Phytamba

Understanding of mercury transformation pathways in the aquatic systems is an active research area. However, opposite to the extensive work on bacteria, the role of the phototrophic microorganisms (phytoplankton) in both abiotic and biotic transformations is not well understood. The primary goal of the project is to get new mechanistic insights into the role of phytoplankton in the Hg cycling and transformations in surface waters. The specific aims of the project are thus twofold: (i) to determine the kinetics and prevailing mechanisms of Hg biotic transformation pathways mediated by phytoplankton, for example the processes of methylation of inorganic Hg (IHg) / methylmercury demethylation (MeHg), reduction / oxidation and; (ii) to examine to what extent and under which conditions the biogenic ligands produced by the phytoplankton will further affect additional abiotic processes. State-of-the-art analytical techniques such as gas chromatography, liquid chromatography, and flow field-flow fractionation coupled with ICP-MS are used throughout the project to explore the interactions between Hg compounds and their binding ligands. Stable Hg isotopes will also be used to distinguish the biotic and abiotic pathways of IHg and MeHg. The results will be of upmost importance for the development of Hg biogeochemical modelling, mitigation strategies and rational environmental risk assessment in aquatic system.

Financement: Swiss National Science Foundation - Agence Nationale de la Recherche France Lead Agency for cross border cooperation

UniGe team : Prof. Vera Slaveykova (Swiss PI), Mr. Thibaut Cossart, Mr. João Santos, Mr. Killian Kavanagh and Dr. Isabelle Worms

IPREM team : Dr. David Amouroux (French PI), Mr. Javier Garcia Calleja, Dr. Zoyne Pedrero, Dr. Emmanuel Tessier, Prof. Laurent Ouerdane, Prof. Thierry Pigot, CNRS-Université de Pau et des Pays de l’Adour, France