Mercury speciation in selenium enriched wheat plants hydroponically exposed to mercury pollution.

Mercury (Hg) pollution in agricultural soils and its potential pathway to the human food chain can pose a serious health concern. Understanding the pathway of Hg in plants and how the speciation may change upon interaction with other elements used for biofortification can be critical to assess the real implications for the final plant-based product. In that respect, selenium (Se) biofortification of crops grown in Se-poor soil regions is becoming a common practice to overcome Se deficient diets. Therefore, it is important to assess the interplay between these two elements since Se may form complexes with Hg reducing its bioavailability and toxicity. In this work, the speciation of Hg in wheat plants grown hydroponically under the presence of Hg (HgCl2) and biofortified with Se (selenite, selenate, or a 1:1 mixture of both) has been investigated by X-ray absorption spectroscopy at the Hg L3-edge. The main Hg species found in wheat grains was the highly toxic methylmercury. It was found that the Se-biofortification of wheat did not prevent, in general, the Hg translocation to grains. Only the 1:1 mixture treatment seemed to have an effect in reducing the levels of Hg and the presence of methylmercury in grains.

Structural differences and adsorption behaviour of alkaline metals doped zinc oxide nanoparticles.

Nanotechnology plays a vital role in all the scientific fields including environmental research due to their surface: volume ratio compared to bulk materials. Recent studies prove their effectiveness as pollutant removal and remediation practices. Zinc oxide (ZnO) nanoparticles a multifunctional material with distinct properties and their doped counterparts were widely being studied in different fields of science. However, its application in environmental waste treatment is starting to gain attention due to its low cost and high productivity. Heavy metal pollution is one of the major pollutants affecting aquatic and terrestrial life forms. Pollution in water bodies has also raised alarming concerns in the past decades. Most of the heavy metals are essential elements in trace amounts and omnipresent in the environment, causing toxicity for living organisms, for instance, nickel. In our work, we analysed the prospect of selective removal of nickel ions by different alkaline metals (K+, Rb+, and Cs+) doped zinc oxide nanoparticles fabricated by different treatment methods (as-prepared and heat-treated). We found morphological variations from flower like to rod like owing to the alkaline cations of  the dopants. In addition, the crystal structure and its different fractions presented amorphous content of the fabricated samples increased from 2 to 10 wt% with respect to the atomic radius of dopant in as-prepared samples and not present in heat-treated samples. We report, how the structure and the sample composition directly affected their adsorption behaviour towards Nickel ions in aqueous solutions based on the micro and nano zincite ratio of the ZnO particles.