Particulate organic matter export by two contrasting small mountainous rivers from the Pacific Northwest, U.S.A.

Goñi, Miguel A.; Hatten, J. A.; Wheatcroft, Robert A.; Borgeld, Jeffry C.

doi:10.1002/jgrg.20024

Cited by 105 publications

(106 citation statements)

References 85 publications

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“…Therefore, systematic δ 13 C and δ 15 N investigations in hadal environments may shed some lights about whether the dark ocean is an environment of substantial terrestrial C pool or not. In addition, radiocarbon ( 14 C) measurements of particles and sediments in hadal trenches, similar to studies made from other river and marine realms (Bauer et al, 1992;Raymond and Bauer, 2001;Goñi et al, 2013), may provide additional constraints on age, fate and reactivity of OM and therefore provide clues about the transport mechanism and the nature of particles and sediments in the dark ocean.…”

Section: Biogeochemistry Of Hadal Worldmentioning

confidence: 88%

Perspectives on the Terrestrial Organic Matter Transport and Burial along the Land-Deep Sea Continuum: Caveats in Our Understanding of Biogeochemical Processes and Future Needs

Kandasamy

Nath

2016

Front. Mar. Sci.

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The natural carbon cycle is immensely intricate to fully understand its sources, fluxes and the processes that are responsible for their cycling in different reservoirs and their balances on a global scale. Anthropogenic perturbations add another dimension to such a complex cycle. Therefore, it is necessary to update the global carbon cycle by combining both natural and anthropogenic sources, fluxes and sinks along the land-sea continuum to assess whether these terms are currently in balance or not. Here, we review the export and burial rates of terrestrial organic carbon in the oceans to understand the issue of "missing terrigenous carbon" by comparing data-and model-based estimates of terrestrial carbon fluxes. Our review reveals large disparities between field data and model output in terms of dissolved and particulate organic carbon/matter (OC/OM) fluxes and their ratios, especially for Oceania and Arctic rivers, suggesting the need of additional investigations in these regions to refine terrestrial OC export budget. Based on our budgeting of global sources and sinks of OC with updated estimates of marine productivity and terrestrial OM burial rate, we find that the marginal sediments are key burial sites of terrestrial OM (TOM), which is consistent with earlier views of Berner (1982) and Hedges and Keil (1995). While about 60-80% of TOM is remineralized in the margins, the estimated budget further reveals the ocean derived OM is efficiently remineralized than that of terrestrial OM, emphasizing the need of further improvements of carbon burial estimation in the marine realm. When we look back in the past, higher terrestrial OC burial (by ∼50%) in the deep ocean during the glacials than during the interglacials and suggests the subdued role of continental margins and an efficient transfer and preservation of OM from the shelf to deep sea in glacials. Based on the review of terrestrial and marine OM burial, we suggest some critical regions/ways that need to be investigated/addressed further, identification of new biogeochemical proxies and their grouping to better constrain the global carbon cycle along the land-deep sea continuum in future.

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Section: Biogeochemistry Of Hadal Worldmentioning

confidence: 88%

Perspectives on the Terrestrial Organic Matter Transport and Burial along the Land-Deep Sea Continuum: Caveats in Our Understanding of Biogeochemical Processes and Future Needs

Kandasamy

Nath

2016

Front. Mar. Sci.

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“…Apart from the indications of OC mineralisation, the MOC concentration of suspended sediments was low and very variable (3.8-0.1 %), which can be attributed to the diverse characteristics of the events that mobilise material from different sources (Smith et al, 2013;Goñi et al, 2013;Sanchez-Vidal et al, 2013) or to sediments mobilised by different erosion processes (Nadeu et al, 2011(Nadeu et al, , 2012.…”

Section: Processes Affecting Organic Carbon Dynamics During Transportmentioning

confidence: 99%

“…Differences in OC pools between sediment deposits can also be the result of transport conditions due to higher or lower rainfall intensity (Martínez-Mena et al, 2012;Zhang et al, 2013) or to the discharge. Smith et al (2013) related high discharge rates with transport of modern C, associated with erosion and the release of organic matter (Sanchez-Vidal et al, 2013), and C from vascular sources (Goñi et al, 2013). Low flows were associated with export of fossil OC (Smith et al, 2013) from biogenic sources dominated by non-vascular plants (Goñi et al, 2013) or from freshwater primary producers (Sanchez-Vidal et al, 2013).…”

Section: Size Selectivity and Sources Of Sedimentmentioning

confidence: 99%

“…Smith et al (2013) related high discharge rates with transport of modern C, associated with erosion and the release of organic matter (Sanchez-Vidal et al, 2013), and C from vascular sources (Goñi et al, 2013). Low flows were associated with export of fossil OC (Smith et al, 2013) from biogenic sources dominated by non-vascular plants (Goñi et al, 2013) or from freshwater primary producers (Sanchez-Vidal et al, 2013). A comparison of the particle sizes of the studied sediments and soils of the catchment points to a selection of transported material in a downstream direction.…”

