Source, transport and fluxes of Amazon River particulate organic carbon: Insights from river sediment depth-profiles

Bouchez, Julien; Galy, Valier; Hilton, Robert; Gaillardet, Jérôme; Moreira-Turcq, Patrícia; Pérez, M.; France‐Lanord, Christian; Maurice, Laurence

doi:10.1016/j.gca.2014.02.032

Cited by 146 publications

(196 citation statements)

References 83 publications

Supporting

Mentioning

172

Contrasting

Unclassified

Order By: Relevance

“…The contribution from rock-derived OC in the Fraser River is large in comparison to the Ganges-Brahmaputra and Amazon rivers (0.025% and 0.06%, respectively), but smaller than that of the small mountainous rivers draining Taiwan (0.35%) (Galy et al, 2008a;Hilton et al, 2010;Bouchez et al, 2014). These differences are driven by both the OC content of the bedrock being weathered in these basins, as well as the efficiency of petrogenic OC mineralization during riverine transport.…”

Section: Seasonality Of Oc Age and Compositionmentioning

confidence: 93%

“…For instance, by calculating the amount of modern OC in a suite of samples, a petrogenic (i.e. 14 Cdead) contribution can be estimated, as well as an average age for non-petrogenic OC Bouchez et al, 2014). As the non-petrogenic component is the portion of POC that, when sequestered in marine sediments, represents a net sink of atmospheric CO 2 , this distinction is vital to quantifying the importance of riverine POC flux to long-term global climate cycles.…”

Section: Geochemical Tools For River Biogeochemistrymentioning

confidence: 99%

“…The amount of riverine particulate organic carbon (POC) derived from recent terrestrial photosynthesis versus aquatic productivity and weathering of petrogenic organic carbon is controlled by a range of tectonic, climatic, geomorphologic, and biogeochemical processes (Blair et al, 2004;Leithold et al, 2006;Longworth et al, 2007;Hilton et al, 2010;Hovius et al, 2011;Hilton et al, 2012;Bouchez et al, 2014), which differ significantly across river basins.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective

Voß¹

2014

View full text Add to dashboard Cite

The great geologic and climatic diversity of the Fraser River basin in southwestern Canada render it an excellent location for understanding biogeochemical cycling of sediments and terrigenous organic carbon in a relatively pristine, large, temperate watershed. Sediments delivered by all tributaries have the potential to reach the ocean due to a lack of main stem lakes or impoundments, a unique feature for a river of its size. This study documents the concentrations of a suite of dissolved and particulate organic and inorganic constituents, which elucidate spatial and temporal variations in chemical weathering (including carbonate weathering in certain areas) as well as organic carbon mobilization, export, and biogeochemical transformation. Radiogenic strontium isotopes are employed as a tracer of sediment provenance based on the wide variation in bedrock age and lithology in the Fraser basin. The influence of sediments derived from the headwaters is detectable at the river mouth, however more downstream sediment sources predominate, particularly during high discharge conditions. Bulk radiocarbon analyses are used to quantify terrestrial storage timescales of organic carbon and distinguish between petrogenic and biospheric organic carbon, which is critical to assessing the role of rivers in long-term atmospheric CO 2 consumption. The estimated terrestrial residence time of biospheric organic carbon in the Fraser basin is 650 years, which is relatively short compared to other larger rivers (Amazon, Ganges-Brahmaputra) in which this assessment has been performed, and is likely related to the limited floodplain storage capacity and non-steadystate post-glacial erosion state of the Fraser River. A large portion of the dissolved inorganic carbon load of the Fraser River (>80%) is estimated to derive from remineralization of dissolved organic carbon, particularly during the annual spring freshet when organic carbon concentrations increase rapidly. This thesis establishes a baseline for carbon cycling in a largely unperturbed modern mid-latitude river system and establishes a framework for future process studies on the mechanisms of organic carbon turnover and organic matter-mineral associations in river systems.

show abstract

Section: Seasonality Of Oc Age and Compositionmentioning

confidence: 93%

Section: Geochemical Tools For River Biogeochemistrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective

Voß¹

2014

View full text Add to dashboard Cite

show abstract

“…Physical processes include particle size and density (Rouse, 1950;Wilson et al, 2008;Burd and Jackson, 2009;Bouchez et al, 2011;Lupker et al, 2011), mineral-POC associations Mayer et al, 2004;Bouchez et al, 2014), and advection and mixing of water parcels (Dall'Olmo and Mork, 2014). Processes that control remineralization rates include the composition of phytoplankton, zooplankton and particle-associated bacterial communities (Battin et al, 2008;Guidi et al, 2009;Satinsky et al, 2014), and relatedly, the composition and quality of POC exported by different phytoplankton communities .…”

