Data/hora: 17/06/2024 07:06:27

Provedor de dados: | 5
País: | France
Título: | Dynamique hivernale des nutriments et du carbone dans les exutoires du Marais poitevin et flux terrestres associés en Baie de l’Aiguillon
Autores: | Le Marchand, Marie.
Data: | 2017-06
Ano: | 2017
Palavras-chave: | Zones côtières; Cycles biogéochimiques; Carbone; Nutriments; PCO2; Marais poitevin; Coastal areas; Biogeochemical cycles; Carbon; Nutrients; PCO2; Marais poitevin.
Resumo: | Coastal environments represent key systems in biogeochemical cycle couplings between continents, oceans and the atmosphere. Despite its relatively modest surface area (7 % of global ocean), this zone accounts for 14-30 % of all oceanic primary production. The amount of nutrients (N, P, C, Si) carried by terrestrial aquatic systems directly influences the primary production, the food web structure and the overall quality of these coastal environments. The present study deals with autumn-winter carbon and nutrients dynamics over terrestrial waters of the Marais poitevin watershed flowing to the Aiguillon bay (west of France). Five heterogeneous watercourses were sampled twice a month since January 2017 to measure nutrients and carbon concentrations and associated environmental parameters. Those measurements were compared to an autumn 2004 - winter 2005 similar dataset to study inter-annual variations too along with terrestrial fluxes to the Bay. The first measurements obtained in winter 2017 revealed significant spatial variations among watercourses. For instance, the Lay and Sèvre rivers showed the highest SPM concentrations (470 and 4000 mg L-1) and pCO2 values (1580 and 3600 ppmv) in average due to intense organic matter mineralization. To the contrary, the smaller watercourses, (i.e. Chenal Vieux, Curé and Luçon) looked more productive over winter with lower SPM concentrations associated to higher chlorophyll a concentrations (230 µg L-1 in 2004 into Curé water) and lower pCO2 values. Significant temporal variations were also observed between seasons: for example lower NO3- concentrations were measured in autumn 2004 compared to winter 2005 (140 and 350 µmol L-1 in average, respectively). Significant correlations between measured nutrient-carbon parameters and runoffs and land covers were calculated in winter 2017 mainly, and could partly explain observed spatial and temporal variations. For example, high NO3- concentrations found in Sèvre and Curé watercourses were positively correlated (R² = 0.66) with large agriculture surfaces (&gt;50 % of catchment basin’s total area). However, anthropogenic pressures as hydraulic locks management for regulating water discharges over the Marais poitevin and Aiguillon bay continuum make the studied system dynamic even more complex and justify continuing the high frequency measurements over the whole year.
Tipo: | Text
Idioma: | Francês

Identificador:

http://archimer.ifremer.fr/doc/00393/50487/51223.pdf

http://archimer.ifremer.fr/doc/00393/50487/

Formato: | application/pdf

Fonte:

2017 Ifremer, Université La Rochelle

info:eu-repo/semantics/openAccess

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