scholarly journals Orbital forcing of terrestrial hydrology, weathering and carbon sequestration during the Palaeocene-Eocene Thermal Maximum

2017 ◽  
Author(s):  
Tom Dunkley Jones ◽  
Hayley R. Manners ◽  
Murray Hoggett ◽  
Sandra Kirtland Turner ◽  
Thomas Westerhold ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Organic Carbon ◽  
Radical Change ◽  
Transport Processes ◽  
The Body ◽  
Sediment Flux ◽  
Earth System ◽  
Accumulation Rates ◽  
Thermal Maximum ◽  
Organic Carbon Burial

Abstract. The response of the Earth System to greenhouse-gas driven warming is of critical importance for the future trajectory of our planetary environment. Hypethermal events – past climate transients with significant global-scale warming – can provide insights into the nature and magnitude of these responses. The largest hyperthermal of the Cenozoic was the Palaeocene-Eocene Thermal Maximum (PETM ~ 56 Ma). Here we present a new high-resolution cyclostratigraphy for the classic PETM section at Zumaia, Spain. With this new age model we are able to demonstrate that detrital sediment accumulation rates within this continental margin section increased more than four-fold during the PETM, representing a radical change in regional hydrology that drove dramatic increases in terrestrial to marine sediment flux. During the body of the PETM, orbital-scale variations in bulk sediment Si/Fe ratios are evidence for the continued orbital pacing of sediment erosion and transport processes, most likely linked to precession controls on sub-tropical hydroclimates. Most remarkable is that detrital accumulation rates remain high throughout the body of the PETM, and even reach peak values during the recovery phase of the characteristic PETM carbon isotope excursion (CIE). Using a series of Earth System Model inversions, we demonstrate that the silicate weathering feedback alone is insufficient to recover the PETM CIE, and that active organic carbon burial is required to match the observed dynamics of the CIE. Further, that the period of maximum organic carbon sequestration coincides with the peak in detrital accumulation rates observed at Zumaia. Based on these results, we hypothesize that precession controls on tropical and sub-tropical hydroclimates, and the sediment dynamics associated with this variation, play a significant role in the timing of the rapid climate and CIE recovery from peak-PETM conditions.

scholarly journals Dynamics of sediment flux to a bathyal continental margin section through the Paleocene–Eocene Thermal Maximum

2018 ◽  
Vol 14 (7) ◽  
pp. 1035-1049 ◽  
Author(s):  
Tom Dunkley Jones ◽  
Hayley R. Manners ◽  
Murray Hoggett ◽  
Sandra Kirtland Turner ◽  
Thomas Westerhold ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Isotope ◽  
Continental Margin ◽  
The Body ◽  
Sediment Flux ◽  
Stratigraphic Correlation ◽  
Earth System ◽  
Accumulation Rates ◽  
Thermal Maximum ◽  
Organic Carbon Burial

Abstract. The response of the Earth system to greenhouse-gas-driven warming is of critical importance for the future trajectory of our planetary environment. Hyperthermal events – past climate transients with global-scale warming significantly above background climate variability – can provide insights into the nature and magnitude of these responses. The largest hyperthermal of the Cenozoic was the Paleocene–Eocene Thermal Maximum (PETM ∼ 56 Ma). Here we present new high-resolution bulk sediment stable isotope and major element data for the classic PETM section at Zumaia, Spain. With these data we provide a new detailed stratigraphic correlation to other key deep-ocean and terrestrial PETM reference sections. With this new correlation and age model we are able to demonstrate that detrital sediment accumulation rates within the Zumaia continental margin section increased more than 4-fold during the PETM, representing a radical change in regional hydrology that drove dramatic increases in terrestrial-to-marine sediment flux. Most remarkable is that detrital accumulation rates remain high throughout the body of the PETM, and even reach peak values during the recovery phase of the characteristic PETM carbon isotope excursion (CIE). Using a series of Earth system model inversions, driven by the new Zumaia carbon isotope record, we demonstrate that the silicate weathering feedback alone is insufficient to recover the PETM CIE, and that active organic carbon burial is required to match the observed dynamics of the CIE. Further, we demonstrate that the period of maximum organic carbon sequestration coincides with the peak in detrital accumulation rates observed at Zumaia. Based on these results, we hypothesise that orbital-scale variations in subtropical hydro-climates, and their subsequent impact on sediment dynamics, may contribute to the rapid climate and CIE recovery from peak-PETM conditions.

