污染水灌溉对土壤影响的研究进展及问题分析

Study Progress on Effect of Polluted Water Irrigation on Soil and Problem Analysis

污染水灌溉是缓解中国水资源短缺的重要途径之一。除了城市污水以外,污染水还包括污染的地表水、工业废水、养殖废水、矿区废水、垃圾渗滤液等。文章回顾了污染水灌溉对土壤的污染作用,分析了中国污水灌溉存在的主要问题。污染水灌溉对环境的污染,主要在土壤表层,具体表现为:(1)改变了土壤的p H值,不同地区、不同的污染水类型对土壤p H值的影响结果不同;(2)重金属在土壤表层富集,向深层土迁移的速率比较缓慢,不同种类的重金属在土壤中的累积迁移规律不同,重金属富集程度与污水灌溉时间密切相关,Cd、Pb等的活性较高,生态污染风险最大,应引起足够重视;(3)土壤表层氮、磷及有机质含量增加,长期进行污灌的土壤,易造成地下水中NO3--N污染,土壤全盐量也呈增加的趋势;(4)引起土壤微生物数量和活性的变化。中国的污染水灌溉存在:(1)缺乏整体监管与监测体系;(2)对环境和人类健康的不利影响没有引起足够的重视;(3)缺乏严格的环境影响评价体系等问题。加强污染水灌溉相关理论和技术的研究,制定全面的污染水灌溉规划,为污染水灌溉的应用提供必要的技术支持;通过宣传、设置缓冲区,加强监管力度等,有效避免病原菌传播风险;进行环境影响评价等措施,可以充分、高效地利用污染水,对实现可持续发展具有重要意义。

Irrigation with polluted water is one of important ways to alleviate water source shortage in China. Besides municipal wastewater, polluted water includes polluted surface water, industry wastewater, aquaculture wastewater, mining wastewater and garbage leachate and so on. This paper reviewed the effects of irrigation by polluted water on soils and analyzed the main problems it caused. Pollution by irrigation with polluted water was mainly concentrated on surface soil. (1) Soil pH change depended on different regions and different types of polluted water. (2) The heavy metals enriched in the soil surface layer and moved slowly into the deep soil. Different kinds of heavy metal behaved with different accumulation rules and migration patterns. Heavy metal enrichment degree was closely related with irrigation time. Higher activity of Cd and Pb with the biggest ecological pollution risk should be paid enough attention. (3) Long-term irrigation with polluted water increased soil nitrogen, phosphorus and organic matters content and increased leaching of NO3--N into the groundwater and soil salt content. (4) The number and activity of soil microorganisms were changed. Some existing problems in irrigation with polluted water in China:(1) There is not an overall supervision and monitoring system; (2) The adverse impacts on the environment and human health were not paid enough attention; (3) There is not a strictly environmental impact assessment system, etc. In order to use polluted water efficiently and avoid the pathogen spread risk, we must improve research of polluted water irrigation theory and technology, develop a comprehensive polluted water irrigation strategy and provide necessary technical supports through setting the buffer, propaganda, supervision,, environmental impact assessment and other measures etc.