Chemical composition of hard- and softrock groundwaters from central Norway with special consideration of fluoride and Norwegian drinking water limits

Groundwaters from crystalline and metamorphic rocks (hardrocks) and from Quaternary deposits, i.e., alluvial and glacial deposits (softrocks) from the counties of Nord-Trøndelag and Sør-Trøndelag were analyzed for major and minor elements and ions including fluoride. The median concentration of F^– in water from the hardrock aquifers is 0.28 mg/l (14.7 eq/l) in contrast to water from softrock aquifers in which it is found to be 0.05 mg/1 (2.6 eq/l). More importantly, ca. 15% of the locations where water was abstracted from hardrock wells contain 1.5 mg/l (78.9 eq/l) F^– or more. Thus, 15% of all hardrock wells returned F^– results that are at or above the maximum recommended value for drinking water. Of the softrock wells, none are above 1 mg/l. Geologists would normally expect higher F^–contents in groundwaters derived from acid rocks, e.g., in granitic or gneissic areas. When comparing the host lithology with the observed F^–contents, however, no clear relationship between F^– content and lithology is visible. The highest observed F^– values actually occur in gneissic host rocks. However, wells drilled in amphibolites/greenstones, mica schists, calcareous rocks, and sedimentary rocks all returned some analytical results above 1.5 mg/l F^–. These results suggest that all hardrock wells drilled should be tested for F^– and the users informed about the results and advised to take any necessary precautions. When applying the recently proposed Norwegian drinking water limits to our data, 51% of all softrock well waters and 56% of all hardrock well waters are unfit for consumption without prior treatment, although we analyzed only for about half of the proposed elements/parameters. This result seriously questions the concept of fixed action levels—many of them with totally unproven health implications—for so many parameters/elements for hardrock groundwaters.     

Efficient generation of conditional simulations by chebyshev matrix polynomial approximations to the symmetric square root of the covariance matrix

Consider the problem of generating a realization y₁ of a Gaussian random field on a dense grid of points ₁ conditioned on field observations y₂ collected on a sparse grid of points ₂. An approach to this is to generate first an unconditional realization y over the grid =_{1 2}, and then to produce y₁ by conditioning y on the data y₂. As standard methods for generating y, such as the turning bands, spectral or Cholesky approaches can have various limitations, it has been proposed by M. W. Davis to generate realizations from a matrix polynomial approximations to the square root of the covariance matrix. In this paper we describe how to generate a direct approximation to the conditional realization y₁, on ₁ using a variant of Davis' approach based on approximation by Chebyshev polynomials. The resulting algorithm is simple to implement, numerically stable, and bounds on the approximation error are readily available. Furthermore we show that the conditional realization y₁ can be generated directly with a lower order polynomial than the unconditional realization y, and that further reductions can be achieved by exploiting a nugget effect if one is present. A pseudocode version of the algorithm is provided that can be implemented using the fast Fourier transform if the field is stationary and the grid ₁ is rectangular. Finally, numerical illustrations are given of the algorithm's performance in generating various 2-D realizations of conditional processes on large sampling grids.     

Trace elements distribution and mineralogical composition in the < 2-μm size fraction of shales from the Southern Apennines,Italy

Summary Mineralogical composition and trace elements distribution in the < 2-m size fraction of Late Cretaceous-Oligocene shales from the Southern Apennines (Italy) are presented.The clay mineral assemblage consists of illite, smectite, kaolinite and minor chlorite. Analytical evidence points to a detrital micaceous precursor for illite and smectite. Accessory phases were also found. Chemical data, normalized with respect to the Post-Archean Australian Shales (PAAS), indicate depletion of Ba, Rb, Y, Zr and enrichment of Nb. PAAS-normalized REE-patterns exhibit a positive Eu anomaly and HREE depletion. A kaolinite-rich sample has high REE contents in contrast to smectite-rich fractions. A REE-pattern without appreciable Eu anomaly is displayed by the illite-rich sample.Statistical data processing indicates a link between Ti, P, Y, Zr, Nb and Yb, suggesting that accessory phases may play a role in controlling HREE and that the observed LREE/HREE fractionation may also be due to hydraulic sorting of these phases. An important La-kaolinite relationship accounts for the capability of this phase to host LREE. Smectite and, thus, adsorption mechanisms, appear to exert a limited role in distributing REE. The Eu anomaly is a source inherited feature, probably not determined solely by clay minerals.

