The isotopic composition of oxygen in arsenate and arsenite: a novel approach to constrain the source of arsenic in groundwater

• Applicant: Professor Dr. Stefan Norra, since 10/2013
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2009 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 160548255

The project proposes to provide a basis for the study of the isotopic composition of oxygen in arsenic oxyanions, an isotope system which has not been investigated until now, but which shows a strong potential in getting new insights into the circumstances and processes that led to the development of high arsenic groundwaters in many parts of the world. The required methodical developments consist in elaboration of an adequate sample preparation procedure for the extraction and separation of the arsenic oxyanions (including separation from interfering anions), as well as in the supply of an adequate technique for the measurement of the isotope ratios of oxygen in these species. Basic issues like the kinetic of isotope exchange with water must be investigated. In combination with the isotope composition of oxygen in phosphate the approach will be applied in three locations with distinct redox features (in West Bengal, Vietnam, and Inner Mongolia), intending to find out whether the arsenic in groundwater in these sites originates directly from the surrounding aquifer sediments (autochtonous) or if it was transported from a distant low redox environment to the high arsenic site (allochtonous). The verification of such questions is crucial in finding out the ultimate causes which lead to the occurrence of high arsenic regions and to combat such calamities.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr. Zsolt Berner, until 10/2013