Skip to content
naulon
Get started

No retraction, correction or concern found when last checked on Oct 20, 2026.

Selenium Cycling Across Soil-Plant-Atmosphere Interfaces: A Critical Review

Lenny Winkel, Bas Vriens, Gerrad Jones and 3 more

Nutrients · 2015 · Review · CC BY

doi:10.3390/nu7064199

Abstract

Selenium (Se) is an essential element for humans and animals, which occurs ubiquitously in the environment. It is present in trace amounts in both organic and inorganic forms in marine and freshwater systems, soils, biomass and in the atmosphere. Low Se levels in certain terrestrial environments have resulted in Se deficiency in humans, while elevated Se levels in waters and soils can be toxic and result in the death of aquatic wildlife and other animals. Human dietary Se intake is largely governed by Se concentrations in plants, which are controlled by root uptake of Se as a function of soil Se concentrations, speciation and bioavailability. In addition, plants and microorganisms can biomethylate Se, which can result in a loss of Se to the atmosphere. The mobilization of Se across soil-plant-atmosphere interfaces is thus of crucial importance for human Se status. This review gives an overview of current knowledge on Se cycling with a specific focus on soil-plant-atmosphere interfaces. Sources, speciation and mobility of Se in soils and plants will be discussed as well as Se hyperaccumulation by plants, biofortification and biomethylation. Future research on Se cycling in the environment is essential to minimize the adverse health effects associated with unsafe environmental Se levels.

Full text

From PubMed Central, U.S. National Library of Medicine, as current on Oct 20, 2026. Paragraph numbers are ours, so an answer can point at one.

1. Introduction

The trace element selenium (Se) is essential for human and animal health, while no Se requirement has been shown for higher plants. The role of Se in physiology is mainly derived from its presence in the Se-containing amino acids selenomethionine (SeMet) and selenocysteine (SeCys). The latter has been termed the 21st amino acid since it is needed in a small set of selenoproteins that serve redox functions. Selenoproteins include glutathione peroxidases and thioredoxin reductases, which have a variety of functions including protection from oxidative damage, regulation of intracellular redox state and thyroid hormone metabolism. Adequate Se intake levels have a relatively narrow range between deficiency and toxicity: current estimates indicate that an intake of Se of 30 μg·day−1 is inadequate for humans, while intakes exceeding 900 μg·day−1 are potentially harmful. Dietary Se intake levels mainly depend on the total concentration and bioavailability of Se in food sources (crops, fish and animal products), which depend on the multiple factors such as Se content of soils, irrigation water and animal feed. Selenium content has been found to vary considerably across food sources and geographical origin, and Se deficiency is more widespread than Se excess, both in agricultural and natural areas.

Apart from the total Se content of food sources, the chemical form, i.e., speciation, is important, as it affects the bioavailability and nutritional value of Se. The various chemical forms of Se exhibit highly different properties with regard to sorption, bioavailability, mobility and toxicity. To prevent Se toxicity and to provide adequate Se in the human diet, it is of great importance to obtain insight into the processes that govern the distribution and speciation of Se in agricultural soils and plants. This review is aimed at summarizing the current knowledge of Se cycling across the soil-plant-atmosphere interfaces. These interfaces are of major importance as they control the local-scale mobility of Se in agricultural and natural systems and potentially also play an important role in the global Se distribution. Particular focal points are plant uptake and biomethylation since both are key distribution processes that highly contribute to the mobility of Se in the environment. In addition to sources and sinks of Se in the environment as well as the biotic and abiotic transformation processes of Se in soils and plants, incl. biofortification and Se hyperaccumulation, this review also identifies knowledge gaps and missing links in/between the different areas of research.

2. Selenium in Crops

For organisms that mainly consume a plant-based diet, health problems related to Se deficiency may arise due to selenium’s variable distribution in the soil and its moderate uptake by crops. Selenium toxicity is a problem in areas with seleniferous soils, including parts of China, India and the USA, while Se deficiency is a problem in areas where soil Se is particularly low, such as other parts of China, the USA as well as Australia, New Zealand and Finland. Since low concentrations of plant-available forms of Se in soil can decrease the dietary intake of Se, it is very important to improve the bioavailability of Se and increase the Se content in plant food-products in Se-deficient areas, e.g., China and Finland. Therefore, management strategies aimed at minimizing Se deficiency and associated diet-related disturbances should be focused on establishing a connection between agricultural food-products and Se content and bioavailability in soil.

2.1. Biofortification

One of the most promising approaches to combat a low transfer of Se from soil into the food chain involves a concept called Se biofortification. This agronomic-based strategy can be utilized by growers to produce Se-enriched food products that may help reduce dietary deficiencies of Se occurring throughout susceptible regions of the world. Increasing the dietary intake of Se, as well as the bioavailability and accumulation of Se to food crops, may be accomplished by amending soils with Se, adjusting cropping systems, selecting Se accumulating cultivars, and using modern genetic engineering technologies.

2.1.1. Speciation of Se in Crops

The major determinant of Se bioavailability in Se-enriched food sources is the Se speciation. Although Se may also be present in inorganic forms (e.g., selenite [Se(IV)], selenate [Se(VI)]) in crops, the predominant form of Se extracted with enzymatic hydrolysis is generally organic: selenomethionine (SeMet) (e.g., in biofortified wheat), methylselenocysteine (MeSeCys) (e.g., in carrots and onions and broccoli) and γ-glutamyl-Se-selenomethyl-selenocysteine (γ-Glu-MeSeCys) (e.g., in carrots and onions). More research is needed to determine how application doses and chemical forms of applied Se to the soil or foliar surfaces affect Se speciation and the proportion of organic Se species accumulated in edible plant tissues. The organic forms of Se available in biofortified products are the preferred choice for long-term population-wide Se supplementation strategies as they may have additional health value under Se-deficient conditions. Hence, to elucidate the resulting forms and quantities of Se-amino acids in food products resulting from a biofortification practice more research on Se speciation is needed.

2.1.2. Application of Se to Soils

The strategy of Se biofortification of food crops is practiced in Se-deficient regions by adding inorganic Se-containing fertilizers to soils, e.g., in Finland, UK, and New Zealand, or by adding organic sources of Se to soils, e.g., in the USA. With either source of Se, the efficacy for biofortification of crops with Se strongly depends on the physical, chemical and biological properties of the soil (as discussed in Section 4.2). Although Se-amended inorganic fertilizers can be beneficial for producing Se-biofortified food and animal feed products, disadvantages include low Se recovery rates in edible portions of crops or excessive Se accumulation in the soil with long-term application of Se fertilizer that might become toxic for nearby ecosystems. An effective method of biofortifying food crops with Se is foliar application. Selenite and selenate have been shown to be more bioavailable to plants when applied directly to leaf surfaces opposed to soils. Therefore, foliar application of Se may be a more efficient method of biofortification, especially considering that soils can be effective sinks for Se. Importantly, the direct foliar exposure route ensures a high efficiency of Se assimilation by the plant since it does not depend on root-to-shoot translocation. The rate of biotransformation from absorbed inorganic Se to different organic forms of Se in a plant is species specific and depends on specific biochemical pathways.

2.2. Genetic Engineering

Genetic engineering for the promotion of higher Se levels in plant has been reviewed earlier by others and applied to Brassica crops in field conditions. In addition to genetic manipulation, the interspecific and intraspecific variation in Se accumulation within plant taxa may be exploited for biofortifying food crops. The selection of existing cultivars for their higher accumulation of Se, as well as for the forms of organic Se distributed in the edible parts of a given crop can have an immediate impact on daily dietary Se intake, especially if such cultivars can be used in crop breeding programs. Thus, more effective biofortification could be achieved if plant breeders, molecular biologists, and agronomists collaborate to better understand the limiting factors of Se uptake, accumulation and biotransformation in plants.

Using Naturally-Enriched Se Materials

Despite the widespread occurrence of Se deficiency, some soils, mineral deposits and waters are naturally rich in Se, and exploitation of those seleniferous resources in agricultural practice can lead to an increased Se accumulation in plant tissues. Bañuelos (2002) has observed the increased accumulation of Se in broccoli and canola irrigated with waters containing naturally high levels of Se. In addition, unpublished work by Bañuelos and Freeman (2015) demonstrated that Se-enriched vegetables, e.g., Swiss chard, red and green cabbage, accumulated Se ranging from 3 to 9 mg Se kg−1 (dry weight), when grown in soils containing high levels of naturally occurring Se. Hence, using soils naturally rich in Se for growing foods can be a viable and low-cost agronomic strategy for natural biofortification.

3. Sources and Sinks of Soil Selenium

In general, Se in soils can originate from both local and regional sources. Local sources include rocks (geogenic sources) from which Se can be mobilized via weathering and leaching in addition to anthropogenic sources such as Se-fertilizers. Sources that add Se to soils over medium- to long-range distances include wet and dry atmospheric deposition derived from both anthropogenic (fossil fuel burning, metal smelting, ship emissions) and natural sources (biomethylation, volcanic activity). A number of reviews have been published on atmospheric and geogenic sources of Se to soils (see Table 1). Figure 1 gives a schematic overview of the most important Se species in soils, water, and atmosphere and indicates the main biogeochemical pathways across the interfaces.

3.1. Geogenic Sources of Soil Selenium

In areas where the underlying bedrock is high in Se, elevated Se concentrations can be found in soils as a consequence of weathering, leaching and transport of Se into soils. Examples of high Se regions are areas containing black shales, which are sedimentary rocks high in carbon and metal content. Ireland contains some of the most Se-rich soils in the world derived from black shales, with levels up to 1250 mg·kg−1. Shales are also the primary source of high Se soils found in China, in arid regions in the west and southwest USA, e.g., in the central valley in California and in the Colorado River Basin, as well as in South Dakota and Wyoming. Although weathering and transport of Se from alluvial deposits are natural processes, release of toxic levels of geogenically-derived Se into the environment can additionally be triggered by human actions. For example, Se contamination in the Kesterson reservoir (San Joaquin Valley, California), which seriously affected aquatic organisms and birds, has been the direct effect of the accumulation and evaporation of agricultural drainage water enriched in geogenic Se. Another source of Se to soils that is related to human activities are dusts in the vicinity of coal burning sites.

3.2. Atmospheric Sources of Soil Selenium

Although geogenic sources may be a major local source of Se to soils, a comparison between the average Se content in soils (ranging from 0.01 to 2 mg·kg−1, world mean 0.4 mg·kg−1, and the average Se concentration in the Earth’s crust (0.05 mg·kg−1, indicates that a surface source such as atmospheric deposition may play an important role in the global distribution of Se in soils. Sources and sinks of atmospheric Se have been reviewed in Wen and Carignan (2007) (see Table 1). Global atmospheric Se budgets indicated that atmospheric Se input fluxes are between 15.5 and 15.7 × 109 g·year−1, of which ~60 and 40% are natural and anthropogenic emissions, respectively, although the contribution of natural emissions was found to be smaller (i.e., 25%) in the northern hemisphere due to anthropogenic emissions. Natural emissions include crustal weathering, sea spray, volcanic eruptions, and biological activity in the marine and continental biosphere (see Figure 1), while anthropogenic emissions include fossil fuel combustion, non-ferrous metal production and manufacturing ( and references therein). The main estimated anthropogenic source is coal combustion (3 × 109 g·year−1; 1.83 × 109 g·year−1) and the predominant natural atmospheric Se source may be the marine biosphere via biomethylation of Se by marine organisms (see chapter 7).

Marine-Derived Atmospheric Selenium

Global biogenic emissions of sulfur (S), which has similar chemical properties as Se, significantly contribute to the global S cycle and may even affect global climate. Even though the contribution of biogenic Se emissions to its global atmospheric budget is around 3 to 4 orders of magnitude smaller than for S emissions (approximately 6.5 × 109 g Se year−1 versus approximately 35 × 1012 g S year−1, a comparison of these fluxes with the average concentrations in seawater (8.9 × 10−1 g L−1 S and 1.6 × 10−7 L−1 Se) illustrates that Se is up to 3 orders of magnitude more enriched in the volatile phase than S. This relative enrichment of Se over S is corroborated by direct measurements of methylated Se and S species in seawater and in a pristine wetland by elemental analysis of aerosols. Although the mechanisms underlying this enrichment of Se over S (e.g., selective biological uptake of Se over S) remain unelucidated and require further study, field measurements of biogenic Se species in the marine environment and global-scale extrapolations of these observations indicate that biogenic Se emissions from the marine environment may indeed be larger than previously estimated (28.5 × 109 g Se year−1 and 35 × 109 g Se year−1 compared to 0.4–9 × 109 g year−1). However, most studies that measured biogenic Se concentrations were conducted during algal blooms and extrapolated global fluxes may therefore be overestimated.

3.3. Atmospheric Selenium Deposition

In contrast to global estimates of atmospheric Se emissions, global estimates of atmospheric Se deposition are not available. In the region between 30°N to 90°N, Ross (1985) estimated fluxes of 36–100 × 108 g Se year−1 and 5.5–26 × 108 g Se year−1, for wet and dry deposition, respectively. Furthermore, Cutter (1993) estimated a deposition of 2.2 × 109 g Se year−1 over the North Atlantic Ocean, which comprises ~12%–18% of total global emissions as estimated by Mosher and Duce, 1987. However, most studies on atmospheric Se deposition are based on locally collected precipitation and aerosol samples and therefore do not account for spatial and temporal variation in atmospheric Se deposition.

Local studies carried out in the US (Chesapeake Bay, Massachusetts Bay), China (Mt Heng), Japan and the UK (various sites) have reported wet Se deposition fluxes between 140 and 502 μg·m−2·year−1, whereas a dry deposition flux of 2 μg·m−2·year−1 and 140 μg·m−2·year−1 was estimated in the UK and Japan, respectively. These deposition fluxes are roughly the same order of magnitude as emission fluxes from terrestrial systems (see Section 7.2). The measured fluxes of wet deposition do not, to a large extent, depend on the locations where they were measured, although coastal locations were generally characterized by higher fluxes. For example, coastal deposition of Se has been found in Norwegian forest soils, which shows a distinct decrease in Se concentration with increasing distance from the ocean. Recently, Blazina et al. (2014) used sediment sequences from the Loess Plateau in central China to show that over the last 6.8 million years rainfall likely controlled Se distributions in these sediments. This suggests that precipitation may be an important factor in controlling the broad-scale Se distribution in soils in monsoonal China. Further research is required to understand to what extent precipitation determines large-scale soil Se patterns in other parts of the world.

3.4. Anthropogenic versus Natural Sources of Atmospheric Selenium

Both anthropogenic and biogenic sources of atmospheric Se may contribute to Se levels in surface environments (see Figure 1). For example, anthropogenic sources of atmospheric Se were identified as an important source of Se to soils based on simultaneous decreases in Se levels in UK herbage and reductions in industrial emissions. Similarly, water, soil, dust, air and locally produced food analyzed around the largest coking area in China were found to be enriched in Se, and aerosol samples collected over the North Pacific Ocean were concluded to be Se-enriched from Asian coal combustion activity. On the other hand, Se concentrations measured in aerosols collected over the mid-North Pacific Ocean were concluded to originate from a dominantly biogenic input from the Bering Sea. These examples indicate that the dominant sources of Se in the atmosphere (and thus the surface environment) may be highly variable depending on location and time. As a result, the extent to which different Se sources contribute to crop Se levels in different regions of the world is largely unknown.

