Microbial dissolution of As(V)-bearing minerals

Summary: Throughout the world there are many places with a high concentration of arsenic in water. In the Czech Republic is such a place the gold-bearing area of Mokrsko, where arsenic in groundwater reaches the values, which are well above recommended limits for drinking water. Arsenic in the soil at Mokrsko is bound to secondary minerals with iron. Due to the work of microorganisms the weathering of these phases occurs, the reduction of Fe (III) and As (V) occurs, by which the toxic arsenic in its dissolved form gets into the groundwater. Microbial dissolution of minerals containing arsenic is being researched by many teams of scientist. If the stability of Fe and As minerals during the microbial reduction is explained, it is possible to understand and perhaps effectively solve the problem of arsenic contamination in natural aquifers. For the purpose of this research the microbial reduction rate of iron and arsenic synthetic mineral phases (arseniosiderite, goethite, scorodite and ferrihydrite) and natural pharmacosiderite has been determined and compared. The results of the dissolution kinetics were compared with the reductive dissolution of the natural sample from the Mokrsko area. The samples were characterized by X-ray methods, SEM-WDX, SEM, BET; the content of iron and arsenic in the phases has been..