Selenium analysis in waters. Part 2: Speciation methods

In aquatic ecosystems. there is often no correlation between the total concentration of selenium present in the water column and the toxic effects observed in that environment. This is due. in part, to the variation in the bio- availability of different selenium species to organisms at the base of the aquatic food chain. The first pan of this review (Kumkrong et al.. 2019) discusses regulatory framework and standard methodologies for selenium analysis in waters. In this second article, we are reviewing the state or Speciation analysis and importance of speciation data for decision makers in industry and regulators. we look In detail at fractionation methods for spedation. including the popular selective sequential hydride generation. We examine advantages and limitations of these methods. In terms of achievable detection limits and Interferences foam other matrix species, as well as the potential to over- or under-estimate operationally-defined fractions based on the various conversion steps involved In fractionation processes. Additionally. we discuss methods of discrete speciation (through separation methods), their importance in analyzing individual selenium species, difficulties associated with their implementation, as well as ways to overcome these difficulties. We also provide a brief overview of biological treatment methods for the remediation: of selentum-contaminated waters. we discuss the Importance of selenium speciation in the application of these methods and their potential to actually increase the bioavailability of selenium de-spite decreasing its total waterborne concentration. (C) 2018 Elsevier B.V. All rights reserved.