scholarly journals Organic carbon burial by river meandering partially offsets bank-erosion carbon fluxes in a discontinuous permafrost floodplain

2021 ◽  
Author(s):  
Madison M. Douglas ◽  
Gen K. Li ◽  
Woodward W. Fischer ◽  
Joel C. Rowland ◽  
Preston C. Kemeny ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Bank Erosion ◽  
Carbon Fluxes ◽  
Erosion And Deposition ◽  
Carbon Burial ◽  
Discontinuous Permafrost ◽  
Organic Carbon Burial ◽  
River Erosion ◽  
Point Bars ◽  
River Meandering

Abstract. Arctic river systems erode permafrost in their banks and mobilize particulate organic carbon (OC). Meandering rivers can entrain particulate OC from permafrost many meters below the depth of annual thaw, potentially enabling OC oxidation and the production of greenhouse gases. However, the amount and fate of permafrost OC that is mobilized by river erosion is uncertain. To constrain OC fluxes due to riverbank erosion and deposition, we collected riverbank and floodplain sediment samples along the Koyukuk River, which meanders through discontinuous permafrost in central Alaska. We measured sediment total OC (TOC), radiocarbon content, water content, bulk density, grain size, and floodplain stratigraphy. Radiocarbon abundance and TOC were higher in samples dominated by silt as compared to sand, which we used to map OC content onto floodplain stratigraphy and estimate carbon fluxes due to river meandering. Results showed that sediment being eroded from cutbanks and deposited as point bars had similar OC stocks (mean ± 1SD of 125.3 ± 13.1 kgOC m−2 in cutbanks versus 114.0 ± 15.7 kgOC m−2 in point bars) whether or not the banks contained permafrost. We also observed radiocarbon-depleted biospheric OC in both cutbanks and permafrost-free point bars. These results indicate that a significant fraction of aged biospheric OC that is liberated from floodplains by bank erosion is subsequently re-deposited in point bars, rather than being oxidized. The process of aging, erosion, and re-deposition of floodplain organic material may be intrinsic to river-floodplain dynamics, regardless of permafrost content.

scholarly journals Past climate variations recorded in needle-like aragonites correlate with organic carbon burial efficiency as revealed by lake sediments in Croatia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ivan Razum ◽  
Petra Bajo ◽  
Dea Brunović ◽  
Nikolina Ilijanić ◽  
Ozren Hasan ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Stable Carbon Isotope ◽  
Climate Variations ◽  
Before Present ◽  
Stable Carbon ◽  
Climate Trends ◽  
Geochemical Proxies ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Burial Efficiency

AbstractThe drivers of organic carbon (OC) burial efficiency are still poorly understood despite their key role in reliable projections of future climate trends. Here, we provide insights on this issue by presenting a paleoclimate time series of sediments, including the OC contents, from Lake Veliko jezero, Croatia. The Sr/Ca ratios of the bulk sediment are mainly derived from the strontium (Sr) and calcium (Ca) concentrations of needle-like aragonite in Core M1-A and used as paleotemperature and paleohydrology indicators. Four major and six minor cold and dry events were detected in the interval from 8.3 to 2.6 calibrated kilo anno before present (cal ka BP). The combined assessment of Sr/Ca ratios, OC content, carbon/nitrogen (C/N) ratios, stable carbon isotope (δ13C) ratios, and modeled geochemical proxies for paleoredox conditions and aeolian input revealed that cold and dry climate states promoted anoxic conditions in the lake, thereby enhancing organic matter preservation and increasing the OC burial efficiency. Our study shows that the projected future increase in temperature might play an important role in the OC burial efficiency of meromictic lakes.

scholarly journals Climate influence on organic carbon burial efficiency as revealed from a multi-proxy lake sediment record in Croatia

2020 ◽  
Author(s):  
Ivan Razum ◽  
Petra Bajo ◽  
Dea Brunović ◽  
Nikolina Ilijanić ◽  
Ozren Hasan ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Lake Sediment ◽  
Sediment Record ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Burial Efficiency

Long-term Aptian marine osmium isotopic record of Ontong Java Nui activity

Geology ◽  
2021 ◽  
Author(s):  
Hironao Matsumoto ◽  
Rodolfo Coccioni ◽  
Fabrizio Frontalini ◽  
Kotaro Shirai ◽  
Luigi Jovane ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Volcanic Eruptions ◽  
Hydrothermal Activity ◽  
Published Data ◽  
Isotopic Data ◽  
Oceanic Plateaus ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Isotopic Records

