Effect of hydrocarbon-contaminated fluctuating groundwater on magnetic properties of shallow sediments

We investigate magnetic phase (trans)formation in the presence of petroleum hydrocarbons and its relation to bacterial activity, in particular in the zone of remediation driven fluctuating water levels at a former military air base in the Czech Republic. In a previous study an increase of magnetite concentration from the groundwater table towards the top of the groundwater fluctuation zone (GWFZ) was reported, however with limited reliability as there was no control on small-scale effects. To recognize statistically significant magnetic signatures versus depth, we obtained multiple sediment cores from three locations in January 2011 and April 2012, penetrating the unsaturated zone, the GWFZ and the uppermost one meter below the groundwater level (～2.3 m depth at the time of sampling). Magnetic concentration variation versus depth was determined by measuring magnetic susceptibility (MS) and remanence parameters. Small-scale features were identified and eliminated by statistical processing of multiple cores. A trend of increasing MS values from the lowermost position of the groundwater table upward was verified and highest magnetic concentration was found at the top of the GWFZ. Magnetic mineralogy indicates that newly formed fine-grained magnetite in the single domain to small pseudo-single domain range is responsible for the MS enhancement confirming previous results. There is no correlation with the depth variation of hydrocarbon (HC) concentrations; however, total organic carbon is linked to MS and may represent a degradation product of HC that is bioavailable for microorganisms. Bacterial activity is likely responsible for magnetite formation as indicated by most probable number (MPN) results of iron-metabolizing bacteria. The comparison of our results with an earlier study conducted at the same site revealed that magnetic concentration clearly decreased since remediation was terminated in 2008, possibly due to dissolution of magnetite.     

Unusual nickel mineralisation at Nullagine,Western Australia

Nickel mineralisation occurs in shears in Archaean serpentinised peridotite near Nullagine, Western Australia. The principal nickel minerals are millerite, polydymite and pecoraite, which occur chiefly as concentrations of nodular grains, mostly between 1 and 5 mm in diameter. The polydymite represents a replacement of millerite, and is in turn partly replaced by gaspéite. The pecoraite grains generally contain several percent chromium, and are frequently rimmed by millerite‐containing magnetite. A similar type of nodule consists of nullaginite (Ni₂(OH)₂CO₃). Other major minerals in the shears include various types of serpentine and magnesite, coarse chlorite, and apatite. The assemblage is cut by late veinlets of gaspéite, pecoraite, otwayite (Ni₂(OH)₂CO₃.H₂O), and nullaginite. Trace amounts of barite, cinnabar, parkerite, shandite, breithauptite, and nickeloan greenockite are also present.

The bulk of the mineralisation is attributed to the effects of hydrothermal and/or metasomatic activity along shears in the serpentine. Concretionary magnesite in some of the shears is believed to be the result of Tertiary weathering. The late veinlets of nickel minerals and the replacement of millerite and polydymite are attributed to supergene effects.     

The end of the Ediacara biota: Extinction,biotic replacement,or Cheshire Cat?

The Ediacaran–Cambrian transition signals a drastic change in both diversity and ecosystem construction. The Ediacara biota (consisting of various metazoan stem lineages in addition to extinct eukaryotic clades) disappears, and is replaced by more familiar Cambrian and Paleozoic metazoan groups. Although metazoans are present in the Ediacaran, their ecological contribution is dwarfed by Ediacaran-type clades of uncertain phylogenetic affinities, while Ediacaran-type morphologies are virtually non-existent in younger assemblages. Three alternative hypotheses have been advanced to explain this dramatic change at, or near, the Ediacaran–Cambrian boundary: 1) mass extinction of most Ediacaran forms; 2) biotic replacement, with early Cambrian organisms eliminating Ediacaran forms; and 3) a Cheshire Cat model, with Ediacaran forms gradually disappearing from the fossil record (but not necessarily going extinct) as a result of the elimination of unique preservational settings, primarily microbial matgrounds, that dominated the Ediacaran. To evaluate these proposed explanations for the biotic changes observed at the Ediacaran–Cambrian transition, environmental drivers leading to global mass extinction are compared to biological factors such as predation and ecosystem engineering. We explore temporal and biogeographic distributions of Ediacaran taxa combined with evaluations of functional guild ranges throughout the Ediacaran. The paucity of temporally-resolved localities with diverse Ediacaran assemblages, combined with difficulties associated with differences in taphonomic regimes before, during, and after the transition hinders this evaluation. Nonetheless, the demonstration of geographic and niche range changes offers a novel means of assessing the downfall of Ediacara-type taxa at the hands of emerging metazoans, which we hypothesize to be most likely due to the indirect ecological impact metazoans had upon the Ediacarans. Ultimately, the combination of studies on ecosystem construction, biostratigraphy, and biogeography showcases the magnitude of the transition at the Ediacaran–Cambrian boundary.     

Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos

Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA > 2H1NA > 2H3NA > 6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations.     

In situ bioremediation of 1,2-dichloroethane under anaerobic conditions

Historic spillages of chlorinated hydrocarbons at a vinyl chloride plant in the Rotterdam–Botlek area in The Netherlands has lead to deep-seated pollution of the underlying aquifer. The principal pollutant is 1,2-dichloroethane (1,2-DCA). As a temporary measure, the contamination is being contained using a pump and treat system. In the long term, in-situ bioremediation has been proposed using a biologically active zone where pollutants would be dechlorinated by microorganisms that simultaneously degrade other carbon sources. In order to investigate the suitability of this new technology, a programme of laboratory tests was carried out. The laboratory programme involved a series of anaerobic soil column tests, where the selection and delivery of different carbon substrates that stimulated 1,2-DCA dechlorination were investigated. The soil columns were prepared using soil and groundwater samples from boreholes. Groundwater was flushed through the columns under anaerobic conditions. A comparison was made between the transformation of 1,2-DCA without a carbon substrate and in the presence of sugars (molasses) and alcohol (methanol) respectively. In addition, different modes of delivery were investigated. In the case of molasses, the material was injected into the column as a plug to simulate grout injection in the field, whereas methanol was delivered as a constant flow dissolved in the influent. Both carbon substrates resulted in the biotransformation of 1,2-DCA. However, fermentation of molasses produced secondary effects that led to a drop in pH and an excessive production of carbon dioxide, which temporarily blocked the flow of groundwater.     

The IMA Commission on New Minerals and Mineral Names: procedures and guidelines on mineral nomenclature, 1998

Summary An author wishing to introduce a new mineral name into the literature, or to redefine, discredit or rename an existing mineral, must obtain prior approval of the IMA Commission on New Minerals and Mineral Names. This paper outlines the procedure to be followed in the preparation and submission of a proposal for approval, and describes how such proposals are handled by the Commission. The paper also gives general guidelines on mineral nomenclature and provides a list of nomenclature changes approved since 1987.

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Zusammenfassung Autoren, die einen neuen Mineralnamen in die Literatur einführen, oder einen solchen neu definieren, abschaffen oder ein schon bekanntes Mineral mit einem neuen Namen belegen wollen, müssen dafür vorher die Zustimmung der IMA Commission of New Minerals and Mineral Names einholen. In dieser Arbeit wird die empfohlene Vorgangsweise für die Vorbereitung und Einreichung eines Antrages dargestellt. Ebenso wird die Vorgangsweise der Kommission, die sich mit solchen Anträgen befaßt, in Übersicht gebracht. Weiters geben wir allgemeine Hinweise zur Nomenklatur von Mineralen und geben eine Liste von Nomenklatur-Änderungen vor, die seit 1987 genehmigt worden ist.

