Relevance of carbon stocks of marine sediments for national greenhouse gas inventories of maritime nations

Avelar, Silvania; Voort, Tessa Sophia van der; Eglinton, Timothy I.

doi:10.1186/s13021-017-0077-x

Cited by 41 publications

(49 citation statements)

References 42 publications

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“…The protection of areas further offshore is also likely to impact the carbon budget of the shelf and may have added value in conserving sediment carbon stocks (Avelar et al, 2017;Howard et al, 2017). While Marine Protected Areas (MPAs) are primarily designated to protect biodiversity through regulation of human activities, the reduction in benthic disturbance may also increase the carbon stock (see section "Trawling").…”

Section: Protection Of Coastal and Marine Habitatsmentioning

confidence: 99%

Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

et al. 2020

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A carbon budget for the northwest European continental shelf seas (NWES) was synthesized using available estimates for coastal, pelagic and benthic carbon stocks and flows. Key uncertainties were identified and the effect of future impacts on the carbon budget were assessed. The water of the shelf seas contains between 210 and 230 Tmol of carbon and absorbs between 1.3 and 3.3 Tmol from the atmosphere annually. Offshelf transport and burial in the sediments account for 60-100 and 0-40% of carbon outputs from the NWES, respectively. Both of these fluxes remain poorly constrained by observations and resolving their magnitudes and relative importance is a key research priority. Pelagic and benthic carbon stocks are dominated by inorganic carbon. Shelf sediments contain the largest stock of carbon, with between 520 and 1600 Tmol stored in the top 0.1 m of the sea bed. Coastal habitats such as salt marshes and mud flats contain large amounts of carbon per unit area but their total carbon stocks are small compared to pelagic and benthic stocks due to their smaller spatial extent. The large pelagic stock of carbon will continue to increase due to the rising concentration of atmospheric CO 2 , with associated pH decrease. Pelagic carbon stocks and flows are also likely to be significantly affected by increasing acidity and temperature, and circulation changes but the net impact is uncertain. Benthic carbon stocks will be affected by increasing temperature and acidity, and decreasing oxygen concentrations, although the net impact of these interrelated changes on carbon stocks is uncertain and a major knowledge gap. The impact of bottom trawling on benthic carbon stocks Frontiers in Marine Science | www.frontiersin.org 1 March 2020 | Volume 7 | Article 143Legge et al.Carbon on the Northwest European Shelf is unique amongst the impacts we consider in that it is widespread and also directly manageable, although its net effect on the carbon budget is uncertain. Coastal habitats are vulnerable to sea level rise and are strongly impacted by management decisions. Local, national and regional actions have the potential to protect or enhance carbon storage, but ultimately global governance, via controls on emissions, has the greatest potential to influence the long-term fate of carbon stocks in the northwestern European continental shelf.

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Section: Protection Of Coastal and Marine Habitatsmentioning

confidence: 99%

Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

et al. 2020

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“…results are reported in terms of ocean provinces based largely on water depth, and temporally in 749 terms of the Holocene and Pleistocene, but the data sets and methods can be used to assess the 750 amount of POC in marine sediments at any location or time-period (≤ 2.59 Ma). One such 751 application of this model is the quantification of near-shore carbon stocks for maritime nations as 752 part of climate-mitigation action (Avelar et al, 2017 0.01 The depth of the bioturbated layer is set to 10 cm, but the depths of the Holocene and Pleistocene layers are based on their ages and are therefore variable (see Fig. 4).…”

Section: Microbial Degradation Of Organic Carbon 671mentioning

confidence: 99%

Organic carbon and microbial activity in marine sediments on a global scale throughout the Quaternary

