青海湖流域主要河口区沉积物中重金属元素生态风险评价

doi:10.11934/j.issn.1673-4831.2016.06.011

摘要/Abstract

摘要：

为摸清青海湖流域重金属的污染现状，对流域内11处河口区0~5 cm层沉积物进行调查取样，分析测定了表层沉积物中Zn、Cu、Pb、Hg、Ni、As、Cd和Cr 8种重金属元素含量，并对其来源、生态风险及污染状况进行评价。结果显示：（1）青海湖流域沉积物中8种重金属含量和介于151.61~277.31 mg·kg^-1，平均值为209.65 mg·kg^-1，略高于青海湖流域表层土壤环境背景值。重金属含量由高到低依次为As、Zn、Cr、Ni、Cu、Pb、Cd和Hg，其中As、Cr和Zn占8种重金属总含量的73.63%。青海湖流域重金属元素间具有相似来源，人类对重金属元素的影响主要体现在交通运输和农业活动上。重金属地累积系数I_geo从大到小依次为As、Hg、Cd、Cu、Cr、Ni、Zn和Pb，其中As的污染程度为偏中度，平均地累积指数I_geo为1.67。重金属潜在生态风险值从大到小依次为Hg、Cd、As、Cu、Ni、Pb、Cr和Zn，其中Hg、Cd和As对综合潜在生态风险指数I_R的平均贡献率分别为40.76%、25.56%和25.53%。（2）近年来青海湖流域内的交通运输、农业废水、小城镇化及旅游开发等人类活动造成的重金属排放问题已经开始显现，流域生态系统的自净能力不能将所有重金属元素均净化至低风险水平。因此，必须加强对中小河流与季节性河流中重金属元素的监测和预警，制定出针对性的治理和修复措施，保证青海湖流域内不受重金属污染的威胁。

关键词: 青海湖流域, 河口, 沉积物, 重金属, 生态风险评价

Abstract:

In order to investigate the status of heavy metal pollution of Qinghai Lake Basin, samples of sediments were collected from 0-5 cm sediment layers at 11 sampling sites around the inlet estuaries of the lake for analysis of contents of 8 heavy metals (Zn, Cu, Pb, Hg, Ni, As, Cd and Cr) in an attempt to determine their sources, ecological risks and pollution statuses. Results show:(1) The total contents of the 8 heavy metals in the samples varied in the range of 151.61-277.31 mg·kg^-1 and averaged 209.65 mg·kg^-1, which was slightly higher than the environmental background values of the surface soil in the Qinghai Lake Basin. In terms of concentration, the 8 elements followed an order of As >Zn >Cr >Ni >Cu >Pb >Cd >Hg, and As, Cr and Zn accounted for 73.63% of the total of the 8. The heavy metals in the sediment brought in by human activities came from similar sources, that are agriculture and transportation. In terms of geo-accumulation coefficient (I_geo) the heavy metal displayed an order of As >Hg >Cd >Cu >Cr >Ni >Zn >Pb. Among the 8, As tended to be moderate in pollution level, with an mean I_geo being 1.67. In terms of potential ecological risk, the 8 heavy metals followed an order of Hg >Cd >As >Cu >Ni >Pb >Cr >Zn. Hg, Cd and As were the major contributors of the integrated potential ecological risk index (I_R), contributing 40.76%, 25.56% and 25.53% respectively. And (2) In recent years, the problem of heavy metal pollution has emerged as a result of intensified human activities, such as transportation, discharge of waste water from agriculture, urbanization (or townization) and development of tourism in the basin. The ecosystem of the basin is not so capable of purifying all the heavy metal pollutions down to a low-risk level. Therefore, it is essential to intensify monitoring and early-warning of heavy metal pollution in the medium and small inlets and seasonal inlets of the Qinghai Lake Basin, and work out case-specific control and remediation measures, so as to ensure the basin free from heavy metal pollution.

Key words: Qinghai Lake Basin, estuary, sediment, heavy metal, ecological risk assessment

中图分类号:

X522

李少华, 王学全, 兰岚, 高琪, 杨占武. 青海湖流域主要河口区沉积物中重金属元素生态风险评价[J]. 生态与农村环境学报, 2016, 32(6): 940-945.

LI Shao-hua, WANG Xue-quan, LAN Lan, GAO Qi, YANG Zhan-wu. Ecological Risk Assessment of Heavy Metals in Sedimentsat Estuaries of Major Inlets of the Qinghai Lake Basin[J]. Journal of Ecology and Rural Environment, 2016, 32(6): 940-945.

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