The Global Marine Selenium Cycle: Insights From Measurements and Modeling

Mason, Robert P.; Soerensen, Anne L.; DiMento, Brian P.; Balcom, Prentiss H.

doi:10.1029/2018gb006029

Cited by 32 publications

(26 citation statements)

References 101 publications

(235 reference statements)

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“…The range of previously estimated Se lifetimes from global atmospheric budgets is between 0.8 and 6 d, similar to our result (Ross, 1985;Mosher and Duce, 1987). The recent value from Mason et al (2018) of a 0.15-year (55 d) Se lifetime seems overestimated compared to our results and past budgets, especially since Mason et al (2018) only consider gas-phase Se in their model, which tends to be shorter lived in the atmosphere than aerosol-bound Se. According to our sensitivity analysis results, the atmospheric Se lifetime could be further constrained by measuring the OCSe+OH reaction rates, and in general knowing more about whether OCSe is present in the atmosphere.…”

Section: Discussionsupporting

confidence: 85%

“…N values for each parameter are drawn randomly from within each subinterval. The se-lected values for all input parameters are then matched randomly with each other, to yield N points that cover the parameter space better than purely random Monte Carlo sampling (McKay et al, 1979). The general rule of thumb is to select around 10M training simulations, to adequately cover the sample space (Loeppky et al, 2009).…”

Section: Experimental Setup and Model Outputsmentioning

confidence: 99%

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Mapping the drivers of uncertainty in atmospheric selenium deposition with global sensitivity analysis

et al. 2020

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Abstract. An estimated 0.5–1 billion people globally have inadequate intakes of selenium (Se), due to a lack of bioavailable Se in agricultural soils. Deposition from the atmosphere, especially through precipitation, is an important source of Se to soils. However, very little is known about the atmospheric cycling of Se. It has therefore been difficult to predict how far Se travels in the atmosphere and where it deposits. To answer these questions, we have built the first global atmospheric Se model by implementing Se chemistry in an aerosol–chemistry–climate model, SOCOL-AER (modeling tools for studies of SOlar Climate Ozone Links – aerosol). In the model, we include information from the literature about the emissions, speciation, and chemical transformation of atmospheric Se. Natural processes and anthropogenic activities emit volatile Se compounds, which oxidize quickly and partition to the particulate phase. Our model tracks the transport and deposition of Se in seven gas-phase species and 41 aerosol tracers. However, there are large uncertainties associated with many of the model's input parameters. In order to identify which model uncertainties are the most important for understanding the atmospheric Se cycle, we conducted a global sensitivity analysis with 34 input parameters related to Se chemistry, Se emissions, and the interaction of Se with aerosols. In the first bottom-up estimate of its kind, we have calculated a median global atmospheric lifetime of 4.4 d (days), ranging from 2.9 to 6.4 d (2nd–98th percentile range) given the uncertainties of the input parameters. The uncertainty in the Se lifetime is mainly driven by the uncertainty in the carbonyl selenide (OCSe) oxidation rate and the lack of tropospheric aerosol species other than sulfate aerosols in SOCOL-AER. In contrast to uncertainties in Se lifetime, the uncertainty in deposition flux maps are governed by Se emission factors, with all four Se sources (volcanic, marine biosphere, terrestrial biosphere, and anthropogenic emissions) contributing equally to the uncertainty in deposition over agricultural areas. We evaluated the simulated Se wet deposition fluxes from SOCOL-AER with a compiled database of rainwater Se measurements, since wet deposition contributes around 80 % of total Se deposition. Despite difficulties in comparing a global, coarse-resolution model with local measurements from a range of time periods, past Se wet deposition measurements are within the range of the model's 2nd–98th percentiles at 79 % of background sites. This agreement validates the application of the SOCOL-AER model to identifying regions which are at risk of low atmospheric Se inputs. In order to constrain the uncertainty in Se deposition fluxes over agricultural soils, we should prioritize field campaigns measuring Se emissions, rather than laboratory measurements of Se rate constants.