Quantifying Se Sources and Sinks in Soils

Few studies systematically investigate the Se mass balance in soil/plant systems. As a result, the extent to which different Se sources contribute to plant Se content in different regions of the world is largely unknown. Nevertheless, the contribution of different Se input pathways into the soil was recently studied in a Se-rich area of China (Fujiang River Basin, Sichuan Province). The authors calculated annual average Se input and output fluxes of 20.45 g·ha−1·year−1 and 2.58 g·ha−1·year−1, respectively, and concluded that precipitation and infiltration were the main input and output pathways, respectively. Further mass balance studies of Se in soils are required to i) quantify the extent to which different Se sources contribute to the Se content of agricultural systems, ii) understand how the different sources affect the Se speciation in soils, and iii) how much Se is retained in the soil and how much is removed via leaching, volatilization and crop harvest. Recently, the leaching and shallow subsurface-transport potential of agricultural contaminants (e.g., nitrate and steroids) has been evaluated utilizing lysimeters and tile drains beneath agricultural fields. Such systems could be useful for quantifying the leaching potential for Se from soils. Only when we can better understand Se inputs and retention in soils we will be able to make predictions on future Se status in soils. There is still limited information on how atmospheric Se deposition affects the distribution of Se in the terrestrial environment. Due to the large mobility of atmospheric Se, understanding the role of atmospheric Se deposition in soil/plant systems is essential.

Stable Se isotope analysis is a promising tool to investigate redox reactions and to distinguish between potential Se sources. Johnson (2004) noted that microbial reductions yield fractionations less than 5‰, whereas abiotic processes yield fractionations greater than 7.3‰, suggesting that it may be possible to distinguish microbial from abiotic reduction. Assimilation by higher plants, Se(IV) oxidation, sorption, and biological volatilization induce little or no isotopic fractionation. In the last decade, analysis of Se isotopic fractionations to study geochemical processes and sources were applied to black shale-hosted Se-rich deposits in China, USGS shale standards, black shale samples from Australia and Canada and sediments and soils. A promising development is the ability to conduct stable Se isotope analysis of volatile organoselenides (after chemotrapping), which may help distinguish biogenic atmospheric Se sources from anthropogenic sources.

4. The Mobility and Bioavailability of Soil Se

While broad and regional scale processes are important for governing the global distribution of Se, the local distribution of Se in terrestrial environments is governed by small and micro scale processes related to mobility and bioavailability (e.g., speciation, solubility, partitioning, uptake, etc.). Mobility and bioavailability are interrelated but not necessarily synonymous. For example, highly immobile chemicals are unlikely to be bioavailable but highly mobile constituents may or may not be bioavailable depending on specific plant uptake mechanisms. Similarly, following uptake of bioavailable constituents, plants can facilitate the regional redistribution of Se via volatilization to the atmosphere but can also decrease mobility by accumulating Se into plant tissues.

4.1. Factors Affecting Se Mobility in Soils

Over the last several decades, the chemical processes affecting Se mobility in the environment have been well characterized. In the environment, Se can exist in the (-II), (-I), (0), (IV), (VI) oxidation states, and in general, Se solubility, and therefore mobility, increases with increasing redox potential (i.e., more oxidizing conditions). Soil Se is mainly inorganic but it can also be present in organic forms, e.g., as complexes with organic matter and incorporated into organic or organo-mineral colloids (Figure 1). Based on their acid dissociation constants (pKa), seleneous acid (H2SeO3) and selenic acid (H2SeO4) are anionic under common environmental conditions, e.g., as selenite (SeO32−) and selenate (SeO42−). Selenium in the (-II) oxidation state exists as gaseous hydrogen selenide, as well as numerous metallic selenides (e.g., iron selenide), which are the most insoluble forms of Se. A number of studies have reported that soil bacteria can form (nano)-sized Se(0) from selenate and selenite but it is unclear if microbial production of (nano) Se(0) is important in natural environments and what the fate of biogenic nanoparticular Se is in soil systems. In addition, volatile organic forms of Se such as dimethyl selenide (DMSe) and dimethyl diselenide (DMDSe) may be present in soils.

Due to the anionic form of Se, electrostatic forces are likely to dominate sorption-interactions in soil. Selenium can be sorbed to layered double hydroxides or anionic clays through electrostatic interactions, which are highly pH sensitive. As pH decreases, Se adsorption increases due to fewer negatively charged clay surfaces and sesquioxide edges, resulting in stronger electrostatic interactions. Therefore, the mobility and bioavailability of inorganic Se in the environment increases with increasing pH, as well as with decreasing clay and iron oxide content in the soil.

The Role of Organic Matter in Se Retention by Soils

Soil organic matter (OM) is known to influence the retention of Se in soils; however, the mechanisms of Se-OM interactions are poorly understood. Three hypotheses explaining the OM mediated retention of Se are generally discussed: (i) OM has increased sorption sites, which facilitates direct complexation with Se; (ii) indirect complexation via OM-metal complexes; or (iii) microbial reduction and incorporation into amino acids, proteins, and natural organic matter. Depending on the type of binding, Se may be easily mobilized (e.g., through pH adjustment) or immobilized (e.g., covalent incorporation to OM). In general, however, the molecular structure and speciation of Se bound to OM is still unclear. Many studies have reported large amounts of unidentified Se fractions in soil extracts, up to 100%. Organo-Se compounds could make up a major fraction of the unidentified species. Therefore, further studies will be required to identify unknown Se species and ultimately learn more about the fate of Se in the environment.

While general trends have been reported to describe the relationship between organic matter and pH in soils, few studies have examined Se accumulation trends in soils across broad (i.e., nation or continental) scales. Figure 2 illustrates the relationship between OM, pH, and soil Se across the United States and western Europe and clearly shows that the relationships between Se and chemical soil properties over large spatial scales are complex. This complexity is likely a result of increased environmental heterogeneity compared to small-scale experiments, for example due to different Se source contributions, resulting in highly nonlinear patterns. The factors driving the relationships between Se, soil, OM and pH over large spatial scales is not clear and further studies are required to elucidate the role of soil and climate variables in driving these relationships.

4.2. Soil Factors Affecting Uptake of Se by Plants

Depending on the soil type, selenate and selenite are bioavailable to plants and factors affecting Se mobility in soils thus also affect plant bioavailability (see Figure 3 for a schematic diagram of Se cycling at the plant-soil interface). Nevertheless, Se bioavailability to plants is poorly characterized due to the lack of studies that quantify the collective factors known to affect Se mobility and uptake in the environment. Most studies have been conducted in controlled environments (e.g., pot and greenhouse experiments), which oversimplifies the chemical, physical and biological processes present in nature. Increases in pH are commonly mentioned as the most important driver leading to higher Se concentrations in crops. As with mobility, uptake is generally positively correlated with pH but this relationship is most apparent near pH values where selenate adsorption on iron oxides ceases (~pH 6.5). The relationship between pH and Se uptake varies depending on other factors including soil type: increases in pH have been correlated to higher Se uptake in sandy and loamy soils but not for clay soils. Furthermore, in soils rich in OM, Se uptake was shown to decrease with increasing pH. Such studies illustrate that trends in Se uptake largely depend on the type of soil.

4.2.1. The Role of Soil OM in Plant Se Uptake

In addition to pH, Se uptake is greatly affected by OM. Because OM increases Se retention in soils, it would be logical to assume that bioavailability should be negatively correlated with OM. As expected, several studies have observed decreased Se uptake with increasing OM; however, strong positive correlations between OM and Se uptake have also been reported. Conversely, Johnsson (1991) reported an increase in Se uptake under moderate OM concentrations (5% to 11%) but a decrease in uptake when OM was >11%. Various hypotheses have been proposed to explain the seemingly contradictory findings between Se uptake and soil OM, which is likely to improve soil structure and promote oxidizing conditions thus increasing bioavailability. Conversely, differential partitioning of Se to fulvic (FA) and humic (HA) acids may alter Se bioavailability in soils. Qin et al. (2011) reported that Se was weakly partitioned to FA but was relatively strongly bound to HA. Thus, soils with high FA content could increase bioavailability by acting as a source of Se, which is supported by observations. Finally, increases in OM have been proposed to increase microbial activity and therefore promote the incorporation of inorganic Se into biomass.

4.2.2. The Role of Combined Soil Properties in Plant Se Uptake

While the effect of individual factors on Se uptake is generally known in controlled experiments, the combination of factors affecting Se uptake in natural systems is largely unknown. For example, Liu et al. (2015) reported that S addition to soils decreased pH and increased Se partitioning to Fe/Mn oxides, as well as to OM, all of which decrease Se uptake, but the dominant mechanisms governing the Se uptake in wheat were not identified. More sophisticated analyses that are capable of differentiating the importance of individual factors, as well as interactions among factors, are required for identifying the dominant processes that drive Se mobility and bioavailability within the environment. In addition to greenhouse or plot scale experiments, comprehensive medium/large scale observational studies are needed in combination with multivariate statistical analyses. Such analyses facilitate the examination of interactive effects of various combinations of factors. Furthermore, such studies should be conducted in a variety of ecosystems with different plant communities and different soil physicochemical properties to identify how the dominance of processes that govern Se bioavailability shifts along environmental gradients. Such knowledge is critical for manipulating the Se status of edible crops, as well as for optimizing phytoremediation efforts.

When all factors are held constant, the Se status of crops is linearly related to the soil Se concentrations, but this linear relationship may be a simplification of the complexities observed in nature. Overall, mobility and bioavailability are not only interdependent but are also dependent on interactions between soil pH, clay content, and ionic composition (e.g., iron, sulfate, phosphate, etc.) in addition to the microbial community and climatic factors (e.g., humidity and evapotranspiration;). Collectively, interactions among all these variables fundamentally result in a highly non-linear relationship between Se and mobility/bioavailability, which makes identifying the dominant processes governing this interaction difficult. Relatively recently, several standardized, large-scale (e.g., nation-wide) soil geochemical analyses have been conducted within China, Europe, the US, the UK, and others. Such datasets could be coupled with other broad scale data (e.g., climate and soil physicochemical properties) to understand how Se bioavailability and mobility change along such environmental gradients. These datasets can further be used to explore relationships between Se and other soil parameters over large spatial scale.

5.1.1. Uptake of inorganic Se

Although Se has not been shown to be an essential micronutrient in higher plants, plants differentially take up various Se species. These differences in uptake drastically alter the bioavailability of Se to plants, and may have a profound influence on the redistribution of Se in the environment. Plants may take up both inorganic and organic Se via active membrane transport (Figure 3) while the role of simple diffusion is limited. The active transport of Se appears to occur via shared transporter-proteins: selenate may be actively internalized by sulfate transporters and selenite is likely internalized via phosphate transporters and possibly Si-transporters (e.g in rice. Uptake of Se in the presence of sulfate and phosphate is suppressed. Conversely, selenate and selenite uptake is enhanced by low S and P concentrations in soils, respectively causing plants to increase the expression of sulfate and phosphate transporter genes in order to compensate for the lower availability of these nutrients. As a consequence, both selenate and selenite are taken up more readily when present in solution in the absence of sulfate and phosphate. Response to lower availability of nutrients has been reported to be more pronounced for selenate than for selenite uptake, which could be due to a different level of gene up-regulation in reaction to P or S starvation and/or to the lower affinity of the phosphate transporters for selenite compared with that of sulfate transporters for selenate.

5.1.2. Uptake of Organic Se

In addition to inorganic Se, plant uptake of organic Se is known to occur and has been reported at much higher rates (20–100 fold greater) than the uptake of inorganic species. Evidence suggests that amino acid transporters are important. To date, no Se-specific uptake mechanisms have been reported but these may exist in Se hyperaccumulator species since selenate uptake is much less inhibited by sulfate, and they typically have a higher Se:S ratio compared to their growth substrate and to other plant species (see chapter 6). Given the need to optimize the Se status in crops in low-Se areas, the importance of understanding plant physiology and the cell-membrane transport of Se cannot be overstated.

5.2. Uptake of Inorganic and Organic Se by Other Organisms

Similar to plants, many microalgae and bacteria take up both inorganic and organic Se via active membrane transport using shared transporter-proteins. There are indications that selenate is internalized via sulfate transporters and selenite may be internalized with phosphate-transporters (e.g., in algae and yeast. Selenite may also be internalized via monocarboxylate transporters (e.g., in yeast). Specific Se influx transporter proteins for inorganic Se have not been identified but have been suggested to exist. The membrane-transport of organo-Se species SeMet and SeCys has been investigated in animal and human cells and also occurs via shared transporters, i.e., methionine and cysteine transporters. In general, higher animals and humans directly acquire organic Se compounds (SeMet and SeCys are the major Se species in the diet) but they can also internalize inorganic Se. In contrast, plants and microorganisms may predominantly take up inorganic Se and therefore need to synthesize their own Se-amino acids, which probably occurs through the same metabolic reactions involved in the synthesis of S amino acids discussed below.

Selenium Metabolism

The uptake of Se and synthesis of Se amino acids has been investigated in algae and plants; a schematic overview is given in Figure 4. Briefly, intracellular selenate is reduced to selenite via activation with ATP-sulfurylase, and selenite may be further reduced to selenide, which may occur both enzymatically and non-enzymatically. Subsequently, selenide is incorporated into SeCys via the coupling with O-acetylserine that is catalyzed by the enzyme cysteine synthase (Figure 4). In turn, SeCys may be further metabolized into SeMet via the methionine cycle, which includes enzymatic transformation of SeCys to Se-cysthationine, Se-homocysteine and finally SeMet. The amino acids SeMet and SeCys are pivotal Se molecules because they have direct antioxidant functions and fulfill a number of essential physiological functions through deliberate incorporation of SeCys into Se-proteins. On the other hand, non-specific incorporation of Se-amino acids (SeCys) proteins is a major cause of Se toxicity. Furthermore, the Se-amino acids may be considered precursors of methylated, volatile Se species that can be emitted to the atmosphere. Biomethylation will be further discussed in chapter 7.

6. Selenium Hyperaccumulation by Plants

Some plant species native to seleniferous soils accumulate Se to levels typically 100-fold higher than other vegetation: upwards of 1000 mg·kg−1 (dry weight) and up to 15,000 mg·kg−1 (dry weight); these are considered Se hyperaccumulators. Selenium hyperaccumulation has been reported in ~30 species in the families Brassicaceae (Stanleya), Fabaceae (Astragalus) and Asteraceae (Xylorhiza, Oonopsis, Symphyotrichum). Hyperaccumulation is found in the more evolutionary derived taxa within a family suggesting that Se hyperaccumulation is a derived trait that evolved independently in different families, perhaps under similar selection pressures. It is intriguing that Se hyperaccumulators accumulate an element that is not essential for higher plants, and that they not only tolerate but even grow better at tissue Se levels that are lethal for other plant species.

