LEGOS Marine Geochemisrty Group
Published by: François Lacan
Marine Geochemistry allows the quantification of fluxes transported from the land to the ocean, within the ocean and from the ocean to the seafloor. This quantification is a key for a better understanding of what controls the average chemical composition of the ocean, the low frequency transports and mixing of water masses. These are essential components in climate regulation, anthropogenic CO2 sequestration or distribution of polluting elements in water masses. Geochemical approaches rely on the use of tracers (trace elements and isotopes, named TEIs). In order to quantify fluxes, the physical and chemical behaviours of the tracers have to be understood a priori, which is an important part of the geochemist's work. Understanding the present day cycle of these tracers is also a cornerstone for applying them as paleo proxies.
Scientific objectives of our GEOMAR team are focused on 1) quantifying the inputs of TEIs at the land-ocean interface 2) tracking and quantifying the slow and large scale oceanic circulation 3) understanding detailed processes that are governing the TEIs distribution as for example dissolved/particle exchange or release from the sediments during early diagenesis.
In order to achieve this goal, we analyse a set of different tracers on seawater, particles and sediments collected in focused areas. All tracers are contributing different information on oceanic processes on different spatial and temporal scales. Sampling strategy focuses on the dynamics of the studied area, and is carried out on interdisciplinary oceanographic cruises (e.g.: EUC-Fe, Amandes, Bonus-GoodHope, KEOPS, Pandora). Finally, modelling helps us to test hypotheses and to extrapolate information deduced from local studies to larger spatial and temporal scales.
F. Poitrasson, J.Sonke, P.Seyler, Y.Godderis, (GET); JC Dutay, JL Reyss, M.Roy-Barman, L. Bopp (LSCE); G. Sarthou (LEMAR); B. Peucker-Ehrenbrink (WHOI); P. BEHRA (LCA)