Félicitations à Mariia Petrova (CEM) qui a soutenu sa thèse par visioconférence le jeudi 19 novembre 2020
Sur le sujet suivant :
"Sources and processes governing mercury cycling in a changing Arctic Ocean"
Directeur de thèse : Bruno Hamelin, Professeur des Universités AMU
Co directeur : Lars-Eric Heimbürger-Boavida, Chargé de recherche CNRS
Meeting ID: 970 6202 6489
Résumé du projet de thèse en anglais: Understanding persistent high levels of mercury (Hg) in the Arctic biota had been an elusive goal for nearly three decades. But the major sources and degradation pathways of mercury in seawater are still not well understood. Mercury (Hg) is a naturally occurring trace metal, which is sensitive to global change. A long history of Hg mining, anthropogenic use, as well as its release from various industrial activities has resulted in a significant amount of Hg emission to the atmosphere. Hg that is deposited to the earth’s surface can be subjected to various biogeochemical processes determining the fate of Hg in the ecosystem. The processes governing Hg transformation and fate have been studied more extensively in aquatic ecosystems, compared to terrestrial ecosystems, due to the important health implications of Hg and methylmercury (MeHg) related to human consumption of marine fish. However, the open ocean realm has only been started to be thoroughly studied with the GEOTRACES programme, allowing for organized TM clean sampling, and systematic exploration with other GEOTRACES key TEIs. The intense exchange of gaseous Hg species (Hg0 ) at the ocean-atmosphere interface and ocean Hg species dynamics, as well as the production of MeHg open up a variety of potential uses of Hg as a biogeochemical tracer. My preliminary results show that the inflow North Atlantic water masses are characterized by low Hg content, whereas the outflow water exports higher Hg levels. This study concerns also the importance of the river runoff as one of sources of Hg to the Arctic Ocean.