| Summary: | Investigations into the environmental fate and effect of anthropogenic sources of selenium in the water and sediment downstream of some mining areas are ongoing. Complimentary investigations into the sources and mechanisms of selenium release from the host geology are also underway. The existing geochemical data for selenium concentration in rock samples has a reported analytical variability of between 6% and 135% (of the sample mean, 95% confidence limits). The difficulties and implications of utilizing data with this level of variability, to interpret and quantify mechanisms of selenium leaching, are discussed. Many authors subscribe primarily to a sulfate-oxidation release mechanism, as selenium is known to substitute for a variable portion of the sulfur within a rock matrix. No data has been reported that fully supports this hypothesis. Data that would support competing or alternative sources and mechanisms of selenium release are discussed. The industry is currently collecting thousands of selenium samples for each environmental assessment, even though there are no protocols on how and where geological samples should be collected, stored or on how the data should be interpreted. A collaborative research program to develop new analytical techniques, to aid in resolution of this situation, is introduced.
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