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Published October 2009 | public
Journal Article

Enhancement of Arsenic(III) Sequestration by Manganese Oxides in the Presence of Iron(II)


Mobilization of arsenic (As) in the subsurface environment can result in elevated concentrations of As in groundwater and potential human exposure and adverse health effects. Natural attenuation (i.e., sequestration) of As may, under appropriate geochemical conditions, serve to limit human exposure to As. The effectiveness of As sequestration by sorption, co-precipitation, and/or precipitation can be strongly influenced by redox conditions, which can control the solubility of sorbent phases and the stability of As-containing solids. The redox transformation of As between the +III and +V oxidation states can also affect the extent of As sorption. The effect of amendment with synthetic manganese (Mn) oxide birnessite (nominally MnO2) on As sequestration in a sediment suspension was examined in the absence and presence of iron (Fe) added as Fe(II). In the absence of Fe(II), the extent of As(III) oxidation to As(V) increased with increasing birnessite amendment, but As sequestration was not increased. In the presence of Fe(II), however, As sequestration did increase with increasing birnessite amendment. Concurrently, Fe(II) was also sequestered, and the Fe(III) content of the solid phase was observed to increase, suggesting that the oxidative precipitation of an Fe(III) oxyhydroxide phase plays an important role in As sequestration. These results suggest that amendment with Mn(III, IV) oxides could be an effective way to augment natural attenuation of As in cases where As-contaminated groundwater also contains elevated concentrations of Fe(II).

Additional Information

© 2009 Springer. Received: 12 September 2008; Accepted: 9 February 2009; Published online: 5 March 2009. This work was supported by funding from the Strategic Environmental Research and Development Program (SERDP ER-1374). The authors would like to acknowledge Integrated Science and Technology, Inc. for assistance with sediment sampling. We also want to thank Drs. Kate Campbell and Nathan Dalleska for their help with LC-ICP-MS for arsenic analysis and speciation.

Additional details

August 21, 2023
October 19, 2023