Arsenic removal from groundwater of the Chaco-Pampean Plain (Argentina) using natural geological materials as adsorbents

Use of natural geological materials for arsenic (As) removal is an emerging solution at a household level for poor people in remote rural settlements, especially when the materials are locally available and can be collected by the local population. Their low or zero cost makes these materials very attractive compared with synthetic or commercial materials. Sometimes, this may be the only option to provide safe water to very poor settlements. Their suitability for As removal from water is mainly due to adsorption, co-precipitation and ion exchange processes involving Fe-and Al-rich minerals and clay minerals present in the soils or sediments. In the present study, various clay-rich soils from the Santiago del Estero province (SDE, NW Argentina) and, for comparison, a laterite from the Misiones province have been tested as adsorbents for As in shallow naturally contaminated groundwaters of the Rio Dulce alluvial aquifer in SDE. Batch adsorption experiments showed higher As(V) removal for the Misiones laterite sample (99 %) as compared with the soils from SDE (40-53 %), which can be related to lower contents of water-soluble and oxalate extractable Al and Fe in the last samples. These results suggest the application of the Misiones laterite soil as an alternative for As removal. However, high transportation costs from Misiones to SDE can be an economical restriction for the low-income population of SD

Hydrogeochemistry of the alluvial aquifers of the central Gangetic Plain in India: constraints on source and mobility of arsenic

Until recently, most estimates of arsenic (As) pollution have focused on the predominance of As poisoning in the groundwater of West Bengal (India) and Bangladesh (Ahmed et al., 2004), which has been thought to be limited to the Ganges Delta (the lower Ganges Plain). Several authors suggested that the reductive dissolution of Fe(Ill)-­ oxyhydroxides in strongly reducing conditions of the young alluvial sediments is the cause for As mobilization (Bhattacharya et al., 1997; Ahmed et al., 2004; McArthur et al., 2001; Nickson el al., 1998; von Bromssen et al., 2007). Holocene alluvial aquifers of Ballia, Ghazipur and Bhagalpur district in the middle Gangetic Plain have high concentra­tions of geogenic As. The As contaminated aquifers are pervasive within lowland organic rich, clayey deltaic sedi­ments in the Bengal Basin and locally within simi­lar facies in narrow, entrenched river valleys within the Ganges Alluvial Plain (Acharyya & Shah, 2004; Mukherjee et al., 2006). This study has been carried out with the following objectives: I) to quantify the As in the groundwater of the Ghazipur District, Uttar Pradesh, India, and 2) to understand the mechanism controlling the mobilization of As and its evolution