Title : The effects of Arctic amplification on particle fluxes and circulation in the modern Arctic Ocean using geochemical and numerical tracers
Summary: Continental inputs to the ocean provide most of the nutrients required for photosynthesis, and thus modulate the efficiency of the oceanic biological carbon pump. Under the impact of climate change, these inputs are set to evolve and modify marine chemistry and biological activity. This is particularly true in the Arctic, where coastal erosion is accelerating and where the gradual retreat of the sea ice allows more light to penetrate, stimulating photosynthesis. Mélanie Grenier will present the geochemical tracers (230Th, 231Pa and Nd) and numerical tracers (Lagrangian tracers) she has used since her PhD to characterise, in the context of Arctic amplification, the variability of particle flux and circulation in the Amerindian Basin of the Arctic Ocean. She will detail the results she obtained from comparing her data (2007, 2009, 2011, 2015) with pre-2000s data (Grenier et al., JGR, 2019), as well as the associated modelling results (Yu et al., JGR, 2020). She will conclude with a presentation of the research project to which her studies have led her, which she is proposing through CR CNRS and ERC starting grant applications in Toulouse. Her project is based on a natural laboratory for Arctic change, the Canadian Arctic Archipelago. It combines lagrangian and geochemical analyses - including the development of tracers of continent-ocean and ice-ocean exchanges, 9Be, 10Be and 7Be - in order to better characterise the fate of the Arctic biological carbon pump under the effects of permafrost erosion and pack ice retreat.
Biography: Mélanie Grenier completed her PhD at the Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (LEGOS) in Toulouse (France) from 2009 to 2012, working with geochemist Catherine Jeandel and physicist Sophie Cravatte. Her thesis focused on the study of fertilisation in the Equatorial Pacific, using an approach combining physics and geochemistry. Mélanie did her first post-doctorate in Hobart (Tasmania, Australia) in 2013-2014, at the ACE-CRC (Antarctic Climate & Ecosystems - Cooperative Research Centre), with biogeochemist Thomas Trull. This post-doc focused on the study of water fertilisation in the Kerguelen Plateau region. She then completed a second post-doctorate, under a Marie Curie fellowship, between the University of British Columbia (UBC) in Vancouver and LEGOS, from 2015 to 2018. Supervised at UBC by geochemist Roger François and physicist Susan Allen, she took part in the physical and geochemical components of the Canadian Arctic GEOTRACES project. Since then, she has been working on promoting the large Arctic dataset she obtained, in parallel with her applications to the CNRS and the ERC.