Mercury speciation in selenium enriched wheat

Overview

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Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

• ALBA synchrotron https://orcid.org/0000-0001-5331-0633
• License:   This work is licensed under a Creative Commons Attribution 4.0 International License.
• treatments (selenite, selenate and a 1:1 mixture of both) have been investigated by X-ray absorption
• spectroscopy at the Hg L3-edge. The main Hg species found in wheat grains is the highly toxic
• translocation to grains. Only the 1:1 Se mixture treatment helps in reducing the levels of Hg and the
• (Hylander and Goodsite 2006; Esdaile and Chalker 2018) to medicine (e.g., dental amalgams (Faheem et
• al. 2014), and antimicrobial preservative in vaccine production (Baker 2008; de Vries et al. 2015)).
• environment and to human health (Nica et al. 2017; Sánchez-Báscones et al. 2017).
• environment a cyclic process (Tangahu et al. 2011; Alvarez-Fernández et al. 2014; Arif et al. 2016; Singh
• et al. 2015). Among all, methylated Hg species cause a major threat due to their high toxicity. The ability
• nervous and nephron pathologies in humans (Sharma et al. 2019). Moreover, in pregnant women,
• (Humaira 2016; Karita et al. 2016; Nica et al. 2017).
• concentration on dry mass ranged from 0.003 to 3.12 mg·kg− 1 (Ottesen et al. 2013). The study indicates
• of soil organic material. Taking into account that the presence of a Hg concentration above 2 mg·kg− 1 in
• the soil is considered an ecological risk (Tóth et al. 2016), these results highlight the importance of
• mercuric salts which can be reduced into elemental and methylated forms (Humaira 2016).
• level of Hg and its chemical state present in plant-based food (Humaira 2016). Organic forms and methyl
• complexes of Hg formed by bacterial methylation are usually absorbed by plants over Hg0 at suitable
• acidic pH (Hylander and Goodsite 2006; Tangahu et al. 2011; Arif et al. 2016). The bioaccumulation and
• Goodsite 2006; Tangahu et al. 2011; Arif et al. 2016) produced in Hg polluted soils (Cooke Andrews 2006;
• Navarro et al. 2006; Sysalová et al. 2017), although less severe than consequences of the Hg pollution in
• the aquatic environment (Cooke Andrews 2006), is also becoming a health concern.
• activity in humans (Ellis and Salt 2003; Zhu et al. 2009). Biofortification of food crops with Se is a viable
• Selenocysteine) which are more bioavailable for humans (Ellis and Salt 2003; Wang et al. 2020).
• 2011; Alvarez-Fernández et al. 2014; Arif et al. 2016). In addition, the adsorption can simply occur by the
• diffusion of the ions into the root cells driven by concentration gradients (Alvarez-Fernández et al. 2014).
• the efficiency of the absorption mechanism (Arif et al. 2016; Dubey et al. 2018). Regarding Hg, different
• (Shumaker and Begonia 2005; Krupp et al. 2009; Sahu et al. 2012; Li et al. 2017; Dubey et al. 2018).
• nutrients uptake mechanisms (Liu et al. 2010; Dubey et al. 2018). In cereal crops, Hg accumulates more
• 2011; Wang et al. 2016; Dang et al. 2019; Li et al. 2019). In addition, Hg generates oxidative stress and
• affects root formation, biomass, and grain yield (Sahu et al. 2012).
• The antagonism between Hg and Se (Dang et al. 2019; Li et al. 2019) has been widely studied in animals
• (Cuvin-Aralar and Furness 1991; Khan et al. 2009; Khan and Wang 2009), and aquatic life (Gailer et al.
• 2000; George et al. 2011). In the case of plants, Hg and Se antagonism is gaining attention for various
• uptake reduces the Hg accumulation by modifying the uptake of other essential nutrients (Li et al. 2019;
• Chang et al. 2020). Similarly, in vegetables like radish, it has been reported that Se helps in circumventing
• Hg uptake (Shanker et al. 1996). Regarding the metabolism of plants, the sulfur pathway is the most
• other redox reactions (Alvarez-Fernández et al. 2014; Singh et al. 2015; Li et al. 2019). Hence, this
• nature (Liu et al. 2009; Meng et al. 2011; Wang et al. 2016; Li et al. 2017).
• our previous hydroponic studies on Se biofortification wheat (Xiao et al. 2020; Xiao et al. 2021), and set
• speciation of Hg in the different parts of the plant (roots, shoots, grains). Hg L3-edge X-ray absorption
• 12 L opaque containers (6 plants per container and 2 containers per treatment to obtain experimental

Methods (brief)

• Matured wheat plants were harvested and divided into roots, shoots, and grains. Samples were oven dried
• For shoots and grains, the Hg content from powdered dry samples was determined using a direct mercury
• analyser, (DMA-80; Milestone Inc., Italy). For the analysis, 2 mg of lyophilized powdered sample were
• Spain (Simonelli et al. 2016). Powdered samples (~ 20 mg) were pressed into 5 mm pellets using a
• spectra were collected using the CLEAR spectrometer available at the beamline based on Johansson-like
• 2023). The Hg Lα1 emission was collected using the Si(444) reflection of the analysers working in back-
• shows the comparison of the Hg L3-edge XAS spectra collected on roots, shoots, and grains with the
• of each Hg species contained in the sample contributes additively to the total spectrum of the sample,
• spectra can allow the determination of the species present in the plant samples. The X-ray absorption
• Although the spectral features of the XANES spectra collected on the samples are not as defined as the
• probable overlapping contributions, variations in between the samples at the main characteristic features
• To better resolve the XANES spectral features, high resolution XANES spectra (HERFD) were collected on
• the root samples, where the concentration of Hg made this approach viable. This technique allows
• clearly seen for the HgS, HgCH3Cl, and HgSe references (Fig. 3). In the case of the plant samples, the
• The comparison of the samples and references spectra suggests that the presence of HgS in roots might
• in the samples appears at higher energy, ~ 12288 eV, than feature A in HgS reference, ~ 12286 eV (Fig. 3).
• results are reported in Supplementary Table S3. They suggest that, in the Se treated sample, the main Hg
• standard XANES were performed over all the samples considering the three Hg references (HgSe, HgS,

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

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• Mercury
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Verification notes

• Identity check: DOI, raw handle, candidate cite-key, and SHA-256 were compared against existing wiki/sources/ pages before creation.
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Update history

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