scholarly journals On the tuning of plateaus in atmospheric and oceanic <sup>14</sup>C records to derive calendar chronologies of deep-sea cores and records of <sup>14</sup>C marine reservoir age changes

2021 ◽  
Vol 17 (4) ◽  
pp. 1701-1725
Author(s):  
Edouard Bard ◽  
Timothy J. Heaton
Keyword(s):  
Marine Sediments ◽  
Deep Sea ◽  
A Priori ◽  
Radioactive Decay ◽  
Independent Method ◽  
Age Changes ◽  
14C Age ◽  
Additional Noise ◽  
Sediment Records ◽  
Reservoir Age

Abstract. We assess the methodology of the so-called 14C plateau tuning (PT) technique used to date marine sediment records and determine 14C marine reservoir ages (MRAs) as recently reviewed by Sarnthein et al. (2020). The main identified problems are linked to the assumption of constant MRA during 14C age plateaus; the lack of consideration of foraminifera abundance changes coupled to bioturbation that can create spurious plateaus in marine sediments; the assumption that plateaus have the same shapes and durations in atmospheric and oceanic records; the implication that atmospheric 14C / 12C peaked instantaneously from one plateau to the next; that the 14C plateaus represent 82 % of the total time spent between 14 000 and 29 000 cal yr BP, whereas during the remaining 18 % of the time, the radiocarbon clock was running almost 5 times faster than the radioactive decay; that the sparsity, combined with the level of analytical uncertainties and additional noise, in both atmospheric and marine data do not currently allow one to reliably or robustly identify plateaus (should they exist) beyond 15 000 cal yr BP; and that the determination and identification of plateaus in the deep-sea cores is reliant upon significant changes in sedimentation rate within those marine sediments which are, a priori, unknown and are not verified with an independent method. The concerns we raise are supported and strengthened with carbon cycle box model experiments and statistical simulations of pseudo-atmospheric and pseudo-marine records, allowing us to question the ability to identify and tune 14C age plateaus in the context of noisy and sparse data.

scholarly journals On the tuning of plateaus in atmospheric and oceanic <sup>14</sup>C records to derive calendar chronologies of deep-sea cores and records of <sup>14</sup>C marine reservoir age changes

2021 ◽  
Author(s):  
Edouard Bard ◽  
Timothy J. Heaton
Keyword(s):  
Marine Sediments ◽  
A Priori ◽  
Independent Method ◽  
Age Changes ◽  
14C Age ◽  
Additional Noise ◽  
Sediment Records ◽  
Marine Data ◽  
Reservoir Age

Abstract. As an extended comment on the paper by Sarnthein et al. (2020), we express strong reservations about the methodology of the so-called 14C plateau tuning (PT) technique used to date marine sediment records and its implications on the determination of 14C marine reservoir ages (MRA). The main problems are linked to: the assumption of constant MRA during 14C-age plateaus; the lack of consideration of foraminifera abundance changes coupled to bioturbation that can create spurious plateaus in marine sediments; the assumption that plateaus have the same shapes and durations in atmospheric and oceanic records; the implication that atmospheric 14C/12C peaked instantaneously from one plateau to the next; that the 14C plateaus represent 82 % of the total time spent between 14,000 and 29,000 cal yr BP, whereas during the remaining 18 % of the time, the radiocarbon clock was running almost 5 times too fast; that the sparsity, combined with the level of analytical uncertainties and additional noise, in both atmospheric and marine data do not currently allow one to reliably or robustly identify plateaus (should they exist) beyond 15,000 cal yr BP; and that the determination and identification of plateaus is reliant upon significant changes in sedimentation rate within the marine sediments which are, a priori, unknown and are not verified with an independent method. The concerns we raise are supported and strengthened with carbon cycle box-model experiments and statistical simulations of pseudo-atmospheric and pseudo-marine records, allowing us to test the ability to identify and tune 14C-age plateaus, in the context of noisy and sparse data.

scholarly journals Pseudodesulfovibrio cashew sp. Nov., a Novel Deep-Sea Sulfate-Reducing Bacterium, Linking Heavy Metal Resistance and Sulfur Cycle

2021 ◽  
Vol 9 (2) ◽  
pp. 429
Author(s):  
Rikuan Zheng ◽  
Shimei Wu ◽  
Chaomin Sun
Keyword(s):  
Heavy Metal ◽  
Sulfate Reduction ◽  
Marine Sediments ◽  
Deep Sea ◽  
Sulfur Cycle ◽  
Metal Sulfides ◽  
Phenotypic Traits ◽  
Dissimilatory Sulfate Reduction ◽  
Metabolic Potential ◽  
Sulfate Reducing