6.1. Physological and Ecological Benefits

Plant accumulation of Se may have a physiological benefit since Se can have a growth-promoting effect in many species and therefore is considered a beneficial element. Selenium hyperaccumulators show a particularly strong positive growth effect when supplied with Se, which may exceed a 2-fold increase in biomass production. The mechanism by which Se exerts this positive physiological effect is largely unclear; however, Se has been shown to upregulate antioxidant responses in plants, which may allow them to withstand a variety of oxidative stresses. Selenium accumulation also confers several ecological benefits to plants. There is ample evidence to indicate that Se protects plants from herbivory and some evidence that it may also protect from pathogens and offer a benefit via elemental allelopathy (for a review see El Mehdawi and Pilon-Smits, 2012). The protective effects of Se have been found not only for hyperaccumulators but also for other plants at lower Se concentrations. Thus, Se hyperaccumulation may have the additional benefit of decreasing competition from other vegetation. Therefore, it appears that Se offers the plant multiple benefits: protection from herbivores and pathogens, reduced competition from other plant species and also a physiological benefit through enhanced growth. These benefits likely have driven the independent evolution of Se hyperaccumulation in different lineages. There is no clear evidence that Se hyperaccumulation carries an evolutionary cost in terms of negative effects on mutualistic ecological partners.

6.2. Mechanisms of Plant Se Hyperaccumulation

Like other plants, hyperaccumulators use the sulfate uptake and assimilation pathway to metabolize Se, since Se is sufficiently chemically similar to S that most transporters and enzymes cannot distinguish S and Se analogues. However, hyperaccumulators have been found to differ from non-hyperaccumulators in several ways. They have higher S levels than non-hyperaccumulators, indicative of an upregulated S/Se uptake system. Furthermore, selenate uptake by hyperaccumulators is not inhibited by high sulfate concentration, and hyperaccumulators also tend to have a higher Se/S ratio in their tissues compared to their growth medium. This observation points to the presence of a transporter with enhanced selenate specificity relative to sulfate. Indeed, a high-affinity root sulfate transporter was found to be expressed at much higher levels in S. pinnata relative to B. juncea. Hyperaccumulators also show evidence of enhanced S/Se assimilation to organic forms: the main form of Se accumulated by hyperaccumulator species is organic methyl-SeCys, while in related non-hyperaccumulators a large fraction of the Se remains in the inorganic form of selenite. The mechanism underlying the enhanced S assimilation may be upregulated expression of genes involved in S/Se assimilation, particularly ATP sulfurylase and APS reductase. Furthermore, hyperaccumulators have particularly high levels of SeCys methyltransferase, which converts SeCys to methyl-SeCys.

At the whole-plant level, hyperaccumulators differ from other plants in that they translocate more Se from roots to shoots via xylem transport and from leaves to reproductive organs via phloem transport. They store Se mainly in young leaves and reproductive organs (pollen, ovules, seeds), within epidermal vacuoles. The transporters involved in these sequestration processes remain to be identified. Non-hyperaccumulators mainly store Se in vascular tissues in leaves, and have higher Se levels in leaves than flowers. The finding that hyperaccumulators store Se in their epidermal tissues as methyl-SeCys may explain their Se tolerance: this form of Se does not cause oxidative stress (like selenate and selenite), does not get incorporated into proteins (like SeCys and SeMet), and can safely be accumulated. While not toxic to the plant, methyl-SeCys may become toxic to herbivores and pathogens upon ingestion and demethylation and can therefore serve a defensive function. The preferential sequestration of methyl-SeCys in reproductive organs and peripheral tissues may optimize its defensive effect. In hyperaccumulators, MethylSeCys can also be converted to DMDSe (see Figure 3 and chapter 7), an odorous volatile Se compound, which may contribute to herbivore deterrence.

6.3. Ecological Impacts of Hyperaccumulators on Seleniferous Areas

Furthermore, it is likely that Se hyperaccumulators affect Se distribution and speciation in soil: they are perennials with deep root systems that scavenge a large volume of soil for Se and translocate it to the aboveground organs. In the process, inorganic Se is converted to organic methyl-SeCys. In the fall, part of the sequestered Se is deposited on the soil surface as litter, and some is remobilized to the root. Over time, deposition of Se-rich litter may enrich the soil around hyperaccumulators with Se, creating Se hot spots. The organic Se-enriched soil and litter around hyperaccumulators, as well as the Se-rich organs of the living plant itself may be utilized by a variety of Se-tolerant organisms, thereby facilitating Se transport into the food chain with subsequent cycling in the local ecosystem.

7. Biomethylation of Se

The term ‘biomethylation’ includes all chemical processes in biological systems that involve the transfer of a methyl group. At the cellular level, methyl-transferase enzymes catalyze the transfer of a methyl group from an organic substrate to an acceptor molecule, which can yield both volatile and non-volatile methylated products. When volatile methylated species are formed, these may diffuse out of the cell and be released into the atmosphere. Therefore, biomethylation is a mechanism that likely enhances the mobility of Se in the environment and can lead to environmental redistribution of Se. The most commonly detected volatile organo-Se compounds in environmental samples and as microbial and plant products are dimethyl selenide (CH3SeCH3, DMSe), dimethyl selenenyl sulfide (CH3SeSCH3, DMSeS), and dimethyl diselenide (CH3SeSeCH3, DMDSe). The majority of information on the pathways of Se methylation is based on research conducted with (Se-tolerant) plants and has been extensively reviewed. A schematic overview of the biochemical reactions involved in Se methylation is given in Figure 5. Biomethylation of Se has been observed in all phylogenetic kingdoms, but not all organisms appear to methylate Se. Organisms that have the physiological tools to perform Se biomethylation include bacteria, fungi, photosynthesizing microalgae and plants, animals and humans.

7.1. The Mechanism of Se Biomethylation

The microbial methylation of arsenic occurs through a single, generally accepted mechanism: the ‘Challenger mechanism’. This mechanism involves an alternation of reduction and methylation reactions, involving S-adenosyl methionine (SAM) as the methyl-donor compound. Although originally thought to be valid for the biomethylation of Se as well, the Challenger methylation mechanism has been repeatedly updated and adjusted, based on discoveries of new Se metabolic pathways and compounds, as reviewed by Chasteen and Bentley 2003. Currently, the Se amino acids SeMet and SeCys are considered central metabolites in the pathway of Se methylation (see Figure 5).

7.1.1. Selenium Methylation by Plants

Pathways of Se metabolism and methylation are known to vary between Se hyperaccumulator and non-hyperaccumulator plants. In plants, the amino acids SeMet and SeCys can be methylated to form methyl-SeMet and methyl-SeCys, respectively. This occurs through the activity of methyl-transferase enzymes that catalyze the transfer of a carbocation (CH3+, donated from S-adenosyl methionine or methyltetrahydrofolate) to the Se atom on the respective amino-acid. Alternatively, SeCys may be converted into methyl-SeCys via glutamination into γ-glutamyl-SeCys, subsequent methylation into γ-glutamyl-methyl-SeCys and finally deglutamination (Figure 5). The methylated amino-acids methyl-SeCys and methyl-SeMet can be regarded as the direct precursors for the volatile Se species DMSe and DMDSe, respectively. The first methylated Se-amino acid, methyl-SeCys, may be oxidized to methyl-SeCys-selenoxide by the action of cysteine-oxidase and subsequently be cleaved by cysteine sulfoxide lyase to yield the volatile methyl selenol (MeSeH) and DMDSe (Figure 5). The second methylated Se-amino acid, methyl-SeMet, may be directly cleaved to DMSe by the action of the enzyme methyl-methionine hydrolase. Alternatively, methyl-SeMet may be transformed into dimethyl-selenopropionate (DMSeP), which is a direct analogue of dimethyl sulfoniopropionate (DMSP), and ultimately be cleaved by DMSP-lyase to yield DMSe and acrylic acid. The compound DMSP is a known precursor of volatile dimethyl sulfide (DMS, the direct analogue compound of DMSe) and fulfills osmoprotective- and other physiological roles in marine algae and bacteria. Although DMSP is abundant in marine algae and bacteria, its Se analogue has only been identified in Se-accumulator plants in very small amounts. Furthermore, the reactions and enzymes involved in the synthesis of DMSP (and likely DMSeP as well) are still unknown for many organisms.

7.1.2. Formation of DMSe versus DMDSe

The production of DMSe has been found in many environments, usually at higher rates than DMDSe (see Section 7.2), with exception of the production of DMDSe by Se-tolerant hyperaccumulator plants. Traditionally, biomethylation is often regarded as a detoxification mechanism since the methylated volatile Se species are less toxic than their inorganic precursors and because volatilization offers a loss-mechanism of excess intracellular Se. The abundance of DMSe suggests that the pathway of DMSe synthesis via methyl-SeMet is the most common way for Se methylation by plants and soil microbes. In turn, the formation of DMDSe via methyl-SeCys in Se-tolerant plants has been explained by the fact that these plants have higher intracellular Se concentrations and thus are required to detoxify more Se (DMDSe may be regarded as a more efficient detoxification product than DMSe). This hypothesis is supported by the fact that methyl-SeCys, the precursor for DMDse, is not incorporated into proteins and may therefore be a means for Se-accumulator plants to safely store Se (Figure 3). However, the amino-acids SeMet and SeCys may be continuously interconverted via the methionine cycle and transsulfuration so that either of the methylation pathways of these amino acids (and subsequent formation of the volatile species DMSe and DMDSe) may become alternately prevailing. In addition, transformation of volatile Se compounds may occur after release from the cell (i.e., by demethylation-, (photo)-oxidation- and chalcogenide exchange reactions) so that the observed volatile speciation in the environment may not be a direct reflection of the cellular mechanism operating. Therefore, further research is required to resolve the exact biochemical mechanisms by which different organisms synthesize different volatile Se species. Such information on the production mechanisms is particularly important considering that the different volatile Se species may have different atmospheric lifetimes.

7.2. The Occurrence of Methylated Se in Soils, Water and Air

The biogenic volatile Se compounds DMSe and DMDSe have been found in soils, freshwaters, marine waters and air. However, quantitative measurements of volatile, methylated Se compounds in the natural environment are relatively scarce. Relatively high concentrations of DMSe and DMDSe have been measured in surface waters in Se-rich systems: up to 2.1 nM DMDSe has been detected in contaminated lake water and concentrations of 130–943 nM and 13.2–38.3 nM DMSe and DMDSe, respectively, have been reported in Se-rich San Joaquin groundwater. Concentrations of up to 9 nM DMSe and 11 nM DMDSe have been measured in river sediments, while in river water up to 37 pM DMSe has been quantified. Quantification of volatile Se has also been conducted in pristine estuarine waters: Tessier et al. (2002) report concentrations of 0.2–99.5 pM DMSe and up to 1.8 pM DMDSe and Pécheyran et al. (1998) concentrations of 0.65–6.49 pM DMSe and up to 2.39 pM DMDSe in estuarine surface waters. In the open marine environment, concentrations of DMSe and DMDSe are usually lower: 0.14–4.73 pM DMSe and 0.02–0.11 pM DMDSe in the North Atlantic and 0.06–0.64 pM DMSe and 0.07–0.26 pM DMDSe in the Mediterranean. The lowest concentrations of methylated Se compounds have been measured in air: 6–80 pmol·m−3 DMSe was measured in urban air, up to 22 pmol·m−3 DMSe and up to 2 pmol·m−3 DMDSe in air collected near rivers and streams in Belgium and 0.3–1.2 pmol DMSe m−3 and 0.3–0.6 pmol·m−3 DMDSe in remote marine air.

In addition to DMSe and DMDSe, the volatile Se species MeSeH and the mixed Se-S species dimethyl selenylsulfide have been identified in natural waters. Other volatile Se species such as dimethyl triselenide, ethylated-, mixed methyl-ethylated selenides and mixed Se-S species such as dimethylselenyl sulfide, dimethyl selenyldisulfide, dimethyl diselenyl sulfide have been identified in the headspace of Se-amended bacterial cultures but never in natural environmental samples. It remains unclear by which mechanisms such volatile Se species can be produced.

7.2.1. Measurements of Biogenic Se Emissions

Atmospheric emissions of Se may occur either directly from vegetation (e.g., through the plant leaf surface) or through the water-air or soil-air interfaces (Figure 1). Similar to measurements of Se emissions from the ocean (see Section 3.2), there is a limited number of studies that have quantified Se fluxes from terrestrial environments, especially in natural, pristine environments. Methylation and volatilization of Se from soils has been of particular interest for bioremediation strategies in high-Se environments that rely on the activity of microbes and vegetation to volatilize Se and thereby reduce Se contamination in the surface environment. Field emissions of methylated Se have been measured using flux chambers combined with trapping systems (e.g., acid traps or cold traps). Sensitive measurements of Se volatilization in laboratory settings have also been obtained by spiking soil and sediment samples with radioactive 75Se.

Although quantitative measurements are relatively scarce, the biogenic production of volatile Se compounds and the corresponding Se emissions have been assessed in a variety of environmental compartments including soils and sediments, plant leaves, peat bogs, estuarine waters, lakes and in the marine environment. A summary of observed biogenic production of volatile Se is provided in Table 2.

Recently, direct flux-chamber measurements of Se emissions in a pristine wetland showed that Se fluxes can be substantial: an average volatile flux of 0.12 mg·m−2·day−1 was measured. Extrapolation of this flux to the global wetland area would equal a flux of 0.19–0.37 × 109 g Se year−1 from wetlands, which is 5%–10% of the currently estimated marine Se volatilization. However, further field studies in naturally-low Se areas are critically needed to assess the importance of terrestrial emissions of Se.

7.2.2. Limitations of Emission Data

Due to differences in experimental conditions (laboratory or field, amendment with Se and/or carbon versus natural Se levels) and differences in units (some Se emissions are reported per kilogram soil or sediment, while other fluxes are expressed per square meter of soil/air interface), a comparison between measured Se emissions is complicated. Nevertheless, the range of fluxes given in Table 2 illustrates that there is a high spatial and temporal variability in Se emissions (up to 4 orders of magnitude within comparable systems) caused by the fact that emissions of biogenic methylated Se depend heavily on a number of environmental parameters: the total Se content in the studied soil or water, the species involved in Se biomethylation, the prevailing temperature, the environment’s carbon content, the soil water content, and other parameters.

Furthermore, flux measurements do not necessarily reflect the amount of methylated species that has been produced in a certain environment. Methylated Se compounds are highly soluble and the concentrations in the aqueous-phase usually exceed those in the gaseous phase (as predicted by their Henry’s law constants. Because the dissolved volatile Se species are also prone to (photo-) chemical or biological degradation and sorption to particles prior to volatilization, flux measurements may consistently underestimate biomethylation.

The biomethylation and volatilization of Se may critically affect the mobility and bioavailability of Se in the environment. Relative to the transport speeds in the vadose and saturated zones, atmospheric transport is comparatively fast. As a result, the transport of volatile species, including methylated and oxidized forms in the atmosphere, could be a major mechanism for redistributing Se at local to global scales.

8. Concluding Remarks

In this review we have addressed sources and pathways of Se across the soil-plant-atmosphere interfaces. Sources and sinks of Se, in addition to the speciation of Se along these pathways are all of key importance in determining Se content in soils and plants and thus in terrestrial food chains. The research presented in this review has been instrumental in providing an understanding of these sources and sinks, as well as the factors controlling plant uptake and losses, allowing us to evaluate the Se status of agricultural systems. Furthermore, understanding the mobility of Se and its interactions across system borders continues to be an important research activity since the environmental distribution of Se in the environment at different spatial and time scales is likely to be affected by environmental and climatic changes. Knowledge of the factors controlling distributions of Se in the environment will allow for current and future predictions of these distributions, which will be essential in the prevention of Se-related health hazards in the future.

