Characteristics of iron isotopes in high arsenic groundwater systems of the Hetao basin, Inner Mongolia, PR China

Iron (Fe) isotopes have been developed as a new important technology in geochemical studies. However, there are few studies on characteristics of Fe isotopes in aquifer sediments and ground-waters from Arsenic (As)-affected basins. Sediment samples from different depths and groundwater samples were taken in the Hetao basin, Inner Mongolia. After separation and enrichment of the Fe element in the samples, Fe isotopes were analyzed by means of MC-ICP-MS. Results showed that high As ground-waters occurred in the reducing conditions, with Eh values < 150 mv. In reducing aquifers, the heavy Fe isotope was enriched in sediments, while light was found in groundwaters. Iron isotope fractionation between sediments and groundwater lay in the range of Fe fractionation between Fe minerals and solutions affected by microbial reduction of Fe oxides.