PubMed · 14858879
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
D G WILLIAMS. 1951-08-25. Colliery practice.. https://doi.org/10.1136/bmj.2.4729.441
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Chemical speciation determines Se solubility and therefore its bioavailability and potential for transport in the environment. In this study we investigated the speciation of Se in soil developed on reclaimed mine sites in the U.S. Western Phosphate Resource Area (WPRA) using micro-X-ray absorption near-edge structure (micro-XANES) spectroscopy and micro-X-ray fluorescence (micro-XRF) mapping. Selenium was nonuniformly distributed in the soils and positively correlated with Fe, Mn, Cu, Zn, and Ni. Sixteen points of interest (POI) from three soil samples were analyzed with micro-XANES spectroscopy. The XANES data indicated that Se is present in the soils in at least three oxidation states, Se(-II, 0), Se(IV), and Se(VI). Selenides or elemental Se dominated 7 of the 16 POI. Selenate was the dominant species at only one of the POI. The remaining eight POI were composed of both Se(IV) and Se(VI), with minor Se(-II, 0) contributions. The results of this research suggest that the reduced Se species in the soil parent material are oxidizing to Se(VI), one of the more mobile species of Se in the environment. This information can be used to better predict and manage Se availability in soils.
Explore the source record for details and available documents.
Theoretical calculations are presented for partially enclosed uranium- and thorium-bearing subterranean environments, such as tunnels and underground uranium mines. The variables of practical interest considered here are the 222Rn and 220Rn concentrations in the wall, and the flux densities of the same radioactive gases in the wall and at the wall/air interface of these underground sites. Calculations have been conducted based on a plane, semi-infinite geometry model (commonly used to predict radiation levels in mines) and a cylindrical (i.e., tunnel) geometry model. The 220Rn flux density, J(220Rn), calculated according to the plane and cylindrical geometries agree with each other within 5% for wall media of porosity equal to or greater than about 2%, even for tunnels of small radii. However, for 222Rn the cylindrical geometry gives values for the 222Rn flux density, J(222Rn), substantially higher (by a factor of 1.4 to approximately 3) than those predicted by the plane semi-infinite geometry. A practical difficulty arises in the experimental verification of the models in underground environments. The results are relevant for predicting radioactivity levels (222Rn, 220Rn, and their progeny) in underground environments such as uranium mines. Health Phys.