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Spurenelement-Verteilung und mineralogische Zusammensetzung der < 2m Fraktion von Schiefern aus dem südlichen Appenin (Italien)

Zusammenfassung Die mineralogische Zusammensetzung und die Verteilung der Spurenelemente in der < 2 m Fraktion von spät-kretazischen-oligozänen Schiefern aus dem südlichen Appenin (Italien) werden in Übersicht gebracht. Die Tonmineral-Vergesellschaftung besteht aus Illit, Smectit, Kaolinit und kleineren Mengen von Chlorit. Analytische Daten weisen darauf hin, daß Illit und Smectit aus einem detritischen Glimmermineral hervorgegangen sein dürften. Auch akzessorische Phasen kommen vor. Chemische Daten zeigen gegenüber post-Archaischen australischen Schiefern (PAAS) eine Verarmung in Ba, Rb, Y, Zr und eine Anreicherung von Nb. PAAS-normalisierte SEE-Verteilungsmuster zeigen eine positive Eu Anomalie und eine Verarmung an HSEE. Eine Kaolinit-reiche Probe zeigt hohe Gehalte an gesamten SEE im Gegensatz zu einer Smectit-reichen. Die Illit-reiche Probe zeigt ein SEE-Verteilungsmuster ohne deutliche Eu Anomalie.Statistische Verarbeitung der Daten läßt eine Verbindung zwischen Ti, P, Y, Zr, Nb und Yb erkennen; dies weist darauf hin, daß akzessorische Phasen einen Einfluß auf die HSEE-Verteilung haben und daß die beobachtete LSEE/HSEE Fraktionierung auch auf hydraulische Sortierung dieser Phasen zurückgehen könnte. Es gibt eine bedeutsame Beziehung zwischen La und Kaolinit und diese unterstreicht die Fähigkeit des Kaolinits für die Aufnahme von LSEE. Smectit und Adsorptionsmechanismen scheinen eine geringe Rolle für die Verteilung der SEE zu spielen. Die Eu Anomalie ist eine Erscheinung, die auf die Quelle der sedimentären Minerale zurückgeht und wahrscheinlich nicht ausschließlich durch Tonminerale bestimmt wird.

     

A search for endogenous amino acids in the Martian meteorite EETA79001

The Antarctic shergottite EETA79001 is believed to be an impact-ejected fragment of the planet Mars. Samples of the carbonate (white druse) and the basaltic (lithology A) components from this meteorite have been found to contain amino acids at a level of approximately 1 ppm and 0.4 ppm, respectively. The detected amino acids consist almost exclusively of the L-enantiomers of the amino acids commonly found in proteins, and are thus terrestrial contaminants. There is no indication of the presence of alpha-aminoisobutyric acid, one of the most abundant amino acids in several carbonaceous chondrites. The relative abundances of amino acids in the druse material resemble those in Antarctic ice, suggesting that the source of the amino acids may be ice meltwater. The level of amino acids in EETA79001 druse is not by itself sufficient to account for the 600-700 ppm of volatile C reported in druse samples and suggested to be from endogenous martian organic material. However, estimates of total terrestrial organic C present in the druse material based on our amino acid analyses and the organic C content of polar ice can account for most of the reported putative organic C in EETA79001 druse.     