scholarly journals Reduced carbon cycle resilience across the Palaeocene–Eocene Thermal Maximum

2018 ◽  
Vol 14 (10) ◽  
pp. 1515-1527 ◽  
Author(s):  
David I. Armstrong McKay ◽  
Timothy M. Lenton
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Deep Ocean ◽  
Tipping Point ◽  
Tipping Points ◽  
Carbon Burial ◽  
Thermal Maximum ◽  
Organic Carbon Burial ◽  
Carbon Release ◽  
Hyperthermal Events

Abstract. Several past episodes of rapid carbon cycle and climate change are hypothesised to be the result of the Earth system reaching a tipping point beyond which an abrupt transition to a new state occurs. At the Palaeocene–Eocene Thermal Maximum (PETM) at ∼56 Ma and at subsequent hyperthermal events, hypothesised tipping points involve the abrupt transfer of carbon from surface reservoirs to the atmosphere. Theory suggests that tipping points in complex dynamical systems should be preceded by critical slowing down of their dynamics, including increasing temporal autocorrelation and variability. However, reliably detecting these indicators in palaeorecords is challenging, with issues of data quality, false positives, and parameter selection potentially affecting reliability. Here we show that in a sufficiently long, high-resolution palaeorecord there is consistent evidence of destabilisation of the carbon cycle in the ∼1.5 Myr prior to the PETM, elevated carbon cycle and climate instability following both the PETM and Eocene Thermal Maximum 2 (ETM2), and different drivers of carbon cycle dynamics preceding the PETM and ETM2 events. Our results indicate a loss of “resilience” (weakened stabilising negative feedbacks and greater sensitivity to small shocks) in the carbon cycle before the PETM and in the carbon–climate system following it. This pre-PETM carbon cycle destabilisation may reflect gradual forcing by the contemporaneous North Atlantic Volcanic Province eruptions, with volcanism-driven warming potentially weakening the organic carbon burial feedback. Our results are consistent with but cannot prove the existence of a tipping point for abrupt carbon release, e.g. from methane hydrate or terrestrial organic carbon reservoirs, whereas we find no support for a tipping point in deep ocean temperature.

scholarly journals A geochemical study of marine sediments from the Mac. Robertson shelf, East Antarctica: initial results and palaeoenvironmental implications

1998 ◽  
Vol 27 ◽  
pp. 268-274 ◽  
Author(s):  
P. N. Sedwick ◽  
P.T. Harris ◽  
L. G. Robertson ◽  
G. M. Mcmurtry ◽  
M. D. Cremer ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Late Holocene ◽  
Sediment Accumulation ◽  
Transport Processes ◽  
East Antarctica ◽  
Outer Shelf ◽  
Geochemical Data ◽  
Accumulation Rates ◽  
Inner Shelf ◽  
The Holocene

Sediments from the Antarctic continental margin may provide detailed palaeoenvironmental records for Antarctic shelf waters during the late Quaternary. Here we present results from a palaeoenvironmental study of two sediment cores recovered from the continental shelf off Mac. Robertson Land, East Antarctica. These gravity cores were collected approximately 90 km apart from locations on the inner and outer shelf. Both cores are apparently undisturbed sequences of diatom ooze mixed with fine, quartz-rich sand. Core stratigraphies have been established from radiocarbon analyses of bulk organic carbon. Down-core geochemical determinations include the lithogenic components AÍ and Fe, biogenic components opal and organic carbon, and palaco-redox proxies Mn, Mo and U. We use the geochemical data to infer past variations in the deposition of biogenic and lithogenic materials, and the radiocarbon dates to estimate average sediment accumulation rates. The Holocene record of the outer-shelf core suggests three episodes of enhanced diatom export production at about 1.8, 3.8 and 5.5 ka BP, as well as less pronounced bloom episodes which occurred over a shorter period. Average sediment accumulation rates at this location range from 13.7 cm ka−1 in the late Pleistocene early Holocene to 82 cm ka−1 in the late Holocene, and suggest that the inferred episodes of enhanced biogenic production lasted 100-1000 years. in contrast, data for the inner-shelf core suggest that there has been a roughly constant proportion of biogenic and lithogenic material accumulating during the middle to late Holocene, with a greater proportion of biogenic material relative to the outer shelf. Notably, there is an approximately 7-fold increase in average sediment accumulation rate (from 24.5 to 179 cm ka−1) at this inner-shelf location between the middle and late Holocene, with roughly comparable increases in the mass accumulation rates of both biogenic and lithogenic material. This may represent changes in sediment transport processes, or reflect real increases in pelagic sedimentation in this region during the Holocene. Our results suggest quite different sedimentation regimes in these two shelf locations during the middle to late Holocene.

