Respiration and dissolution in sediments of the western Atlantic

We present in situ microelectrode measurements of sediment formation factor and porewater oxygen and pH from six stations in the North Atlantic varying in depth from 2159 to 5380 m. A numerical model of the oxygen data indicates that fluxes of oxygen to the sediments are as much as an order of magnitude higher than benthic chamber flux measurements previously reported in the same area. Model results require dissolution driven by metabolic CO2 production within the sediments to explain the pH data; even at the station with the most undersaturated bottom waters >60% of the calcite dissolution occurs in response to metabolic CO2. Aragonite dissolution alone cannot provide the observed buffering of porewater pH, even at the shallowest station. A sensitivity test of the model that accounts for uncertainties in the bottom water saturation state and the stoichiometry between oxygen consumption and CO2 production during respiration constrains the dissolution rate constant for calcite to between 3 and 30% day**-1, in agreement with earlier in situ determinations of the rate constant. Model results predict that over 35% of the calcium carbonate rain to these sediments dissolves at all stations, confirmed by sediment trap and CaCO3 accumulation data.

Sedimentology and planktonic foraminiferal dissolution during the latest Cretaceous in the South Atlantic

A high-resolution (10-20 kyr) record of variations in CaCO3 content and dissolution was established for latest Cretaceous (last 0.7 Myr) deep-sea sediments from the South Atlantic Ocean (DSDP Site 516 from the Rio Grande Rise, and sites 525 and 527 from the Walvis Ridge). The degree of fragmentation of planktonic foraminifera (DFP) was used as a measure of calcite dissolution. High negative correlations between DFP and other independent measures of carbonate dissolution (percentage of sand fraction, absolute abundance of planktonic foraminifera, and planktonic/benthic foraminiferal ratio) validate its use as a sensitive index of calcite dissolution in upper Maastrichtian deep-sea sediments. Very high DFP and a significant negative correlation between DFP and CaCO 3 content suggest that Site 516 was located below the foraminiferal lysocline during the entire interval studied. Such a shallow position of the lysocline (paleodepth of Site 516 was 1.2 km) may be explained by "upwelling" of corrosive deep waters along the southern margin of the Rio Grande Rise. Sites 525 and 527 were located above the foraminiferal lysocline; however, three short periods of enhanced dissolution were recognised at Site 525 (paleodepth 1 km) and one interval of strong dissolution was identified at Site 527 (paleodepth 2.7 km). The lack of correspondence between the dissolution regimes at sites from the Walvis Ridge suggests limited deep-water communication across this physiographic barrier. Two of the dissolution maxima recognised at Site 525 correspond to carbonate maxima at Site 527. Variations in "upwelling" intensity along the Walvis Ridge, resulting in fluctuations in primary productivity in this area, may be the proximal cause of both carbonate cycles at Site 527 and dissolution cycles at Site 525. We suggest that development of the bottom Ekman layer between a hypothetical westward geostrophic current and the topographical height of the Rio Grande Rise-Walvis Ridge system may be a plausible hydrodynamical explanation for the proposed "'upwelling" along the southern margin of this topographical structure.

Barium isotope fractionation during witherite (BaCO3) dissolution, precipitation and at equilibrium

This study examines the behavior of Ba isotope fractionation between witherite and fluid during mineral dissolution, precipitation and at chemical equilibrium. Experiments were performed in batch reactors at 25 oC in 10-2 M NaCl solution where the pH was adjusted by continuous bubbling of a water saturated gas phase of CO2 or atmospheric air. During witherite dissolution no Ba isotope fractionation was observed between solid and fluid. In contrast, during witherite precipitation, caused by a pH increase, a preferential uptake of the lighter 134Ba isotopomer in the solid phase was observed. In this case, the isotope fractionation factor αwitherite-fluid is calculated to be 0.99993 ± 0.00004 (or Δ137/134Bawitherite-fluid ≈ -0.07 ± 0.04 ‰, 2sd). The most interesting feature of this study, however, is that after the attainment of chemical equilibrium, the Ba isotope composition of the aqueous phase is progressively becoming lighter, indicating a continuous exchange of Ba2+ ions between witherite and fluid. Mass balance calculations indicate that the detachment of Ba from the solid is not only restricted to the outer surface layer of the solid, but affects several (~7 unit cells) subsurface layers of the crystal. This observation comes in excellent agreement with the concept of a dynamic system at chemical equilibrium in a mineral-fluid system, denoting that the time required for the achievement of isotopic equilibrium in the witherite-fluid system is longer compared to that observed for chemical equilibrium. Overall, these results indicate that the isotopic composition of Ba bearing carbonates in natural environments may be altered due to changes in fluid composition without a net dissolution/precipitation to be observed.

Cases of divorce for several causes : viz. I. Memoirs of the life of Robert Feilding esq; containing an account of his amours ... and a true copy of his last will and testament. II. The case of Barbara late Dutchess of Cleaveland, with the whole proceedings between Her Grace, and Major-General Feilding in Doctors-Commons ... III. The case of John Dormer, esq. IV. The case of Sir George Downing, bart. and Mrs. Mary Forester. V. Depositions taken in the Lady Howard's case : also the judgment of the most eminent divines, &c. concerning the dissolution of marriage.

ESTC

Leached zone : dissolution of values using heat treated feeds /

"U.S. AEC Contract AT(49-1)-545."

Le Texas, ou Notice historique sur le Champ-d'Asile, comprenant tout ce qui s'est passé depuis la formation jusqu'à la dissolution de cette colonie, les causes qui l'ont amenée, et la liste de tous les colons français, avec renseignemens utiles à leurs familles

Streeter

A short history of Europe, from the fall of the Eastern empire to the dissolution of the Holy Roman empire,

Mode of access: Internet.

A short history of Europe from the dissolution of the Holy Roman empire to the outbreak of the German war,

Mode of access: Internet.

The sacred and profane history of the world connected, from the creation of the world to the dissolution of the Assyrian empire at the death of Sardanapalus, and to the declension of the kingdoms of Judah and Israel under the reigns of Ahaz and Pekah: including the dissertation on the creation and fall of man.

"Illustrated with a new and correct set of maps and plans."

The last abbot of Glastonbury : a tale of the dissolution of the monasteries /

Mode of access: Internet.

The sacred and prophane history of the world connected, from the creation of the world to the dissolution of the Assyrian empire at the death of Sardanapalus, and to the declension of the kingdoms of Judah and Israel, under the reigns of Ahaz and Pekah.

The author's Creation and fall of man, a supplemental discourse to the preface of v.1, forms v.4 in some of the later editions. cf. Lowndes.

A compendious history of the world from the creation to the dissolution of the Roman Republic ... with a continuation to the peace of Amiens, 1802 ...

Mode of access: Internet.

A narrative of the dissolution of the medical faculty of Transylvania University.

Mode of access: Internet.

A plain statement of the reasons which led to a dissolution of the connection of the author with the Methodist Episcopal church,

Mode of access: Internet.