Selenium (Se 79 34) is an essential element in living organisms.It is the 30th most abundant naturally occurring metalloid element on the Earth's crust. Selenium is present in the earth's crust at an estimated amount of 0.05–0.5 mg Se kg − 1 (Lemly, 2004), with total selenium concentrations in rocks amounting to 40% of the total earth's crust …
Selenium (Se) is an essential trace element for human health, and humans mainly consume Se through diet. China is recognized as a Se-deficient country, and the study of Se migration and …
The concentration of selenium in the soil is different from one region to the next. Humans absorb selenium primarily through plant-based foodstuffs. But even in plants, the selenium content varies greatly …
Selenium belongs to the group of trace elements, with the average concentration of Se in the Earth's crust estimated at 0.05 mg kg −1 (Taylor and McLennan 1995).The Se concentration in the Earth's crust is ~0.09 mg Se kg −1 (NRC 1983).It is located in the group VI of the periodic table.
The selenium (Se), heavy metal (Cd, Zn, Pb), and rare earth element (La, Ce, Nd) concentrations in husks, brown rice, and soils planted in different soils with various rice cultivars are shown in Table 6. All elemental concentrations in the soils and plant tissues showed large-scale spatial and temporal variation, even within the same cultivar ...
2. Sources of Selenium in the Environment and its Location Most plant and animal tissues contain traces of selenium [11]. It is widespread in the Earth's crust where average concentration is 0.09 mg·kg−1. 2.1. In Soils In soils, selenium occurrence is mainly due to the erosion of rocks containing selenites and
IOP Conf. Series: Earth and Environmental Science 199 (2018) 042027 IOP Publishing. ... The Effects of six selenium concentrations (0, 5, 10, 25, 50, 75, and 100 mg/kg) on physiological property ...
It can be found in the atmosphere, lithosphere, biosphere, and hydrosphere of the Earth . This element circulating in the environment initiates the process of weathering in rocks. Selenium is emitted into the atmosphere through volcanic gasses. ... In general, the concentration of selenium in urban air is in the range from 1 to 10 ng/m 3.
Selenium (Se) is a ubiquitous element akin to sulfur (S) existing in the Earth crust in various organic and inorganic forms. Selenium concentration varies greatly depending on the geographic area. Consequently, the content of selenium in food products is also variable. It is known that low Se is associated with increased incidence of cancer …
However, it can be toxic at high concentrations. Physical properties • It exists in solid form at room temperature. • Its melting point is 217.8°C. • Its boiling point is 685°C. ... Selenium is a rare earth element, but it is still used in different industries. It shows photoconductive and photovoltaic effects, due to which it is found ...
Selenium is widely but unevenly distributed in nature. The average concentration in the earth's crust is 0.009 μg/g. The average concentrations in local soils range from below 0.06 μg/g (selenium impoverished) to above 8 μg/g (seleniferous), and …
In inland lakes, the concentration of Se is ~25 µg/liter . Se is also found in the atmosphere as a component of ash produced by the volcanic activity and burning of fossil fuels. The level of Se in the air near the Earth surface ranges from 0.1 to 10 ng/m 3, whereas its local concentration in certain areas may be as high as 500 ng/m 3 .
Distribution of selenium content in the earth crust is extremely uneven, and the mean selenium content is 0.05 mg/kg (Clarke and Washington 1922). Selenium content in the bedrock varies greatly (0.01–56.22 mg/kg), with an average of 2.02 mg/kg, which is higher than the mean selenium content in earth crust (0.05 mg/kg) (Table 4). The …
However, Se is not uniformly distributed throughout the Earth's crust. In certain areas, soil selenium concentrations are between 0.01 and 2 mg/kg, and the world average is 0.4 mg/kg (Fordyce, 2007).
According to an analysis of 2003–2004 NHANES data, the mean serum selenium concentration in U.S. adults age 40 years or older is 13.67 mcg/dL [ 17 ]. Men have …
plants in selenium cycling to the animal and the return of selenium to the soil. Geochemistry Selenium is widely distributed in trace amounts in nearly all materials of the earth's crust, having an average abundance of about 0.09 ppm.' Selenium is only seidom present in concentrations greater than 500 ppm . It
Selenium concentrations in sulfide minerals and other phases, in various ... Selenium concentrations in selected Earth and lunar materials ..... Q16 Q6. Estimated world selenium reserves in 2014, in metric tons.....Q21 Q7. National Institutes of Health recommended dietary reference intakes ...
The total selenium concentration in seven fish species' muscles was determined. TDSe in the surface water of Al-Arbaeen and Sharm Obhur lagoons showed a maximum concentration of 18.56 and 8.38 nM, respectively. ... Its relative abundance in the Earth's crust is around 1.9 ppb .
Once in the earth, selenium can enter surface water and groundwater supplies through surface runoff, rain, snowfall, ... 56 utilities in 11 states serve more than 34,000 people water containing higher concentrations of selenium than recommended in the EPA health guidelines.
4.3. Selenium Concentration in Egg Yolk and Tissue. Avian eggs are among the models used to assess the absorption and retention of microminerals, including Se of varying dosages and forms [105,106]. The amount of selenium transferred to the egg is determined by the source and level of selenium in the diet .
The reference range for plasma selenium is about 60–150 ng/mL. Selenium deficiency (serum concentration <40 ng/mL) is rare and is associated with loss of glutathione peroxidase activity. Dietary selenium deficiency is generally seen in hospitalized patients or with the use of TPN.
Selenium is found in trace amounts in the Earth's crust, typically in the range of 0.05–0.09 mg/kg. Soils can be classified into selenium-deficient (<0.13 mg/kg), selenium-marginal ... The selenium concentrations in KD patients' muscle, heart, liver, and kidneys are 10-fold lower than those in healthy people .
Selenium is a chemical element with the atomic number 34 in the periodic table. It occurs naturally in Earth's crust, especially in carbonate rocks and volcanic and sedimentary soils. Being a member of the sulphur group of periodic table elements, this chalcogen has six electrons in the outermost shell and valences of -2, 4, and 6.
Selenium is an essential toxin that functions as essential micronutrient for maintaining good health with a small safety margin, but is toxic at slightly higher …
Different climate and soil parameters determine how much selenium is concentrated in the soil. As a rule of thumb: if the soil is …
Much of the selenium in the earth's crust occurs associated with sulfide minerals. The presence or absence of selenium in any soil is dependent upon the …
3.1 Origin of Soil Selenium and Variable Levels in the Earth's Crust. Total Se concentrations are low in most soils, usually in the range 0.01–2.0 mg kg −1, although levels as high as 1,200 mg kg −1 can occur in seleniferous soils [].The average concentration of Se is much higher in some of the common sedimentary rocks, …
Selenium is a naturally occurring, solid substance that is widely but unevenly distributed in the earth's crust. It is also commonly found in rocks and soil. Selenium, in its pure form of metallic gray to black crystals, is often referred to as elemental selenium or selenium dust. ... Selenium concentrations in aquatic organisms have been a ...
Se is a non-metallic element naturally present in the earth's crust; the global average concentration of Se in soil is 0.4 mg kg −1, ranging from 0.01 to 2 mg kg −1 (Dungan and Frankenberger Citation 1999). The …
Selenium in Counties of the Conterminous States. (Hold the mouse over a county to view the concentration of the element; click on a county to retrieve all geochemical data within the county.)