scholarly journals Erosion-induced massive organic carbon burial and carbon emission in the Yellow River basin, China

2014 ◽  
Vol 11 (4) ◽  
pp. 945-959 ◽  
Author(s):  
L. Ran ◽  
X. X. Lu ◽  
Z. Xin
Keyword(s):  
Soil Erosion ◽  
Organic Carbon ◽  
River Basin ◽  
Yellow River ◽  
River System ◽  
Yellow River Basin ◽  
Transport Processes ◽  
The Yellow River ◽  
Organic Carbon Burial ◽  
The Yellow River Basin

Abstract. Soil erosion and terrestrial deposition of soil organic carbon (SOC) can potentially play a significant role in global carbon cycling. Assessing the redistribution of SOC during erosion and subsequent transport and burial is of critical importance. Using hydrological records of soil erosion and sediment load, and compiled organic carbon (OC) data, estimates of the eroded soils and OC induced by water in the Yellow River basin during the period 1950–2010 were assembled. The Yellow River basin has experienced intense soil erosion due to combined impact of natural process and human activity. Over the period, 134.2 ± 24.7 Gt of soils and 1.07 ± 0.15 Gt of OC have been eroded from hillslopes based on a soil erosion rate of 1.7–2.5 Gt yr−1. Approximately 63% of the eroded soils were deposited in the river system, while only 37% were discharged into the ocean. For the OC budget, approximately 0.53 ± 0.21 Gt (49.5%) was buried in the river system, 0.25 ± 0.14 Gt (23.5%) was delivered into the ocean, and the remaining 0.289 ± 0.294 Gt (27%) was decomposed during the erosion and transport processes. This validates the commonly held assumption that 20–40% of the eroded OC would be oxidized after erosion. Erosion-induced OC redistribution on the landscape likely represented a carbon source, although a large proportion of OC was buried. In addition, about half of the terrestrially redeposited OC (49.4%) was buried behind dams, revealing the importance of dam trapping in sequestering the eroded OC. Although several uncertainties need to be better constrained, the obtained budgetary results provide a means of assessing the redistribution of the eroded OC within the Yellow River basin. Human activities have significantly altered its redistribution pattern over the past decades.

scholarly journals Carbon Sequestration Rate Estimates in Delaware Bay and Barnegat Bay Tidal Wetlands Using Interpolation Mapping

Data ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 11
Author(s):  
Champlin ◽  
Velinsky ◽  
Tucker ◽  
Sommerfield ◽  
Laurent ◽  
...  
Keyword(s):  
Spatial Analysis ◽  
Carbon Sequestration ◽  
Organic Carbon ◽  
Sediment Cores ◽  
Delaware Bay ◽  
Carbon Accumulation ◽  
Tidal Wetlands ◽  
Accumulation Rates ◽  
Barnegat Bay ◽  
Carbon Accumulation Rates

Quantifying carbon sequestration by tidal wetlands is important for the management of carbon stocks as part of climate change mitigation. This data publication includes a spatial analysis of carbon accumulation rates in Barnegat and Delaware Bay tidal wetlands. One method calculated long-term organic carbon accumulation rates from radioisotope-dated (Cs-137) sediment cores. The second method measured organic carbon density of sediment accumulated above feldspar marker beds. Carbon accumulation rates generated by these two methods were interpolated across emergent wetland areas, using kriging, with uncertainty estimated by leave-one-out cross validation. This spatial analysis revealed greater carbon sequestration within Delaware, compared to Barnegat Bay. Sequestration rates were found to be more variable within Delaware Bay, and rates were greatest in the tidal freshwater area of the upper bay.

