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(09-08) Assessing bioavailable arsenic in soils contaminated by mining. Flynn, Helen*,1, Meharg, Andy1, Paton, Graeme1, 1 Univesity of Aberdeen, Aberdeen, UK ABSTRACT- Elevated levels of arsenic are often associated with mining activities. Quantifying total concentrations fails to define or describe the bioavailable fraction. Luminescence-based bacterial biosensors show a dose-dependent response to arsenic solutions, indicating the presence of toxic components. This investigation used a suite of tools to report on environmental samples. A combination of three biosensors was used to assess aqueous extracts of soils from mining sites in the UK and Chile. Two of these biosensors, Escherichia coli HB101 pUCD607 and Pseudomonas fluorescens 10586r pUCD607, are metabolic sensors where luminescence declines as metabolism is inhibited by toxicity. The third biosensor, E. coli CM1166 pC200, is a specific sensor such that luminescence is induced by the presence of arsenic in the form of arsenite. The results from the Chile samples demonstrate that biosensors are a powerful tool for providing an environmentally relevant hazard assessment of arsenic bioavailability and toxicity. This may allow local regulators to identify risks without the need for expensive specialised chemical analysis. In contrast to this, the UK samples, characterised as having a range of contaminants, highlight some of the limitations of the system; the problem of co-contamination and the limitations of a specific sensor for arsenite when arsenate is the most common form in the environment. Biosensors may enable real time monitoring of potential contamination, either by using focussed analysis with specific promoters or general metabolic reporter systems. Key words: arsenic, biosensors, bioavailability, soil |
