Seasonal variability of total dissolved fluxes and origin of major dissolved elements within a large tropical river: The Orinoco, Venezuela

Laraque, Alain; Moquet, Jean-Sébastien; Alkattan, Rana; Steiger, Johannes; Mora, Abrahan; Adèle, Georges; Castellanos, Bartolo; Lagane, Christèle; López, José Luís; Perez, Jesus; Rodríguez, Militza; Rosales, Judith

doi:10.1016/j.jsames.2012.12.011

Cited by 32 publications

(27 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Tropical river ecosystem processes associated with floodplain ecological functions clearly depend on their complex interaction with regular annual flood pulses (Junk, Bayley, & Sparks, ), that is, channel–floodplain interactions (Dunne, Mertes, Meade, Richey, & Forsberg, ; Rudorff, Dunne, & Melack, ). The characteristics of the flood pulse, such as the unimodal floods observed on the Orinoco River (Laraque et al, ), include the magnitude, frequency, duration, timing, and rate of change, which influence river ecosystem integrity both directly and indirectly (Poff et al, ). However, sediment regime and overbank sedimentation dynamics also play a major role in modulating fluvial landforms and structuring ecological and biogeochemical processes within riverine ecosystems (Steiger, Gurnell, & Corenblit, ; Wohl et al, ).…”

Section: Introductionmentioning

confidence: 99%

Multi‐annual contemporary flood event overbank sedimentation within the vegetated lower Orinoco floodplain, Venezuela

Rodríguez

Steiger

Rosales

et al. 2019

River Research & Apps

Self Cite

View full text Add to dashboard Cite

Multi‐annual contemporary flood event overbank sedimentation rates were quantified on the World's third largest river in terms of discharge, the tropical lower Orinoco. We discuss the role of variables at the basin and reach scales that contributed to the complexity of spatio‐temporal overbank sediment deposition patterns. Monitored in situ plots were characterized by distance to the main channel, hydroperiod, different geomorphological units, and vegetation cover. Flood event sedimentation rates showed a high spatial variability ranging from the absence of sediment deposition up to 225.46 kg m‐2 yr‐1. Banks and levees received relatively high amounts of sediment (39.6 kg m‐2 yr‐1), whereas observed mean sedimentation rates on the more distant floodplain and backswamps tended to be lower (17.7 kg m‐2 yr‐1). Significant differences in sedimentation rates were observed in two major vegetation types: dense herbaceous and shrubby vegetation (42.2 kg m‐2 yr‐1) and floodplain forest (12.7 kg m‐2 yr‐1). However, overbank sedimentation patterns also reflected imbricated hydrosedimentary and biogeomorphological vegetation feedbacks that co‐construct fluvial landforms. The incidence of an El Niño–Southern Oscillation–La Niña episode during the study period on sediment availability and floodplain sedimentation suggests that within whitewater rivers, where suspended sediment concentrations are naturally high, hydrological connectivity seems to be more important for floodplain sedimentation than variations in suspended sediment concentrations. These results may provide a good basis for future biogeomorphological investigation projects using complementary methodologies, in order to better anticipate global change and fluctuations in the occurrence, strength or duration of El Niño–La Niña episodes in the tropical zone and their consequences for flood discharge and sediment dynamics during channel–floodplain exchanges.

show abstract

Section: Introductionmentioning

confidence: 99%

Multi‐annual contemporary flood event overbank sedimentation within the vegetated lower Orinoco floodplain, Venezuela

Rodríguez

Steiger

Rosales

et al. 2019

River Research & Apps

Self Cite

View full text Add to dashboard Cite

show abstract

“…With regard to the temporal variability of organic carbon, the seasonal patterns of the DOC and POC concentrations show that the highest values of these variables in both rivers occur during the increasing branch of the hydrogram, a few months before the maximum values of water discharge, whereas the lowest values were found at the beginning of the low water stage. The enhancement of DOC concentrations during rising waters is a typical behaviour observed in several large worldwide rivers such as the Niger, Congo, Ganges, Brahmaputra, and Orinoco Rivers (Chowdhury, Safiullah, Iqbal, Mofizuddin, & Enamul, ; Laraque et al, ; Martins, ; Mora et al, ), and it is produced mainly by the washout of the organic matter accumulated in soils during the preceding dry season, which is leached from the soils to the rivers during rainfall. Conversely, another factor that can increase the concentrations of DOC during rising and decreasing waters is the decomposition of the submerged vegetation in the floodplain of large rivers (Geeraert, Omengo, Borges, Govers, & Bouillon, ; Mora et al, ).…”