scholarly journals Erosion-induced massive organic carbon burial and carbon emission in the Yellow River basin, China

2013 ◽  
Vol 10 (8) ◽  
pp. 13491-13534 ◽  
Author(s):  
L. Ran ◽  
X. X. Lu ◽  
Z. Xin
Keyword(s):  
Soil Erosion ◽  
Organic Carbon ◽  
River Basin ◽  
Yellow River ◽  
Yellow River Basin ◽  
Transport Processes ◽  
The Yellow River ◽  
Soil Erosion Rate ◽  
Organic Carbon Burial ◽  
The Yellow River Basin

Abstract. Soil erosion and terrestrial deposition of soil organic carbon (SOC) can potentially play a significant role in global carbon cycling. Assessing the fate of SOC during erosion and subsequent transport and sedimentation is of critical importance. Using hydrological records of soil erosion and sediment load, and compiled organic carbon (OC) data, budgets of the eroded soils and OC induced by water in the Yellow River basin during 1950–2010 were analyzed. The Yellow River basin has experienced intense soil erosion due to integrated impact of natural process and human activity. Over the period, 134.2 ± 24.7 Gt of soils and 1.07 ± 0.26 Gt of OC have been eroded from slope lands based on a soil erosion rate of 1.7–2.5 Gt yr–1. Among the produced sediment, approximately 63% of it was deposited on land, while only 37% was discharged into the ocean. For the OC budget, approximately 0.53 ± 0.18 Gt (49.5%) was buried on land, 0.25 ± 0.14 Gt (23.5%) was delivered into the ocean, and the remaining 0.289 ± 0.202 Gt (27%) was decomposed during the erosion and transport processes. This validates the commonly used assumption that 20–40% of the eroded OC would be oxidized after erosion. Erosion-induced OC transport in the basin likely represents an atmospheric carbon source. In addition, about half of the terrestrially redeposited OC (around 49.4%) was buried in reservoirs and behind silt check dams, revealing the importance of dam sedimentation in trapping the eroded OC. Although with several uncertainties to be better constrained, the obtained budgetary results provide a means of assessing the potential fates of the eroded OC within the Yellow River basin.

scholarly journals Effects of eutrophication on sedimentary organic carbon cycling in five temperate lakes

2019 ◽  
Author(s):  
Annika Fiskal ◽  
Longhui Deng ◽  
Anja Michel ◽  
Philip Eickenbusch ◽  
Xingguo Han ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Trophic State ◽  
Management Practices ◽  
Microbial Respiration ◽  
Accumulation Rates ◽  
Temperate Lakes ◽  
Artificial Lake ◽  
Eutrophic Lakes ◽  
Organic Carbon Burial

Abstract. Even though human induced eutrophication has severely impacted temperate lake ecosystems over the last centuries, the effects on total organic carbon (TOC) burial and mineralization are not well understood. We study these effects based on sedimentary records from the last 180 years in five Swiss lakes that differ in trophic state. We compare changes in content of TOC and modeled TOC accumulation rates through time to historical data on algae blooms, water column anoxia, wastewater treatment, artificial lake ventilation, and water column phosphorus (P) concentrations. We furthermore investigate the effects of eutrophication on rates of microbial TOC remineralization and vertical distributions of microbial respiration reactions in sediments. Our results indicate that the history of eutrophication is well reflected in the sedimentary record. Subsurface peaks in sedimentary TOC coincide with past periods of elevated P concentrations in lake water. Sediments of eutrophic lakes show overall higher rates of microbial respiration, and a higher relative contribution of methanogenesis to total respiration. Yet, a clear impact of lake trophic state on the zonation of microbial respiration reactions is absent. Moreover, even though water column P concentrations have been reduced by ~ 80 % (range: ~ 50–90 %) since the period of peak eutrophication in the 1970s, TOC burial and accumulation rates have only decreased significantly (~ 20 and 25 %) in two of the five lakes. Hereby we found no clear relationship between the magnitude of the decrease in P concentrations and the change in TOC burial and accumulation rate. Instead, artificial lake ventilation, which is used to prevent water column anoxia in eutrophic lakes, may help sustain high rates of TOC burial and accumulation in sediments despite strongly reduced water column P concentrations. Our results provide novel insights into how eutrophication and eutrophication management practices affect organic carbon burial and the distribution of microbial respiration reactions in temperate lakes. These insights are important to understanding how anthropogenic activities affect the size of the carbon pool that is stored globally in lacustrine sediments.