References 289

  1. 1.

    Rayman M.P. The importance of selenium to human health. Lancet. 2000;356:233-241.

    Not in our library10.1016/s0140-6736(00)02490-9

  2. 2.

    Combs G.F. Selenium in global food systems. Brit. J. Nutr. 2001;85:517-547.

    Not in our library10.1079/bjn2000280

  3. 3.

    Finley J.W. Selenium accumulation in plant foods. Nutr. Rev. 2005;63:196-202.

    Not in our library10.1111/j.1753-4887.2005.tb00137.x

  4. 4.

    Zhu Y.G., Pilon-Smits E.A., Zhao F.J., Williams P.N., Meharg A.A. Selenium in higher plants: Understanding mechanisms for biofortification and phytoremediation. Trends Plant Sci. 2009;14:436-447.

    Not in our library10.1016/j.tplants.2009.06.006

  5. 5.

    Cone J.E., Del Río R.M., Davis J.N., Stadtman T.C. Chemical characterization of the selenoprotein component of clostridial glycine reductase: Identification of selenocysteine as the organoselenium moiety. Proc. Natl. Acad. Sci. USA. 1976;73:2659-2663.

    Not in our library10.1073/pnas.73.8.2659

  6. 6.

    Fairweather-Tait S.J., Collings R., Hurst R. Selenium bioavailability: Current knowledge and future research requirements. Am. J. Clin. Nutr. 2010;91:1484S-1491S.

    Not in our library10.3945/ajcn.2010.28674j

  7. 7.

    Kryukov G.V., Castellano S., Novoselov S.V., Lobanov A.V., Zehtab O., Guigó R., Gladyshev V.N. Characterization of mammalian selenoproteomes. Science. 2003;300:1439-1443.

    Not in our library10.1126/science.1083516

  8. 8.

    Castellano S., Gladyshev V.N., Guigo R., Berry M.J. SelenoDB 1.0: A database of selenoprotein genes, proteins and SECIS elements. Nucleic Acids Res. 2008;36:D332-D338.

    Not in our library10.1093/nar/gkm731

  9. 9.

    Fairweather-Tait S.J., Bao Y., Broadley M.R., Collings R., Ford D., Hesketh J.R., Hurst R. Selenium in human health and disease. Antioxid. Redox Signal. 2011;14:1337-1383.

    Not in our library10.1089/ars.2010.3275

  10. 10.

    Steinnes E. Soils and geomedicine. Environ. Geochem. Hlth. 2009;31:523-535.

    Not in our library10.1007/s10653-009-9257-2

  11. 11.

    Rayman M.P., Infante H.G., Sargent M. Food-chain selenium and human health: Spotlight on speciation. Br. J. Nutr. 2008;100:238-253.

    Not in our library10.1017/s0007114508922522

  12. 12.

    Hamilton S.J. Review of selenium toxicity in the aquatic food chain. Sci. Total Environ. 2004;326:1-31.

    Not in our library10.1016/j.scitotenv.2004.01.019

  13. 13.

    Fernandez-Martinez A., Charlet L. Selenium environmental cycling and bioavailability: A structural chemist point of view. Rev. Environ. Sci. Biotechnol. 2009;8:81-110.

    Not in our library10.1007/s11157-009-9145-3

  14. 14.

    Wallschlaeger D., Feldmann J., Sigel A. Formation, occurrence, significance, and analysis of organoselenium and organotellurium compounds in the environment. Organometallics in Environment and Toxicology. 2010;Volume 7:319-364.

    Not in our library10.1039/bk9781847551771-00319

  15. 15.

    Zwolak I., Zaporowska H. Selenium interactions and toxicity: A review. Cell Biol. Toxicol. 2012;28:31-46.

    Not in our library10.1007/s10565-011-9203-9

  16. 16.

    Oldfield J.E. Selenium World Atlas: Updated Edition. 2002.

    Not in our library

  17. 17.

    Bañuelos G.S., Lin Z.-Q. Development and Use of Biofortified Agricultural Products. 2009;297.

    Not in our library

  18. 18.

    Broadley M.R., White P.J., Bryson R.J., Meacham M.C., Bowen H.C., Johnson S.E., Hawkesford M.J., McGrath S.P., Zhao F.J., Breward N., et al. Biofortification of UK food crops with selenium. Proc. Nutr. Soc. 2006;65:169-181.

    Not in our library10.1079/pns2006490

  19. 19.

    Thiry C., Schneider Y-J., Pussemier L., de Temmerman L., Ruttens A. Selenium bioaccessibility and bioavailability in Se-enriched food supplements. Biol. Trace Elem. Res. 2013;152:152-160.

    Not in our library10.1007/s12011-013-9604-0

  20. 20.

    Poblaciones M.J., Rodrigo S., Santamaría O., Chen Y., McGrath S.P. Agronomic selenium biofortification in triticum durum under mediterranean conditions: From grain to cooked pasta. Food Chem. 2014;146:378-384.

    Not in our library10.1016/j.foodchem.2013.09.070

  21. 21.

    Kápolna E., Hillestrøm P.R., Laursen K.H., Husted S., Larsen E.H. Effect of foliar application of selenium on its uptake and speciation in carrot. Food Chem. 2009;115:1357-1363.

    Not in our library10.1016/j.foodchem.2009.01.054

  22. 22.

    Kápolna E., Laursen K.H., Husted S., Larsen E.H. Bio-fortification and isotopic labelling of Se metabolites in onions and carrots following foliar application of Se and 77Se. Food Chem. 2012;133:650-657.

    Not in our library10.1016/j.foodchem.2012.01.043

  23. 23.

    Bañuelos G.S., Arroyo I., Pickering I.J., Yang S.I., Freeman J.L. Selenium biofortification of broccoli and carrots grown in soil amended with Se-enriched hyperaccumulator Stanleya pinnata. Food Chem. 2014.

    Not in our library10.1016/j.foodchem.2014.06.071

  24. 24.

    Kieliszek M., Blazejak S. Selenium: Significance, and outlook for supplementation. Nutrition. 2013;29:713-718.

    Not in our library10.1016/j.nut.2012.11.012

  25. 25.

    Tsai C., Ou B., Liang Y., Yeh F. Growth inhibition and antioxidative status induced by selenium enriched broccoli extract and selenocompounds in DNA mismach repair-deficient human colon cancer cells. Food Chem. 2013;139:267-273.

    Not in our library10.1016/j.foodchem.2013.02.001

  26. 26.

    Alfthan G.P., Aspila P., Ekhyolm M., Hartikainen. H., Hero H., Hietaniemi V., Root T., Salminen P., Venäläinen E.-R., Aro A., Thompson B., Amoroso L. Nationwide supplementation of sodium selenate to commercial fertilizers: History and 25 year results from the Finnish selenium monitoring program. Combating Micronutrient Deficiencies: Food-Based Approaches. 2011;312-337.

    Not in our library

  27. 27.

    Hartikainen H. Biogeochemistry of selenium and its impact on food chain quality and human health. J. Trace Elem. Med. Biol. 2005;18:309-318.

    Not in our library10.1016/j.jtemb.2005.02.009

  28. 28.

    Lyons G. Selenium in cereals: Improving the efficiency of agronomic biofortification in the UK. Plant Soil. 2010;332:1-4.

    Not in our library10.1007/s11104-010-0282-9

  29. 29.

    Rayman M.P. Selenium and human health. Lancet. 2012;379:1256-1268.

    Not in our library10.1016/s0140-6736(11)61452-9

  30. 30.

    Curtin D., Hanson R., Lindley T.N., Butler R.C. Selenium concentration in wheat grain as influenced by method, rate, and timing of sodium selenate application. N. Z. J. Crop Hort. 2006;34:324-339.

    Not in our library10.1080/01140671.2006.9514423

  31. 31.

    Zhao C.Y., Ren J.H., Xue C.Z., Lin E. Study on the relationship between soil Se and plant Se uptake. Plant Soil. 2005;277:197-206.

    Not in our library10.1007/s11104-005-7011-9

  32. 32.

    Ohlendorf H.M., Hoffman D.J., Saiki M.K., Aldrich T.W. Embryonic mortality and abnormalities of aquatic birds: Apparent impacts of selenium from irrigation drain-water. Sci. Total Environ. 1986;52:49-63.

    Not in our library10.1016/0048-9697(86)90104-x

  33. 33.

    Freeman J.L., Tamaoki M., Stushnoff C., Quinn C.F., Cappa J.J., Devonshire J., Fakra S., Marcus M.A., McGrath S., van Hoewyk D., et al. Molecular mechanisms of selenium tolerance and hyperaccumulation in Stanleya pinnata. Plant Physiol. 2010;153:1630-1652.

    Not in our library10.1104/pp.110.156570

  34. 34.

    Terry N., Zayed A.M., de Souza M.P., Tarun A.S. Selenium in higher plants. Ann. Rev. Plant Physiol. 2000;51:401-432.

    Not in our library10.1146/annurev.arplant.51.1.401

  35. 35.

    Pilon-Smits E.A.H., LeDuc D.L. Phytoremediation of selenium using transgenic plants. Curr. Opin. Biotechnol. 2009;20:207-212.

    Not in our library10.1016/j.copbio.2009.02.001

  36. 36.

    Bañuelos G.S., Terry N., Leduc D.L., Pilon-Smits E.A.H., Mackey B. Field trial of transgenic Indian mustard plants shows enhanced phytoremediation of selenium-contaminated sediment. Environ. Sci. Technol. 2005;39:1771-1777.

    Not in our library10.1021/es049035f

  37. 37.

    Bañuelos G.S., Lin Z.-Q. Acceleration of selenium volatilization in seleniferous agricultural drainage sediments amended with methionine and casein. Environ. Pollut. 2007;150:306-312.

    Not in our library10.1016/j.envpol.2007.02.009

  38. 38.

    Bañuelos G.S. Irrigation of broccoli and canola with boron and selenium laden effluent. J. Environ. Qual. 2002;31:1802-1808.

    Not in our library10.2134/jeq2002.1802

  39. 39.

    Bañuelos G.S., Freeman J.L. Natural biofortification of vegatables. Food Chem. 2015.

    Not in our library

  40. 40.

    Wen H., Carignan J. Reviews on atmospheric selenium: Emissions, speciation and fate. Atmos. Environ. 2007;41:7151-7165.

    Not in our library10.1016/j.atmosenv.2007.07.035

  41. 41.

    Floor G.H., Román-Ross G. Selenium in volcanic environments: A review. Appl. Geochem. 2012;27:517-531.

    Not in our library10.1016/j.apgeochem.2011.11.010

  42. 42.

    Plant J.A., Bone J., Voulvoulis N., Kinniburgh D.G., Smedley P.L., Fordyce F.M., Klinck B., Turekian K.H., Holland H.D. Arsenic and Selenium. Treatise on Geochemistry. 2014;13-57.

    Not in our library

  43. 43.

    Gissel-Nielsen G., Gupta U.C., Lamand M., Westermarck T. Selenium in soils and plants and its importance in livestock and human nutrition. Adv. Agron. 1984;37:397-460.

    Not in our library

  44. 44.

    Jacobs L.W. Selenium in Agriculture and the Environment. 1989;233.

    Not in our library

  45. 45.

    Ross H., Broekaert J.A.C., Güçer Ş., Adams F. Biogeochemical cycling of atmospheric selenium. Metal Speciation in the Environment. 1990;Volume 23:523-543.

    Not in our library

  46. 46.

    Masscheleyn P.H., Patrick W.H. Biogeochemical processes affecting selenium cycling in wetlands. Environ. Toxicol. Chem. 1993;12:2235-2243.

    Not in our library10.1002/etc.5620121207

  47. 47.

    Conde J.E., Alaejos M.S. Selenium concentrations in natural and environmental waters. Chem. Rev. 1997;97:1979-2003.

    Not in our library10.1021/cr960100g

  48. 48.

    Séby F., Potin-Gautier M., Giffaut E., Borge G., Donard O.F.X. A critical review of thermodynamic data for selenium species at 25 °C. Chem. Geol. 2001;171:173-194.

    Not in our library10.1016/s0009-2541(00)00246-1

  49. 49.

    Chasteen T.G., Bentley R. Biomethylation of selenium and tellurium: microorganisms and plants. Chem. Rev. 2003;103:1-25.

    Not in our library10.1021/cr010210+

  50. 50.

    Johnson T.M. A review of mass-dependent fractionation of selenium isotopes and implications for other heavy stable isotopes. Chem. Geol. 2004;204:201-214.

    Not in our library10.1016/j.chemgeo.2003.11.015

  51. 51.

    Wu L. Review of 15 years of research on ecotoxicology and remediation of land contaminated by agricultural drainage sediment rich in selenium. Ecotoxicol. Environ. Saf. 2004;57:257-269.

    Not in our library10.1016/s0147-6513(03)00064-2

  52. 52.

    Yudovich Y.E., Ketris M.P. Selenium in coal: A review. Int. J. Coal Geol. 2006;67:112-126.

    Not in our library10.1016/j.coal.2005.09.003

  53. 53.

    White P.J., Broadley M.R. Biofortification of crops with seven mineral elements often lacking in human diets—iron, zinc, copper, calcium, magnesium, selenium and iodine. New Phytol. 2009;182:49-84.

    Not in our library10.1111/j.1469-8137.2008.02738.x

  54. 54.

    Lenz M., Lens P.N. The essential toxin: The changing perception of selenium in environmental sciences. Sci. Total Environ. 2009;407:3620-3633.

    Not in our library10.1016/j.scitotenv.2008.07.056

  55. 55.

    Pilon-Smits E.A.H., Quinn C.F., Hell R., Mendel R.-R. Selenium metabolism in plants. Cell Biology of Metals and Nutrients. 2010;Volume 17:225-241.

    Not in our library

  56. 56.

    Quinn Q.F., Lindblom S.D., Pilon-Smits E.A.H., Columbus F. Ecological aspects of selenium phytoremediation. Phytoremediation: Processes, Characteristics, and Applications. 2011;651-666.

    Not in our library

  57. 57.

    El-Mehdawi A.F., Pilon-Smits E.A.H. Ecological aspects of plant selenium hyperaccumulation. Plant Biol. 2012;14:1-10.

    Not in our library10.1111/j.1438-8677.2011.00535.x

  58. 58.

    Garcia Moreno R., Burdock R., Díaz Álvarez M.C., Crawford J.W. Managing the selenium content in soils in semiarid environments through the recycling of organic matter. Appl. Environ. Soil Sci. 2013;2013:1-10.

    Not in our library10.1155/2013/283468

  59. 59.

    Nakamaru Y.M., Altansuvd J. Speciation and bioavailability of selenium and antimony in non-flooded and wetland soils: A review. Chemosphere. 2014;111:366-371.

    Not in our library10.1016/j.chemosphere.2014.04.024

  60. 60.

    Pilon-Smits E.A.H., Bañuelos G.S., Parker D.R., Chang A.C., Brawer Silva D. Uptake, Metabolism, and Volatilization of Selenium by Terrestrial Plants. Salinity and Drainage in San Joaquin Valley. 2014;Volume 5:147-164.

    Not in our library

  61. 61.