Section: Resultsmentioning

confidence: 99%

Dynamics and fluxes of organic carbon and nitrogen in two Guiana Shield river basins impacted by deforestation and mining activities

Gallay¹,

Mora

Martinez

et al. 2017

Hydrological Processes

Self Cite

View full text Add to dashboard Cite

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 × 10 5 tonC year −1 and 1.77 × 10 4 tonN year −1 , respectively) in the Maroni River than those (1.84 × 10 5 tonC year −1 and 0.54 × 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.

show abstract

“…Relações similares são encontradas em outras bacias hidrológicas do mundo (e.g. Zakharova et al 2005;Godsey et al 2009;Laraque et al 2013) sugerindo que estas observações podem ser globalmente aplicáveis.…”

Section: Variação Temporal Dos íOnsunclassified

Spatial-temporal variation of dissolved inorganic material in the Amazon basin

et al. 2015

Self Cite

View full text Add to dashboard Cite

A bacia do rio Amazonas é importante no aporte de material dissolvido para o oceano (4% a nível mundial apresentaram concentrações quase constantes ao longo dos anos e entre as estações, indicando que seus fluxos dependem da variação da vazão. Portanto, a variação temporal do fluxo de material inorgânico dissolvido no rio Solimões e Amazonas depende do fator hidroclimatológico e da heterogeneidade das fontes. Nos rios Madeira e Purus há menor influência desses fatores, o que evidencia maior aporte dos silicatos. Como a bacia do Solimões aporta aproximadamente 84% do fluxo total de material dissolvido na bacia e está sob influência, principalmente, do fator hidroclimático, pode-se concluir que a variabilidade temporal desse fator controla a temporalidade dos fluxos do material dissolvido na bacia Amazônica. PALAVRAS CHAVE: intemperismo, fluxos hidroquímicos, diluição teórica, hidroclimatologia. Spatial-temporal variation of dissolved inorganic material in the Amazon basin ABSTRACTThe Amazon River basin is important in the contribution of dissolved material to oceans (4% worldwide). The aim of this work was to study the spatial and the temporal variability of dissolved inorganic materials in the main rivers of the Amazon basin. Data from 2003 to 2011 from six gauging stations of the ORE-HYBAM localized in Solimões, Purus, Madeira and Amazon rivers were used for this study. , HCO 3 -and SO 4 -2 had heterogeneous distribution over the years and did not show seasonality. At the stations of Madeira river, the concentration of these ions had seasonality inversely proportional to water discharge (dilution-concentration effect). Similar behavior was observed for the concentrations of Cl -and Na + at the stations of the Solimões, Amazon and Madeira rivers, indicating almost constant release of Cl -and Na + fluxes during the hydrological cycle. K + and SiO 2 showed almost constant concentrations throughout the years and all the stations, indicating that their flows depend on the river discharge variation. Therefore, the temporal variability of the dissolved inorganic material fluxes in the Solimões and Amazon rivers depends on the hydro-climatic factor and on the heterogeneity of the sources. In the Madeira and Purus rivers there is less influence of these factors, indicating that dissolved load fluxes are mainly associated to silicates weathering. As the Solimões basin contributes approximately 84% of the total flux of dissolved materials in the basin and is mainly under the influence of a hydro-climatic factor, we conclude that the temporal variability of this factor controls the temporal variability of the dissolved material fluxes of the Amazon basin.

show abstract

Seasonal variability of total dissolved fluxes and origin of major dissolved elements within a large tropical river: The Orinoco, Venezuela

Cited by 32 publications

References 31 publications

Multi‐annual contemporary flood event overbank sedimentation within the vegetated lower Orinoco floodplain, Venezuela

Multi‐annual contemporary flood event overbank sedimentation within the vegetated lower Orinoco floodplain, Venezuela

Dynamics and fluxes of organic carbon and nitrogen in two Guiana Shield river basins impacted by deforestation and mining activities

Spatial-temporal variation of dissolved inorganic material in the Amazon basin

Contact Info

Product

Resources

About