The early to mid-Aptian was punctuated by episodic phases of organic-carbon burial in various oceanographic settings, which are possibly related to massive volcanism associated with the emplacement of the Ontong Java, Manihiki, and Hikurangi oceanic plateaus in the southwestern Pacific Ocean, inferred to have formed a single plateau called Ontong Java Nui. Sedimentary osmium (Os) isotopic compositions are one of the best proxies for determining the timing of voluminous submarine volcanic episodes. However, available Os isotopic records during the age are limited to a narrow interval in the earliest Aptian, which is insufficient for the reconstruction of long-term hydrothermal activity. We document the early to mid-Aptian Os isotopic record using pelagic Tethyan sediments deposited in the Poggio le Guaine (Umbria-Marche Basin, Italy) to precisely constrain the timing of massive volcanic episodes and to assess their impact on the marine environment. Our new Os isotopic data reveal three shifts to unradiogenic values, two of which correspond to black shale horizons in the lower to mid-Aptian, namely the Wezel (herein named) and Fallot Levels. These Os isotopic excursions are ascribed to massive inputs of unradiogenic Os to the ocean through hydrothermal activity. Combining the new Os isotopic record with published data from the lowermost Aptian organic-rich interval in the Gorgo a Cerbara section of the Umbria-Marche Basin, it can be inferred that Ontong Java Nui volcanic eruptions persisted for ~5 m.y. during the early to mid-Aptian.

Organic Carbon Burial in Lakes and Reservoirs of the Conterminous United States

2015 ◽  
Vol 49 (13) ◽  
pp. 7614-7622 ◽  
Author(s):  
David W. Clow ◽  
Sarah M. Stackpoole ◽  
Kristine L. Verdin ◽  
David E. Butman ◽  
Zhiliang Zhu ◽  
...  
Keyword(s):  
United States ◽  
Organic Carbon ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Lakes And Reservoirs

Mechanism and geochemical implications of the Late Holocene organic carbon burial event: an example from the southwest coast of India

2009 ◽  
Vol 59 (7) ◽  
pp. 1409-1416 ◽  
Author(s):  
B. Ajaykumar ◽  
Mahesh Mohan ◽  
M. S. Shylesh Chandran ◽  
K. K. Jayasooryan ◽  
K. S. Unni ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Late Holocene ◽  
Southwest Coast Of India ◽  
Southwest Coast ◽  
Carbon Burial ◽  
Organic Carbon Burial

Enhanced paleo-wildfire occurrences caused by marine organic carbon burial during the Late Devonian Frasnian–Famennian mass extinction

2021 ◽  
Author(s):  
Man Lu ◽  
YueHan Lu ◽  
Takehitio Ikejiri ◽  
Richard Carroll
Keyword(s):  
Organic Carbon ◽  
Mass Extinction ◽  
Atmospheric Oxygen ◽  
Burial Rate ◽  
Carbon Burial ◽  
Chattanooga Shale ◽  
Chemical Index ◽  
Organic Carbon Burial ◽  
Polycyclic Aromatic ◽  
Extinction Events

<p>The Frasnian–Famennian (F–F) boundary is characterized by worldwide depositions of organic-rich strata, a series of marine anoxia events and one of the biggest five mass extinction events of the Phanerozoic. Due to the enhanced burial of organic matter, a coeval positive carbon isotope (δ<sup>13</sup>C) excursion occurred around the F–F boundary, raising questions about carbon cycle feedbacks during the mass extinction. In this study, we test the hypothesis that enhanced burial organic carbon during the F–F mass extinction led to the rise of paleo-wildfire occurrences. Here, we reconstructed paleo-wildfire changes across the F–F boundary via analyzing fossil charcoal (inertinites) and pyrogenic polycyclic aromatic hydrocarbons (PAHs) from an Upper Devonian Chattanooga Shale in the southern Appalachian Basin. Our data show low abundances of inertinites and pyrogenic PAHs before the F–F transition and an increasing trend during the F–F transition, followed by a sustained enhancement through the entire Famennian interval. The changes in paleo-wildfire proxies suggest a rise of wildfires starting from the F–F transition. Furthermore, we quantified the amount of organic carbon burial required to drive the observed δ<sup>13</sup>C excursion using a forward box model. The modeling results show an increased carbon burial rate after the onset of the F–F transition and peaking during its termination. The comparison of the carbon burial rate and wildfire proxies indicates that widespread organic carbon burial during the F–F transition might cause elevated atmospheric oxygen levels and hence increased occurrences of wildfires. In addition, chemical index alteration index and plant biomarkers suggest a drying climate initiated during the F–F transition, implying that the enhanced carbon burial probably result in the climate change and amplify the wildfire occurrences.</p>

Increased Organic Carbon Burial in Northern Florida Mangrove‐Salt Marsh Transition Zones

2020 ◽  
Vol 34 (5) ◽  
Author(s):  
Derrick R. Vaughn ◽  
Thomas S. Bianchi ◽  
Michael R. Shields ◽  
William F. Kenney ◽  
Todd Z. Osborne
Keyword(s):  
Salt Marsh ◽  
Organic Carbon ◽  
Transition Zones ◽  
Carbon Burial ◽  
Organic Carbon Burial
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