    Sharma V.K., McDonald T.J., Sohn M., Anquandah G.A.K., Pettine M., Zboril R. Biogeochemistry of selenium. A review. Environ. Chem. Lett. 2015;13:49-58.

    Not in our library10.1007/s10311-014-0487-x

  62. 62.

    Nancharaiah Y.V., Lens P.N.L. Ecology and biotechnology of selenium-respiring bacteria. Microbiol. Mol. Biol. Rev. 2015;79:61-80.

    Not in our library10.1128/mmbr.00037-14

  63. 63.

    Pilon-Smits E.A.H., Luettge U. Selenium in plants. Progress in Botany. 2015;93-107.

    Not in our library

  64. 64.

    Malagoli M., Schiavon M., Dall’Acqua S., Pilon-Smits E.A.H. Implications of selenium biofortification in food nutritional quality. Front. Plant Sci. 2015.

    Not in our library10.3389/fpls.2015.00280

  65. 65.

    Vine J.D., Tourtelot E.B. Geochemistry of black shale deposit—A summary report. Econ. Geol. 1970;65:253-272.

    Not in our library10.2113/gsecongeo.65.3.253

  66. 66.

    Vine J.D. Element Distribution in Some Paleozoic Black Shales and Associated Rocks: USGS Bulletin 1214-G. 2013;40.

    Not in our library

  67. 67.

    Kim J.H. Geochemistry and genesis of the Guryongsan (Ogcheon) uraniferous black slates. J. Korean Inst. Min. Geol. 1989;22:35-63.

    Not in our library

  68. 68.

    Webb J.S., Thornton I., Fletcher W.K. Seleniferous soils in parts of England and Wales. Nature. 1966;211:327.

    Not in our library10.1038/211327a0

  69. 69.

    Rogers P.A.M., Arora S.P., Fleming G.A., Crinion R.A.P., McLaughlin J.G. Selenium toxicity in farm animals: Treatment and prevention. Ir. Vet. J. 1990;43:151-153.

    Not in our library

  70. 70.

    Thornton I., Kinniburgh D.G., Pullen G., Smith C.A., Hemphill D.D. Geochemical aspects of selenium in British soils and implications to animal health. Trace Substances in Environmental Health. 1983;Volume XVII:391-398.

    Not in our library

  71. 71.

    Wen H.J., Qiu Y.Z. Organic and inorganic occurrence of selenium in Laerma Se-Au deposit. Sci. China Ser. D. 1999;42:662-669.

    Not in our library10.1007/bf02877794

  72. 72.

    Zhang G.D., Ge X.L., Zhang Y.L., Luo D.H., Liu X.P., Fordyce F.M., Mao D., Su H. Selenium geological and geochemical environmental background in Enshi, Hubei. Acta Geosci. Sin. 1998;19:59-67.

    Not in our library

  73. 73.

    Shao S.X., Zheng B.S. The biogeochemistry of selenium in Sunan grassland, Gansu, Northwest China, casts doubt on the belief that Marco Polo reported selenosis for the first time in history. Environ. Geochem. Hlth. 2008;30:307-314.

    Not in our library10.1007/s10653-008-9166-9

  74. 74.

    Presser T.S., Sylvester M.A., Low W.H. Bioaccumulation of selenium from natural geologic sources in western states and its potential consequences. Environ. Manag. 1994;18:423.

    Not in our library10.1007/bf02393871

  75. 75.

    Tuttle M.L.W., Fahy J.W., Elliott J.G., Grauch R.I., Stillings L.L. Contaminants from Cretaceous black shale: I. Natural weathering processes controlling contaminant cycling in Mancos Shale, southwestern United States, with emphasis on salinity and selenium. Appl. Geochem. 2014;46:57-71.

    Not in our library10.1016/j.apgeochem.2013.12.010

  76. 76.

    Kulp T.R., Pratt L.M. Speciation and weathering of selenium in upper cretaceous chalk and shale from South Dakota and Wyoming, USA. Geochim. Cosmochim. Acta. 2004;68:3687-3701.

    Not in our library10.1016/j.gca.2004.03.008

  77. 77.

    Presser T.S., Swain W.C. Geochemical evidence for Se mobilization by the weathering of pyritic shale, San Joaquin Valley, California, USA. Appl. Geochem. 1990;5:703-717.

    Not in our library10.1016/0883-2927(90)90066-e

  78. 78.

    Seiler R.L., Skorupa J.P., Peltz L.A. Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States. 1999;36.

    Not in our library

  79. 79.

    Ohlendorf H.M. The birds of Kesterson Reservoir: A historical perspective. Aquat. Toxicol. 2002;57:1-10.

    Not in our library10.1016/s0166-445x(01)00266-1

  80. 80.

    Hanson B.R. A master plan for drainage in the San Joaquin Valley. Calif. Agric. 1982;36:9-11.

    Not in our library

  81. 81.

    Luo K.L., Xu L.R., Tan J.A., Wang D.H., Xiang L.H. Selenium source in the selenosis area of the Daba region, South Qinling Mountain, China. Environ. Geol. 2004;45:426-432.

    Not in our library

  82. 82.

    Li Y.H., Wang W., Luo K.L., Li H.R. Environmental behaviors of selenium in soil of typical selenosis area. China J. Environ. Sci. 2008;20:859-864.

    Not in our library10.1016/s1001-0742(08)62138-5

  83. 83.

    Fordyce F.M. Selenium geochemistry and health. Ambio. 2007;36:94-97.

    Not in our library10.1579/0044-7447(2007)36[94:sgah]2.0.co;2

  84. 84.

    Taylor S.R., McLennan S.M. The geochemical evolution of the continental crust. Rev. Geophys. 1995;33:241-265.

    Not in our library10.1029/95rg00262

  85. 85.

    Lantzy R.J., Mackenzie F.T. Atmospheric trace metals: Global cycles and assessment of man’s impact. Geochim. Cosmochim. Acta. 1979;43:511-525.

    Not in our library10.1016/0016-7037(79)90162-5

  86. 86.

    Mosher B.W., Duce R.A. A global atmospheric selenium budget. J. Geophys. Res. 1987;92:13289-13298.

    Not in our library10.1029/jd092id11p13289

  87. 87.

    Nriagu J.O., Pacyna J.M. Quantitative assessment of worldwide contamination of air, water and soils by trace metals. Nature. 1988;333:134-139.

    Not in our library10.1038/333134a0

  88. 88.

    Nriagu J.O. A global assessment of natural sources of atmospheric trace metals. Nature. 1989;338:47-49.

    Not in our library10.1038/338047a0

  89. 89.

    Pacyna J.M., Pacyna E.G. An assessment of global and regional emissions of trace metals to the atmosphere from anthropogenic sources worldwide. Environ. Rev. 2001;9:269-298.

    Not in our library10.1139/a01-012

  90. 90.

    Ross H.B. An atmospheric selenium budget for the region 30° N to 90° N. Tellus. 1985;37B:78-90.

    Not in our library10.1111/j.1600-0889.1985.tb00057.x

  91. 91.

    Amouroux D., Liss P.S., Tessier E., Hamren-Larsson M., Donard O.F.X. Role of oceans as biogenic sources of selenium. Earth Planet. Sci. Lett. 2001;189:277-283.

    Not in our library10.1016/s0012-821x(01)00370-3

  92. 92.

    Sievert S.M., Kiene R.P., Schulz-Vogt H.N. The sulfur cycle. Oceanography. 2007;20:117-123.

    Not in our library10.5670/oceanog.2007.55

  93. 93.

    Yoch D.C. Dimethylsulfoniopropionate: Its sources, role in the marine food web, and biological degradation to dimethylsulfide. Appl. Environ. Microbiol. 2002;68:5804-5815.

    Not in our library10.1128/aem.68.12.5804-5815.2002

  94. 94.

    Vriens B., Lenz M., Charlet L., Berg M., Winkel L.H.E. Natural wetland emissions of methylated trace elements. Nat. Commun. 2014;5:3035.

    Not in our library10.1038/ncomms4035

  95. 95.

    Mackenzie F., Lantzy R., Paterson V. Global trace metal cycles and predictions. J. Int. Assoc. Math. Geol. 1979;11:99-142.

    Not in our library10.1007/bf01028961

  96. 96.

    Amouroux D., Donard O.F.X. Maritime emission of selenium to the atmosphere in eastern mediterranean seas. Geophys. Res. Lett. 1996;23:1777-1780.

    Not in our library10.1029/96gl01271

  97. 97.

    Cutter G.A. Metalloids in wet deposition on bermuda: concentrations, sources, and fluxes. J. Geophys. Res. 1993;98:16777-16786.

    Not in our library10.1029/93jd01689

  98. 98.

    Scudlark J.R., Conko K.M., Church T.M. Atmospheric wet deposition of trace elements to Chesapeake Bay: CBAD study year 1 results. Atmos. Environ. 1994;28:1487-1498.

    Not in our library10.1016/1352-2310(94)90209-7

  99. 99.

    Haygarth P.M., Fowler D., Stvirup S., Davison B.M., Jones K.C. Determination of gaseous and particulate selenium over a rural grassland in the U.K. Atmos. Environ. 1994;28:3655-3663.

    Not in our library10.1016/1352-2310(94)00196-r

  100. 100.

    Golomb D., Ryan D., Eby N., Underhill J., Zemba S. Atmospheric deposition of toxics onto Massachusetts Bay—I. Metals. Atmos. Environ. 1997;31:1349-1359.

    Not in our library10.1016/s1352-2310(96)00276-2

  101. 101.

    Zhou J., Wang Y., Yue T., Li Y., Wai K.M., Wang W. Origin and distribution of trace elements in high-elevation precipitation in southern China. Environ. Sci. Pollut. Res. 2012;19:3389-3399.

    Not in our library10.1007/s11356-012-0863-7

  102. 102.

    Sakata M., Marumoto K., Narukawa M., Asakura K. Regional variations in wet and dry deposition fluxes of trace elements in Japan. Atmos. Environ. 2006;40:521-531.

    Not in our library10.1016/j.atmosenv.2005.09.066

  103. 103.

    Låg J., Steinnes E. Regional distribution of selenium and arsenic in humus layers of Norwegian forest soils. Geoderma. 1978;20:3-14.

    Not in our library10.1016/0016-7061(78)90045-9

  104. 104.

    Blazina T., Sun Y., Voegelin A., Lenz M., Berg M., Winkel L.H.E. Terrestrial selenium distribution in China is potentially linked to monsoonal climate. Nat Commun. 2014;5:4717.

    Not in our library10.1038/ncomms5717

  105. 105.

    Haygarth P.M., Cooke A.I., Jones K.C., Harrison A.F., Johnston A.E. Long-term change in the biogeochemical cycling of atmospheric selenium: Deposition to plants and soil. J. Geophys. Res. 1993;98:16769-16776.

    Not in our library10.1029/93jd01023

  106. 106.

    Cao S., Duan X., Zhao X., Ma J., Dong T., Huang N., Sun C., He B., Wei F. Health risks from the exposure of children to As, Se, Pb and other heavy metals near the largest coking plant in China. Sci. Total Environ. 2014;472:1001-1009.

    Not in our library10.1016/j.scitotenv.2013.11.124

  107. 107.

    Ranville M.A., Cutter G.A., Buck C.S., Landing W.M., Cutter L.S., Resing J.A., Flegal A.R. Aeolian contamination of Se and ag in the north pacific from asian fossil fuel combustion. Environ. Sci. Technol. 2010;44:1587-1593.

    Not in our library10.1021/es902523m

  108. 108.

    Yu T., Yang Z., Lv Y., Hou Q., Xia X., Feng H., Zhang M., Jin L., Kan Z. The origin and geochemical cycle of soil selenium in a Se-rich area of China. J. Geochem. Explor. 2014;139:97-108.

    Not in our library10.1016/j.gexplo.2013.09.006

  109. 109.

    Gall H.E., Sassman S.A., Lee L.S., Jafvert C.T. Hormone discharges from a midwest tile-drained agroecosystem receiving animal wastes. Environ. Sci. Technol. 2011;45:8755-8764.

    Not in our library10.1021/es2011435

  110. 110.

    Tarkalson D.D., Payero J.O., Ensley S.M., Shapiro C.A. Nitrate accumulation and movement under deficit irrigation in soil receiving cattle manure and commercial fertilizer. Agric. Water Manag. 2006;85:201-210.

    Not in our library10.1016/j.agwat.2006.04.005

  111. 111.

    Van Donk S.J., Biswas S., Kranz W.L., Snow D.D., Bartelt-Hunt S.L., Mader T.L., Shapiro C.A., Shelton D.P., Tarkalson D.D., Zhang T.C.L., et al. Transport of steroid hormones in the vadose zone after land application of beef cattle manure. Trans. ASABE. 2013;56:1327-1338.

    Not in our library

  112. 112.

    Wen H., Carignan J. Selenium isotopes trace the source and redox processes in the black shale-hosted Se-rich deposits in China. Geochim. Cosmochim. Acta. 2011;75:1411-1427.

    Not in our library10.1016/j.gca.2010.12.021

  113. 113.

    Wen H., Carignan J., Chu X., Fan H.F., Cloquet C., Huang J., Zhang Y., Chang H. Selenium isotopes trace anoxic and ferruginous seawater conditions in the Early Cambrian. Chem. Geol. 2014;390:164-172.

    Not in our library10.1016/j.chemgeo.2014.10.022

  114. 114.

    Zhu J-M., Johnson T.M., Clark S.K., Zhu X-K., Wang X-L. Selenium redox cycling during weathering of Se-rich shales: A selenium isotope study. Geochim. Cosmochim. Acta. 2014;126:228-249.

    Not in our library

  115. 115.

    Pogge von Strandmann P.A.E., Coath C.D., Catling D.C., Poulton S.W., Elliott T. Analysis of mass dependent and mass independent selenium isotope variability in black shales. J. Anal. At. Spectrom. 2014;29:1648-1659.

    Not in our library10.1039/c4ja00124a

  116. 116.

    Stüeken E.E., Foriel J., Nelson B.K., Buick R., Catling D.C. Selenium isotope analysis of organic-rich shales: Advances in sample preparation and isobaric interference correction. J. Anal. At. Spectrom. 2013;28:1734-1749.

    Not in our library10.1039/c3ja50186h

  117. 117.

    Ellis D.R., Salt D.E. Plants, selenium and human health. Curr. Opin. Plant Biol. 2003;6:273-279.

    Not in our library10.1016/s1369-5266(03)00030-x

  118. 118.

    Schilling K., Johnson T.M., Mason P.R.D. A sequential extraction technique for mass-balanced stable selenium isotope analysis of soil samples. Chem. Geol. 2014;381:125-130.

    Not in our library10.1016/j.chemgeo.2014.04.014

  119. 119.

    Schilling K., Wilcke W. A method to quantitatively trap volatilized organoselenides for stable selenium isotope analysis. J. Environ. Qual. 2011;40:1021-1027.

    Not in our library10.2134/jeq2010.0474

  120. 120.

    Sposito G. The Chemistry of Soils. 1989;277.

    Not in our library

  121. 121.

    Le Hécho I., Tolu J., Thiry Y., Bueno M., Potin-Gautier M., Magdi Selim H. Influence of selenium speciation and fractionation on its mobility in soils. Competitive Sorption and Transport of Heavy Metals in Soils and Geological Media. 2012;216-230.

    Not in our library

  122. 122.

