Selenium enrichment in Carboniferous Shales, Britain and Ireland: Problem or opportunity for shale gas extraction?. (March 2016) - Parnell, John
Abstract: The Carboniferous Bowland Shale in England, and its correlatives in Ireland, contain anomalously high concentrations of trace elements, including selenium (Se), molybdenum (Mo) and arsenic (As). High levels of these elements reflect high sulphur contents as these elements occur as trace constituents of pyrite. Anomalous Se in particular may have a volcanic provenance, from contemporary volcanic activity and/or drainage from Ordovician volcanogenic sulphide deposits. Following concern over the release of Se and As into groundwater during shale gas extraction in the US, the potential fate of Se and As during any future shale gas extraction from the Bowland Shale merits attention. It is at least an environmental issue that must be managed, but at best it could be an opportunity for extraction of Se in an environmentally sensitive manner. Highlights: We report selenium contents for the Carboniferous Bowland Shale. We show that the Bowland Shale selenium contents are anomalously high. Given environmental concerns, shale gas extraction should monitor selenium in water. Selenium in water could be extracted as a bi-product.