Liberation of selenium from alteration of the Bowland Shale Formation: evidence from the Mam Tor landslide

Abstract

The Bowland Shale Formation is anomalously rich in selenium (Se) at levels an order of magnitude greater than other black shales. The Mam Tor landslide, Derbyshire, England, offers an opportunity to measure whether the Se anomaly is conferred to the alteration products formed by oxidative water flow through the shale. Selenium in the shale is concentrated in diagenetic pyrite. Alteration of the shale causes decomposition of the pyrite to iron oxyhydroxide, which is carried in colloidal form (ochre) by springs draining the landslide. The iron oxyhydroxide contains anomalously high Se, and anomalously high Se was measured in water ponded where the ochre precipitated, although not in flowing groundwater. Other trace elements including cadmium and thallium also occur at concentrations higher than in other ochres. Given the widespread nature of the Se anomaly in the Bowland Shale Formation and equivalents across Britain and Ireland, any alteration products derived from workings through the shale should be disposed of with care.

A Bibliometric Analysis of Research on Selenium in Drinking Water during the 1990–2021 Period: Treatment Options for Selenium Removal

“…Although the selenium content of most natural waters does not threaten human health, the aquifers and the related surface water bodies in natural selenium-rich geological areas can present selenium concentrations that require further treatment to obtain safe drinking water. Chinese, Indian, American and Canadian seleniumrich regions have been deeply investigated [46][47][48], but other countries with localized areas characterized by high selenium contents can be mentioned, such as Argentina, Brazil, France, Ireland, Israel, Italy or Venezuela [49][50][51][52][53][54][55][56]. Nevertheless, anthropogenic activities account for a widespread selenium contamination as the result of some industrial activities, such as coal mining and combustion; gold, silver and nickel mining; metal smelting (especially pyrometallurgical copper, nickel and zinc production); oil transport, refining and utilization; and agricultural irrigation with selenium-rich waters [57].…”