A Michaelis–Menten type equation for describing methylmercury dependence on inorganic mercury in aquatic sediments

Abstract : Methylation of mercury (Hg) is the crucial process that controls Hg biomagnification along the aquatic food chains. Aquatic sediments are of particular interest because they constitute an essential reservoir where inorganic divalent Hg (HgII) is methylated. Methylmercury (MeHg) concentrations in sediments mainly result from the balance between methylation and demethylation reactions, two opposite natural processes primarily mediated by aquatic microorganisms. Thus, Hg availability and the activity of methylating microbial communities control the MeHg abundance in sediments. Consistently, some studies have reported a significant positive correlation between MeHg and HgII or total Hg (HgT), taken as a proxy for HgII, in aquatic sediments using enzyme-catalyzed methylation/demethylation mechanisms. By compiling 1,442 published and unpublished HgT–MeHg couples from lacustrine, riverine, estuarine and marine sediments covering various environmental conditions, from deep pristine abyssal to heavily contaminated riverine sediments, we show that a Michaelis–Menten type relationship is an appropriate model to relate the two parameters: MeHg = aHgT/(K m + HgT), with a = 0.277 ± 0.011 and K m = 188 ± 15 (R 2 = 0.70, p < 0.001). From K m variations, which depend on the various encountered environmental conditions, it appears that MeHg formation and accumulation are favoured in marine sediments compared to freshwater ones, and under oxic/suboxic conditions compared to anoxic ones, with redox potential and organic matter lability being the governing factors.
Type de document :
Article dans une revue
Biogeochemistry, Springer Verlag, 2014, 119 (1-3), pp.35-43. 〈10.1007/s10533-013-9924-3〉
Liste complète des métadonnées

Littérature citée [71 références]  Voir  Masquer  Télécharger

https://hal.archives-ouvertes.fr/hal-01717783
Contributeur : Sylvain Rigaud <>
Soumis le : lundi 26 février 2018 - 17:12:17
Dernière modification le : mardi 29 mai 2018 - 12:51:02
Document(s) archivé(s) le : lundi 28 mai 2018 - 16:47:00

Fichier

Cossa et al_HAL.pdf
Fichiers produits par l'(les) auteur(s)

Identifiants

Citation

Daniel Cossa, Cédric Garnier, Roselyne Buscail, Françoise Elbaz-Poulichet, Nevenka Mikac, et al.. A Michaelis–Menten type equation for describing methylmercury dependence on inorganic mercury in aquatic sediments. Biogeochemistry, Springer Verlag, 2014, 119 (1-3), pp.35-43. 〈10.1007/s10533-013-9924-3〉. 〈hal-01717783〉

Partager

Métriques

Consultations de la notice

391

Téléchargements de fichiers

69