scholarly journals Warm plankton soup and red herrings: calcareous nannoplankton cellular communities and the Palaeocene–Eocene Thermal Maximum

2018 ◽  
Vol 376 (2130) ◽  
pp. 20170075 ◽  
Author(s):  
Samantha J. Gibbs ◽  
Rosie M. Sheward ◽  
Paul R. Bown ◽  
Alex J. Poulton ◽  
Sarah A. Alvarez
Keyword(s):  
Global Warming ◽  
Organic Carbon ◽  
Inorganic Carbon ◽  
Climate Feedback ◽  
Short Term ◽  
Cell Size Distribution ◽  
Carbon Burial ◽  
Thermal Maximum ◽  
Carbon Transfer ◽  
Organic Carbon Burial

Past global warming events such as the Palaeocene–Eocene Thermal Maximum (PETM—56 Ma) are attributed to the release of vast amounts of carbon into the ocean, atmosphere and biosphere with recovery ascribed to a combination of silicate weathering and organic carbon burial. The phytoplanktonic nannoplankton are major contributors of organic and inorganic carbon but their role in this recovery process remains poorly understood and complicated by their contribution to marine calcification. Biocalcification is implicated not only in long-term carbon burial but also both short-term positive and negative climatic feedbacks associated with seawater buffering and responses to ocean acidification. Here, we use exceptional records of preserved fossil coccospheres to reconstruct cell size distribution, biomass production (particulate organic carbon, POC) and (particulate) inorganic carbon (PIC) yields of three contrasting nannoplankton communities (Bass River—outer shelf, Maud Rise—uppermost bathyal, Shatsky Rise—open ocean) through the PETM onset and recovery. Each of the sites shows contrasting community responses across the PETM as a function of their taxic composition and total community biomass. Our results indicate that nannoplankton PIC:POC had no role in short-term climate feedback and, as such, their importance as a source of CO 2 to the environment is a red herring. It is nevertheless likely that shifts to greater numbers of smaller cells at the shelf site in particular led to greater carbon transfer efficiency, and that nannoplankton productivity and export across the shelves had a significant modulating effect on carbon sequestration during the PETM recovery. This article is part of a discussion meeting issue ‘Hyperthermals: rapid and extreme global warming in our geological past’.

scholarly journals Sediment Organic Carbon Sequestration of Balkhash Lake in Central Asia

2021 ◽  
Vol 13 (17) ◽  
pp. 9958
Author(s):  
Wen Liu ◽  
Long Ma ◽  
Jilili Abuduwaili ◽  
Gulnura Issanova ◽  
Galymzhan Saparov
Keyword(s):  
Carbon Sequestration ◽  
Organic Carbon ◽  
The Past ◽  
Burial Rate ◽  
Carbon Burial ◽  
Sediment Organic Carbon ◽  
Organic Carbon Burial ◽  
Organic Carbon Burial Rate ◽  
Organic Carbon Sequestration ◽  
Global Carbon

As an important part of the global carbon pool, lake carbon is of great significance in the global carbon cycle. Based on a study of the sedimentary proxies of Balkhash Lake, Central Asia’s largest lake, changes in the organic carbon sequestration in the lake sediments and their possible influence over the past 150 years were studied. The results suggested that the organic carbon in the sediments of Lake Balkhash comes mainly from aquatic plants. The organic carbon burial rate fluctuated from 8.16 to 30.04 g·m−2·a−1 and the minimum appeared at the top of the core. The organic carbon burial rate continues to decline as it has over the past 150 years. Global warming, higher hydrodynamic force, and low terrestrial input have not been conducive to the improvement of organic carbon sequestration in Balkhash Lake; the construction of a large reservoir had a greater impact on the sedimentary proxy of total organic carbon content, which could lead to a large deviation for environmental reconstruction. This is the first study to assess the sediment organic carbon sequestration using the modern sediments of Central Asia’s largest lake, which is of great scientific significance. The results contribute to an understanding of organic carbon sequestration in Central Asia and may provide a scientific basis for carbon balance assessment in regional and global scales.

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