典型制革污染场地地下水盐污染特征

Characteristics of groundwater salt pollution in a typical leather-contaminated site

在区域地下水调查的基础上,以某制革污染场地为研究对象,采集场地及其周围地下水样,对地下水中无机组分检出值进行了统计分析,识别了各组分的平面分布特征,最后对地下水盐污染机理以及各组分之间的关系进行了探讨。研究结果表明,制革厂废水排放、废弃物堆放已对地下水造成盐污染,主要污染组分为总硬度、溶解性总固体、Cl-和SO2-4;受污染的地下水环境以微酸性和还原性为特征;沿地下水流向,地下水中总硬度、溶解性总固体、Cl-、SO2-4、三氮由制革区向下游逐渐减小,基本上呈现出以皮革厂为中心的污染区,污染范围大概为0.20km2;制革污染场地地下水中硬度的升高,同时伴随着溶解性总固体、Cl-、SO2-4浓度升高,各组分之间具有明显的相关性,其主要原因是皮革区地表水污水和固体废物淋滤液入渗过程中经历阳离子交换、钙镁易溶盐溶解及难溶盐溶解等作用,导致地下水中Ca2+、Mg2+Cl-和SO2-4含量增加,最终溶解性总固体也升高;铵氮在含水介质中的迁移转化也是地下水硬度升高的一个重要因素。地下水三氮之间转化主要的途径是硝化作用,与地下水的氧化还原条件有关,氧化性相对较强的地下水中NO3-N含量高,而NH3-N和NO2-N含量相对较低。

On the basis of a regional groundwater survey, this paper places its emphasis on a leathercontaminated site. The site and the surrounding groundwater were sampled and the inorganic components in groundwater were analyzed. Characteristics of space distribution of each component were identified and the mechanism of groundwater salt pollution and the relationship among the various components were discussed. The research results show that the leather wastewater emissions and solid waste have caused groundwater salt pollution, and the main pollution components include total hardness, total dissolved solids, sulphate and chloride. The contaminated groundwater environment was characterized by subacidity and reducibility. Along the groundwater flow direction, the total hardness, total dissolved solids, sulphate, chloride, and ＂three nitrogen＂ of groundwater gradually decreased from the leather area to downstream. Basically the pollution area was centered around tanneries with a range of 0. 20km2. With the increase in hardness of groundwater in the leather-pollution site, total dissolved solids, sulphate and chloride increase, and an obvious correlation exists among the components. The main reason for this is that the cation exchange and the dissolution of soluble and insoluble calcium and magnesium salts occurred in the infiltration process of wastewater and solid waste leachate in the leather-site＇ s surface, causing the increase in Ca2 ＋, Mg2 ＋, Cl - and SO4^2 - contents of groundwater, and eventually resultig in the increase in total dissolved solids. The migration and transformation of ammonium nitrogen in the water-bearing media also has an important bearing on the increase in hardness in the groundwater. The transformation of ＂three nitrogen＂ in groundwater is mainly nitrification associated with the redox conditions of groundwater, and the content of NO3 -N in groundwater is high under relatively strong oxidizing conditions, and content of NH3-N and NO2-N are relatively low.