Sulfur cycling is primarily driven by sulfate reduction mediated by sulfate-reducing bacteria (SRB) in marine sediments. The dissimilatory sulfate reduction drives the production of enormous quantities of reduced sulfide and thereby the formation of highly insoluble metal sulfides in marine sediments. Here, a novel sulfate-reducing bacterium designated Pseudodesulfovibrio cashew SRB007 was isolated and purified from the deep-sea cold seep and proposed to represent a novel species in the genus of Pseudodesulfovibrio. A detailed description of the phenotypic traits, phylogenetic status and central metabolisms of strain SRB007 allowed the reconstruction of the metabolic potential and lifestyle of a novel member of deep-sea SRB. Notably, P. cashew SRB007 showed a strong ability to resist and remove different heavy metal ions including Co2+, Ni2+, Cd2+ and Hg2+. The dissimilatory sulfate reduction was demonstrated to contribute to the prominent removal capability of P. cashew SRB007 against different heavy metals via the formation of insoluble metal sulfides.

scholarly journals Carbon burial in deep-sea sediment and implications for oceanic inventories of carbon and alkalinity over the last glacial cycle

2018 ◽  
Vol 14 (11) ◽  
pp. 1819-1850 ◽  
Author(s):  
Olivier Cartapanis ◽  
Eric D. Galbraith ◽  
Daniele Bianchi ◽  
Samuel L. Jaccard
Keyword(s):  
Marine Sediments ◽  
Active Carbon ◽  
Deep Sea ◽  
Dissolved Inorganic Carbon ◽  
Glacial Cycle ◽  
Last Glacial ◽  
Carbon Burial ◽  
Order Constraint ◽  
The Last Glacial ◽  
Carbon Inventory

Abstract. Although it has long been assumed that the glacial–interglacial cycles of atmospheric CO2 occurred due to increased storage of CO2 in the ocean, with no change in the size of the “active” carbon inventory, there are signs that the geological CO2 supply rate to the active pool varied significantly. The resulting changes of the carbon inventory cannot be assessed without constraining the rate of carbon removal from the system, which largely occurs in marine sediments. The oceanic supply of alkalinity is also removed by the burial of calcium carbonate in marine sediments, which plays a major role in air–sea partitioning of the active carbon inventory. Here, we present the first global reconstruction of carbon and alkalinity burial in deep-sea sediments over the last glacial cycle. Although subject to large uncertainties, the reconstruction provides a first-order constraint on the effects of changes in deep-sea burial fluxes on global carbon and alkalinity inventories over the last glacial cycle. The results suggest that reduced burial of carbonate in the Atlantic Ocean was not entirely compensated by the increased burial in the Pacific basin during the last glacial period, which would have caused a gradual buildup of alkalinity in the ocean. We also consider the magnitude of possible changes in the larger but poorly constrained rates of burial on continental shelves, and show that these could have been significantly larger than the deep-sea burial changes. The burial-driven inventory variations are sufficiently large to have significantly altered the δ13C of the ocean–atmosphere carbon and changed the average dissolved inorganic carbon (DIC) and alkalinity concentrations of the ocean by more than 100 µM, confirming that carbon burial fluxes were a dynamic, interactive component of the glacial cycles that significantly modified the size of the active carbon pool. Our results also suggest that geological sources and sinks were significantly unbalanced during the late Holocene, leading to a slow net removal flux on the order of 0.1 PgC yr−1 prior to the rapid input of carbon during the industrial period.

scholarly journals Targeted search for actinomycetes from nearshore and deep-sea marine sediments

2013 ◽  
Vol 84 (3) ◽  
pp. 510-518 ◽  
Author(s):  
Alejandra Prieto-Davó ◽  
Luis J. Villarreal-Gómez ◽  
Stephanie Forschner-Dancause ◽  
Alan T. Bull ◽  
James E.M. Stach ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Deep Sea

Introduction

2009 ◽  
Author(s):  
John S. Gray ◽  
Michael Elliott
Keyword(s):  
Marine Sediments ◽  
Deep Sea ◽  
Marine Species ◽  
Dark Side ◽  
Marine Animals ◽  
Linnaean System ◽  
Lofoten Islands ◽  
Linnaean Classification ◽  
Marine Biologist ◽  
New System

