Grant: Discovery Grants Program - Individual

Selenium (Se) is an inorganic contaminant of high current importance in North America. It is discharged accidentally into the aquatic environment from some major industrial processes, including coal-fired power plants, petroleum refineries and various types of mining operations (e.g. coal, gold and uranium). In some receiving environments, there is concern about ecotoxicological effects arising from Se discharges, which may lead to Se bioaccumulation in aquatic organisms, and to reproductive effects in aquatic birds and predatory fish that can ultimately endanger the survival of entire local populations. Selenium (Se) forms volatile chemical compounds ("species"), and can therefore escape to the atmosphere from waters, soils and vegetation impacted by industrial operations. However, the biogeochemical mechanisms by which volatile Se compounds are formed are not understood completely. Additionally, the magnitude of Se air-surface exchange processes can currently not be measured directly, and the corresponding estimates have large uncertainty. In this proposed research program, we will develop analytical methods for the measurement of all potentially-relevant individual volatile Se species, as well as for total volatile Se (TVSe), in air and waters. These analytical methods will then be used to design and test experimental approaches which can measure the fluxes of TVSe and its individual components from contaminated aquatic ecosystems and from industrial operations to the atmosphere. Understanding which volatile Se species occur at what relative concentrations will allow us to understand the biogeochemical mechanisms by which Se is volatilized, and thereby make more accurate predictions about the effects of changing environmental parameters on these processes. Measuring atmospheric Se emissions will allow us to forecast better how impacted aquatic ecosystems will respond to changing industrial Se discharges, and what role atmospheric transport plays in the natural attenuation of such ecosystems. At the affected industrial sites, quantifying Se volatilization, especially in Se treatment systems, will permit us to predict more accurately the remaining Se concentration in process waters that need to be subjected to treatment prior to discharge. Overall, the role of atmospheric exchange on Se ecotoxicity in impacted aquatic ecosystems has been largely neglected in the past, but with the proposed research program, we aim to close this gap, so that environmental Se regulations can take this mitigating factor into consideration when projecting future exposure of aquatic organisms to Se. This will assist the regulatory dialogue with Se dischargers, so that the uncertainty affecting the quantitative connection between current and future Se discharges and the anticipated resulting ecotoxicological effects can be narrowed down.