Section: Mechanisms Of Poc Export and Transfer Efficiencymentioning

confidence: 99%

“…Further, interpreting point measurements at one location of the river network is limiting because large rivers systems like the Amazon are heterogeneous in space and time. Within the Amazon cross-section, hydrodynamic sorting causes large grain-size sediments to settle faster and thus concentrate at deeper depths (Rouse 1950;Gibbs, 1967;Curtis et al, 1979;Bouchez et al, 2011b), leading to compositional differences between the deeper, coarser sediments and the shallower, finer sediments (Bouchez et al, 2011a;Bouchez et al, 2014). Finally, seasonality presents another challenge to measuring fluxes.…”

Section: Introductionmentioning

confidence: 99%

Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles

Rosengard¹

2017

View full text Add to dashboard Cite

Particulate organic carbon (POC) in the ocean and mobilized by rivers on land transfers ~0.1% of global primary productivity to the deep ocean sediments. This small fraction regulates the long-term carbon cycle by removing carbon dioxide from the atmosphere for centuries to millennia. This thesis investigates mechanisms of POC transfer to the deep ocean by analyzing particles collected in transit through two globally significant carbon reservoirs: the Southern Ocean and the Amazon River Basin. These endeavors test the hypothesis that organic matter composition controls the recycling and transfer efficiency of POC to the deep ocean, and illustrate new applications for ramped pyrolysis/oxidation (RPO), a growing method of POC characterization by thermal stability. By coupling RPO to stable and radiocarbon isotope analyses of riverine POC, I quantify three thermally distinct soil organic carbon pools mobilized by the Amazon River, and evaluate the degradability and fate of these different pools during transport to the coastal Atlantic Ocean. More directly, RPO analyses of marine samples suggest that POC transfer in the water column is in fact selective. Observations of consistent biomolecular changes that accompany transport of phytoplankton-derived organic matter to depth across the Southern Ocean support the argument for preferential degradation of specific POC pools in the water column. Combining discussions of POC recycling and transfer across both marine and terrestrial systems offer new perspectives of thermal stability as a proxy for diagenetic stability and POC degradation state. The challenges of interpreting RPO data in these two environments set the stage for applying the technique to more controlled experiments that trace POC from source to long-term sink.

show abstract

Dam‐triggered organic carbon sequestration makes the Changjiang (Yangtze) river basin (China) a significant carbon sink

Wang

Yang

et al. 2015

JGR Biogeosciences

View full text Add to dashboard Cite

Worldwide dam building in large river basins has substantially altered the carbon cycle by trapping much of the riverine transported particulate organic carbon (POC) in terrestrial reservoirs. Here we take the Changjiang (Yangtze) River basin, in which~50,000 dams were built over the past 50 years, as an example to evaluate the effect of dam building on POC sequestration. We report the characteristics (elemental composition, radiocarbon and stable carbon isotopic compositions, and Raman spectra) of bulk POC in the lower Changjiang from October 2007 to September 2008, and we estimate the POC sequestration induced by dam building since the 1950s for the Changjiang Basin. Using radiocarbon measurements, we quantify the fraction of biospheric POC (POC bio ) and petrogenic POC (POC petro ) in Changjiang POC. Over the study period, around 25% of the Changjiang POC is radiocarbon-dead POC petro ; the remaining is POC bio with a mean radiocarbon age of~3.5 kyr. Studies on the East China Sea (ECS) shelf along with an oxidation experiment suggest that, prior to dam building, the Changjiang POC bio was significantly oxidized in the ECS margin. In contrast, high preservation of POC is observed in Changjiang reservoirs. Combining our POC data with hydrometric data sets, our study indicates that, over the past five decades, dam building may have largely shifted the Changjiang POC burial site from the ECS margin to terrestrial reservoirs. This shift in burial site preserved labile POC bio that would have been oxidized, suggesting a new temporary carbon sink. We estimate that dam building in the Changjiang has sequestered~4.9 ± 1.9 megatons POC bio every year since 2003, approximately 10% of the global riverine POC burial flux to the oceans.

show abstract

Source, transport and fluxes of Amazon River particulate organic carbon: Insights from river sediment depth-profiles

Cited by 146 publications

References 83 publications

Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective

Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective

Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles

Dam‐triggered organic carbon sequestration makes the Changjiang (Yangtze) river basin (China) a significant carbon sink

Contact Info

Product

Resources

About