Temporal variation and fluxes of dissolved and particulate organic carbon in the Apure, Caura and Orinoco rivers, Venezuela

Mora, Abrahan; Laraque, Alain; Moreira-Turcq, Patrícia; Alfonso, Juan A.

doi:10.1016/j.jsames.2014.04.010

Cited by 26 publications

(30 citation statements)

References 40 publications

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“…The range of concentration of DOC found in the Maroni River corresponds to that observed previously by Sondag et al, () at LT between 2004 and 2008, whereas the range of concentrations of DOC in the Oyapock is very similar to that shown by Gadel, Serve, and Blazi () downstream of the Petit Saut dam in the Sinnamary River basin, which is another small basin in French Guiana. When comparing the results of DOC concentrations in both French Guiana rivers to those obtained in other rivers draining the Guiana and Brazilian Shields, it can be seen that the DOC values in the Maroni and Oyapock are higher than those found in the blackwaters of the Caura River (2.08–4.93 mgC L −1 ; Mora et al, ), but lower than those found in the Negro River (2–18 mgC L −1 ) (Moreira‐Turcq et al, ). However, these values are similar to those reported in the clearwaters of the Trombetas River (Moreira‐Turcq et al, ; between 2 and 12 mgC L −1 ).…”

Section: Resultsmentioning

confidence: 95%

“…This is because the Guiana Shield has one of the lowest erosion rates in the world, with only two metres eroded every 1 million years in French Guiana and Suriname (Théveniaut & Delor, ). Indeed, such low TSS concentrations are typical from rivers draining the Guiana and Brazilian Shields, such as the Caura and Caroni Rivers in the Orinoco River basin and the Negro, Branco, Tapajós, Trobetas, and Xingú Rivers in the Amazon River basin (Lewis & Weibezahn, ; Mora, Laraque, Moreira‐Turcq, & Alfonso, ; Moreira‐Turcq, Seyler, Guyot, & Etcheber, ).…”

Section: Resultsmentioning

confidence: 99%

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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

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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.

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Section: Resultsmentioning

confidence: 95%

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

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“…In recent years, the environmental effects of sediment movement through a river basin ha ve been investigated in terms of variations in natural organic matter, nutrients, and contaminants in water-sediment two-phase systems, extending to multiphase systems of water-sediment-carbon, water-sediment-nitrogen, and water-sediment-phosphorous, owing to the considerable annual losses of carbon, total nitrogen (TN) and total phosphorous (TP ) to surface waters (Panagopoulos et al, 2007;Mora et al, 2014). At the time of writing, there is an increasing research focus on the migration and transformation of the organic and inorganic forms of carbon, largely because of their sensitivity to global environmental change (Raymond and Bauer, 2001;Galy et al, 2007).…”

