New insights into the biomineralization of mercury selenide nanoparticles through stable isotope analysis in giant petrel tissues

• Published in: Journal of hazardous materials 2022-03, Vol.425, p.127922-127922, Article 127922
• Main Authors: Queipo-Abad, Silvia, Pedrero, Zoyne, Marchán-Moreno, Claudia, El Hanafi, Khouloud, Bérail, Sylvain, Corns, Warren T., Cherel, Yves, Bustamante, Paco, Amouroux, David
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Animals; Biomineralization; Birds; Chemical Sciences; Environmental Monitoring; HgSe nanoparticles; Isotopes; Isotopic fractionation; MeHg demethylation; Mercury; Mercury - analysis; Methylmercury Compounds; Nanoparticles; Seabirds; Water Pollutants, Chemical - analysis
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.127922

Tiemannite (HgSe) is considered the end-product of methylmercury (MeHg) demethylation in vertebrates. The biomineralization of HgSe nanoparticles (NPs) is understood to be an efficient MeHg detoxification mechanism; however, the process has not yet been fully elucidated. In order to contribute to the understanding of complex Hg metabolism and HgSe NPs formation, the Hg isotopic signatures of 40 samples of 11 giant petrels were measured. This seabird species is one of the largest avian scavengers in the Southern Ocean, highly exposed to MeHg through their diet, reaching Hg concentrations in the liver up to more than 900 µg g-1. This work constitutes the first species-specific isotopic measurement (δ202Hg, Δ199Hg) of HgSe NPs in seabirds and the largest characterization of this compound in biota. Similar δ202Hg values specifically associated to HgSe (δ202HgHgSe) and tissues (δ202Hgbulk) dominated by inorganic Hg species were found, suggesting that no isotopic fractionation is induced during the biomineralization step from the precursor (demethylated) species. In contrast, the largest variations between δ202Hgbulk and δ202HgHgSe were observed in muscle and brain tissues. This could be attributed to the higher fraction of Hg present as MeHg in these tissues. Hg-biomolecules screening highlights the importance of the isotopic characterization of these (unknown) complexes. [Display omitted] •First report of species-specific isotopic characterization of HgSe NPs in seabirds.•Largest HgSe isotopic study in biota (tissues from 11 individuals), first time reported in brain and kidneys.•Contrasting δ202HgSe and δ202bulk depending of the fraction of MeHg in the organ.•Screening of Hg-proteins reveals the presence of several unknown Hg-compounds.