scholarly journals Metaschoepite Dissolution in Sediment Column Systems—Implications for Uranium Speciation and Transport

2019 ◽  
Vol 53 (16) ◽  
pp. 9915-9925 ◽  
Author(s):  
William R. Bower ◽  
Katherine Morris ◽  
Francis R. Livens ◽  
J. Frederick W. Mosselmans ◽  
Connaugh M. Fallon ◽  
...  
Keyword(s):  
Sediment Column ◽  
Uranium Speciation

Effect of Redox Zonation on the Reductive Transformation ofp-Cyanonitrobenzene in a Laboratory Sediment Column

2000 ◽  
Vol 34 (17) ◽  
pp. 3617-3622 ◽  
Author(s):  
Rupert Simon ◽  
Dalizza Colón ◽  
Caroline L. Tebes-Stevens ◽  
Eric J. Weber
Keyword(s):  
Sediment Column ◽  
Reductive Transformation ◽  
Redox Zonation

scholarly journals A model of the methane cycle, permafrost, and hydrology of the Siberian continental margin

2015 ◽  
Vol 12 (10) ◽  
pp. 2953-2974 ◽  
Author(s):  
D. Archer
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Methane Hydrate ◽  
Fossil Fuel ◽  
Methane Flux ◽  
Pore Fluid ◽  
Permafrost Zone ◽  
Sediment Surface ◽  
Sediment Column ◽  
Atmospheric Flux

Abstract. A two-dimensional model of a sediment column, with Darcy fluid flow, biological and thermal methane production, and permafrost and methane hydrate formation, is subjected to glacial–interglacial cycles in sea level, alternately exposing the continental shelf to the cold atmosphere during glacial times and immersing it in the ocean in interglacial times. The glacial cycles are followed by a "long-tail" 100 kyr warming due to fossil fuel combustion. The salinity of the sediment column in the interior of the shelf can be decreased by hydrological forcing to depths well below sea level when the sediment is exposed to the atmosphere. There is no analogous advective seawater-injecting mechanism upon resubmergence, only slower diffusive mechanisms. This hydrological ratchet is consistent with the existence of freshwater beneath the sea floor on continental shelves around the world, left over from the last glacial period. The salt content of the sediment column affects the relative proportions of the solid and fluid H2O-containing phases, but in the permafrost zone the salinity in the pore fluid brine is a function of temperature only, controlled by equilibrium with ice. Ice can tolerate a higher salinity in the pore fluid than methane hydrate can at low pressure and temperature, excluding methane hydrate from thermodynamic stability in the permafrost zone. The implication is that any methane hydrate existing today will be insulated from anthropogenic climate change by hundreds of meters of sediment, resulting in a response time of thousands of years. The strongest impact of the glacial–interglacial cycles on the atmospheric methane flux is due to bubbles dissolving in the ocean when sea level is high. When sea level is low and the sediment surface is exposed to the atmosphere, the atmospheric flux is sensitive to whether permafrost inhibits bubble migration in the model. If it does, the atmospheric flux is highest during the glaciating, sea level regression (soil-freezing) part of the cycle rather than during deglacial transgression (warming and thawing). The atmospheric flux response to a warming climate is small, relative to the rest of the methane sources to the atmosphere in the global budget, because of the ongoing flooding of the continental shelf. The increased methane flux due to ocean warming could be completely counteracted by a sea level rise of tens of meters on millennial timescales due to the loss of ice sheets, decreasing the efficiency of bubble transit through the water column. The model results give no indication of a mechanism by which methane emissions from the Siberian continental shelf could have a significant impact on the near-term evolution of Earth's climate, but on millennial timescales the release of carbon from hydrate and permafrost could contribute significantly to the fossil fuel carbon burden in the atmosphere–ocean–terrestrial carbon cycle.

scholarly journals Origin of sediment column profiles of gases and organic matter at a Laptev Sea gas seeps area (Arctic)

2021 ◽  
Author(s):  
Vyacheslav Sevastyanov ◽  
Valeria Fedulova ◽  
Veniamin Fedulov ◽  
Olga Kuznetsova ◽  
Nikita Dushenko ◽  
...  
Keyword(s):  
Organic Matter ◽  
Laptev Sea ◽  
Sediment Column ◽  
Gas Seeps

Phase partitioning and uranium speciation in brannerite-based ceramics

2017 ◽  
Vol 37 (2) ◽  
pp. 771-777 ◽  
Author(s):  
S.V. Stefanovsky ◽  
S.V. Yudintsev ◽  
A.A. Shiryaev ◽  
V.Y. Murzin ◽  
A.L. Trigub
Keyword(s):  
Phase Partitioning ◽  
Uranium Speciation

Intracellular behaviour of uranium(VI) on renal epithelial cell in culture (LLC-PK1): influence of uranium speciation

1999 ◽  
Vol 104 (3) ◽  
pp. 249-256 ◽  
Author(s):  
H Mirto ◽  
M.H Hengé-Napoli ◽  
R Gibert ◽  
E Ansoborlo ◽  
M Fournier ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Renal Epithelial Cell ◽  
Uranium Speciation

Uranium Speciation in Solution by Time-Resolved Laser-Induced Fluorescence

1995 ◽  
Vol 67 (2) ◽  
pp. 348-353 ◽  
Author(s):  
Christophe. Moulin ◽  
Pierre. Decambox ◽  
Valerie. Moulin ◽  
Jean Gary. Decaillon
Keyword(s):  
Laser Induced Fluorescence ◽  
Time Resolved ◽  
Uranium Speciation

Uranium speciation studies at alkaline pH and in the presence of hydrogen peroxide using time-resolved laser-induced fluorescence spectroscopy

Polyhedron ◽  
2013 ◽  
Vol 55 ◽  
pp. 92-101 ◽  
Author(s):  
Albert Martínez-Torrents ◽  
Sandra Meca ◽  
Nils Baumann ◽  
Vicenç Martí ◽  
Javier Giménez ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Fluorescence Spectroscopy ◽  
Laser Induced Fluorescence ◽  
Alkaline Ph ◽  
Time Resolved ◽  
Uranium Speciation
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