Radiometric constraints on hydrothermal circulation in cooling granite plutons

Improved precision of radiometric dating of ore deposits can provide information about the thermal history of hydrothermal circulation in cooling plutons. In Jales a Hercynian porphyritic two-mica granite and pre-Ordovician mica schists are cut and intensely altered by the Campo gold-quartz vein. The unaltered granite must be younger than 320 ± 6 Ma, and gives mica Rb-Sr ages of 308.5 ± 2.4 (1) Ma (muscovite) and 294.5 ± 1.1 Ma (biotite). Alteration muscovites from the granite give a weighted mean Rb-Sr age of 308.1 ± 1.5 Ma, and a mean ³⁹Ar-⁴⁰Ar age of 300.7 ± 2.8 Ma. Alteration muscovites from the mica schists give similar ³⁹Ar-⁴⁰Ar ages, averaging 303.0 ± 2.8 Ma. The results suggest that circulation of the Campo mineralising fluids took place no more than 2–4 Ma after the granite cooled through the muscovite Rb-Sr closure temperature, about 500 °C, and that subsequent cooling to biotite closure at about 300 °C took place at less than 14°C/Ma. The mean cooling rate following emplacement was 15 to 25 °C/Ma. The most detailed comparable published data, for the Cornubian ore field, imply much faster cooling rates.     

Powder- and single crystal Mössbauer spectroscopy on synthetic fayalite

Mössbauer measurements on synthetic iron orthosilicate Fe₂SiO₄ (fayalite) were carried out in the antiferromagnetic spin state below T _N 65 K. The Mössbauer parameters isomer shift , inner magnetic field H(0), angle between H(0) and the z-component of the electric field gradient (efg), quadrupole splitting QS and asymmetry parameter were determined as a function of temperature. These parameters could be attributed to the two crystallographic sites M1 and M2.The smaller isomer shift on M1 with respect to M2 displays the more covalent character of the Fe-O bond on M1, which is supported by previous neutron diffraction experiments. H(0) shows a Brillouin-type behaviour with different fields on the two crystallographic sites (stronger on M1) and a small discontinuity at T = 23 K which corresponds with previous magnetic measurements. The quadrupole splitting is equal on both sites within error bars, in agreement with previous theoretical results and in contradiction to previous Mössbauer refinements published elsewhere.     

Mössbauer spectroscopic and x-ray powder diffraction studies of synthetic micas on the join annite KFe3AlSi3O10(OH)2-phlogopite KMg3AlSi3O10(OH)2

Micas of the composition K(Fe_3–x Mg _x )AlSi₃ O₁₀(OH)₂ (x=0.6, 1.2, 1.8, 2.4 and 3.0, corresponding to ann₈₀phl₂₀, ann₆₀phl₄₀, ann₄₀phl₆₀, ann₂₀phl₈₀ and ann₀phl₁₀₀) were synthesized hydrothermally under controlled oxygen fugacity conditions. Lattice parameters a ₀ and b ₀ show a distinct linear decrease with increasing Mg content. With increasing ferric iron content a deviation from this linear trend is observed especially within iron rich samples. The tetrahedral rotation angle increases smoothly from 0° in annite to 9.1° in phlogopite. Mössbauer spectra show Fe²⁺ and Fe³⁺ on the octahedral M1 and M2 sites and partially also Fe³⁺ on the tetrahedral site. There is a smooth increase of the quadrupole splitting on both the M1 and the M2 site going from annite to phlogopite, probably due to changes in the lattice contribution to the electric field gradient, assuming a positive correlation between quadrupole splitting and distortion. Fe³⁺ contents, as determined by Mössbauer spectroscopy, versus oxygen fugacity shows that, depending on the composition of the micas, minimum amounts of Fe³⁺ are present. For ann₈₀phl₂₀ this minimum amount of Fe³⁺ is about 8% decreasing to about 1–2% Fe³⁺ for ann₂₀phl₈₀.The molar volume of each solid solution member has been estimated from the determined relations of the molar volume versus % Fe³⁺ contents, extrapolated back to 0% Fe³⁺. Plotting these volumes as a function of X_phl shows that negative excess volume occur in the annitephlogopite join, with the maximum deviation from ideality around X _phl=0.3. Margules volume parameters have been constrained as: Wv, AnnPhl=0.018±0.016 J/(bar.mol) and Wv, PhlAnn=-0.391±0.025 J(bar.mol) (three site basis).     

