浑河上游矿山重金属污染源解析及迁移机制研究

Dahuofang Reservoir, which supplies water to nine cities in centre part of Liaoning province, is one of the most important drinking water sources in China. The upper reaches watershed of Hun River is the key headwaters of Dahuofang Reservoir. However, mining increases quickly in this area, which leads to heavy mental pollution to water and soils. And the heavy metals in both soils and water poses seriously threat to the water quality of Dahuofang Reservoir.The source apportionment and transter mechanism of heavy metals in water and soils draw ever more attention.The distribution and chemical speciation of heavy metals (including Cu, Cd, Pb, Zn, Ni, Cr, As, and Hg) in water and soils in/around Houtoushan Mining District and Erdaogou Mining District will be studied in the proposal, aiming to get a clear understanding of the source and transfer characteristics of heavy metals in water and soils of mining district. BCR three stage sequential extraction procedure was applied to examine the speciation of eight heavy metals in the soils. On the basis of basic source information get by speciation analysis, profile analysis, and multivariate statistical analysis, a composite model named CMB-UNMIX will be used to quantify the pollution contribution of every single step of mining and transportation process to the soils and water in/around the mining district. The transfer behavior of heavy metals in water and soils is closely related to the chemical speciations of heavy metals. The transfer characteristics of different heavy metals and different chemical speciations of heavy metal in soils will be analyzed. The transfer coefficient of different speciations will be used to reflect transfer characteristics of heavy metals in soils. Implementing of the proposal will be helpful to the pollution controlling of heavy metals in this area and in other similar mining districts. Consequently, these researches have important theoretical and practical significance.

浑河流域大伙房水库是抚顺和沈阳两市生活饮用水的重要水源地，目前担负着辽宁省中部9个城市的供水任务。浑河上游是大伙房水库的关键水源涵养区，该区矿山开发引起的重金属污染，已威胁到下游水库的水质安全。查清矿区重金属污染物的来源及其贡献率，明确重金属在矿区及周围土壤和水体中的迁移机制，一直是环境界所关注而又未得到很好解决的问题。本项目以浑河上游流域内红透山矿区和二道沟矿区作为研究区，系统研究重金属(Cu、Cd、Pb、Zn、Ni、Cr、As、Hg)在矿区及周围土壤和水体中的分布特征和赋存形态；运用形态分析、剖面分析和多元统计方法，初步辨识矿区及周围土壤和水体中重金属污染物来源的类型，利用CMB-UNMIX复合模型，定量矿产开采、洗选和运输过程对矿区及周围土壤和水体重金属污染物的贡献。同时，利用剖面分析和形态分析阐明重金属在土壤和水体中的迁移机制，为水源地矿区重金属污染的的有效控制和治理提供科学依据。

以辽宁大伙房水库汇水区——浑河上游流域为研究对象，利用遥感、实地调查、实验室分析和国民经济数据等多种数据源分析了浑河上游地区土地利用方式与土壤养分、土壤重金属以及水环境的关系，对该区域的重金属污染状况进行了评价，初步确定了重金属污染的来源；分析地表水与土壤中非点源污染物的时空分布特征；对非点源污染负荷进行了模拟，综合评价了上游流域生态环境质量。在景观水平上，林地景观类型构成了浑河上游流域的整体骨架，所占总面积的70%以上，其次是耕地，而草地、工矿用地和未利用地等镶嵌其中。总体上，SOM含量和土壤TN含量比较丰富。由于该区域主要施用氮肥（硝酸铵），旱地土壤中的AN含量最高。土壤总体为弱酸性土壤，尤其针叶林和旱地土壤。土壤中磷分布不均，浑河（清原段）流域土壤中磷含量低于苏子河流域，农田土壤中磷含量低于林地。在浑河流域，土壤中Pb处于安全水平，而土壤Cd和Zn含量超过了相应的背景水平，在表层土壤中有一定程度的富集。从重金属的空间分布图上看，除土壤Zn为，苏子河流域土壤Cu、Cd、Pb、Ni和Cr含量水平高于浑河（清原段）流域。浑河上游土壤重金属总体潜在生态危害程度较轻，红透山铜矿区域和敖家堡的大东沟铁矿区域比较重。水环境中，河流底质重金属主要是Cd和Zn累积较高，由于Zn的毒性较小，对生态环境造成危害的主要是Cd；清原县出口下游1000 m河段，敖家堡乡河段，红河漂流河段，红透山镇的浑河干流河段，重金属潜在生态危害程度较大。河流沉积物中的重金属Cu可能来自上游矿山企业。土壤中的Cu-Ni-Cr主要是自然来源，Cd和Zn主要是人为来源。对地表水中非点源污染进行分析，TN、NO3-N具有显著的季节差异；雨期，监测点的TP浓度超标率最高（地表水Ⅱ类标准）；NH3-N时间变异最为明显，浓度从雨前到雨后期递减。TN、NO3-N、TP在三个季节的浓度变化趋势基本相同。TN在三个时段均与NO3-N正相关；NO3-N与PO43--P呈正相关关系。基于子流域的土地利用方式与河流水质关系分析表明，林地、水田对河流水质的具有改善作用，而建筑用地、旱地、未利用地对河流水质具有一定的恶化作用。浑河上游流域泥沙、总氮和总磷的空间分布受到土地利用类型、土壤类型、坡度和降雨等众多因素的综合影响。浑河上游生态环境目前处于一般或良状态，浑河上游流域生态环境的响应措施太少，对环境保护重视不够。