Development of analytical methods to identify and quantify existing selenium species in waters from Canadian mining operations
Mrs Paramee Kumkrong, Mr Patrick Mercier, Mr Bussaraporn Patarachao, Mrs Cindy Jiang, Mrs Judy Kung, Mr Daniel DTyo, Mr Charles Wgreer
The presence of selenium in water from mining activities is a source of concern among environmental regulators. Selenium is present in mine water and tailings mainly as oxyanions (SeO32- and HSeO42-). These species may then be transformed into organoselenium (selenomethionine, selenocysteine), or even converted into gaseous forms (selenocyanide, dimethyldiselenide, dimethylselenide), by microorganisms and other biota before selenium is released into the environment. The development of analytical methods to determine selenium and its species is challenging. As a result, there currently exists no internationally recognized standard reference method for selenium speciation. This conundrum is not only due to the ultralow levels of Se present, but also to the fact that identification of Se species is not trivial. Moreover, each Se species has a different toxicity, which is not yet well understood, especially in the context of the ecotoxicology of Se species arising from mining activities. The identification and quantification of selenium species is normally accomplished by using coupled techniques, i.e. ion chromatography or high performance liquid chromatography interfaced with inductively coupled plasma collision reaction cell mass spectrometry (IC/HPLC-ICP-CRC-MS). At NRC, we are also investigating HPLC coupled with electrospray ionization mass spectrometry (ESI-MS), as a potential method to detect organic selenium species in mine water. NRC has initiated a project for understanding the forms of Se in mine water and tailings from Canadian operations. This will help industry to identify technologies for waste remediation and water treatment before releasing effluents into the environment. Furthermore, the identification and quantification of selenium profiles in discharge waters from various mining activities will add information needed to enable a rational environmental assessment of the impact of Se arising from Canadian mining operations.