Possible creep-related tilt precursors obtained in the Central Apennines (Italy) and in the Southern Caucasus (Georgia)

Daily averaged tilt component data from two sites of the Central Apennines (Italy) and of the Southern Caucasus (Georgia), respectively, revealed intermediate-term tilts as possible precursors to earthquakes (M=3.0÷4.7) which occurred in the above-mentioned seismic areas within a distance of 50 km from the sites. A good temporal correlation as well as a fair spatial correspondence between these residual tilts (with amplitude and duration of some microradians and months, respectively) and main shocks were pointed out, by removing both secular trends and seasonal thermoelastic effects from the raw tilts. An attempt was made to justify the above-mentioned results, based on the assumption that the observed intermediate-term preseismic tilts are the manifestation of aseismic creep episodes of comparable duration in the fault materials of thrust faults close to the tilt sites. The mechanism refers to a strain field slowly propagating from the preparation focal area to the tilt site, through crustal blocks separated by weak transition zones. This propagation is thought to be the cause of the local aseismic fault slip recorded by the tiltmeters. Previously, both discrete structures and strain propagation effects were revealed in the Central Apennines and are thought also to exist in the Southern Caucasus. As in the past, the rheological properties of fault materials are revealed as viscoelastic ones. In fact, creep equations obtained by applying several viscoelastic models on our data, proved to fit quite well some of the observed tilt precursors, producing viscosity and rigidity values very similar to those reported in literature.Professor Petr Viktorovich Manjgaladze died during the writing of this paper     

Seasonal variations of diffuse solar radiation at Ilorin (8°32′N,4°46′E), Nigeria

Hourly diffuse solar irradiance (H_d) and the corresponding global irradiance (H) falling on a horizontal surface at Ilorin (8°32N,4°46E), Nigeria has been measured for a period of fifteen months commencing from February, 1993. As expected, each monthly mean diurnal variation of H_d exhibits a mid-day maximum, while that of the ratio H_d/H exhibits a minimum. The month to month variations of these parameters are consequent on the dominant atmospheric conditions observed in the months concerned. The monthly average daily total of diffuse radiation (H_dm) was found to be highest in February, 1994 with a value of (3347 ± 45) Wm^–2day^–1, mainly due to the effects of Harmattan haze and thin clouds, while it was found to be lowest in November, 1993 and January, 1994 with a value of about 2500 Wm^–2day^–1. Similarly, the ratio of the monthly average daily total of diffuse radiation to the monthly average daily total of global radiation (H_dm/H_m) had the lowest value of 0.49 in the relatively clear sky month of November, 1993 and the highest value of 0.74 in the mainly cloudy month of August, 1993. On an annual average, the diffuse component constituted about 60% of the global solar radiation arriving on the ground at Ilorin, Nigeria primarily due to clouds and Harmattan haze which are seasonal, in addition to the constant background of molecular scattering.     

Analysis of COMPTEL gamma-ray burst locations and spectra

In its first three years of operation, the COMPTEL instrument on theCompton Gamma-Ray Observatory has measured the locations (mean accuracy 1°) and spectra (0.75-30 MeV) of 18 gamma-ray bursts and continues to observe new events at a rate of 1/month. With good angular resolution and sensitivity at MeV energies, the growing COMPTEL burst catalog is an important new piece of evidence in the on-going GRB mystery. The COMPTEL burst locations are consistent with an isotropic distribution of sources, yet the spatial coincidence of two of the bursts indicates the possibility of repetition. The COMPTEL burst spectra are in most cases consistent with a single power law model with spectral index in the range 2–3. However, two bursts show evidence of a spectral break in the MeV range. Measurement of rapid variability at MeV energies in the stronger bursts provides evidence that either the sources are nearby (within the Galaxy) or the gamma-ray emission is relativistically beamed. We present an overview of analysis results obtained from the COMPTEL burst catalog concentrating on the search for burst repetition and the implications of highly variable MeV emission.