黑河上中游流域梯级库区夏季重金属汇源解析

Distribution characteristics and aggregating and releasing of heavy metals during Summer in a cascade Reservoir of the upper and middle reaches of the Heihe River

为探究梯级筑坝对河流重金属空间分布的影响,于2019年8月在黑河上、中游的干、支流河段采集水体、沉积物及岸边土壤样本,测定了8种重金属(Cr、Cu、Ni、Pb、Zn、Cd、Mn、As)的含量,利用反距离加权插值法、主成分分析法等分析了河流重金属的空间分布和来源.结果表明,黑河中上游库区重金属仍处于“汇”阶段,筑坝蓄水主要表现出“拦截效应”,源于各重金属迁移释放能力不同,少量重金属被“拦截”于中部库区.同时,受干支交汇水力特性影响,其富集效应也较明显.主成分分析等指出,As、Cd、Pb、Zn和Cu主要源于矿产开采活动,Mn、Cr、Ni分别源于工业生产、城市排污、自然因素等.Cu含量的空间分布特征还显示,其于沉积物、岸边土壤中的含量能指示断面附近有矿产开采等迹象.研究结果可为我国梯级筑坝河段的重金属控制和有效管理提供参考.

To explore impacts of a cascade reservoir on the spatial distribution of heavy metals in rivers,we collected samples(including water,sediment and shoreside soil)from the trunk and tributaries of the upper and middle reaches of the Heihe River in August 2019 to determine the contents of Cr,Cu,Ni,Pb,Zn,Cd,Mn and As elements.The spatial distribution and sources of these heavy metals were analyzed through inverse distance weighting and principal component analysis.The result show that these elements were still in the"sink"stage in the middle and upper reaches.Damming for impoundment had the"interception effect"due to the different migration and release capacities of various heavy metals.A small portion of heavy metals was"intercepted"in the middle reservoir area and a significant enrichment in the trunk stream and its tributaries due to the hydraulic characteristics of their confluences.Furthermore,As,Cd,Pb,Zn and Cu were mainly resulted from mineral exploitation,while Mn,Cr and Ni from industrial production,urban sewage and natural factors,respectively.According to the horizontal characteristics of Cu concentration,sediments and soils on the shores indicated mineral exploitation near the sections.The findings could provide a reference to the control and effective management of heavy metals in the cascade damming reaches of China.