Publications des scientifiques de l'IRD

Gallay M., Mora A., Martinez Jean-Michel, Gardel A., Laraque Alain, Sarrazin Max, Beaucher Eric, Doudou Jean-Claude, Lagane Christelle. (2018). Dynamics and fluxes of organic carbon and nitrogen in two Guiana Shield river basins impacted by deforestation and mining activities. Hydrological Processes, 32 (1), p. 17-29. ISSN 0885-6087.

Titre du document
Dynamics and fluxes of organic carbon and nitrogen in two Guiana Shield river basins impacted by deforestation and mining activities
Année de publication
2018
Type de document
Article référencé dans le Web of Science WOS:000460813300002
Auteurs
Gallay M., Mora A., Martinez Jean-Michel, Gardel A., Laraque Alain, Sarrazin Max, Beaucher Eric, Doudou Jean-Claude, Lagane Christelle
Source
Hydrological Processes, 2018, 32 (1), p. 17-29 ISSN 0885-6087
Deforestation and mining activities have proven to be very damaging to rivers because these activities disturb the environmental characteristics of rivers. Thus, the concentrations of dissolved organic carbon (DOC), particulate organic carbon (POC), particulate nitrogen (PN), and Chlorophyll-a (Chl-a) were measured monthly during 2 hydrological years in the Maroni and Oyapock Rivers to assess the dynamics and fluxes of organic carbon and nitrogen in these 2 Guiana Shield basins, which have been strongly (Maroni) and weakly (Oyapock) impacted by deforestation and mining activities. The 2-year time series show that DOC, POC, PN, and Chl-a concentrations vary seasonally with discharge in both rivers, indicating a hydrologically dominated control. Temporal patterns of DOC, POC, and PN indicate that these variables show maximum concentrations in rising waters due to the yield of organic matter and nitrogen accumulated in soils, which are incorporated into the rivers during rainfall. However, the Chl-a concentrations were at a maximum during low-water stages. The C/N and C/Chl-a ratios also showed a seasonal trend, with lower values during the low water periods due to an increase in algal biomass. During high water, the POC in both rivers is the result of terrestrial organic matter, whereas during low-water autochthonous organic matter can reach up to 34% of the POC. The mean annual fluxes of TOC and PN were higher (4.56 x 10(5) tonC year(-1) and 1.77 x 10(4) tonN year(-1), respectively) in the Maroni River than those (1.84 x 10(5) tonC year(-1) and 0.54 x 10(4) tonN year(-1), respectively) in the Oyapock River. However, the specific fluxes of DOC, POC, and PN from both basins were nearly the same. Although gold mining activities are performed in both basins, there is no conclusive evidence regarding the impact of these activities on the dynamics of organic matter and particulate nitrogen in the Maroni and Oyapock Rivers.
Plan de classement
Pollution [038] ; Hydrologie [062]
Description Géographique
GUYANE FRANCAISE
Localisation
Fonds IRD [F B010072030]
Identifiant IRD
fdi:010072030
Contact