The impact of Saharan dust on the particulate export in the water column of the North Western Mediterranean Sea

Autor: Nathalie Leblond, Beat Gasser, E. Bosc, Jacobo Martín, Cécile Guieu, E. Ternon, Marie-Dominique Loÿe-Pilot, Juan-Carlos Miquel
Přispěvatelé: Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), The publication of this article is financed by CNRS-INSU, Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2010
Předmět:
Zdroj: Biogeosciences, Vol 7, Iss 3, Pp 809-826 (2010)
Biogeosciences
Biogeosciences, European Geosciences Union, 2010, 7 (3), pp.809-826. ⟨10.5194/bg-7-809-2010⟩
Biogeosciences, 2010, 7 (3), pp.809-826. ⟨10.5194/bg-7-809-2010⟩
Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2010-03-02, Vol. 7, N. 3, P. 809-826
ISSN: 1726-4189
1726-4170
DOI: 10.5194/bg-7-809-2010⟩
Popis: Simultaneous measurements of atmospheric deposition and of sinking particles at 200 and 1000 m depth, were performed in the Ligurian Sea (North-Western Mediterranean) between 2003 and 2007, along with phytoplanktonic activity derived from satellite images. Atmospheric deposition of Saharan dust particles was very irregular and confirmed the importance of sporadic high magnitude events over the annual average (11.4 g m−2 yr−1 for the 4 years). The average marine total mass flux was 31 g m−2 yr−1, the larger fraction being the lithogenic one (~37%). The marine total mass flux displayed a seasonal pattern with a maximum in winter, occurring before the onset of the spring bloom. The highest POC fluxes did not occur during the spring bloom nor could they be directly related to any noticeable increase in the surface phytoplanktonic biomass. Over the 4 years of the study, the strongest POC fluxes were concomitant with large increases of the lithogenic marine flux, which had originated from either recent Saharan fallout events (February 2004 and August 2005), from "old" Saharan dust "stored" in the upper water column layer (March 2003 and February 2005), or alternatively from lithogenic material originating from Ligurian riverine flooding (December 2003, Arno, Roya and Var rivers). Those associated export fluxes defined as "lithogenic events", are believed to result from a combination of forcing (winter mixing or Saharan events, in particular extreme ones), biological (zooplankton) activity, and also organic-mineral aggregation inducing a ballast effect. By fertilising the surface layer, mixed Saharan dust events were shown to be able to induce "lithogenic events" during the stratification period. These events would be more efficient in transferring POC to the deeper layers than the spring bloom itself. The extreme Saharan event of February 2004 exported ~45% of the total annual POC, compared to an average of ~25% for the bloom period. This emphasises the role played by these "lithogenic events", and in particular those that are induced by the more extreme Saharan events, in the carbon export efficiency in the North-western Mediterranean Sea.
Databáze: OpenAIRE
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