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

Silvia Queipo-Abad (1) , Zoyne Pedrero (1) , Claudia Marchán-Moreno (1) , Khouloud El Hanafi (1) , Sylvain Bérail (1) , Warren T Corns (1, 2) , Yves Cherel (3) , Paco Bustamante (4, 5) , David Amouroux (1)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
2 PS Analytical [Kent, UK]
3 CEBC - Centre d'Études Biologiques de Chizé - UMR 7372
4 LIENSs - LIttoral ENvironnement et Sociétés
5 IUF - Institut universitaire de France

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 (δ 202 Hg, Δ 199 Hg) of HgSe NPs in seabirds and the largest characterization of this compound in biota. Similar δ 202 Hg values specifically associated to HgSe (δ 202 HgSe) and tissues (δ 202 bulk) 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 δ 202 Hgbulk and δ 202 HgSe 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.

Mots clés: HgSe nanoparticles; MeHg demethylation; Mercury; seabirds; isotopic fractionation

Domaines: Chimie analytique

Silvia Queipo-Abad, Zoyne Pedrero, Claudia Marchán-Moreno, Khouloud El Hanafi, Sylvain Bérail, et al.. New insights into the biomineralization of mercury selenide nanoparticles through stable isotope analysis in giant petrel tissues. Journal of Hazardous Materials, 2022, 425, pp.127922. ⟨10.1016/j.jhazmat.2021.127922⟩. ⟨hal-03475304⟩