Arsenic-sulfur speciation - a potential key to understanding arsenic accumulation and mobilisation in sulfidic aquifers of Bangladesh

• Applicant: Professorin Dr. Britta Planer-Friedrich
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2006 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 25229056

Bangladesh is currently the country believed to show the largest impact of arsenic poisoning worldwide from drinking water. Screening on total arsenic concentrations and householdbased remediation measures have been implemented over the past 10 years, but the origin of the arsenic is still not clear. During the proposed project we will screen wells of different depths tapping different geological formations with major focus on pH, redox potential, redox sensitive species, and stable isotopes. Sediment samples in column experiments will be exposed to O2, CO2, phosphate, humic acids, and respiratory inhibitors to illuminate different mechanisms of arsenic mobilization. Continuous sampling of monitoring wells of different depths will show depth and time dependent variations in chemistry. Contrary to all other studies conducted before, arsenic speciation beyond inorganic As(lll)/As(V) speciation will be done. The importance of methylated arsenic species in organic-rich strata and the potential of arsenic-sulfur species formation on the mobilization of arsenic from ironsulfides will be investigated. Arsenic-sulfur species have seldom been investigated so far but can be an important clue in arsenic chemistry in sulfidic waters. Modeling will help to better understand the situation in Bangladesh and predict similar scenarios in other countries worldwide.

• DFG Programme: Research Grants