地表灌溉对浅层地下水系统中砷迁移富集的影响研究

The high arsenic groundwater is widely distributed at the Datong Basin. In this arid and semi-arid area, the groundwater quality deteriorates continuously due to the extensive irrigation practice. The Xiaogeda village will be selected as the study area for this project. On the basis of the well know of hydrological and hydrochemical setting, monitoring and modeling study will be conducted to understand the impact of irrigation practice on the mobilization and enrichment of arsenic in the shallow groundwater system in this area. A quasi 3-D and a biochemical reaction and transport approach will be applied to simulate water flow and solute transport and biochemical reaction within the aquifer during irrigation period, respectively. The relative weight of the solution transport, hydrochemical and biogeochemical processes contributed to the enrichment of arsenic in the groundwater can be figured out by comparison the monitoring and modeling results. This study provides a better understanding of the mechanism that arsenic groundwater occurrence in a typical agricultural irrigation area. The study results can provide scientific supports regarding to endemic arsenic posioning prevention and groundwater resource exploration and utilization at the Datong Basin as well as other areas with the similar conditions.

大同盆地是我国典型高砷地下水分布区，强烈的农业灌溉已对该地区地下水环境造成极大影响。本项目将以大同盆地小疙瘩村为研究区，在对研究区非饱和带-含水层水文地质结构及水文地球化学特征进行精细刻画的基础上，采用野外监测与室内模拟相结合的方法，开展灌溉条件下地下水系统中砷迁移富集的影响因素研究。重点采用准三维水流模型与化学反应-运移耦合模型，分别定量模拟物理溶质运移与生物化学过程对地下水中砷富集的影响。基于监测数据与模拟结果，采用差减法求取水化学过程对地下水中砷富集的贡献量。通过对比明确物理溶质运移、水化学及生物化学过程对地下水中砷富集贡献的大小，揭示地表灌溉对地下水系统中砷迁移富集影响的机制。研究结果可为本区及同类型高砷区地下水资源开发与利用、饮水型砷中毒防治提供科学依据。

本项目将以大同盆为研究区，在对研究区非饱和带-含水层水文地质结构及水文地球化学特征进行精细刻画的基础上，采用野外监测与室内模拟相结合的方法，开展灌溉条件下地下水系统中砷迁移富集的影响因素研究。重点采用准三维水流模型与化学反应-运移耦合模型，分别定量模拟物理溶质运移与生物化学过程对地下水中砷富集的影响。基于监测数据与模拟结果，采用差减法求取水化学过程对地下水中砷富集的贡献量。通过对比明确物理溶质运移、水化学及生物化学过程对地下水中砷富集贡献的大小，揭示地表灌溉对地下水系统中砷迁移富集影响的机制。本项目初步建立地表灌溉对非饱和带-地下水系统中砷迁移转化水文地球化学模型，量化了灌溉条件下不同的物理、水化学及生物地球化学过程对地下水中砷富集的影响程度及范围，深化了对高砷地下水形成机理的认识。研究结果可为本区及同类型高砷区地下水资源开发与利用、饮水型砷中毒防治提供科学依据。