染的潜在指示生物.

Space distribution of heavy metals and its relationship with macrozoobenthos in the Heihe River,Northwest China

A study of exploring the distribution characteristics of heavy metals between river water and surface sediments and analyzing the response to macrozoobenthos were carried out different areas in August 2019 in the upper and middle reaches of the Heihe River. The contents of eight heavy metals (Cr, Cu, Ni, Pb, Zn, Cd, Hg and As) were determined for macrozoobenthos, water and surface sediments samples in this study. The spatial distribution characteristics of heavymetals in macrozoobenthos, water and surface sediments were analyzed by multivariate statistical method. Moreover, the pollution risk of heavy metals in river water and surface sediments was evaluated by comprehensive pollution index and potential ecological risk index. Finally, the relationship between macrozoobenthos and river water and surface sediments was analyzed by correlation analysis. The results showed that heavy metal concentrations was low in river water and the spatial variation was not significant. The average values of w(Mn), w(Zn), w(Cr), w(Ni), w(Cu), w(Pb), w(As), w(Cd) in surface sediments were 1.36, 2.26, 2.66, 2.10, 1.98, 1.85, 1.89 and 3.33 times higher than the background values of water and soil respectively, and the spatial differences were significant, Cu, Cr and Ni in the surface sediments may come from the application of pesticides and fertilizers and the discharge of industrial wastewater. Cd, Pb and Mn may come from the superposition of slag and its leachate and natural background; as and Zn may be related to the discharge of domestic and industrial wastewater. The pollution level of heavy metals in water was very low and the pollution of heavy metals in surface sediments was mainly caused by Cd, Cr, Zn and Ni. Furthermore, the spatial variation trend was as follows:upstream tributary > upstream main stream > middle stream. The RI values of Mn and Cd in surface sediments were 17.20 and 12.30, respectively, which belonged to high risk level. What's more, other elements were at low risk level. The macrozoobenthos biomass and diversity showed spatial difference distribution and the density of Basommatophora was positively correlated with as in water body. The density of Coleoptera, Hemiptera and Basommatophora and the three biodiversity indexes were significantly correlated with heavy metal content in surface sediments, which could be used as potential indicators of heavy metal pollution in river water and surface sediments in the upper and middle reaches of Heihe River.