Stability constants of NaSO4−, MgSO4, MgF+, MgCl+ ion pairs at the ionic strength of seawater by potentiometry     

Bengt Elgquist  Margareta Wedborg 《Marine Chemistry》1978,6(3):243-252

The stability of the ion pair NaSO₄ was determined by measuring the change in sodium activity with medium composition at constant ionic strength, using a sodium-sensitive glass electrode. The stability constants of MgSO₄ and MgCl⁺ were determined indirectly from measurements of the stability of MgF⁺ in different media. All measurements were performed at 1 atm pressure, 25 ± 0.1 °C and 0.7 M formal ionic strength. The stability constants for NaSO₄^?, MgSO₄, MgF⁺ and MgCl⁺ are 1.8 ± 0.1, 6.3 ± 0.1, 22.9 ± 0.1 and 0.34 ± 0.02 M^?1, respectively.  相似文献   

Sulphate complexation in seawater: A relation between the stability constants of sodium sulphate and magnesium sulphate in seawater from a determination of the stability constant of hydrogen sulphate and a calculation of the single ion activity coefficient of sulphate     

Bengt Elgquist  Margareta Wedborg 《Marine Chemistry》1974,2(1):1-15

The conditional stability constant of HSO₄^? has been determined at 25°C, 1 atm and a formal ionic strength of 0.7 M in solutions containing sodium, magnesium, chloride and sulphate. This was done spectrophotometrically (UV), using diphenylamine as indicator. The value obtained was 17.0 ± 0.1 (molar scale). Single ion activity coefficients for Na₂SO₄, K₂SO₄ and MgSO₄ have been calculated according to the Bates et al. (1970) model, assuming that the sulphate ion is not hydrated. It was found that the single ion activity coefficient of sulphate changes very little between Na₂SO₄, K₂SO₄ and MgSO₄ when the formal ionic strength is kept constant.These results have been used to obtain relations between the stability constants of NaSO₄^? and MgSO₄ valid for seawater.  相似文献   

Tectonic control of pyrrhotite phase distribution studied on a fold structure     

Lutz Kübler  Bengt Lindqvist 《Lithos》1979,12(3):241-249

A fold structure within a pyrite ore specimen has been analysed with respect to the amount and distribution of pyrrhotite modifications present. The relative distribution of the two types of pyrrhotite, hexagonal 5C and monoclinic 4C, was found to be strongly dependent upon the stress distribution. Within very short distances the hexagonal fraction of the total amount of pyrrhotite varied from nearly zero up to 0.65 giving steep and structurally well defined gradients. The monoclinic phase was preferably located to regions deformed by intense shearing. It is suggested that the influence of anisotropic stresses accelerated the conversion of hexagonal to monoclinic pyrrhotite. Variations in the distribution of the total amount of pyrrhotite were also observed and partly ascribed to migration of pyrrhotite.  相似文献   

Analytically processed Landsat TM images for visual geological interpretation in the northern Scandinavian Caledonides     

Kjell Wester  Bengt Lundn  Gerhard Bax 《ISPRS Journal of Photogrammetry and Remote Sensing》1990,45(5-6)

The best results for lithogical mapping and mineral exploration using remote sensing have hitherto been achieved in areas with arid or semi-arid climates, residual soils and with little or no vegetation cover. This study concerns the applicability of Landsat TM data for lithological mapping in a part of the northernmost Scandinavian Caledonides, dominated by bare rock but with frequent occurrence of vegetation-covered glacial deposits. In order to efficiently use existing image enhancement methods, e.g., principal component analysis and ratios, it is important to concentrate, as far is possible, on the spectral characteristics of the bedrock within the areas to be interpreted. The statistics for the processed images are then concentrated on bare rock and spectrally similar objects like soils. Various methods for image enhancement for geological purposes are discussed, and procedures for the removal of picture elements influenced by vegetation, water, clouds, snow and deep shadows are described.  相似文献   

Palynomorph content of the uraniferous alum shales of Cambrian-Ordovician age in Sweden     

Dorothy Guy-Ohlson  Bengt Lindqvist 《Ore Geology Reviews》1990,5(5-6)

Preliminary investigations were carried out on selected samples of different ages from various alum shale localities in order to document palynofacies and content of palynomorphs as well as content and distribution of various minerals and chemical elements. There preliminary results indicate that the shales not only contain a variety of microfossils not previously recorded, but also that these fossils indicate a fresh water or saline influence. The tentative conclusion is that the uranium-bearing alum shales may have been deposited under shallow, brackish conditions with an anoxic bottom environment.  相似文献   