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Section: Discussionsupporting

confidence: 85%

Section: Experimental Setup and Model Outputsmentioning

confidence: 99%

Mapping the drivers of uncertainty in atmospheric selenium deposition with global sensitivity analysis

et al. 2020

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“…In these processes, volatile selenium compounds such as dimethylselenium (DMSe), hydrogen selenide (H 2 Se), and selenium oxide (SeO 2 ) are produced. The average selenium content in the arable layer of soil varies from 0.33 to 2 mg/kg on a global scale [12]. Soils that have arisen from parent rocks rich in selenium such as sandstones and limestone have been reported to have selenium in large content [7,13].…”

Section: Occurrence Of Selenium In the Environmentmentioning

confidence: 99%

Selenium–Fascinating Microelement, Properties and Sources in Food

2019

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Selenium is a micronutrient that is essential for the proper functioning of all organisms. Studies on the functions of selenium are rapidly developing. This element is a cofactor of many enzymes, for example, glutathione peroxidase or thioredoxin reductase. Insufficient supplementation of this element results in the increased risk of developing many chronic degenerative diseases. Selenium is important for the protection against oxidative stress, demonstrating the highest activity as a free radical scavenger and anti-cancer agent. In food, it is present in organic forms, as exemplified by selenomethionine and selenocysteine. In dietary supplementation, the inorganic forms of selenium (selenite and selenate) are used. Organic compounds are more easily absorbed by human organisms in comparison with inorganic compounds. Currently, selenium is considered an essential trace element of fundamental importance for human health. Extreme selenium deficiencies are widespread among people all over the world. Therefore, it is essential to supplement the deficiency of this micronutrient with selenium-enriched food or yeast cell biomass in the diet.

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“…These mechanisms contribute to the presence of volatile Se compounds, viz., hydrogen selenide (H 2 Se), dimethyl selenide (DMSe), and selenium oxide (SeO 2 ). Globally, the Se content in arable soils ranges between 0.33 and 2 mg/kg [ 13 ]. Se-rich areas are known as seleniferous areas [ 14 ].…”

Section: The Natural Form Of Selenium and Its Deficiency And Toxicmentioning

confidence: 99%

Selenium Biofortification: Roles, Mechanisms, Responses and Prospects

et al. 2021

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The trace element selenium (Se) is a crucial element for many living organisms, including soil microorganisms, plants and animals, including humans. Generally, in Nature Se is taken up in the living cells of microorganisms, plants, animals and humans in several inorganic forms such as selenate, selenite, elemental Se and selenide. These forms are converted to organic forms by biological process, mostly as the two selenoamino acids selenocysteine (SeCys) and selenomethionine (SeMet). The biological systems of plants, animals and humans can fix these amino acids into Se-containing proteins by a modest replacement of methionine with SeMet. While the form SeCys is usually present in the active site of enzymes, which is essential for catalytic activity. Within human cells, organic forms of Se are significant for the accurate functioning of the immune and reproductive systems, the thyroid and the brain, and to enzyme activity within cells. Humans ingest Se through plant and animal foods rich in the element. The concentration of Se in foodstuffs depends on the presence of available forms of Se in soils and its uptake and accumulation by plants and herbivorous animals. Therefore, improving the availability of Se to plants is, therefore, a potential pathway to overcoming human Se deficiencies. Among these prospective pathways, the Se-biofortification of plants has already been established as a pioneering approach for producing Se-enriched agricultural products. To achieve this desirable aim of Se-biofortification, molecular breeding and genetic engineering in combination with novel agronomic and edaphic management approaches should be combined. This current review summarizes the roles, responses, prospects and mechanisms of Se in human nutrition. It also elaborates how biofortification is a plausible approach to resolving Se-deficiency in humans and other animals.

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The Global Marine Selenium Cycle: Insights From Measurements and Modeling

Cited by 32 publications

References 101 publications

Mapping the drivers of uncertainty in atmospheric selenium deposition with global sensitivity analysis

Mapping the drivers of uncertainty in atmospheric selenium deposition with global sensitivity analysis

Selenium–Fascinating Microelement, Properties and Sources in Food

Selenium Biofortification: Roles, Mechanisms, Responses and Prospects

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