Sediment geochemistry and arsenic mobilization in shallow aquifers of the Datong basin, northern China

Abstract

Understanding the mechanism of arsenic (As) mobilization from sediments to groundwater is important for water quality management in areas of endemic arsenic poisoning, such as the Datong basin in northern China. The bulk geochemistry analysis of sediment samples from three 50-m boreholes drilled specifically for this study at As-contaminated aquifers, the groundwaters of which have an As concentration up to 1060 microg/l, revealed that the average bulk concentrations of major and trace elements of the samples are similar to those of the average upper continental crust. The average As content of the sediment samples (18.7 mg/kg) is higher than that of modern unconsolidated sediments (5-10 mg/kg). Moreover, the abundance of elements varied with grain size, with higher concentrations in finer fractions of the sediments, such as silt and clay. The concentration of NH(2)OH-HCl-extracted iron (Fe) strongly correlated with that of extracted As, suggesting that Fe oxyhydroxides may be the major sink of As in the aquifer. The results of microcosm experiments showed that As mobilization from sediments to groundwater is probably mainly related to changes in the redox conditions, with moderately reducing conditions being favorable for As release from sediments into groundwater.

Hydrogeochemistry of high iodine groundwater: a case study at the Datong Basin, northern China

“…Several of our previous studies have shown the occurrence of reductive dissolution of iron oxyhydroxides in a reducing environment. 37,38,52 During this processes, iodine adsorbed on iron oxyhydroxides could be released into groundwater, thereby increasing the iodine concentration of the aqueous phase.…”

Reactivity and speciation of mineral-associated arsenic in seasonal and permanent wetlands of the Mekong Delta

“…Linking As reactivity and speciation to the identity, relative quantity, and reactivity of Fe-bearing minerals in the river basins of South and Southeast Asia is needed to understand the distribution and transport of As. Moreover, efforts to this end have concentrated in the Bengal Basin (Akai et al, 2004;Datta et al, 2009;Ghosh et al, 2006;Hasan et al, 2009;Itai et al, 2010;Polizzotto et al, 2006;Polizzotto et al, 2005;Seddique et al, 2008;Seddique et al, 2011;Swartz et al, 2004;Uddin et al, 2011), and to a lesser extent in the Red River Delta (Vietnam) (Phuong et al, 2012;Postma et al, 2010;Postma et al, 2007) and Datong Basin (China) (Xie et al, 2009a;Xie et al, 2009b;Xie et al, 2011;Xie et al, 2008). Little is known about mineralogical aspects of the Mekong Delta influencing dissolved As concentrations (Kocar et al, 2008;Rowland et al, 2008).…”

Hierarchical cluster analysis of arsenic and fluoride enrichments in groundwater from the Datong basin, Northern China

“…Since the As poisoning cases were reported at Datong in 1990, many studies have been done to study the geological, hydrological, geochemical, hydrogeochemical, biogeochemical and mineralogical factors of high As groundwater in the Datong basin Wang, 2004, 2005;Xie et al, 2008Xie et al, , 2009aXie et al, , 2009bXie et al, , 2011. High As groundwater mainly occurred in lacustrine aquifers containing high organic matter (1.0% organic carbon) and was characterized by high pH and low SO 4 concentration (Guo and Wang, 2005;Wang et al, 2009).…”