Dept of Earth & Environmental Sciences
Centre for Environmental and Information Technology (EIT)
200 University Ave. W
Waterloo, Ontario, Canada N2L 3G1
Phone: (519) 888-4567
Dr. Raoul-Marie Couture
School of Earth and Atmospheric Sciences
Georgia Institute of Technology
Coupled biogeochemical cycling of arsenic, sulphur and iron in the subsurface.
In the last few years, the speciation and mobility of arsenic under the reducing conditions encountered in many aquatic sediments, water-logged soils and aquifers has been hotly debated. Sample preservation methods, measurement techniques, thermodynamic databases and environmental fate models once considered reliable are being challenged, bringing the results of many previous studies into question. Here, I combine field, laboratory and theoretical results in an attempt to close the existing gap in our understanding of the coupled biogeochemical cycling of arsenic, iron and sulfur. I will present our current conceptual model of the behavior of arsenic in redox-dynamic subsurface environments, and delineate promising avenues of further experimentation. In particular, I will discuss i) the transformations of iron minerals under redox-oscillating conditions and their implications for arsenic mobility, ii) the potential role of zero-valent sulfur in controlling As speciation, and iii) the formation and environmental significance of thioarsenate complexes.
200 University Ave West
Waterloo, ON N2L 3G1