Mobilization of arsenic in aquifers from the Datong Basin, China: Evidence from geochemical and iron isotopic data

摘要: Iron isotope compositions of various Fe pools in aquifer sediments were measured at a known As-contaminated site the Datong Basin, China. The δ56Fe values HCl-extracted poor-crystalline Fe(III) range widely from −0.41‰ to 0.36‰. We interpret low Fe(II)/FeExtractable ratios (<50%) and negative correlation between be best explained by redox cycling induced microbial reduction. However, high (≳70%) positive for indicates production sulfides (FeSs). crystalline extracted reductant appears comparatively small varying −0.01‰ 0.24‰, which is consistent with ferric oxides/hydroxides having undergone composition shows transformation secondary Fe(II) phases has already occurred or occurring sediments. More importantly, there significant difference As concentrations phases. 1.6 29.9 mg kg−1 0.6 3.0 mg kg−1, respectively. Accordingly, minerals reduction can contribute mobilization As. This study first examine sediments; results show that would an important tool demonstrating enrichment groundwater.