Mechanism of arsenic release to groundwater, Bangladesh and West Bengal

Abstract

In some areas of Bangladesh and West Bengal, concentrations of As in groundwater exceed guide concentrations, set internationally and nationally at 10 to 50 mg l À1 and may reach levels in the mg l À1 range. The As derives from reductive dissolution of Fe oxyhydroxide and release of its sorbed As. The Fe oxyhydroxide exists in the aquifer as dispersed phases, such as coatings on sedimentary grains. Recalculated to pure FeOOH, As concentrations in this phase reach 517 ppm. Reduction of the Fe is driven by microbial metabolism of sedimentary organic matter, which is present in concentrations as high as 6% C. Arsenic released by oxidation of pyrite, as water levels are drawn down and air enters the aquifer, contributes negligibly to the problem of As pollution. Identi®cation of the mechanism of As release to groundwater helps to provide a framework to guide the placement of new water wells so that they will have acceptable concentrations of As. #

Assessment of Arsenic Accumulation by Different Varieties of Rice (Oryza sativa L.) Irrigated with Arsenic-contaminated Groundwater in West Bengal (India)

“…Nine out of the total twenty districts of West Bengal have groundwater arsenic contamination [1,2]. Arsenic accumulation in rice straw argued to cause threat to cattle population and, thus contaminated meat and milk may indirectly cause further threat to humans, especially children [3,4].…”

Leaching behavior of arsenic from various rocks by controlling geochemical conditions

“…On the other hand, the As concentration in the leachate did not correlate well with the Fe concentration in the leachate of sedimentary rock samples, since the Fe concentration was nearly at the detection limit. The correlation between the As concentration and Fe concentration has been reported by many researchers (Ahmed et al, 2003;Dowling et al, 2002;Kim et al, 2000;Nickson et al, 2000; Shreiber et al, 2000).The relationship between the solid-phase and liquid-phase concentrations was examined based on the chemistry of the leachate and the chemical composition of the rock samples. The As concentration in leachate versus the As content of rock is presented in Fig.…”

“…The origin of the As has been reported to be As-containing minerals in sediments (Akai et al, 2004;Dowling et al, 2002;Kim et al, 2000;Peters et al, 1999;Shimada, 1996). There has been exhaustive research into the behavior of As leaching and migration in subsurface environments (Livesey and Huang, 1981; Manning and Goldberg, 1997;Nickson et al, 2000;Yoshimura and Akai, 2003) and to remediate polluted groundwater (Welch and Stollenwerk, 2003). However, As leaching from crushed rock has never been systematically studied.…”

“…The extensive As pollution of groundwater as in the cases of Bangladesh (Acharyya et al, 2000; Ahmed et al, 2003;Akai et al, 2004;Anawar et al, 2003;Nickson et al,1998;Nickson et al, 2000; Stollenwerk, 2003), West Bengal (Acharyya et al, 2000;Das et al, 1996;Dowling et al, 2002;Nickson et al, 2000), and other locations (Chen et al, 1994;Kim et al, 2000; Kelley et al, 2005;Nimick, 1998;Peters et al, 1999;Robertson, 1989;Schreiber et al, 2000;Smedley and Kinniburgh, 2002;Yoshimura and Akai, 2003;Welch et al, 1988;Welch and Stollenwerk, 2003;Williams et al, 2005) is a well known concern worldwide. There are also reports of As pollution of groundwater, sediments, soils, and/or rocks in Japan (Shimada, 1996;Masuda et al, 1999).…”

Mobilization and speciation of arsenic from hydrothermally altered rock containing calcite and pyrite under anoxic conditions

“…Arsenic (As) contamination of soil and groundwater from natural or anthropogenic sources is a serious problem encountered in many countries around the world that is affecting millions of people (Acharyya et al 2000;Akai et al, 2004;Das et al, 1996;Dowling et al, 2002;Nickson et al, 2000). Arsenic is a toxic trace element that is ubiquitous in nature, and is usually concentrated in mineral sulfide ore bodies (Fleet et al, 1989;Huston et al, 1995;Smedley and Kinniburgh, 2002).…”