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Welcome to the Marine Environmental Chemistry (CEM) Group collection

The Marine Environment Chemistry (CEM) team focuses on several environmental issues:

  1. Characterization and quantification of organic and inorganic elements in the marine environment,
  2. Estimation of their flow from the continent to the oceans and their monitoring by optical means,
  3. Definition of their sources and fate in the water column,
  4. effect of sedimentary diagenesis on anthropogenic inputs.

These themes are a component of the general problem of understanding the cycles of elements and the effect of the anthropization of environments, which are crucial phenomena in the context of global climate change.

 

Number of resources

228

 

Number of fulltexts

233

 

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Latest submissions in HAL !

[hal-01110987] The significance of the episodic nature of atmospheric deposition to Low Nutrient Low Chlorophyll regions

 (31/10/2020)  
In the vast Low Nutrient Low-Chlorophyll (LNLC) Ocean, the vertical nutrient supply from the sub-surface to the sunlit surface waters is low, and atmospheric contribution of nutrients may be one order of magnitude greater over short timescales. The short turnover time of atmospheric Fe and N supply (<1 month for nitrate) further supports deposition being an important source of nutrients in LNLC regions. Yet, the extent to which atmospheric inputs are impacting biological activity and modifying the carbon balance in oligotrophic environments has not been constrained. Here, we quantify and compare the biogeochemical impacts of atmospheric deposition in LNLC regions using both a compilation of experimental data and model outputs. A metadata-analysis of recently conducted field and laboratory bioassay experiments reveals complex responses, and the overall impact is not a simple "fertilization effect of increasing phytoplankton biomass" as observed in HNLC regions. Although phytoplankton growth may be enhanced, increases in bacterial activity and respiration result in weakening of biological carbon sequestration. The application of models using cli-matological or time-averaged non-synoptic deposition rates produced responses that were generally much lower than observed in the bioassay experiments. We demonstrate that experimental data and model outputs show better agreement on short timescale (days to weeks) when strong synoptic pulse of aerosols deposition, similar in magnitude to those observed in the field and introduced in bioassay experiments, is superimposed over the mean atmospheric deposition fields. These results suggest that atmospheric impacts in LNLC regions have been underestimated by models, at least at daily to weekly timescales, as they typically overlook large synoptic variations in atmospheric deposition and associated nutrient and particle inputs. Inclusion of the large synoptic variability of atmospheric input, and improved representation and parameterization of key processes that respond to atmospheric deposition, is required to better constrain impacts in ocean biogeochemical models. This is critical for understanding and prediction of current and future functioning of LNLC regions and their contribution to the global carbon cycle.

[insu-02978433] The Malina oceanographic expedition: How do changes in ice cover, permafrost and UV radiation impact biodiversity and biogeochemical fluxes in the Arctic Ocean?

 (30/10/2020)  

[hal-02976591] Preparing the New Phase of Argo: Scientific Achievements of the NAOS Project

 (28/10/2020)  

 

Contact

Catherine Beaussier
Tél. (+33) 4 95 04 41 43
catherine.beaussier@osupytheas.fr

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