It is well known that microorganisms may dissolve different nutrients and utilize them as resources of nutrition and energy. simply no. 2). Desk 2 Common supplementary arsenic-bearing nutrients Secondary arsenic nutrients exhibit an array of solubility. For instance, claudetite and arsenolite, and some calcium mineral arsenates (haidingerite, pharmacolite), are soluble in drinking water extremely, whereas some iron arsenates, MLN4924 (HCL Salt) such as for example beudantite, scorodite and pharmacosiderite, are insoluble relatively. Sparingly soluble nutrients can efficiently immobilize arsenic in polluted sites and their precipitation lowers the quantity of arsenic in water. Alternatively, the re-dissolution of supplementary arsenic nutrients due to various environmental elements (pH increase, temperatures, supply of fresh chemical substances with drinking water) and specifically microbial activity, may significantly affect the amount of contaminants of floor and surface waters by arsenic species (Drahota and Filippi 2009). The processing of ores as a source of arsenic in the environment Arsenic is present in the mining environment not only in the rock KDELC1 antibody minerals, but also as water-soluble compounds and in gaseous form. Mining is focused around the recovery of elements and materials from mineral deposits, but during the process, side effects like the release of contaminants can occur. Mining and the processing of As-bearing minerals may contribute to the release of high concentrations of arsenic into the water, soil and air. Coal combustion in power stations, and the roasting and smelting of ores in non-ferrous metal smelters also cause the release of arsenic into the atmosphere (Han et al. 2003; Yudovic MLN4924 (HCL Salt) and Ketris 2005). The oxidation of sulfide minerals in hydrometallurgical and biometallurgical processes causes the acidification of waters and their enrichment in sulfate anions and heavy metals (Johnson 2003). The presence of extremely high levels of toxic metals in acidic mine waters, commonly known as acid mine drainage (AMD) or acid rock drainage (ARD) waters, constitutes one of MLN4924 (HCL Salt) the main environmental problems faced by the worlds mining industries. Arsenic is present in many AMD or ARD waters as a result of the oxidation of arsenic-bearing sulfide minerals. This two-step process is described by the following equations: 1 2 Mine spoils and wastes from ore treatment plants have often been dumped into or near streams. The fine fraction of ash (flying ashes) produced by smelting of ore concentrates causes the widespread airborne dispersal of arsenic, thus contaminating ground and streams over a wide area. Once distributed by these means, arsenic can MLN4924 (HCL Salt) produce toxic effects in nature. The 1,000-12 months history of mining and smelting has left a legacy of arsenic pollution in several regions of Europe and in USA. Contaminated sites in Devon and Cornwall in the UK display one of the world’s highest concentrations of arsenic in ground of up to 2,500?ppm, compared with normal values of less than 40?ppm found elsewhere in the UK and the rest of the world (WHO). Similarly, in south western Poland in the area of the Zloty Stok ancient gold mine (active since the 13th century) and in the neighboring Lower Silesia district, very high levels of arsenic have been recorded in ground and water sediments (3,400 and 6,125?ppm, respectively) (Lis and Pasieczna 1995; Drewniak, unpublished data). Microbial activity from the biogeochemistry of.