Selenium

Neal, Rosemary H.

doi:10.1007/978-94-011-1344-1_12

Cited by 50 publications

(34 citation statements)

References 77 publications

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“…However, there are exceptions to the generally low levels of Se in some types of sedimentary rocks and deposits. Very high concentrations (> 300 mg Se/kg) are reported in some phosphatic rocks, reflecting similarities in the PO 4 3-and SeO 4 2-anions (21)(22)(23)(24) . Coal and other organic-rich deposits tend to have higher levels of Se, with typical ranges from 1 mg/kg to 20 mg/kg, although values of > 600 mg/kg are reported for some black shales (22) .…”

Section: Distribution and Cyclingmentioning

confidence: 96%

“…Generally, sedimentary rocks are richer in Se than are igneous rocks but limestones and sandstones will rarely contain >0 . 1 mg/kg (24) . As it is estimated that (25) , generally low concentrations of Se are therefore to be expected over much of the Earth's surface.…”

Section: Distribution and Cyclingmentioning

confidence: 99%

“…For extrusive (volcanic) rocks Se concentrations are more complex. Ash and gases associated with volcanic activity can contain substantial quantities of Se (20) but this process leaves behind volcanic rocks such as basalts and rhyolites that have relatively very low concentrations of Se (21)(22)(23)(24) . Generally, sedimentary rocks are richer in Se than are igneous rocks but limestones and sandstones will rarely contain >0 .…”

Section: Distribution and Cyclingmentioning

confidence: 99%

“…There are Se minerals such as crookesite (Cu, Tl, Ag 2 Se), clausthalite (PbSe) and berzelianite (Cu 2 Se), but these minerals are rare compared with sulfides. Elemental Se 0 is occasionally reported (21,24,27) .…”

Section: Distribution and Cyclingmentioning

confidence: 99%

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Symposium on ‘Geographical and geological influences on nutrition’ Factors controlling the distribution of selenium in the environment and their impact on health and nutrition

2009

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Se is essential to human and animal health but can be toxic in excess. An interest in its geochemistry has developed alongside a greater understanding of its function in a number of health conditions. Geology exerts a strong control on the Se status of the surface environment; low-Se rock-types (0·05–0·09 mg Se/kg) make up the majority of rocks occurring at the Earth's surface, which in turn account for the generally low levels of Se in most soils. However, there are exceptions such as associations with sulfide mineralisation and in some types of sedimentary rocks (e.g. black shales) in which contents of Se can be much higher. Baseline geochemical data now enable a comparison to be made between environmental and human Se status, although a direct link is only likely to be seen if the population is dependent on the local environment for sustenance. This situation is demonstrated with an example from the work of the British Geological Survey in the Se-deficiency belt of China. The recent fall in the daily dietary Se intake in the UK is discussed in the context of human Se status and declining use of North American wheat in bread making. Generally, US wheat has ten times more Se than UK wheat, attributed to the fact that soils from the wheat-growing belt of America are more enriched in Se to a similar order of magnitude. In agriculture effective biofortification of crops with Se-rich fertilisers must be demonstrably safe to the environment and monitored appropriately and baseline geochemical data will enable this process to be done with confidence.

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Section: Distribution and Cyclingmentioning

confidence: 96%

Section: Distribution and Cyclingmentioning

confidence: 99%

Section: Distribution and Cyclingmentioning

confidence: 99%

Section: Distribution and Cyclingmentioning

confidence: 99%

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Symposium on ‘Geographical and geological influences on nutrition’ Factors controlling the distribution of selenium in the environment and their impact on health and nutrition

2009

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“…However, many of these studies show conflicting results. Phosphate can influence Se sorption on soil surface since orthophosphate anions will readily displace sorbed Se from the clay mineral and organic matter surface and compete with Se for inner surface complexation sites on soil surfaces (Neal 1995). Carter et al (1972) showed that Se concentration in alfalfa (Medicago sativa) grown in alkaline and acid conditions increased when P fertilizer was applied.…”

Section: Introductionmentioning

confidence: 99%

Effect of phosphate and sulfate fertilizers on selenium uptake by wheat (Triticum aestivum)

Lee

Woodard

Doolittle

2011

Soil Science and Plant Nutrition

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The objective of this study was to investigate whether oxyanionic phosphate (P) and sulfate (S) fertilizer management could influence selenium (Se) uptake by wheat (Triticum aestivum) in medium and high Se areas. Field studies were established at two locations for two growing seasons in central South Dakota, USA. Phosphate fertilizer was applied using three different methods (banded with seed, surfacebroadcasted in the fall, or surface-broadcasted in the spring) using six different P rates. Sulfate fertilizers were broadcasted at four rates in the fall. Selenium concentration in wheat grain was significantly influenced by the interaction of P application methods and rates, but it was dependent on location. Grain Se concentration decreased in high Se availability soil when P fertilizer was applied, due to the dilution effect. Grain Se concentration and uptake was significantly decreased as S applications increased due to the competition effect, but the depression was apparent in high Se availability soil. The results from this study showed that P and S fertilizer management can influence Se level in wheat grain grown in naturally high Se areas, even though overall grain Se level was strongly associated with location variation.

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Selenium: Radionuclides

Shaw

Ashworth

2005

Encyclopedia of Inorganic Chemistry

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Selenium in the environment has been studied intensively for several decades, since it is both a trace nutrient and a toxin. It is a ubiquitous element in soils, waters, and the atmosphere, with chemical similarities to the other group 16 elements sulfur, polonium, and tellurium. Important selenium species in environmental media include inorganic oxyanions as well as organic species produced by biological methylation mechanisms. The only probable long‐term source of radioactive selenium to the environment is the leakage from radioactive waste repositories. Only 79 Se is of concern in this respect, since it is the only long‐lived radioactive isotope of selenium (physical half‐life = 377 000 years). Under alkaline geochemical conditions, there is the potential for 79 Se to migrate from geological radioactive waste repositories in very small quantities over very long periods. It is expected that any 79 Se released into the environment will behave in the same way as nonradioactive selenium, though the kinetics of isotopic exchange between 79 Se and stable selenium in soils, sediments, and other environmental media have never been studied over timescales relevant to radioactive waste disposal. It is unlikely that environmental concentrations of 79 Se will ever lead to exposures approaching the intake levels associated with stable selenium. Any exposure that does occur is likely to be primarily through the dietary intake pathway, since the principal environmental reservoirs, and therefore potential sources, of selenium in the environment are waters and soils.

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Selenium

Cited by 50 publications

References 77 publications

Symposium on ‘Geographical and geological influences on nutrition’ Factors controlling the distribution of selenium in the environment and their impact on health and nutrition

Symposium on ‘Geographical and geological influences on nutrition’ Factors controlling the distribution of selenium in the environment and their impact on health and nutrition

Effect of phosphate and sulfate fertilizers on selenium uptake by wheat (Triticum aestivum)

Selenium: Radionuclides

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