Arsenic Mobility and Groundwater Extraction in Bangladesh

Abstract

High levels of arsenic in well water are causing widespread poisoning in Bangladesh. In a typical aquifer in southern Bangladesh, chemical data imply that arsenic mobilization is associated with recent inflow of carbon. High concentrations of radiocarbon-young methane indicate that young carbon has driven recent biogeochemical processes, and irrigation pumping is sufficient to have drawn water to the depth where dissolved arsenic is at a maximum. The results of field injection of molasses, nitrate, and low-arsenic water show that organic carbon or its degradation products may quickly mobilize arsenic, oxidants may lower arsenic concentrations, and sorption of arsenic is limited by saturation of aquifer materials.

Evaluation of arsenic immobilization in red mud by CO2 or waste acid acidification combined ferrous (Fe2+) treatment

“…Meanwhile, the arsenic removal efficiency by ferrous improved with more WA added. The results were consistent with former studies that high (bi)carbonates concentrations inhibited the aqueous arsenic removal by iron [27]. The pH was another important factor that affected arsenic adsorption or co-precipitation with iron.…”

The impacts of different long-term fertilization regimes on the bioavailability of arsenic in soil: integrating chemical approach with Escherichia coli arsRp::luc-based biosensor

“…It has been reported that the application of inorganic or organic fertilizers can increase the content of organic carbon in soil and maintain soil productivity (Liu et al 2013;Yang et al 2011). Additionally, it has been confirmed that As mobilization is associated with the concentration of dissolved organic carbon ND not determined in soil, which is due to the organic ligands of dissolved organic carbon (DOC) that facilitate the release of inactive As (F4 fraction) to active soluble As (F1 fraction) through competitive sorption or through solution complexation (Cao et al 2003;Harvey et al 2002;Jackson et al 2006;Mladenov et al 2010). In addition, Fe oxyhydroxides precipitated by microbes have a strong adsorption capacity to As in soil (Harvey et al 2002;Mladenov et al 2010;Yang et al 2002); Consequently, the enhancement of soluble As could also lead to an increase of As bound to Fe oxyhydroxides which belonged to F2 fraction of As .…”

“…Additionally, it has been confirmed that As mobilization is associated with the concentration of dissolved organic carbon ND not determined in soil, which is due to the organic ligands of dissolved organic carbon (DOC) that facilitate the release of inactive As (F4 fraction) to active soluble As (F1 fraction) through competitive sorption or through solution complexation (Cao et al 2003;Harvey et al 2002;Jackson et al 2006;Mladenov et al 2010). In addition, Fe oxyhydroxides precipitated by microbes have a strong adsorption capacity to As in soil (Harvey et al 2002;Mladenov et al 2010;Yang et al 2002); Consequently, the enhancement of soluble As could also lead to an increase of As bound to Fe oxyhydroxides which belonged to F2 fraction of As . Given that the organicbound As was negligible in polluted soil (Sarkar et al 2007), only exchangeable As (F1 fraction) and Fe-Mn-oxide-bound As (F2 fraction) were considered to be potential bioavailable As as determined by BCR-SEPs in this research.…”

“…However, the application of long-term fertilization increased organic carbon concentration (Liu et al 2013;Yang et al 2011) and the content of phosphorus (P) (Ge et al 2008;Zheng et al 2008a) and changed the acidity of soil depending on the soil conditions (Dong et al 2012;Zheng et al 2008b). Meanwhile, the release of metal including As from the solid phase of soil was influenced by organic carbon based on the formation of soluble metal-organic complexes (Cao et al 2003;Grafe et al 2002;Harvey et al 2002;Jackson et al 2006;Mladenov et al 2010;Wang and Mulligan 2006). pH and P also have been confirmed as major factors impacting the release of As by the mechanism of competitive anion exchange (De Brouwere et al 2004;Grafe et al 2002;Signes-Pastor et al 2007;Wang and Mulligan 2006;Yang et al 2002;Zhao and Stanforth 2001).…”

Temporal variability of groundwater chemistry in shallow and deep aquifers of Araihazar, Bangladesh

“…There is growing evidence that at least part of this heterogeneity can be attributed to variations in local geology and its effect on shallow groundwater flow Stute et al, 2007;Aziz et al, in revision;Weinman et al, in press.). Such spatial variability naturally leads to the concern that shallow groundwater As concentration may also change over time, especially because subsurface flow is likely to be affected by large water withdrawals for irrigation in certain areas of Bangladesh (Harvey et al, 2002;Klump et al, 2006). The persisting gaps in our knowledge of the mechanisms that lead to As mobilization (Horneman et al, 2004;Zheng et al, 2004), combined with pronounced seasonal fluctuations in water levels in shallow and deep aquifers linked to the monsoon, make it particularly difficult to predict variations of groundwater As concentration over space or time.…”