    Weng L., Vega F.A., Supriatin S., Bussink W., Van Riemsdijk W.H. Speciation of Se and DOC in soil solution and their relation to Se bioavailability. Environ. Sci. Technol. 2011;45:262-267.

    Not in our library10.1021/es1016119

  123. 123.

    Elrashidi M.A., Adriano D.C., Lindsay W.L., Jacobs L.W. Solubility, speciation, and transformations of selenium in soils. Agriculture and the Environment. 1889;51-63.

    Not in our library

  124. 124.

    Masscheleyn P.H., Delaune R.D., Patrick W.H. transformations of selenium as affected by sediment oxidation-reduction potential and pH. Environ. Sci. Technol. 1990;24:91-96.

    Not in our library10.1021/es00071a010

  125. 125.

    Buchs B., Evangelou M.H.W., Winkel L.H.E., Lenz M. Colloidal properties of nanoparticular biogenic selenium govern environmental fate and bioremediation effectiveness. Environ. Sci. Technol. 2013;47:2401-2407.

    Not in our library10.1021/es304940s

  126. 126.

    Eszenyi P., Sztrik A., Babka B., Prokisch J. Elemental, Nano-Sized (100–500 nm) Selenium production by probiotic lactic acid bacteria. Int. J. Biosci. Biochem. Bioinform. 2011;1:148-152.

    Not in our library10.7763/ijbbb.2011.v1.27

  127. 127.
    Aerobic biogenesis of selenium nanospheres by Bacillus cereus isolated from coalmine soil · 2010
    No notice
  128. 128.

    Tam K., Ho C.T., Lee J.H., Lai M., Chang C.H., Rheem Y., Chen W., Hur H.G., Myung N.V. Growth mechanism of amorphous selenium nanoparticles synthesized by Shewanella sp. HN-41. Biosci. Biotechnol. Biochem. 2010;74:696-700.

    Not in our library10.1271/bbb.90454

  129. 129.

    Lenz M., van Aelst A.C., Smit M., Corvini P.F.X., Lens P.N.L. Biological production of selenium nanoparticles from waste waters. Adv. Mat. Res. 2009;71–73:721-724.

    Not in our library10.4028/www.scientific.net/amr.71-73.721

  130. 130.

    Frost R.R., Griffin R.A. Effect of pH on Adsorption of arsenic and selenium from landfill leachate by clay minerals. Soil Sci. Soc. Am. J. 1977;41:53-57.

    Not in our library10.2136/sssaj1977.03615995004100010019x

  131. 131.

    Bar-Yosef B., Meek D. Selenium sorption by kaolinite and montmorillonite. Soil Sci. 1987;144:11-19.

    Not in our library10.1097/00010694-198707000-00003

  132. 132.

    Yang L., Shahrivari Z., Liu P.K., Sahimi M., Tsotsis T.T. Removal of trace levels of arsenic and selenium from aqueous solutions by calcined and uncalcined layered double hydroxides (LDH). Ind. Eng. Chem. Res. 2005;44:6804-6815.

    Not in our library10.1021/ie049060u

  133. 133.

    Rovira M., Giménez J., Martínez M., Martínez-Lladó X., de Pablo J., Marti V., Duro L. Sorption of selenium (iv) and selenium (vi) onto natural iron oxides: goethite and hematite. J. Hazard. Mater. 2008;150:279-284.

    Not in our library10.1016/j.jhazmat.2007.04.098

  134. 134.

    Eich-Greatorex S., Sogn T.A., Øgaard A.F., Aasen I. Plant Availability of inorganic and organic selenium fertiliser as influenced by soil organic matter content and pH. Nutr. Cycl. Agroecosyst. 2007;79:221-231.

    Not in our library10.1007/s10705-007-9109-3

  135. 135.

    Hamdy A.A., Gissel-Nielsen G. Fractionation of soil selenium. Zeitschrift für Pflanzenernährung und Bodenkunde. 1976;6:697-703.

    Not in our library

  136. 136.

    Peak D., Sparks D.L. Mechanisms of selenate adsorption on iron oxides and hydroxides. Environ. Sci. Technol. 2002;36:1460-1466.

    Not in our library10.1021/es0156643

  137. 137.

    Bruggeman C., Maes A., Vancluysen J. The interaction of dissolved boom clay and gorleben humic substances with selenium oxyanions (selenite and selenate). Appl. Geochem. 2007;22:1371-1379.

    Not in our library10.1016/j.apgeochem.2007.03.027

  138. 138.

    Séby F., Gautier M.P., Lespes G., Astruc M. Selenium speciation in soils after alkaline extraction. Sci. Total Environ. 1997;207:81-90.

    Not in our library10.1016/s0048-9697(97)00269-6

  139. 139.

    Dhillon K.S., Dhillon S.K. Adsorption–desorption reactions of selenium in some soils of India. Geoderma. 1999;93:19-31.

    Not in our library10.1016/s0016-7061(99)00040-3

  140. 140.

    Dhillon S.K., Hundal B.K., Dhillon K.S. Bioavailability of selenium to forage crops in a sandy loam soil amended with se-rich plant materials. Chemosphere. 2007;66:1734-1743.

    Not in our library10.1016/j.chemosphere.2006.07.006

  141. 141.

    Darcheville O., Février L., Haichar F.Z., Berge O., Martin-Garin A., Renault P. Aqueous, solid and gaseous partitioning of selenium in an oxic sandy soil under different microbiological states. J. Environ. Radioact. 2008;99:981-992.

    Not in our library10.1016/j.jenvrad.2007.11.006

  142. 142.

    Shand C.A., Eriksson J., Dahlin A.S., Lumsdon D.G. Selenium concentrations in national inventory soils from scotland and sweden and their relationship with geochemical factors. J. Geochem. Explor. 2012;121:4-14.

    Not in our library10.1016/j.gexplo.2012.06.001

  143. 143.

    Levesque M. Some aspects of selenium relationships in eastern canadian soils and plants. Can. J. Soil Sci. 1974;54:205-214.

    Not in our library10.4141/cjss74-027

  144. 144.

    Gustafsson J.P., Johnsson L. The association between selenium and humic substances in forested ecosystems—laboratory evidence. Appl. Organomet. Chem. 1994;8:141-147.

    Not in our library10.1002/aoc.590080209

  145. 145.

    Coppin F., Chabroullet C., Martin-Garin A. Selenite interactions with some particulate organic and mineral fractions isolated from a natural grassland soil. Eur. J. Soil Sci. 2009;60:369-376.

    Not in our library10.1111/j.1365-2389.2009.01127.x

  146. 146.

    Jordan N., Marmier N., Lomenech C., Giffaut E., Ehrhardt J.J. Competition between selenium (iv) and silicic acid on the hematite surface. Chemosphere. 2009;75:129-134.

    Not in our library10.1016/j.chemosphere.2008.11.018

  147. 147.

    Van Dorst S.H., Peterson P.J. Selenium speciation in the soil solution and its relevance to plant uptake. J. Sci. Food Agric. 1984;35:601-605.

    Not in our library10.1002/jsfa.2740350602

  148. 148.

    Abrams M.M., Shennan C., Zasoski R.J., Burau R.G. Selenomethionine uptake by wheat seedlings. Agron. J. 1990;82:1127-1130.

    Not in our library10.2134/agronj1990.00021962008200060021x

  149. 149.

    Qin H.B., Zhu J.M., Su H. Selenium fractions in organic matter from se-rich soils and weathered stone coal in selenosis areas of China. Chemosphere. 2012;86:626-633.

    Not in our library10.1016/j.chemosphere.2011.10.055

  150. 150.

    Tolu J., Thiry Y., Bueno M., Jolivet C., Potin-Gautier M., Le Hecho I. Distribution and speciation of ambient selenium in contrasted soils, from mineral to organic rich. Sci. Total Environ. 2014;479:93-101.

    Not in our library10.1016/j.scitotenv.2014.01.079

  151. 151.

    Li H.F., Lombi E., Stroud J.L., McGrath S.P., Zhao F.J. Selenium speciation in soil and rice: Influence of water management and Se fertilization. J. Agric. Food Chem. 2010;58:11837-11843.

    Not in our library10.1021/jf1026185

  152. 152.

    Tolu J., Le Hécho I., Bueno M., Thiry Y., Potin-Gautier M. Selenium speciation analysis at trace level in soils. Anal. Chim. Acta. 2011;684:126-133.

    Not in our library10.1016/j.aca.2010.10.044

  153. 153.

    Stroud J.L., McGrath S.P., Zhao F.J. Selenium speciation in soil extracts using LC-ICP-MS. Int. J. Environ. Anal. Chem. 2012;92:222-236.

    Not in our library10.1080/03067310903111661

  154. 154.

    Winkel L.H.E., Johnson C.A., Lenz M., Grundl T., Leupin O.X., Amini M., Charlet L. Environmental selenium research: From microscopic processes to global understanding. Environ. Sci. Technol. 2011;46:571-579.

    Not in our library10.1021/es203434d

  155. 155.

    United States Geologic Survey. 2014. Mineral resources on-line spatial data.

    Not in our library

  156. 156.

    Reimann C., Birke M., Demetriades A., Filzmoser P., OConnor P. Chemistry of Europe’s agricultural soils. part a: methodology and interpretation of the GEMAS data set. 2014;528.

    Not in our library

  157. 157.

    Soltanpour P.N. Use of ammonium bicarbonate dtpa soil test to evaluate elemental availability and toxicity 1. Commun. Soil Sci. Plant Anal. 1985;16:323-338.

    Not in our library10.1080/00103628509367607

  158. 158.

    Barrow N.J., Whelan B.R. Testing a mechanistic model. viii. The Effects of time and temperature of incubation on the sorption and subsequent desorption of selenite and selenate by a soil. J. Soil Sci. 1989;40:29-37.

    Not in our library10.1111/j.1365-2389.1989.tb01251.x

  159. 159.

    Chilimba A.D.C., Young S.D., Black C.R., Rogerson K.B., Ander E.L., Watts M.J., Lammel J., Broadley M.R. Maize grain and soil surveys reveal suboptimal dietary selenium intake is widespread in Malawi. Sci. Rep. 2011;1:1-9.

    Not in our library10.1038/srep00072

  160. 160.

    Gissel-Nielsen G. Influence of pH and texture of the soil on plant uptake of added selenium. J. Agric. Food Chem. 1971;19:1165-1167.

    Not in our library10.1021/jf60178a030

  161. 161.

    Johnsson L. Selenium uptake by plants as a function of soil type, organic matter content and pH. Plant Soil. 1991;133:57-64.

    Not in our library10.1007/bf00011899

  162. 162.

    De Temmerman L., Waegeneers N., Thiry C., du Laing G., Tack F., Ruttens A. Selenium content of Belgian cultivated soils and its uptake by field crops and vegetables. Sci. Total Environ. 2014;468:77-82.

    Not in our library10.1016/j.scitotenv.2013.08.016

  163. 163.

    Geering H.R., Cary E.E., Jones L.H.P., Allaway W.H. Solubility and redox criteria for the possible forms of selenium in soils. Soil Sci. Soc. Am. J. 1968;32:35-40.

    Not in our library10.2136/sssaj1968.03615995003200010009x

  164. 164.

    Wang J., Li H., Li Y., Yu J., Yang L., Feng F., Chen Z. Speciation, distribution, and bioavailability of soil selenium in the Tibetan Plateau Kashin–Beck disease area—a case study in Songpan County, Sichuan Province, China. Biol. Trace Elem. Res. 2013;156:367-375.

    Not in our library10.1007/s12011-013-9822-5

  165. 165.

    Alemi M.H., Goldhamer D.A., Nielsen D.R. Modeling selenium transport in steady-state, unsaturated soil columns. J. Environ. Qual. 1991;20:89-95.

    Not in our library10.2134/jeq1991.00472425002000010014x

  166. 166.

    Yasin M., El-Mehdawi A.F., Anwar A., Pilon-Smits E.A., Faisal M. Microbial-enhanced selenium and iron biofortification of wheat (triticum aestivum l.)—applications in phytoremediation and biofortification. Int J. Phytoremediat. 2015;17:341-347.

    Not in our library10.1080/15226514.2014.922920

  167. 167.
    SoilGrids1km — Global Soil Information Based on Automated Mapping · 2014
    Corrected
  168. 168.

    Liu X., Zhao Z., Duan B., Hu C., Zhao X., Guo Z. Effect of applied sulphur on the uptake by wheat of selenium applied as selenite. Plant Soil. 2015;386:35-45.

    Not in our library10.1007/s11104-014-2229-z

  169. 169.

    Broadley M.R., Alcock J., Alford J., Cartwright P., Foot I., Fairweather-Tait S.J., Hart D.J., Hurst R., Knott P., McGrath S.P., et al. Selenium biofortification of high-yielding winter wheat (Triticum aestivum L.) by liquid or granular Se fertilisation. Plant Soil. 2010;332:5-18.

    Not in our library10.1007/s11104-009-0234-4

  170. 170.

    Hart D.J., Fairweather-Tait S.J., Broadley M.R., Dickinson S.J., Foot I., Knott P., McGrath S.P., Mowat H., Norman K., Scott P.R., et al. Selenium concentration and speciation in biofortified flour and bread: retention of selenium during grain biofortification, processing and production of Se-enriched food. Food Chem. 2011;126:1771-1778.

    Not in our library10.1016/j.foodchem.2010.12.079

  171. 171.

    Renkema H., Koopmans A., Kersbergen L., Kikkert J., Hale B., Berkelaar E. the effect of transpiration on selenium uptake and mobility in durum wheat and spring canola. Plant Soil. 2012;354:239-250.

    Not in our library10.1007/s11104-011-1069-3

  172. 172.

    Huang Q., Yu Y., Wang Q., Luo Z., Jiang R., Li H. Uptake kinetics and translocation of selenite and selenate as affected by iron plaque on root surfaces of rice seedlings. Planta. 2014;1-10.

    Not in our library10.1007/s00425-014-2227-7

  173. 173.

    Zheng C. Atlas of Soil Environmental Background Value in the People’s Republic of China. 1994;196.

    Not in our library

  174. 174.

    Rawlins B.G., McGrath S.P., Scheib A.J., Breward N., Cave M., Lister T.R., Ingham M., Gowing C., Carter S. The Advanced Soil Geochemical Atlas of England and Wales. 2012;227.

    Not in our library

  175. 175.

    Li H.F., McGrath S.P., Zhao F.J. Selenium uptake, translocation and speciation in wheat supplied with selenate or selenite. New Phytol. 2008;178:92-102.

    Not in our library10.1111/j.1469-8137.2007.02343.x

  176. 176.

    Zayed A., Lytle C.M., Terry N. Accumulation and volatilization of different chemical species of selenium by plants. Planta. 1998;206:284-292.

    Not in our library10.1007/s004250050402

  177. 177.

    Zhao X.Q., Mitani N., Yamaji N., Shen R.F., Ma J.F. Involvement of silicon influx transporter osnip2;1 in selenite uptake in rice. Plant Physiol. 2010;153:1871-1877.

    Not in our library10.1104/pp.110.157867

  178. 178.

    Hopper J., Parker D. Plant availability of selenite and selenate as influenced by the competing ions phosphate and sulfate. Plant Soil. 1999;210:199-207.

    Not in our library10.1023/a:1004639906245

  179. 179.