Stability of ion pairs from gypsum solubility degree of ion pair formation between the major constituents of seawater     

Bengt Elgquist  Margareta Wedborg 《Marine Chemistry》1975,3(3):215-225

The stability constants of the ion pairs NaSO₄^?, KSO₄^?, MgSO₄^?, CaSO₄, MgCl⁺ and CaCl⁺ were determined at 25°C and 0.7 M formal ionic strength, by measuring the solubility of gypsum (CaSO₄ · 2H₂O) in different media. The media used contained one or two of the following electrolytes: NaCl, KCl, MgCl₂, NaClO₄, Mg(ClO₄)₂, Na₂SO₄. Values for the stability constants are 1.22, 1.84, 12.3, 30.6, 0.48 and 1.20 M^?1, respectively, and the solubility product for gypsum is 2.87 · 10^?4M². The distribution of the main constituents of seawater was calculated using these results and the values of the carbonate and bicarbonate constants given by Dyrssen and Hansson (1972–1973). The solubility of gypsum in seawater as calculated and determined experimentally was 21.43 mM and 21.10 mM, respectively.  相似文献   

On the energy dependence of the ring current proton precipitation     

F. Søraas  J.Å. Lundblad  B. Hultqvist 《Planetary and Space Science》1977,25(8):757-763

Low altitude satellite measurements of protons in the 1–100 keV range indicate two energy dependent proton precipitation boundaries. At low invariant latitudes mostly below 60° there is a region of moderately weak proton precipitation. The poleward boundary of this region tends to be at higher latitudes for the high energy protons than for the low energy protons. At high invariant latitudes there is a region where both the low and high energy protons precipitate with an isotropic pitch-angle distribution. The equatorward boundary of this region tends to be at lower latitudes for protons with energy more than 100 keV than for those in the 1–6 keV range. This region with isotropic pitch-angle distribution is located well outside the plasmapause both for the 1–6 and 100-keV protons.Between these two precipitation zones there is a region where the proton pitch-angle distribution is highly anisotropic with almost no protons in the loss cone. This region tends to be wider and more pronounced in the 1–6 than in the 100-keV protons.These findings lend further support to the mechanism of ion-cyclotron instability as the cause of proton pitch-angle diffusion in the low and intermediate regions. The process responsible for the strong diffusion at auroral latitudes has not yet been identified.  相似文献   

Insight into the nature of precipitation—Some achievements by T. Bergeron in retrospect     

Bengt Dahlström 《Pure and Applied Geophysics》1980,119(3):548-557

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The Evolution of Giant Oil Field Production Behavior     

Mikael Höök  Bengt Söderbergh  Kristofer Jakobsson  Kjell Aleklett 《Natural Resources Research》2009,18(1):39-56

The giant oil fields of the world are only a small fraction of the total number of fields, but their importance is huge. Over 50% of the world’s oil production came from giants by 2005 and more than half of the world’s ultimate reserves are found in giants. Based on this, it is reasonable to assume that the future development of the giant oil fields will have a significant impact on the world oil supply. In order to better understand the giant fields and their future behavior, one must first understand their history. This study has used a comprehensive database on giant oil fields in order to determine their typical parameters, such as the average decline rate and life-times of giants. The evolution of giant oil field behavior has been investigated to better understand future behavior. One conclusion is that new technology and production methods have generally led to high depletion rates and rapid decline. The historical trend points towards high decline rates of fields currently on plateau production. The peak production generally occurs before half the ultimate reserves have been produced in giant oil fields. A strong correlation between depletion-at-peak and average decline rate is also found, verifying that high depletion rate leads to rapid decline. Our result also implies that depletion analysis can be used to rule out unrealistic production expectations from a known reserve, or to connect an estimated production level to a needed reserve base.  相似文献   

Parallel electric fields accelerating ions and electrons in the same direction     

Bengt Hultqvist  Rickard Lundin 《Astrophysics and Space Science》1988,144(1-2):149-154

In this contribution we present Viking observations of electrons and positive ions which move upward along the magnetic field lines with energies of the same order of magnitude. We propose that both ions and electrons are accelerated by an electric field which has low-frequency temporal variations such that the ions experience an average electrostatic potential drop along the magnetic field lines whereas the upward streaming electrons are accelerated in periods of downward pointing electric field which is quasi-static for the electrons and forces them to beam out of the field region before the field changes direction.Paper dedicated to Professor Hannes Alfvén on the occasion of his 80th birthday, 30 May 1988.  相似文献