灌溉活动对大同盆地表层土壤中砷迁移的影响

发布时间：2018-03-20 07:45

本文选题：砷　切入点：灌溉　出处：《地质科技情报》2017年03期 　论文类型：期刊论文

【摘要】：大同盆地是我国原生高砷地下水典型分布区。高砷地下水常被用作灌溉水源,灌溉回流对表层土壤中砷迁移和富集有着重要影响,但具体机制尚不清晰。通过场地灌溉模拟试验,并结合室内分析,探讨了灌溉活动对表层土壤中砷迁移转化的影响机制。结果表明,灌溉回流不仅导致地表土壤载砷量显著增加,而且引起潜水位快速上升。近地表还原性环境的强化使得含砷铁氧化物还原溶解增强,从而导致了砷的释放。此外,土壤孔隙水离子强度增加促进了离子交换态砷的迁移。灌溉停止后,伴随潜水位回落,氧化环境的增强有利于结晶态铁氧化物的形成,水砷通过吸附和共沉淀作用重新被铁氧化物固定。因此,高砷地下水灌溉通过改变近地表氧化还原环境可促进砷的迁移,砷和铁的输入最终导致表层土壤总砷和铁含量增加。
[Abstract]:Datong basin is a typical distribution area of primary high arsenic groundwater in China. High arsenic groundwater is often used as irrigation water source, and irrigation reflux has an important effect on arsenic migration and enrichment in surface soil. However, the specific mechanism is not clear. The effects of irrigation activities on arsenic transport and transformation in surface soil are discussed by field irrigation simulation test and laboratory analysis. The results show that, Irrigation reflux not only led to a significant increase in arsenic content in the surface soil, but also caused a rapid rise in the groundwater level. The enhancement of the reduced environment near the surface resulted in a greater reduction and dissolution of arsenic-containing iron oxides, which resulted in the release of arsenic. The increase of ionic strength in soil pore water promoted the migration of ion exchange arsenic. After irrigation stopped, the oxidation environment increased with the drop of groundwater level, and the formation of crystalline iron oxides was favorable. Water arsenic is reimbed by iron oxides through adsorption and coprecipitation. Therefore, groundwater irrigation with high arsenic can promote arsenic transport by changing the redox environment near the surface, and the input of arsenic and iron will eventually increase the total arsenic and iron content in surface soil.
【作者单位】：中国地质大学(武汉)环境学院;中国地质大学(武汉)生物地质环境地质国家重点实验室;
【基金】：国家自然科学基金项目(41372254)
【分类号】：S153.6;S27

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