As the oceans cover 70% of the earth’s surface, marine sediments constitute the second largest habitat on earth, after the ocean water column, and yet we still know more about the dark side of the moon than about the biota of this vast habitat. The primary aim of this book is to give an overview of the biota of marine sediments from an ecological perspective—we will talk of the benthos, literally the plants and animals at the bottom of the sea, but we will also use the term to include those organisms living on the intertidal sediments, the sands and muds of the shore. Given that most of that area is below the zone where light penetrates, the photic zone, the area is dominated by the animals and so we will concentrate on this component. Many of the early studies of marine sediments were taxonomic, describing new species. One of the pioneers was Carl von Linnaeus (1707–1778), the great Swedish biologist who developed the Linnaean classification system for organisms that is still used today (but under threat from some molecular biologists who argue that the Linnaean system is outdated and propose a new system called Phylocode). Linnaeus described hundreds of marine species, many of which come from marine sediments. The British marine biologist Edward Forbes was a pioneer who invented the dredge to sample marine animals that lived below the tidemarks. Forbes showed that there were fewer species as the sampled depth increased and believed that the great pressures at depths meant that no animals would be found deeper than 600 m. This was disproved by Michael Sars who in 1869 used a dredge to sample the benthos at 600 m depth off the Lofoten islands in Norway. Sars found 335 species and in fact was the first to show that the deep sea (off the continental shelf) had high numbers of species. Following these pioneering studies, one of the earliest systematic studies of marine sediments was the HMS Challenger expedition of 1872–1876, the first global expedition. The reports of the expedition were extensive but were mostly descriptive, relating to taxonomy and general natural history.

Permeability of Marine Sediments and Tropical Volcanic Soils

2012 ◽  
Author(s):  
Horst G. Brandes
Keyword(s):  
Grain Size ◽  
Marine Sediments ◽  
Deep Sea ◽  
Carbonate Content ◽  
Clayey Soils ◽  
Index Properties ◽  
Volcanic Soils ◽  
Fine Grained ◽  
Deep Sea Sediments ◽  
Tropical Volcanic Soils

Permeability values for a range of fine-grained deep-sea sediments are presented and evaluated in terms of index properties such as plasticity, grain size and carbonate content. It is found that whereas clay-rich sediments have similar permeabilities to those of equivalent land-based fine-grained soils, the presence of volcanic, carbonate and other non-clay fractions tends to increase permeability somewhat. Volcanic silty-clayey soils from Hawaii have comparable permeability values, although they can be slightly more permeable.

scholarly journals North Atlantic circulation and reservoir age changes over the past 41,000 years

2013 ◽  
Vol 40 (14) ◽  
pp. 3693-3697 ◽  
Author(s):  
Joseph V. Stern ◽  
Lorraine E. Lisiecki
Keyword(s):  
North Atlantic ◽  
Age Changes ◽  
The Past ◽  
Reservoir Age

Engineering Properties of Carbonate Marine Sediments

2011 ◽  
Author(s):  
Horst G. Brandes
Keyword(s):  
Water Content ◽  
Marine Sediments ◽  
Relative Abundance ◽  
Deep Sea ◽  
Deep Ocean ◽  
Strength Characteristics ◽  
Engineering Properties ◽  
Carbonate Content ◽  
Frictional Strength

Geotechnical properties of deep-sea sediments are examined in terms of their plasticity, compressibility and frictional strength characteristics, especially in terms of the relative abundance of carbonate and clay fractions. The effect of carbonate content in excess of 40% is to reduce Atterberg limits and compressibility, and to increase peak friction angles, compared to sediments from the deep ocean that have lower carbonate amounts. The presence of carbonate also tends to reduce flocculation and in situ water content.

An improved alpha scintillation counting method for determination of Th, U, Ra-226, Th-230 excess, and Pa-231 excess in marine sediments

1986 ◽  
Vol 23 (7) ◽  
pp. 959-966 ◽  
Author(s):  
D. J. Huntley ◽  
M. K. Nissen ◽  
J. Thomson ◽  
S. E. Calvert
Keyword(s):  
Marine Sediments ◽  
Deep Sea ◽  
Borate Glass ◽  
Surface Sediments ◽  
Scintillation Counting ◽  
Sedimentation Rates ◽  
Counting Method ◽  
Near Surface ◽  
Thick Source

In a previous paper it was shown that thick-source α counting is a simple means for determining Th, U, Th-230 excess, and Pa-231 excess concentrations, and hence sedimentation rates, for deep-sea sediments. Here it is shown that radon escape can lead to inaccurate results if powdered samples are used and that this problem can be overcome by preparing samples as a borate glass before measurement. Glassed samples also permit a novel measurement of the Ra-226 content by measurement of the post-fusion buildup of Rn-222, a determination shown to be necessary for near-surface sediments that have a deficit of Ra-226. It is also shown that Po-210 is lost during the fusion and that this loss can be allowed for in the calculations.The above observations are found on comparisons of measured and calculated α count rates for several Th and U standards and on comparisons with α spectrometry results from four sets of deep-sea core samples.

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