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Molecular Ecology and Ecotoxicology |
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Recently, we traveled to Truelove Lowlands on Devon Island in order to collect soil samples for toxicity tests and nitrogen biogeochemistry. Above from left to right, myself, Wai Mai and Alexis Schafer take a well earned break on a warm sunny day in the High Arctic. |
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Linking Human and Ecosystem Health |
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To develop this linkage our research group focuses on two questions: What are the key molecular biology controls on mercury, arsenic, nitrogen and sulfur chemistry cycling in Arctic and Antarctic environments? How can we insure that polar ecosystems remain sustainable and protected during industrial and social development? To do this we use a combination of field campaigns and in-laboratory microcosms and apply advanced chemical and biological techniques to assess biogeochemical cycling in polar environments. Students in our research group use equipment as diverse as quantitative PCR to cold-vapor atomic fluorescence detectors to assess biogeochemical cycles and anthropogenic impacts. Many of our results can be applied to less extreme systems. For example, we’ve recently been exploring arsenic biogeochemistry in northern Canada to unlock the secrets of arsenic biogeochemistry in the cold ground-waters of southern Canada such as the Ardkenneth aquifer of the southern prairies. Similarly, work on Devon found that the emission of greenhouse gases may be linked to a chemical exuded by plant roots. We are currently investigating if this chemical exudate from plants is also found near St. Denis in Saskatchewan. |
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Steven Siciliano Department of Soil Science 51 Campus Drive University of Saskatchewan Saskatoon, Saskatchewan S7N 5A8 |
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To contact us: |
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Phone: 306-966-4035 Fax: 306-966-6881 E-mail: steven.siciliano@usask.ca |
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Gastrointestinal microbes increase arsenic bioaccessibility of ingested mine tailings using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME)
BD Laird, TR Van de Wiele, MC Corriveau, HE Jamieson, MR Parsons, W Verstraete, SD Siciliano. In Press. 05/2006. Environmental Science and Technology It is widely accepted that the use of total metal concentrations in soil overestimates metal risk from human ingestion of contaminated soils. In vitro simulators have been used to estimate the fraction of arsenic present in soil that is bioaccessible in the human digestive track. These approaches assume that (1) the bioaccessible fraction remains constant across soil total metal concentrations and that (2) intestinal microbiota do not contribute to arsenic release. Here, we evaluate both of these assumptions in two size fractions (bulk and < 38 µm) of mine tailings from the Goldenville, Lower Seal Harbour, and Montague Gold Districts, Nova Scotia. These samples were evaluated using an in vitro gastrointestinal model, the Simulator of the Human Intestinal Ecosystem (SHIME). Arsenic bioaccessibility, which ranged between 2 and 20% in the small intestine and 4 and 70% in the colon, was inversely related to total arsenic concentration in the mine tailings. Additionally, arsenic bioaccessibility was greater in the bulk fraction than in the < 38 µm fraction in the small intestine and colon while colon microbes increased the bioaccessibility of arsenic in mine tailings. These results suggest that using a constant percent arsenic bioaccessibility across all metal concentrations in risk assessment should be revisited. |
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Our Research Goal |