地壳表层砷的循环与污染地下水模式

摘要

In order to better monitor and predict groundwater arsenic contamination and reveal the law and mechanism of groundwater arsenic contamination caused by natural factors, the authors carried out investigation and research on groundwater arsenic contamination in Hetao Plain of Inner Mongolia for years. Based on fully understanding and grasping of arsenic chemical and geochemical properties as well as the situation and distribution characteristics of groundwater arsenic contamination all over the world, the authors summarized the distribution of arsenic in natural environment and the mechanism of groundwater arsenic contamination. This study expounded the formation mechanism of four types of groundwater arsenic contamination and presented the patterns of arsenic cycle and groundwater arsenic contamination on the earth’s surface. With the basic mastering of the geological environment background of a certain region, these patterns could offer a preliminary prediction of the possible locations of arsenic contamination. This study indicates that arsenic contamination in groundwater is an environmental hydrogeochemical phenomenon, which happens in the arsenic cycle on the earth’s surface. The distribution of contaminated areas is related to specific geological and geographical backgrounds and environmental conditions. This study suggests that, in the reductive desorption contamination type, such factors as the closed environment, sulfur and organic carbon constitute the main control factors for the dissolution of arsenic in strata. In the future, it is necessary to reinforce the investigation and monitoring of arsenic contamination in groundwater in closed alluvium-acustrine plains, river-lake deltas, and river-sea deltas.%为了更好地监测和预测地下水砷污染，揭示由自然原因引起的地下水砷污染规律和机制，通过多年来对内蒙古河套平原地下水砷污染的调查研究，在充分了解和掌握砷的化学与地球化学性质以及世界各国地下水砷污染状况与分布特征的基础上，总结了砷在自然环境中的分布和污染地下水的机理。文章阐述了4种地下水砷污染类型的形成机理，并提出了地壳表层砷的循环与污染地下水模式，通过该模式在基本掌握某一地区地质环境背景的情况下，可以初步预测其可能发生地下水砷污染的地段。地下水砷污染是砷在地壳表层循环过程中发生的一种环境水文地球化学现象，污染区的分布与特定的地质、地理背景和环境条件有关。在还原解吸污染类型中，封闭的环境、硫元素和有机碳的存在是地层中砷溶出的主要控制因素。今后应加强对封闭的冲积或湖积平原、河流入湖或入海三角洲等地区地下水砷污染的调查与监测。