Selenium in the Soil-Plant Environment: A Review

Abstract

Selenium (Se) exhibits a "double-edged" behavior in animal and human nutrition. It is a micronutrient required in low concentrations by animals and humans, but toxic at high concentrations. Selenium deficiency has been associated with cancer and other health problems. Selenium requirements are commonly met through soils and plants such as wheat, rice, vegetables and maize in many countries. Selenium concentration in the soil generally ranges from 0.01-2.0 mg kg-1 but seleniferous soils usually contain more than 5 mg kg-1. Seleniferous soils have been reported in Ireland, China, India and USA. Weathering of parent rocks and atmospheric deposition of volcanic plumes are natural processes increasing Se levels in the environment. Anthropogenic sources of Se include irrigation, fertilizer use, sewage sludge and farmyard manure applications, coal combustion and crude oil processing, mining, smelting and waste incineration. Mobility of Se in the soil-plant system largely depends on its speciation and bioavailability in soil which is controlled by pH and redox potential. Plant uptake of Se varies with plant species and Se bioavailability in the soil. The uptake, translocation, transformation, metabolism, and functions of Se within the plant are further discussed in the paper. The release of Se in soils and subsequent uptake by plants has implications for meeting Se requirements in animals and humans.

Selenium biofortification in the 21st century: status and challenges for healthy human nutrition

“…Its content depends on soil type and texture, origin and geological history, mineralogy, organic matter content, weathering degree and rainfalls, dominant soil geogenic processes, and Se deposition (Hartikainen 2005 ; Mehdi et al 2013 ; Wen and Carignan 2007 ). Natural Se emissions (crustal weathering, sea spray, volcanic plumes) and anthropogenic Se emissions (fossil fuel combustion, non-ferrous metal production and manufacturing) largely contribute to Se deposition, which is affected by vicinity to the coast, altitude and wind directions (Saha et al 2017 ; Wen and Carignan 2007 ).…”

Selenium Anticancer Properties and Impact on Cellular Redox Status

“…Therefore, it is important carefully to control intake of this element. It is important to note, that the recommended daily doses of Se depend on the geographical area [2]. The average daily intake of Se for European population recommended by World Health Organization is estimated at 40 µg (30-50 µg/day) and should not exceed 70 µg/day for adult individuals [3].…”

Quantitative determination of selenium in the most common food items sold in Egypt

“…This confirms the theory of Brazilian walnuts are rich in Se content. These differences may be due to geographical, climatologic differences which possibly reflect differences in Se concentration in soil all over the world [ 27 , 28 ].…”