LaRowe¹,

Arndt²,

Bradley³

et al. 2020

Preprint

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Microbial degradation of organic carbon in marine sediments is a key driver of global element cycles on multiple time scales. However, it is not known to what depth microorganisms alter organic carbon in marine sediments or how microbial rates of organic carbon processing change with depth, and thus time since burial, on a global scale. To better understand the connection between the dynamic carbon cycle and life’s limits in the deep subsurface, we have combined a number of global data sets with a reaction transport model (RTM) describing first, organic carbon degradation in marine sediments deposited throughout the Quaternary Period and second, a bioenergetic model for microbial activity. The RTM is applied globally, recognizing three distinct depositional environments – continental shelf, margin and abyssal zones. The results include the masses of particulate organic carbon, POC, stored in three sediment-depth layers: bioturbated Holocene (1.7 × 10^17 g C), non-bioturbated Holocene (2.6 × 10^18 g C) and Pleistocene (1.4 × 1020 g C) sediments. The global depth-integrated rates of POC degradation have been determined to be 6.8 × 10^13, 1.2 × 10^14 and 1.2 × 10^14 g C yr-1 for the same three layers, respectively. A number of maps depicting the distribution of POC, as well as the fraction that has been degraded have also been generated. Using POC degradation as a proxy for microbial catabolic activity, total heterotrophic processing of POC throughout the Quaternary is estimated to be between 10^-11 – 10^-6 g C cm-3 yr-1, depending on the time since deposition and location. Bioenergetic modeling reveals that laboratory-determined microbial maintenance powers are poor predictors of sediment biomass concentration, but that cell concentrations in marine sediments can be accurately predicted by combining bioenergetic models with the rates of POC degradation determined in this study. Our model can be used to quantitatively describe both the carbon cycle and microbial activity on a global scale for marine sediments less than 2.59 million years old.

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“…Globally, delta and shelf environments represent hotspots of carbon sequestration, accounting for >85% of OC buried in modern marine sediments (Hedges & Keil, 1995). In light of ongoing anthropogenic changes in carbon stocks in coastal oceans and their possible socioeconomic ramifications (Avelar et al, 2017), it is more pressing than ever to shed light on and understand the processes governing the spatial variation in quantity and composition of OC in these shelf systems. Over the last decades, significant advances have been made in understanding biogeochemical cycles in the global oceans through classification into distinct regions based on biogeographic, geomorphic or climatological characteristics.…”

Section: Introductionmentioning

confidence: 99%

Deconvolving the Fate of Carbon in Coastal Sediments

Voort

Mannu

Blattmann

et al. 2018

Geophysical Research Letters

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Coastal oceans play a crucial role in the global carbon cycle, and are increasingly affected by anthropogenic forcing. Understanding carbon cycling in coastal environments is hindered by convoluted sources and myriad processes that vary over a range of spatial and temporal scales. In this study, we deconvolve the complex mosaic of organic carbon manifested in Chinese Marginal Sea (CMS) sediments using a novel numerical clustering algorithm based on 14 C and total OC content. Results reveal five regions that encompass geographically distinct depositional settings. Complementary statistical analyses reveal contrasting region-dependent controls on carbon dynamics and composition. Overall, clustering is shown to be highly effective in demarcating areas of distinct organic facies by disentangling intertwined organic geochemical patterns resulting from superimposed effects of OC provenance, reworking and deposition on a shelf region exhibiting pronounced spatial heterogeneity. This information will aid in constraining region-specific budgets of carbon burial and carbon cycle processes. Plain Language SummaryIn the context on ongoing climate change, it is crucial to understand how and where carbon is buried. Coastal oceans are very important areas for carbon burial globally, even though they only form a small part of the total ocean surface. These areas are very complex because there is carbon coming both from the land as well as the sea. By understanding where thecarbon from land and where the carbon from the sea ends up, we can better estimate carbon storage. This paper presents a clustering approach which uses the large dataset of carbon age and concentration in the Chinese marginal seas. The clustering approach shows where the carbon from land goes and how it is buried, which areas lose carbon and which areas bury carbon. This approach could also be used in the future on other datasets such as the Arctic Seas.

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Relevance of carbon stocks of marine sediments for national greenhouse gas inventories of maritime nations

Cited by 41 publications

References 42 publications

Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

Organic carbon and microbial activity in marine sediments on a global scale throughout the Quaternary

Deconvolving the Fate of Carbon in Coastal Sediments

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