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在过去的二十多年以来,世界各地越来越多的地区不断地发现高砷>50ug/L地下水。饮用高砷水危害到几千万人口的健康,尤其在亚洲。学术界普遍认为区域性高砷水的分布不一定与沉积物源区的岩石的砷含量有关。文章对此观点提出疑问和修正。这主要是基于砷在地壳中的分布与地壳的构造历史有着较明显的空间系统关系。在岩浆岩、沉积岩和变质岩体中,砷的浓度范围为<1mg/kg到>100mg/kg。并且砷浓度的分布不为正态,平均值与中值有差异。砷丰度在晶岩中分布的不均一性主要是由于富砷矿物的含量高。目前岩石中砷浓度的数据较少,不足以用于研究砷异常分布,如异常分布图的制定。但是,高砷的硫化物矿物普遍存在于中国的金矿中,而且其分布与板块碰撞的造山带有密切关系。在日本新近的上地壳中,砷(与锡)的丰度均超出地球上地壳的平均值。这里的砷异常已被解释为源于海相沉积物。因此文章提出地壳中的砷高异常与不均一性成因的假说:即海洋-大陆型碰撞之后再加上大陆-大陆型碰撞的不断富集过程。富砷矿物包括硫化物、氧化物及硅酸盐(较少见)。这些富砷矿物在风化之后,被下游的快速沉降的盆地积累,使这些地区较易产生高砷地下水。文章指出两个未来研究方向:源区岩石砷的浓度及矿物学研究,和风化作用及沉积过程的研究,以便确证地表中砷的丰度异常与高砷地下水分布的关系。
Over the past two decades or so, more and more arsenic> 50 ug / L of groundwater has been found in more and more parts of the world. Drinking high-arsenic water harms the health of tens of millions of people, especially in Asia. It is generally accepted by the academic community that the distribution of high-arsenic water in a region is not necessarily related to the arsenic content of rocks in the sedimentary source area. The article put forward questions and amendments to this view. This is mainly due to the obvious spatial relationship between the distribution of arsenic in the crust and the crustal history. In magmatic rocks, sedimentary rocks and metamorphic rocks, arsenic concentrations range from <1 mg / kg to> 100 mg / kg. And the arsenic concentration distribution is not normal, the average and median differences. The heterogeneity of arsenic abundance distribution in cristobalite is mainly due to the high content of arsenic-rich minerals. At present, the data of arsenic concentrations in rocks are few and not enough to study the abnormal distribution of arsenic, such as the development of anomalous distribution maps. However, the arsenic sulfide minerals are ubiquitous in China’s gold mines, and their distribution is closely related to the orogenic collision of the plate. In Japan’s recent upper crust, the abundance of arsenic (and tin) exceeds the average crust on Earth. Arsenic anomalies here have been interpreted as originating from marine sediments. Therefore, the paper proposes the hypothesis that the high arsenic anomalies and inhomogeneities in the crust are caused by the continuous enrichment of continental-continental collisions after the ocean-continental collision. Arsenic-rich minerals include sulfides, oxides, and silicates (less common). After weathered, these arsenic-rich minerals were accumulated in the rapidly settling basins downstream, making it easier for these areas to produce high-arsenic groundwater. The paper points out two future research directions: the concentration and mineralogy of arsenic in the source area, and the study of weathering and sedimentation in order to confirm the relationship between the abnormal abundance of arsenic in the surface and the distribution of high-arsenic groundwater.