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Arsenic

A major area of research at ESG is the study of arsenic in the environment. Arsenic is well known as a poison, but its actual toxic effects are dependent on two important aspects: its chemical form, or speciation, and the degree to which it is absorbed into a living organism, or bioavailability. Arsenic species can vary from highly toxic (e.g., As(III), arsenite) to completely non-toxic (e.g., (CH3)3As+CH2COO-, arsenobetaine). The latter form is commonly found naturally in substantial amounts in seafood such as fish and shellfish.


To differentiate these forms in samples, speciation analysis must be carried out. This analysis may include high performance liquid chromatographic (HPLC) methods combined with atomic absorption spectrometric (AAS) and inductively coupled plasma – mass spectrometric (ICP-MS) detection systems. ESG is equipped with the necessary analytical instruments and has years of expertise in carrying out this specialized analysis. Graduate students with varying backgrounds learn the techniques and receive hands-on support from technical staff that maintain and troubleshoot all of our instruments.


In support of our work on arsenic and other elements (antimony, lead, chromium, mercury), we have access to state-of-the-art solid state analytical techniques in the form of synchrotron-based X-ray absorption spectroscopy (XAS). These techniques allow us to measure the arsenic forms (or forms of other metals) in solid samples with minimal sample preparation. This is especially convenient for samples for which it is difficult to extract the element of interest completely and representatively. We have access to two synchrotrons, the Advanced Photon Source in Argonne, Illinois, and the Canadian Light Source in Saskatoon, Saskatchewan.  


Arsenic research projects currently with funding:

(a) Arsenic transformations in the environment to non-toxic arsenic. Arsenic may be transformed naturally from toxic forms to the non-toxic form, arsenobetaine. Exactly how or why these transformations take place is still unknown, and research is underway with fungus (which are known to undertake these transformations) to explore this topic in more detail. Additional avenues, especially in the marine environment where arsenobetaine is predominant, are of interest.

(b) Arsenic transformations in the environment in extremely contaminated site conditions. We have found that arsenic is transformed minimally at very contaminated sites, remaining predominantly in its toxic form. This phenomenon has been found a few marine sites but needs to be confirmed in different sites and conditions (terrestrial, freshwater, etc.).

(c) Arsenic-sulfur compounds and their analysis. Samples for this research are available through collaborations with Dr. Britta Planar-Friedrich at University of Bayreuth.

(d) Contaminants, especially arsenic, in food and consumer products. Recent developments in the media have revealed that little information exists for arsenic and other inorganic elements  in consumer products ( with apple juice and cosmetics being a focus)  especially with respect to the toxicityThe lack of information is especially prevalent in Canada and thus research is targeted on this topic. At the moment we are compiling results on arsenic in wine, and in country foods (traditional, locally hunted/gathered/fished foods eaten by Aboriginal people) from Yellowknife, Canada.


Not all arsenic compounds are poisonous as history would have us believe. Arsenobetaine, an organic arsenic compound found naturally in high amounts in marine biological systems, is completely non-toxic. ESG is undertaking research to find out how and why arsenic transforms naturally from toxic forms to non-toxic forms in the environment.


  Current areas of research

Arsenic transformation in the environment

Contaminant bioaccessibility

Emerging contaminants

Treatment wetlands

Zero valence metals: synthesis and environmental applications

Fate and effects of nanoparticles in the environment

Microbial community structure and function in the environment