Section: Size Selectivity and Sources Of Sedimentmentioning

confidence: 99%

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Sediment flow paths and associated organic carbon dynamics across a Mediterranean catchment

Boix‐Fayos

Nadeu

Quiñonero

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. Terrestrial sedimentation buries large amounts of organic carbon (OC) annually, contributing to the terrestrial carbon sink. The temporal significance of this sink will strongly depend on the attributes of the depositional environment, but also on the characteristics of the OC reaching these sites and its stability upon deposition. The goal of this study was to characterise the OC during transport and stored in the depositional settings of a mediumsized catchment (111 km 2 ) in SE Spain, to better understand how soil erosion and sediment transport processes determine catchment-scale OC redistribution. Total organic carbon (TOC), mineral-associated organic carbon (MOC), particulate organic carbon (POC), total nitrogen (N) and particle size distributions were determined for soils (i), suspended sediments (ii) and sediments stored in a variety of sinks such as sediment wedges behind check dams (iii), channel bars (iv), a small delta in the conjunction of the channel and a reservoir downstream (v), and the reservoir at the outlet of the catchment (vi). The data show that the OC content of sediments was approximately half of that in soils (9.42 ± 9.01 g kg −1 versus 20.45 ± 7.71 g kg −1 , respectively) with important variation between sediment deposits. Selectivity of mineral and organic material during transport and deposition increased in a downstream direction. The mineralisation, burial or in situ incorporation of OC in deposited sediments depended on their transport processes and on their post-sedimentary conditions. Upstream sediments (alluvial wedges) showed low OC contents because they were partially mobilised by non-selective erosion processes affecting deeper soil layers and with low selectivity of grain sizes (e.g. gully and bank erosion). We hypothesise that the relatively short transport distances, the effective preservation of OC in microaggregates and the burial of sediments in the alluvial wedges gave rise to low OC mineralisation, as is arguably indicated by C : N ratios similar to those in soils. Deposits in middle stream areas (fluvial bars) were enriched in sand, selected upon deposition and had low OC concentrations. Downstream, sediment transported over longer distances was more selected, poorly microaggregated, and with a prevalence of silt and clay fractions and MOC pool. Overall, the study shows that OC redistribution in the studied catchment is highly complex, and that the results obtained at finer scales cannot be extrapolated at catchment scale. Selectivity of particles during detachment and transport, and protection of OC during transport and deposition are key for the concentration and quality of OC found at different depositional settings. Hence, eco-geomorphological processes during the different phases of the erosion cycle have important consequences for the temporal stability and preservation of the buried OC and in turn for the OC budget.

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“…The balance between river inflows, tidal oscillations, and wind stirring processes at the respective boundaries regulates the distribution and fate of material, nutrients and biota. River plume responses for small discharges are not well understood, despite small mountainous rivers delivering disproportionate quantities of particulate organic carbon (POC) to the global budget (Wheatcroft et al, 2010;Goni et al, 2013). Here, the focus is on understanding responses during individual discharge events and evaluating the cumulative role of material transport for a coastal system.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Surface Response of Discharge Events in a New Zealand Gulf-ROFI

O'Callaghan

Stevens

2017

Front. Mar. Sci.

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Using moorings with a surface expression, responses of buoyant river outflows were examined in the Firth-Hauraki Gulf system, New Zealand. The Firth region of freshwater influence (ROFI) behaves as a gulf-type ROFI where the balance of key processes lies between rotation and advection. The latter process is largely regulated by the frequency and amplitude of freshwater discharges. Using 12-months of observations from two inner Firth sites, the system was found to be salinity stratified for up to 4 months of a year. During the largest event (274 m 3 s −1 , mean daily maximum) in 2012 near-oceanic surface salinity (34 psu) freshened substantially down to 28 psu over the upper 3 m. Time lags between freshwater inflows and ROFI response were 4 and 7 days at the Waiheke and WilsonB locations, respectively. Faster seaward advection of surface layers occurred for a minimum of 3 days and up to a week after peak discharges. High frequency winds (∼3-hourly) were persistent in regulating surface flows over the annual cycle. Surface salinity had peaks in energy that were coherent with surface flows at periods of 16-32 days over the Austral winter. The duration of discharge events was O(days), yet responses by buoyancy and advection were evident for weeks to a month in the Firth ROFI.

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Particulate organic matter export by two contrasting small mountainous rivers from the Pacific Northwest, U.S.A.

Cited by 105 publications

References 85 publications

Perspectives on the Terrestrial Organic Matter Transport and Burial along the Land-Deep Sea Continuum: Caveats in Our Understanding of Biogeochemical Processes and Future Needs

Perspectives on the Terrestrial Organic Matter Transport and Burial along the Land-Deep Sea Continuum: Caveats in Our Understanding of Biogeochemical Processes and Future Needs

Sediment flow paths and associated organic carbon dynamics across a Mediterranean catchment

Evaluating the Surface Response of Discharge Events in a New Zealand Gulf-ROFI

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