    Schiavon M., Pilon M., Malagoli M., Pilon-Smits E.A. Exploring the importance of sulfate transporters and ATP sulphurylases for selenium hyperaccumulation—A comparison of Stanleya pinnata and Brassica juncea (Brassicaceae). Front. Plant Sci. 2015;6:1-13.

    Not in our library10.3389/fpls.2015.00002

  180. 180.

    De Souza M.P., Lytle C.M., Mulholland M.M., Otte M.L., Terry N. Selenium assimilation and volatilization from dimethylselenoniopropionate by Indian mustard. Plant Physiol. 2000;122:1281-1288.

    Not in our library10.1104/pp.122.4.1281

  181. 181.

    Kikkert J., Berkelaar E. Plant uptake and translocation of inorganic and organic forms of selenium. Arch. Environ. Contam. Toxicol. 2013;65:458-465.

    Not in our library10.1007/s00244-013-9926-0

  182. 182.

    Fournier E., Adam-Guillermin C., Potin-Gautier M., Pannier F. Selenate bioaccumulation and toxicity in chlamydomonas reinhardtii: Influence of ambient sulphate ion concentration. Aquat. Toxicol. 2010;97:51-57.

    Not in our library10.1016/j.aquatox.2009.12.003

  183. 183.

    Riedel G.F., Sanders J.G. The influence of ph and media composition on the uptake of inorganic selenium by chlamydomonas reinhardtii. Environ. Toxicol. Chem. 1996;15:1577-1583.

    Not in our library10.1002/etc.5620150922

  184. 184.

    Araie H., Sakamoto K., Suzuki I., Shiraiwa Y. Characterization of the selenite uptake mechanism in the coccolithophore emiliania huxleyi (haptophyta). Plant Cell Physiol. 2011;52:1204-1210.

    Not in our library10.1093/pcp/pcr070

  185. 185.

    Lazard M., Blanquet S., Fisicaro P., Labarraque G., Plateau P. Uptake of selenite by saccharomyces cerevisiae involves the high and low affinity orthophosphate transporters. J. Biol. Chem. 2010;285:32029-32037.

    Not in our library10.1074/jbc.m110.139865

  186. 186.

    McDermott J.R., Rosen B.P., Liu Z. Jen1p: A high affinity selenite transporter in yeast. Mol. Biol. Cell. 2010;21:3934-3941.

    Not in our library10.1091/mbc.e10-06-0513

  187. 187.

    Obata T., Araie H., Shiraiwa Y. Bioconcentration mechanism of selenium by a coccolithophorid, emiliania huxleyi. Plant Cell Physiol. 2004;45:1434-1441.

    Not in our library10.1093/pcp/pch164

  188. 188.

    Nickel A., Kottra G., Schmidt G., Danier J., Hofmann T., Daniel H. Characteristics of transport of selenoamino acids by epithelial amino acid transporters. Chem. Biol. Interact. 2009;177:234-241.

    Not in our library10.1016/j.cbi.2008.09.008

  189. 189.

    Bakke A.M., Tashjian D.H., Wang C.F., Lee S.H., Bai S.C., Hung S.S.O. Competition between selenomethionine and methionine absorption in the intestinal tract of green sturgeon (Acipenser medirostris). Aquat. Toxicol. 2010;96:62-69.

    Not in our library10.1016/j.aquatox.2009.09.014

  190. 190.

    Watts S.D., Torres-Salazar D., Divito C.B., Amara S.G. Cysteine transport through excitatory amino acid transporter 3 (eaat3). PLoS ONE. 2014;9:e109245.

    Not in our library10.1371/journal.pone.0109245

  191. 191.

    Riedel G., Ferrier D., Sanders J. Uptake of selenium by freshwater phytoplankton. Water Air Soil Pollut. 1991;57–58:23-30.

    Not in our library10.1007/bf00282865

  192. 192.

    Huber R.E., Criddle R.S. Comparison of the chemical properties of selenocysteine and selenocystine with their sulfur analogs. Arch. Biochem. Biophys. 1967;122:164-173.

    Not in our library10.1016/0003-9861(67)90136-1

  193. 193.

    Gojkovic Ž., Garbayo I., Ariza J.L.G., Márová I., Vílchez C. Selenium bioaccumulation and toxicity in cultures of green microalgae. Algal Res. 2015;7:106-116.

    Not in our library

  194. 194.

    Mason R.P., Dricu A. The methylation of metals and metalloids in aquatic systems. Methylation—From DNA, RNA and Histones to Diseases and Treatment. 2012;71-301.

    Not in our library

  195. 195.

    Thayer J.S. Review: Biological methylation of less-studied elements. Appl. Organomet. Chem. 2002;16:677-691.

    Not in our library10.1002/aoc.375

  196. 196.

    Araie H., Shiraiwa Y. Selenium utilization strategy by microalgae. Molecules. 2009;14:4880-4891.

    Not in our library10.3390/molecules14124880

  197. 197.

    Brown K.M., Arthur J.R. Selenium, selenoproteins and human health: A review. Public Health Nutr. 2001;4:593-599.

    Not in our library10.1079/phn2001143

  198. 198.

    Rahmanto A.S., Davies M.J. Selenium-containing amino acids as direct and indirect antioxidants. IUBMB Life. 2012;64:863-871.

    Not in our library10.1002/iub.1084

  199. 199.

    Hurst R., Collings R., Harvey L.J., King M., Hooper L., Bouwman J., Gurinovic M., Fairweather-Tait S.J. EURRECA-Estimating selenium requirements for deriving dietary reference values. Crit. Rev. Food Sci. Nutr. 2013;53:1077-1096.

    Not in our library10.1080/10408398.2012.742861

  200. 200.

    Stadtman T.C. Selenium biochemistry. Annu. Rev. Biochem. 1990;59:111-127.

    Not in our library10.1146/annurev.bi.59.070190.000551

  201. 201.

    Beath O.A., Gilbert C.S., Eppson H.F. The use of indicator plants in locating seleniferous soils in the Western United States. I. General. Am. J. Bot. 1939;26:257-269.

    Not in our library10.2307/2436499

  202. 202.

    Rosenfeld I., Beath O.A. Selenium: Geobotany, Biochemistry, Toxicity, and Nutrition. 1964;411.

    Not in our library

  203. 203.

    Cappa J.J., Pilon-Smits E.A.H. Evolutionary aspects of hyperaccumulation. Planta. 2014;239:267-275.

    Not in our library10.1007/s00425-013-1983-0

  204. 204.

    Brown T.A., Shrift A. Selenium-toxicity and tolerance in higher plants. Biol. Rev. Camb. Philos. 1982;57:59-84.

    Not in our library10.1111/j.1469-185x.1982.tb00364.x

  205. 205.

    White P.J., Bowen H.C., Parmaguru P., Fritz M., Spracklen W.P., Spiby R.E., Meacham M.C., Mead A., Harriman M., Trueman L.J., et al. Interactions between selenium and sulphur nutrition in Arabidopsis thaliana. J. Exp. Bot. 2004;55:1927-1937.

    Not in our library10.1093/jxb/erh192

  206. 206.

    Zhang Y., Gladyshev V.N. Comparative genomics of trace elements: emerging dynamic view of trace element utilization and function. Chem. Rev. 2009;109:4828-4861.

    Not in our library10.1021/cr800557s

  207. 207.

    Pilon-Smits E.A.H., Quinn C.F., Tapken W., Malagoli M., Schiavon M. Physiological functions of beneficial elements. Curr. Opin. Plant Biol. 2009;12:267-274.

    Not in our library10.1016/j.pbi.2009.04.009

  208. 208.

    Vickerman D.B., Shannon M.C., Bañuelos G.S., Grieve C.M., Trumble J.T. Evaluation of Atriplex lines for selenium accumulation, salt tolerance and suitability for a key agricultural insect pest. Environ. Pollut. 2002;120:463-473.

    Not in our library10.1016/s0269-7491(02)00116-1

  209. 209.

    Bañuelos G.S., Vickerman D.B., Trumble J.T., Shannon M.C., Davis C.D., Finley J.W., Mayland H.F. Biotransfer possibilities of selenium from plants used in phytoremediation. Int. J. Phytoremediat. 2002;4:315-329.

    Not in our library

  210. 210.

    Hanson B., Garifullina G.F., Lindblom S.D., Wangeline A., Ackley A., Kramer K., Norton A.P., Lawrence C.B., Pilon Smits E.A.H. Selenium accumulation protects Brassica juncea from invertebrate herbivory and fungal infection. New Phytol. 2003;159:461-469.

    Not in our library10.1046/j.1469-8137.2003.00786.x

  211. 211.

    Hanson B., Lindblom S.D., Loeffler M.L., Pilon-Smits E.A.H. Selenium protects plants from phloem feeding aphids due to both deterrence and toxicity. New Phytol. 2004;162:655-662.

    Not in our library10.1111/j.1469-8137.2004.01067.x

  212. 212.

    Freeman J.L., Lindblom S.D., Quinn C.F., Fakra S., Marcus M.A., Pilon-Smits E.A.H. Selenium accumulation protects plants from herbivory by Orthoptera via toxicity and deterrence. New Phytol. 2007;175:490-500.

    Not in our library10.1111/j.1469-8137.2007.02119.x

  213. 213.
    Selenium hyperaccumulation offers protection from cell disruptor herbivores · 2010
    Not checked
  214. 214.

    Quinn C.F., Freeman J.L., Galeas M.L., Klamper E.M., Pilon-Smits E.A.H. The role of selenium in protecting plants against prairie dog herbivory: Implications for the evolution of selenium hyperaccumulation. Oecologia. 2008;155:267-275.

    Not in our library10.1007/s00442-007-0907-8

  215. 215.

    Freeman J.L., Quinn C.F., Lindblom S.D., Klamper E.M., Pilon-Smits E.A.H. Selenium protects the hyperaccumulator Stanleya pinnata against black-tailed prairie dog herbivory in native seleniferous habitats. Am. J. Bot. 2009;96:1075-1085.

    Not in our library10.3732/ajb.0800287

  216. 216.

    El Mehdawi A.F., Quinn C.F., Pilon-Smits E.A.H. Effects of selenium hyperaccumulation on plant–plant interactions: Evidence for elemental allelopathy. New Phytol. 2011;191:120-131.

    Not in our library10.1111/j.1469-8137.2011.03670.x

  217. 217.

    Prins C.N., Hantzis L.J., Quinn C.F., Pilon-Smits E.A.H. Effects of Selenium accumulation on reproductive functions in Brassica juncea and Stanleya pinnata. J. Exp. Bot. 2011;247.

    Not in our library10.1093/jxb/err247

  218. 218.

    Quinn C.F., Prins C.N., Freeman J.L., Gross A.M., Hantzis L.J., Reynolds R.J.B., Yang S., Covey P.A., Bañuelos G.S., Pickering I.J., et al. Selenium accumulation in flowers and its effects on pollination. New Phytol. 2011.

    Not in our library10.1111/j.1469-8137.2011.03832.x

  219. 219.

    Arvy M.P. Selenate and selenite uptake and translocation in bean plants (Phaseolus vulgaris). J. Exp. Bot. 1993;44:1083-1087.

    Not in our library10.1093/jxb/44.6.1083

  220. 220.

    Parker D.R., Page A.L., Bell P.F. Contrasting selenate-sulfate interactions in selenium-accumulating and nonaccumulating plant species. Soil Sci. Soc. Am. J. 1992;56:1818-1824.

    Not in our library10.2136/sssaj1992.03615995005600060028x

  221. 221.

    Feist L.J., Parker D.R. Ecotypic variation in selenium accumulation among populations of Stanleya pinnata. New Phytol. 2001;149:61-69.

    Not in our library10.1046/j.1469-8137.2001.00004.x

  222. 222.

    Harris J., Schneberg K.A., Pilon-Smits E.A. Sulfur-selenium-molybdenum interactions distinguish selenium hyperaccumulator Stanleya pinnata from non-hyperaccumulator Brassica juncea (Brassicaceae). Planta. 2014;239:479-491.

    Not in our library10.1007/s00425-013-1996-8

  223. 223.

    White P.J., Bowen H.C., Marshall B., Broadley M.R. Extraordinarily high leaf selenium to sulfur ratios define ‘Se-accumulator’ plants. Ann. Bot. London. 2007;100:111-118.

    Not in our library10.1093/aob/mcm084

  224. 224.

    Freeman J.L., Zhang L.H., Marcus M.A., Fakra S., Pilon-Smits E.A.H. Spatial imaging, speciation and quantification of selenium in the hyperaccumulator plants Astragalus bisulcatus and Stanleya pinnata. Plant Physiol. 2006;142:124-134.

    Not in our library10.1104/pp.106.081158

  225. 225.

    de Souza M.P., Pilon-Smits E.A.H., Lytle C.M., Hwang S., Tai J.C., Honma T.S.U., Yeh L., Terry N. Rate-limiting steps in selenium volatilization by Brassica juncea. Plant Physiol. 1998;117:1487-1494.

    Not in our library10.1104/pp.117.4.1487

  226. 226.

    Van Hoewyk D., Garifullina G.F., Ackley A.R., Abdel-Ghany S.E., Marcus M.A., Fakra S., Ishiyama K., Inoue E., Pilon M., et al. Overexpression of AtCpNifS enhances selenium tolerance and accumulation in Arabidopsis. Plant Physiol. 2005;139:1518-1528.

    Not in our library10.1104/pp.105.068684

  227. 227.

    Neuhierl B., Bock A. On the mechanism of selenium tolerance in selenium-accumulating plants: Purification and characterization of a specific selenocysteine methyltransferase from cultured cells of Astragalus bisulcatus. Eur. J. Biochem. 1996;239:235-238.

    Not in our library10.1111/j.1432-1033.1996.0235u.x

  228. 228.

    Freeman J.L., Quinn C.F., Marcus M.A., Fakra S., Pilon-Smits E.A.H. Selenium tolerant diamondback moth disarms hyperaccumulator plant defense. Curr. Biol. 2006;16:2181-2192.

    Not in our library10.1016/j.cub.2006.09.015

  229. 229.

    Galeas M.L., Zhang L.H., Freeman J.L., Wegner M., Pilon-Smits E.A.H. Seasonal fluctuations of selenium and sulfur accumulation in selenium hyperaccumulators and related non-accumulators. New Phytol. 2007;173:517-525.

    Not in our library10.1111/j.1469-8137.2006.01943.x

  230. 230.

    Bentley R., Chasteen T.G. Microbial methylation of metalloids: Arsenic, antimony, and bismuth. Microbiol. Mol. Biol. Rev. 2002;66:250-271.

    Not in our library10.1128/mmbr.66.2.250-271.2002

  231. 231.

    Meija J., Montes-Bayón M., Le Duc D.L., Terry N., Caruso J.A. Simultaneous monitoring of volatile selenium and sulfur species from se accumulating plants (wild type and genetically modified) by gc/ms and gc/icpms using solid-phase microextraction for sample introduction. Anal. Chem. 2002;74:5837-5844.

    Not in our library10.1021/ac020285t

  232. 232.

    Dungan R.S., Frankenberger W.T. Biotransformations of selenium by enterobacter cloacae sld1a-1: Formation of dimethylselenide. Biogeochemistry. 2001;55:73-86.

    Not in our library10.1023/a:1010640307328

  233. 233.