     

Mg---NH4 exchange on humic acid: A radiotracer technique for conditional exchange constants in a seawater medium

A radiotracer technique, employing ²⁷Mg, is used to determine the Mg released by ammonium exchange on undis-solved humic acid in a seawater medium. This new method allows for the measurement of exchangeable Mg on the solid phase surface, which eliminates the problem caused by the high-Mg background in the seawater matrix. The precision calculated from the counting statistics is better than ±2%; the reproducibility among repeated counts ranged from ±1% to ±3%. The higher sensitivity of the method allows for monitoring the Mg---NH₄ exchange at concentrations as low as 30 mM NH₄. This is a major improvement relative to the data obtained with the analytical methods used so far, which allow detection of exchangeable Mg only at NH₄ concentrations higher than 1 M. The lower experimental concentrations are more in accordance with the natural ammonium levels found in anoxic marine sediments. For the undissolved humic acid used in this experiment, the amount of exchangeable Mg in apparent equilibrium with an ammonium-free seawater matrix was found to be 96.6 ± 0.4 meq/100g. The Mg---NH₄ exchange on humic acid in seawater comes to a steady-state value in < 18 min. The conditional equilibrium constant obtained for this reaction, K_cond = 0.039 ± 0.001 M⁻¹. The technique can be expanded to other geochemical solid phases in seawater and it can be modified to study the behavior of the major cations by using ²⁴Na, ⁴²K and ⁴⁹Ca.     

The ecological implications of a Yakutian mammoth's last meal

Part of a large male woolly mammoth (Mammuthus primigenius) was preserved in permafrost in northern Yakutia. It was radiocarbon dated to ca. 18,500 ¹⁴C yr BP (ca. 22,500 cal yr BP). Dung from the lower intestine was subjected to a multiproxy array of microscopic, chemical, and molecular techniques to reconstruct the diet, the season of death, and the paleoenvironment. Pollen and plant macro-remains showed that grasses and sedges were the main food, with considerable amounts of dwarf willow twigs and a variety of herbs and mosses. Analyses of 110-bp fragments of the plastid rbcL gene amplified from DNA and of organic compounds supplemented the microscopic identifications. Fruit-bodies of dung-inhabiting Ascomycete fungi which develop after at least one week of exposure to air were found inside the intestine. Therefore the mammoth had eaten dung. It was probably mammoth dung as no bile acids were detected among the fecal biomarkers analysed. The plant assemblage and the presence of the first spring vessels of terminal tree-rings of dwarf willows indicated that the animal died in early spring. The mammoth lived in extensive cold treeless grassland vegetation interspersed with wetter, more productive meadows. The study demonstrated the paleoecological potential of several biochemical analytical techniques.     

Berechnung der Lotabweichungen infolge der Meeresgezeitenattraktion für die Erdgezeitenstationen Freiberg,Brezove Hory und Sclaigneaux

Zusammenfassung Vergleicht man die infolge der Gezeitenkräfte an der Erdoberfläche auftretenden Neigungen mit den theoretisch für eine elastische Erde zu erwartenden Deformationen, so zeigt sich, daß die Differenz aus beiden — die sogenannte Residualbewegung — die für die jeweilige Gezeitenstation charakteristische Eigenbewegung darstellt. Sie enthält als wesentlichen Anteil die ozeanischen Wirkungen. Subtrahiert man daher von den Residualbewegungen diese maritimen Gezeiteneinflüsse, so ergeben sich die infolge der lunisolaren Attraktionskräfte auftretenden lokalen Verbiegungen der Erdkruste. Ein Vergleich der in europäischen und asiatischen Horizontalpendelstationen gemessenen Deformationen deutet außerdem auf einen engen Zusammenhang zwischen Residualbewegungen und Tektonik hin.

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Summary A comparison of the tilts excited by tidal forces on the surface of the earth and the theoretical tilts of an elastic earth shows that the difference of both, called the residual movements, represent a caracteristic local deformation of the corresponding observation station. By subtracting the influence of ocean tides from these residuals remain the special local deformations of the earth crust by direct tidal attraction forces. The results of the observations of different stations in Europe and Asia indicate a good agreement between those residuals and the tectonic structure of the crust.