Section: Preamblementioning

confidence: 99%

Sediment Flux and Its Environmental Implications

2014

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Sediment transport in fluvial systems is a key driver of basin-wide global soil loss, river sedimentation, and the movement and transformation of organic, inorganic, and nutrient materials, all of which can contribute to severe eco-environmental degradation. Since the late 1800s, much research effort has focused on the physics of sediment entrainment, transport, and deposition by river flows. This paper reviews ongoing research aimed at considering the simultaneous physical, chemical and biological processes that characterize riverine sediment flux. Four related issues are considered: riverine sediment flux; soil erosion and chemical transport; fluxes of dissolved organic carbon; and sediment-induced CO 2 emission/sequestration.Modelling of sediment flux has moved beyond empirical and statistical approaches to that of a generalized form of the universal integral solution of the basic flux equation, which is now anticipated to lead to a wide range of applications. Whereas soil erosion and riverine chemical transport are now known to cause soil degradation and reduced water quality, limited progress has been made to date on the quantification of erosion rates. As soils erode, CO 2 is emitted at erosion and transport sites and sequestered at deposition sites, the net effect being carbon sequestration. Howe ver, the rates of CO 2 emission/sequestration vary widely, owing to the large spatial variations in soil type, land-slope, rainfall intensity, etc. It is now well established that dissolved organic carbon (DOC) concentrations and fluxes have been increasing over the past two decades, due to reduced atmospheric sulphur concentration, climate warming, and changes in precipitation patterns. The research discussed herein provides insight into the interaction between sediment and multiple material substances, leading to a better understanding of fluvial river ecosystems, which is essential for maintaining river health. KeywordsSediment flux, soil erosion, environmental implication, chemical transport, dissolved organic carbon, CO 2 flux, PreambleConventionally, the main surface material transport processes associated with sediment movement in a river basin may be categorized as runoff and sediment yield, soil erosion and nutrient loss, and river geomorphological evolution. The material transport processes tend to be considered by hydrologists, sedimentologists, hydraulic engineers, agronomists, ecologists, and environmentalists (Kisi et al., 2013;Van Rijn et al., 2013;Miller et al., 2014), whereas the geomorphic evolution of a watershed is the primary concern of geomorphologists (Provansal et al., 2014;Toone et al., 2014).In recent years, the environmental effects of sediment movement through a river basin ha ve been investigated in terms of variations in natural organic matter, nutrients, and contaminants in water-sediment two-phase systems, extending to multiphase systems of water-sediment-carbon, water-sediment-nitrogen, and water-sediment-phosphorous, owing to the considerable annual losses of carbon, tota...

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“…The historical paucity of datasets representing tropical river systems has been a strong impetus for the burgeoning research on sediment and C fluxes within these systems over the past decade, and has also witnessed a broadening geographical coverage. While the Amazon has traditionally functioned as the archetype for tropical rivers (Richey et al 2002;Moreira-Turcq et al 2003Mayorga et al 2005;Abril et al 2014), there has been an increase in data availability from other systems in LatinAmerica (Depetris and Kempe 1993;Laraque et al 2013;Mora et al 2014), as well as a range of systems in Asia (Sarin et al 2002;Aldrian et al 2008;Bird et al 2008;Zhou et al 2013), small islands (Wiegner et al 2009;Lloret et al 2011), and Africa (Coynel et al 2005;Brunet et al 2009;Bouillon et al 2012;Wang et al 2013;Zurbrügg et al 2013;Tamooh et al 2014;Borges et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Seasonal and inter-annual variations in carbon fluxes in a tropical river system (Tana River, Kenya)

et al. 2018

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The hydrological status of river systems is expected to change due to dam operations and climate change. This will affect the riverine fluxes of sediment and carbon (C). In rivers with strong seasonal and inter-annual variability, quantification and extrapolation of sediment and C fluxes can be a challenge as measurement periods are often too short to cover all hydrological conditions. We studied the dynamics of the Tana River (Kenya) from 2012 to 2014 through daily monitoring of sediment concentrations at three sites (Garissa, Tana River Primate Reserve and Garsen) and daily monitoring of C concentrations in Garissa and Garsen during three distinct seasons. A bootstrap method was applied to calculate the range of sediment and C fluxes as a function of annual discharge by using daily discharge data . Overall, we estimated that on average, sediment and carbon were retained in this 600 km long river section between Garissa to Garsen over the 73 years (i.e., fluxes were higher at the upstream site than downstream): integration over all simulations resulted in an average net retention of sediment (~ 2.9 Mt year − 1 ), POC (~ 18,000 tC year − 1 ), DOC (~ 920 tC year − 1 ) and DIC (~ 1200 tC year − 1 ). To assess the impact of hydrological variations, we constructed four different hydrological scenarios over the same period. Although there was significant non-linearity and difference between the C species, our estimates generally predicted a net increase of C retention between the upstream and downstream site when the annual discharge would decrease, for example caused by an increase of irrigation with reservoir water. When simulating an increase in the annual discharge, e.g. as a potential effect of climate change, we predicted a decrease in C retention.

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Temporal variation and fluxes of dissolved and particulate organic carbon in the Apure, Caura and Orinoco rivers, Venezuela

Cited by 26 publications

References 40 publications

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

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

Sediment Flux and Its Environmental Implications

Seasonal and inter-annual variations in carbon fluxes in a tropical river system (Tana River, Kenya)

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