Showing papers in "Geochimica et Cosmochimica Acta in 1981"

TL;DR: For example, the accumulation of biogenic silica in estuarine deposits removes a maximum of 8 × 1014g SiO2/yr or 10% of the dissolved silica input to the oceans as mentioned in this paper.

TL;DR: In this paper, a data base summarising the stability constants of more than 500 complexes is used to calculate speciation pictures for 58 trace elements in model seawater (pH 8.2) and freshwaters (PH 6 and 9).

TL;DR: In this article, the methods used for precise calibrations of Sm/Nd ratios and the average isotopic abundances obtained for normal Sm and Nd are given, and a mixed Sm-Nd normal solution with a precisely known Sm/nd ratio close to the nominal average chondritic value is described and the calibration discussed.

TL;DR: In this article, the interaction of humic substances from Esthwaite Water with hydrous iron oxides (α-FeOOH, α-Fe2O3, amorphous Fe-gel) have been examined by measuring adsorption isotherms and by microelectrophoresis.

TL;DR: In this paper, a pH-stat was used to maintain a constant degree of saturation, and hence precipitation rate, during each coprecipitation run, and the precipitation rate was proportional to the degree of supersaturation and the mass of seed crystal introduced.

TL;DR: In this paper, the authors used carbon and hydrogen isotopic analysis to identify the source of a gas that has been partially oxidized by a bacteria, which can significantly change the carbon isotopic composition of the gas.

TL;DR: The authors measured polycyclic aromatic hydrocarbons (PAH) in dated sediment cores from several sites in the northeastern United States ( Lake Superior, Isle Royale, Somes Sound, Hadlock Lower Pond, Coburn Mountain Pond, and outer Boston Harbor).

TL;DR: In this article, the degree of crude oil maturation in basins from California, Alaska, Russia, Wyoming, and Louisiana can be assessed by specific novel biomarker ratios (20S/20R sterane epimers).

TL;DR: In this paper, the authors made an analysis of the rare earth contents of a suite of deep-sea (> 4000 m) seafloor nodules and associated sediments from the Pacific Ocean and found that 3 + REE concentrations are controlled by the surface chemistry of these phases during diagenetic reactions which vary with sediment accumulation rate.

TL;DR: In this article, the reaction between hydrous iron oxides and aqueous sulfide species was studied at estuarine conditions of pH, total sulfide, and ionic strength to determine the kinetics and formation mechanism of the initial iron sulfide.

TL;DR: In this article, the authors show that young ochreous precipitations from Fe-bearing spring waters in Finland consist mainly of ferrihydrite, a poorly ordered Feoxide with a layer structure and the bulk composition 5 Fe2O3 ·9 H2O Crystallinity ranges from a reasonably well developed structure to a highly disordered one with only two prismatic reflections at 2.5 and 1.5 A.

TL;DR: In the Hubhard Brook watershed, the water path length in the soil zone is the crucial factor in the state of acid rain neutralization, aluminum chemistry and chemical weathering as mentioned in this paper.

TL;DR: In this article, the age of the UNSB (Upper member of North Star Basalt) is established at 3.56-3.57 by both the Rb-Sr and the Sm-Nd methods, which is consistent with the stratigraphic interpretation that the TalgaTalga Subgroup is overlain by the Duffer Formation.

TL;DR: In this article, chemical analyses have been made for total inorganic phosphorus, total organic phosphorus, and organic carbon in plankton and in anoxic sediments from Long Island Sound, U.S.A.

TL;DR: In this article, the dissolution of enstatite, diopside, and tremolite in aqueous solution at low temperatures (20-60°C) and pH 1-6 has been studied in the laboratory by means of chemical analyses of reacting solutions for Ca2+, Mg2+, and Si(OH)4 and by the use of X-ray photoelectron spectroscopy (XPS) for detecting changes in surface chemistry of the minerals.

TL;DR: In this article, three series of monoaromatic steroid hydrocarbons (basepeak = m/z 239, 253 and 267) and four series of triaromatic sterols (base peak =m/z 217, 231, 245 and 259) have been recognized by computerized gas chromatography-mass spectrometry in a variety of samples of Lower Toarcian shales from the Paris Basin.

TL;DR: The abundance and distribution of Au, Pd, Ir, Cu, Co and Cr has been determined in mantle-derived spinel lherzolite xenoliths in basanites from Mt Porndon (Victoria, Australia) and Kilbourne Hole (New Mexico, U.S.A.) and in garnet lhersolites from the Matsoku and Thaba Putsoa kimberlites (Lesotho) as discussed by the authors.

TL;DR: In this paper, Fick's first law was used to calculate the diffusive mobilities of dissolved ammonium, phosphate and phosphate ion pairs in an organic-rich anoxic sediments of Cape Lookout Bight.

TL;DR: In this article, the major and seventeen trace element distribution coefficients between main phenocrysts (olivine, clinopyroxene, amphibole, mica, feldspars and Fe-Ti oxides) and groundmass have been measured in the alkali basalt suite of Chaine des Puys (Massif Central, France).

TL;DR: In this paper, the results demonstrate that solubilities and adsorption properties of certain trace metals in freshwaters can be opposite to those observed with artificial solutions or predicted with chemical models.

TL;DR: In this paper, seawater and NaCl solutions were reacted with basalt (basalt glass and diabase) for several months at 300°C, 500 bars and a water/rock ratio of 10.

TL;DR: In this article, the relative stabilities of these phases were evaluated on the basis of their solubilities, the least soluble aluminium silicate representing the thermodynamically most stable phase under a given set of conditions.

TL;DR: In this article, the chemical characteristics of Columbia River Province basalts displaying a wide range of chemical and isotopic compositions, the isotopic variability calls for the involvement of at least two isotopically distinct components.

TL;DR: In this paper, the stable isotopic ratios of oxygen, carbon and the non-exchangeable carbon-bound hydrogen of cellulose from marine plants (algae and higher vascular forms) and animals (tunicates) collected in their natural habitats and from freshwater vascular plants grown in the laboratory under controlled conditions were determined.

TL;DR: TEM, HRTEM and HVEM methods coupled with energy dispersive X-ray analysis have been used to study the microstructure and the phases comprising the matrix of carbonaceous chondrites Murchison, Cold Bokkeveld, Nawapali and Cochabamba as mentioned in this paper.

TL;DR: The fine-grained, opaque, silicate matrix of type 3 unequilibrated chondrites was examined by optical microscopy, an electron microprobe, and a scanning electron microscope as mentioned in this paper.

TL;DR: Sulfate reduction during seawater reaction with fayalite and with magnetite was rapid at 350°C, producing equilibrium assemblages of talc-pyrite-hematite-magnetite at low water/rock ratios and talc pyrite,hematite, anhydrite-anhydrite at higher water /rock ratios as mentioned in this paper.

TL;DR: In this paper, a variety of minerals from three basic intrusions within the high-grade metamorphic terrane near Haliburton, Ontario, were selected for K-Ar dating.

TL;DR: In this paper, a series of veneer layers chiseled in sequence from the outside toward the center of each of the five 1500-5500yr old ice core sections that had been drilled in Greenland and Antarctic ice.

TL;DR: In this paper, sixtynine analyses were given for NH4 in minerals of metamorphic and granitic rocks mostly from the Ryoke belt, Japan, and the distribution of NH4 was quite systematic, suggesting that NH4 is one of the stable geochemical components in high temperature processes.