    Brady J.M., Tobin J.M., Gadd G.M. Volatilization of selenite in aqueous medium by a penicillium species. Mycol. Res. 1996;100:955-961.

    Not in our library10.1016/s0953-7562(96)80048-7

  234. 234.

    Neumann P.M., de Souza M.P., Pickering I.J., Terry N. Rapid microalgal metabolism of selenate to volatile dimethylselenide. Plant Cell Environ. 2003;26:897-905.

    Not in our library10.1046/j.1365-3040.2003.01022.x

  235. 235.

    Ganther H.E., Levander O.A., Baumann C.A. Dietary control of selenium volatilization in the rat. J. Nutr. 1966;88:55-60.

    Not in our library10.1093/jn/88.1.55

  236. 236.

    Foster S.J., Kraus R.J., Ganther H.E. Formation of dimethyl selenide and trimethylselenonium from selenobetaine in the rat. Arch. Biochem. Biophys. 1986;247:12-19.

    Not in our library10.1016/0003-9861(86)90527-8

  237. 237.

    Kremer D., Ilgen G., Feldmann J. Gc-icp-ms determination of dimethylselenide in human breath after ingestion of se-77-enriched selenite: Monitoring of in vivo methylation of selenium. Anal. Bioanal. Chem. 2005;383:509-515.

    Not in our library10.1007/s00216-005-0001-1

  238. 238.

    Navarro-Alarcon M., Cabrera-Vique C. Selenium in food and the human body: A review. Sci. Total Environ. 2008;400:115-141.

    Not in our library10.1016/j.scitotenv.2008.06.024

  239. 239.

    Challenger F., Lisle D.B., Dransfield P.B. Studies on biological methylation. Part xiv. The formation of trimethylarsine and dimethyl selenide in mould cultures from methyl sources containing 14C. J. Chem. Soc. (Resumed). 1954;1954:1760-1771.

    Not in our library10.1039/jr9540001760

  240. 240.

    Doran J.W., Alexander M. Microbial formation of volatile selenium compounds in soil. Soil Sci. Soc. Am. J. 1977;41:70-73.

    Not in our library10.2136/sssaj1977.03615995004100010022x

  241. 241.

    Reamer D.C., Zoller W.H. Selenium biomethylation products from soil and sewage sludge. Science. 1980;208:500-502.

    Not in our library10.1126/science.208.4443.500

  242. 242.

    Ansede J.H., Yoch D.C. Comparison of selenium and sulfur volatilization by dimethylsulfoniopropionate lyase (DMSP) in two marine bacteria and estuarine sediments. FEMS Microbiol. Ecol. 1997;23:315-324.

    Not in our library10.1016/s0168-6496(97)00039-1

  243. 243.

    Sunda W., Kieber D.J., Kiene R.P., Huntsman S. An antioxidant function for dmsp and dms in marine algae. Nature. 2002;418:317-320.

    Not in our library10.1038/nature00851

  244. 244.

    Stefels J. Physiological aspects of the production and conversion of dmsp in marine algae and higher plants. J. Sea Res. 2000;43:183-197.

    Not in our library10.1016/s1385-1101(00)00030-7

  245. 245.

    Kubachka K.M., Meija J., LeDuc D.L., Terry N., Caruso J.A. Selenium volatiles as proxy to the metabolic pathways of selenium in genetically modified Brassica juncea. Environ. Sci. Technol. 2007;41:1863-1869.

    Not in our library10.1021/es0613714

  246. 246.

    Wilber C.G. Toxicology of selenium: A review. Clin. Toxicol. 1980;17:171-230.

    Not in our library10.3109/15563658008985076

  247. 247.

    Neuhierl B., Thanbichler M., Lottspeich F., Böck A. A family of s-methylmethionine-dependent thiol/selenol methyltransferases: Role in selenium tolerance and evolutionary relation. J. Biol. Chem. 1999;274:5407-5414.

    Not in our library10.1074/jbc.274.9.5407

  248. 248.

    Gabel-Jensen C., Lunoe K., Gammelgaard B. Formation of methylselenol, dimethylselenide and dimethyldiselenide in in vitro metabolism models determined by headspace GC-MS. Metallomics. 2010;2:167-173.

    Not in our library10.1039/b914255j

  249. 249.

    Chau Y.K., Wong P.T.S., Silverberg B.A., Luxon P.L., Bengert G.A. Methylation of selenium in aquatic environments. Science. 1976;192:1130-1131.

    Not in our library10.1126/science.192.4244.1130

  250. 250.

    Cooke T.D., Bruland K.W. Aquatic chemistry of selenium—Evidence of biomethylation. Environ. Sci. Technol. 1987;21:1214-1219.

    Not in our library10.1021/es00165a009

  251. 251.

    Pécheyran C., Amouroux D., Donard O.F.X. Field determination of volatile selenium species at ultra trace levels in environmental waters by on-line purging, cryofocusing and detection by atomic fluorescence spectroscopy. J. Anal. At. Spectrom. 1998;13:615-621.

    Not in our library10.1039/a802246a

  252. 252.

    Jiang S., Robberecht H., Adams F. Identification and determination of alkylselenide compounds in environmental air. Atmos. Environ. 1983;17:111-114.

    Not in our library10.1016/0004-6981(83)90014-8

  253. 253.

    Calle Guntiñas M., Ceulemans M., Witte C., Łobiński R., Adams F. Evaluation of a purge-and-trap injection system for capillary gas chromatography-microwave induced plasma-atomic emission spectrometry for the determination of volatile selenium compounds in water. Microchim. Acta. 1995;120:73-82.

    Not in our library10.1007/bf01244421

  254. 254.

    Krupp E.M., Grümping R., Furchtbar U.R., Hirner A.V. Speciation of metals and metalloids in sediments with ltgc/icp-ms. Anal. Bioanal. Chem. 1996;354:546-549.

    Not in our library10.1007/s0021663540546

  255. 255.

    Campillo N., Aguinaga N., Vinas P., Lopez-Garcia I., Hernandez-Cordoba M. Gas chromatography with atomic emission detection for dimethylselenide and dimethyldiselenide determination in waters and plant materials using a purge-and-trap preconcentration system. J. Chromatogr. A. 2005;1095:138-144.

    Not in our library10.1016/j.chroma.2005.08.002

  256. 256.

    Tessier E., Amouroux D., Abril G., Lemaire E., Donard O.X. Formation and volatilisation of alkyl-iodidesand -selenides in macrotidal estuaries. Biogeochemistry. 2002;59:183-206.

    Not in our library10.1023/a:1015550931365

  257. 257.

    Pécheyran C., Lalére B., Donard O.F.X. Volatile metal and metalloid species (Pb, Hg, Se) in a European urban atmosphere (Bordeaux, France). Environ. Sci. Technol. 2000;34:27-32.

    Not in our library10.1021/es980887n

  258. 258.

    Amouroux D., Donard O.F.X. Evasion of selenium to the atmosphere via biomethylation processes in the Gironde estuary, France. Mar. Chem. 1997;58:173-188.

    Not in our library10.1016/s0304-4203(97)00033-9

  259. 259.

    Swearingen J.W., Frankel D.P., Fuentes D.E., Saavedra C.P., Vásquez C.C., Chasteen T.G. Identification of biogenic dimethyl selenodisulfide in the headspace gases above genetically modified escherichia coli. Anal. Biochem. 2006;348:115-122.

    Not in our library10.1016/j.ab.2005.10.007

  260. 260.

    Burra R., Pradenas G.A., Montes R.A., Vasquez C.C., Chasteen T.G. Production of dimethyl triselenide and dimethyl diselenenyl sulfide in the headspace of metalloid-resistant bacillus species grown in the presence of selenium oxyanions. Anal. Biochem. 2010;396:217-222.

    Not in our library10.1016/j.ab.2009.09.026

  261. 261.

    Vriens B., Ammann A.A., Hagendorfer H., Lenz M., Berg M., Winkel L.H.E. Quantification of methylated selenium, sulfur and arsenic in the enviroment. PLoS ONE. 2014;9:e102906.

    Not in our library10.1371/journal.pone.0102906

  262. 262.

    Stork A., Jury W.A., Frankenberger W.T. Accelerated volatilization rates of selenium from different soils. Biol. Trace Elem. Res. 1999;69:217-234.

    Not in our library10.1007/bf02783874

  263. 263.

    Karlson U., Frankenberger W.T. Effects of carbon and trace element addition on alkylselenide production by soil. Soil Sci. Soc. Am. J. 1988;52:1640-1644.

    Not in our library10.2136/sssaj1988.03615995005200060025x

  264. 264.

    Karlson U., Frankenberger W.T. Accelerated rates of selenium volatilization from California soils. Soil Sci. Soc. Am. J. 1989;53:749-753.

    Not in our library10.2136/sssaj1989.03615995005300030019x

  265. 265.

    Frankenberger W.T., Karlson U. Volatilization of selenium from a dewatered seleniferous sediment: A field study. J. Ind. Microbiol. 1995;14:226-232.

    Not in our library10.1007/bf01569932

  266. 266.

    Lin Z.Q., Cervinka V., Pickering I.J., Zayed A., Terry N. Managing selenium-contaminated agricultural drainage water by the integrated on-farm drainage management system: Role of selenium volatilization. Water Res. 2002;36:3150-3160.

    Not in our library10.1016/s0043-1354(02)00007-6

  267. 267.

    Bañuelos G.S., Lin Z.-Q., Arroyo I., Terry N. Selenium volatilization in vegetated agricultural drainage sediment from the San Luis drain, central California. Chemosphere. 2005;60:1203-1213.

    Not in our library10.1016/j.chemosphere.2005.02.033

  268. 268.

    Terry N., Carlson C., Raab T.K., Zayed A.M. Rates of selenium volatilization among crop species. J. Environ. Qual. 1992;21:341-344.

    Not in our library10.2134/jeq1992.00472425002100030006x

  269. 269.

    Diaz X., Johnson W.P., Wade A.O., Naftz D.L. Volatile selenium flux from the Great Salt Lake, Utah. Environ. Sci. Technol. 2009;43:53-59.

    Not in our library10.1021/es801638w

  270. 270.

    Wu L., Huang Z.-Z. Selenium accumulation and selenium tolerance of salt grass from soils with elevated concentrations of Se and salinity. Ecotoxicol. Environ. Saf. 1991;22:267-282.

    Not in our library10.1016/0147-6513(91)90078-4

  271. 271.

    Dungan R.S., Stork A., Frankenberger W.T. A wind tunnel for measuring selenium volatilization under field-like conditions. J. Environ. Qual. 2000;29:460-466.

    Not in our library10.2134/jeq2000.00472425002900020014x

  272. 272.

    Zawislanski P.T., Jayaweera G.R., Frankenberger W.T., Wu L. The pond 2 selenium volatilization study: A synthesis of five years of experimental results,1990–1995. 1996.

    Not in our library

  273. 273.

    Lin Z.-Q., Hansen D., Zayed A., Terry N. Biological selenium volatilization: Method of measurement under field conditions. J. Environ. Qual. 1999;28:309-315.

    Not in our library10.2134/jeq1999.00472425002800010038x

  274. 274.

    Martens D.A., Suarez D.L., Cai Y.B.O.C. Soil methylation-demethylation pathways for metabolism of plant-derived selenoamino acids. Biogeochemistry of Environmentally Important Trace Elements. 2003;Volume 835:355-369.

    Not in our library

  275. 275.

    Moreno-Jiménez E., Clemente R., Mestrot A., Meharg A.A. Arsenic and selenium mobilisation from organic matter treated mine spoil with and without inorganic fertilisation. Environ. Pollut. 2013;173:238-244.

    Not in our library10.1016/j.envpol.2012.10.017

  276. 276.

    Zieve R., Peterson P.J. Factors influencing the volatilization of selenium from soil. Sci. Total Environ. 1981;19:277-284.

    Not in our library10.1016/0048-9697(81)90022-x

  277. 277.

    Frankenberger W.T., Karlson U. Environmental factors affecting microbial production of dimethylselenide in a selenium contaminated sediment. Soil Sci. Soc. Am. J. 1989;53:1435-1442.

    Not in our library10.2136/sssaj1989.03615995005300050022x

  278. 278.

    Dhillon K.S., Dhillon S.K., Dogra R. Selenium accumulation by forage and grain crops and volatilization from seleniferous soils amended with different organic materials. Chemosphere. 2010;78:548-556.

    Not in our library10.1016/j.chemosphere.2009.11.015

  279. 279.

    Hansen D., Duda P.J., Zayed A., Terry N. Selenium removal by constructed wetlands: Role of biological volatilization. Environ. Sci. Technol. 1998;32:591-597.

    Not in our library10.1021/es970502l

  280. 280.

    Gao S., Tanji K.K., Lin Z.Q., Terry N., Peters D.W. Selenium removal and mass balance in a constructed flow-through wetland system. J. Environ. Qual. 2003;32:1557-1570.

    Not in our library10.2134/jeq2003.1557

  281. 281.

    Zhang Y., Moore J.N. Environmental conditions controlling selenium volatilization from a wetland system. Environ. Sci. Technol. 1997;31:511-517.

    Not in our library10.1021/es960342y

  282. 282.

    Thompson-Eagle E.T., Frankenberger W.T. Volatilization of selenium from agricultural evaporation pond water. J. Environ. Qual. 1990;19:125-131.

    Not in our library10.2134/jeq1990.00472425001900010018x

  283. 283.

    Thompson-Eagle E.T., Frankenberger W.T. Protein-mediated selenium biomethylation in evaporation pond water. Environ. Toxicol. Chem. 1990;9:1453-1462.

    Not in our library10.1002/etc.5620091204

  284. 284.

    Calderone S.J., Frankenberger W.T., Parker D.R., Karlson U. Influence of temperature and organic amendments on the mobilization of selenium in sediments. Soil Biol. Biochem. 1990;22:615-620.

    Not in our library10.1016/0038-0717(90)90006-l

  285. 285.

    Fan T.W.M., Higashi R.M., Lane A.N. Biotransformations of selenium oxyanion by filamentous cyanophyte-dominated mat cultured from agricultural drainage waters. Environ. Sci. Technol. 1998;32:3185-3193.

    Not in our library10.1021/es9708833

  286. 286.

    Frankenberger W.T., Karlson U. Soil management factors affecting volatilization of selenium from dewatered sediments. Geomicrobiol. J. 1994;12:265-278.

    Not in our library10.1080/01490459409377994

  287. 287.

    Guo L., Jury W.A., Frankenberger W.T. Measurement of the henry’s constant of dimethyl selenide as a function of temperature. J. Environ. Qual. 2000;29:1715-1717.

    Not in our library10.2134/jeq2000.00472425002900050044x

  288. 288.

    Beale R., Johnson M., Liss P.S., Nightingale P.D. Air-sea exchange of marine trace gases. Treatise on Geochemistry. 2014;53-92.

    Not in our library

  289. 289.

    Zieve R., Peterson P.J. Sorption of dimethylselenide by soils. Soil Biol. Biochem. 1985;17:105-107.

    Not in our library10.1016/0038-0717(85)90097-5

Cited by papers we hold 5

Reads

Read by people on this page

None yet.

Checked or read by AI through naulon

None yet.

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.

Are you an author?

Is this your paper?

Claim it to add your note and be paid when agents cite it. Free.