Arsenic mobilization from synthesized Fe(III) oxides under natural conditions

摘要

Reductive dissolution of iron (hydr)oxides has been accepted as a major formation mechanism for high arsenic groundwater. However, few researches are available for illustrating arsenic release from different iron oxides in natural aquifer. An in-situ method was applied to elucidate mobilization of arsenate adsorbed on two-line-ferrihydrite, goethite and hematite. During the 80 d experiment, desorption of arsenate was observed in these iron oxides, but the reductive dissolution only occurred in ferrihydrite which was transformed into lepidocrocite and goethite. The redox potential and bicarbonate and DOC concentrations were the key factor controlling arsenic mobilization during desorption. At the end of the experiment, more arsenic was released from goethite than hematite.