Of Xingren High Arsenic Coal Mining Area Of ​​arsenic In The Water Environment, The Natural Purification Mechanism

The High-Arsenic coal mining area in Xingren is one of the High-Arsenic coal mining areas in southwestern Guizhou Province. The coals and waste dump with high arsenic which caused by mining activities, are exposed to the air and continued to oxidation, which lead to arsenic released. The released arsenic through a series of complex physical and chemical process diffuse to the water and sediments around the mining area,. The water and sediment samples in the stream system from the abandoned high-arsenic coal mine area, where are in Shimenkan, Falanmu and Xiaojianshan, and from the mining coal where is in Panjiazhuang in Xingren county were analyzed. Based on analysis of the water chemical characterization, the As distribution in water and sediments, and the fractions of arsenic in the sediments by selective extractions method, this paper discusses the natural attenuated mechanisms of arsenic in mine environment with carbonate rocks of the geological environment. There are several conclusions as follows:1. The pH value in most water samples are increasing while the electric conductivitys are decreasing from upstream to downstream. There is a negative correlation between the electric conductivity and the pH value, especially in water samples from Falanmu. The main ions in most collected water samples are Fe and SO₄^2-, only a few of water samples have more SO₄^2- and Ca.2. From the upstream to downstream, the contents of arsenic in water samples are decreasing while the contents of arsenic in sediments are increasing then decreasing. The arsenic in water transform to the sediment, caused the contents of arsenic in sediment is higher.3. The arsenic fraction in sediments is associated with Al and Fe oxyhydroxides, especially the fraction associated with Al and Fe amorphous oxyhydroxides, which are coincided with a large number of amorphous in sediments mineral composition. And the exchangeable fraction and associated with sulphides and organics fraction were low in sediments.4.There is a large number of amorphous in sediments, and the fraction of arsenic in sediments are the fraction associated with Al and Fe amorphous oxyhydroxides and the fraction associated with Al and Fe crystalline oxyhydroxides. Arsenic in mine environment was mainly attenuated by the adsorption and coprecipitation of Fe and Al oxyhydroxides, while the dilution of water also plays an important role. Usually, from the upstream to downstream, the attenuation speed of arsenic in water is gradually decreased, and the content of arsenic in water was decreased below 10ug/L or lower in a short distance.