Marine Environmental Chemistry (CEM)
The Marine Environment Chemistry (CEM) team focuses on several environmental issues:
- the characterization and quantification of organic and inorganic elements in the marine environment,
- the estimation of their flow from the continent to the oceans and their monitoring by optical means,
- the definition of their sources and fate in the water column,
- the impact of sedimentary diagenesis on anthropogenic inputs.
These themes are part of the general problem of understanding the cycle of elements and the impact of the anthropisation of environments, which are crucial phenomena in the context of global climate change.
Study of the natural organic matter (MON)
Study of the natural organic matter (MON) by the combination of molecular and optical approaches and the identification of tracers, allowing to determine the main sources of the MON (terrigenous, marine, atmospheric, sedimentary, ...) and evaluation of sources and spatio-temporal variability of chromophoric MON (CDOM) through the use of optical laboratory and in situ measurements (absorbance, fluorescence, radiometry),
assessment of the biodegradation and abiotic degradation processes (eg photodegradation) of NOM. The major processes controlling its composition, properties and responsiveness in the marine environment :
structural characterization of the NOM.
Organic and inorganic tracers for the study of biogeochemical cycles in the marine environment
- ocean carbon cycle - fluxes, tracers for the export, mineralization and degradation of the NOM,
- quantification of fluxes and modeling of material transfer at atmosphere/ocean, river/coastal zone, water/sediment, open margin/ocean, surface ocean/mesopelagic zone/bathypelagic range, frontal zones and biogeochemical provinces,
- development of specific tracers (Ba, Ti, Hg, 13 C, 14 C, sugars, lipids, ...) for the study of processes (mineralization, photodegradation, atmospheric deposition, ocean circulation, ...).
Integrated study of sources, behavior, transformation processes and fate of organic and inorganic contaminants
- levels, sources and transfer of historical (metals / metalloids, PAHs, PCBs, ...) and emerging (Ag, Gd, Pt, phthalates, OPEs ...) contaminants between environmental compartments, impact of natural or anthropogenic intense events (eg storm, flood, dredging, industrial / urban discharges, ...),
- influence of the speciation of contaminants on their bioavailability and their impact on the first trophic levels,
- contaminant transfer in food webs, bioaccumulation process and biomagnification,
- biogeochemical cycle of Hg in the marine environment: anthropogenic sources vs. natural resources, trade and transformation, influence of microbial communities,
- role of NOM and microplastics in contaminant behavior and transfer,
- impact of Black Carbon on contaminant transfer and element cycling.
Tools and analytical development
- development of in situ sensors for MON monitoring (eg Fluorescence, Raman, Laser),
- development of sensors specific for chemical contaminants (eg fluorescent HAPs, metals by functionalized polymers, Hg by functionalized nanoparticles, etc.) and urban tracers (eg fluorescent faecal bacteria),
- geochemical modeling of speciation and contaminant transfer,
- signal processing techniques, statistical processing of data, ..