Arsenic transformations in the terrestrial environment

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Arsenic is well known as a poison and cancer-causing agent. The proposed research aims to study how the chemical form of arsenic changes from a toxic to a non-toxic form in the environment. One objective is to study the change of toxic arsenic in soil (inorganic arsenic) to non-toxic arsenobetaine in mushrooms. In doing this we hope to isolate the mechanisms that are responsible for detoxifying arsenic and specifically if these changes can take place in the absence of biological organisms. The second objective is to determine if these detoxifying mechanisms also take place in peat bogs in Canada, as a recent study suggests that peat bogs may represent the only other terrestrial compartment besides mushrooms with significant amounts of arsenobetaine. The third objective is to develop a method of looking for non-toxic arsenobetaine in the previous experiments and in environmental samples using a field portable instrument that is cost-effective and quick. For these studies, in addition to the field portable method that will be developed, synchrotron-based X-ray analysis methods (called X-ray absorption spectroscopy) will be used for the measurement of arsenic species in samples, complemented by conventional testing methods that can be done in our laboratory. The proposed work will give insight into how the hazardous effects of arsenic can be ameliorated or managed through detoxification, and a greater fundamental understanding of how arsenic behaves in the environment.