Basic physiological biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden)     

Linderoth M  Hansson T  Liewenborg B  Sundberg H  Noaksson E  Hanson M  Zebühr Y  Balk L 《Marine pollution bulletin》2006,53(8-9):437-450

By measuring a battery of basic physiological biomarkers and the concentration of SigmaDDT in adult female perch (Perca fluviatilis), an assumed aquatic pollution gradient was confirmed, with the city of Stockholm (Sweden) as a point source of anthropogenic substances. The investigation included an upstream gradient, westwards through Lake M?laren (46 km), and a downstream gradient, eastwards through the Stockholm archipelago (84 km). The results indicated a severe pollution situation in central Stockholm, with poor health status of the perch: retarded growth, increased frequency of sexually immature females, low gonadosomatic index, and disturbed visceral fat metabolism. SigmaDDT, measured as a pollution indicator, was 10-28 times higher than the background in perch from the Baltic Proper. Besides the main gradient other sources of pollution also influenced the response pattern of the measured biomarkers. In particular, there were strong indications of pollution coming from the Baltic Sea.  相似文献   

The galaxy population of intermediate-redshift clusters     

Tomas Dahlén †  Claes Fransson  Göran Östlin  Magnus Näslund 《Monthly notices of the Royal Astronomical Society》2004,350(1):253-266

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geneGIS: Geoanalytical Tools and Arc Marine Customization for Individual‐Based Genetic Records     

Dorothy M. Dick  Shaun Walbridge  Dawn J. Wright  John Calambokidis  Erin A. Falcone  Debbie Steel  Tomas Follett  Jason Holmberg  C. Scott Baker 《Transactions in GIS》2014,18(3):324-350

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Shock experiments in range of 10–45 GPa with small multidomain magnetite in porous targets     

Tomas KOHOUT  Lauri J. PESONEN  Alexander DEUTSCH  Kai WÜNNEMANN  Daniela NOWKA  Ulrich HORNEMANN  Erkki HEIKINHEIMO 《Meteoritics & planetary science》2012,47(10):1671-1680

Abstract– Physical properties of multidomain magnetite‐bearing porous pellets shocked up to 45 GPa were measured. The results show general magnetic softening as a result of shock. However, a relative magnetic hardening trend and slight magnetic susceptibility decrease is observed with increasing pressure among shocked samples. Initially, the shock also seems to cause a slight decrease in porosity, but at higher shock pressures macroscopic porosity increases progressively in our pellets. The microscopic porosity remains almost unchanged. Since our samples have distinctly higher initial porosity compared with samples used in previous studies, our results may be representative for impacts into highly porous magnetite‐bearing sedimentary or volcanic rocks and are relevant to impacts into such target rocks on Earth and Mars.  相似文献   

Petrology and zircon U–Pb dating of well‐preserved eclogites from the Thongmön area in central Himalaya and their tectonic implications     

Qingyun Li  Lifei Zhang  Bin Fu  Tomas Bader  Huanglu Yu 《Journal of Metamorphic Geology》2019,37(2):203-226

The discovery of eclogites is reported within the Great Himalayan Crystalline Complex in the Thongmön area, central Himalaya, and their metamorphic evolution is deciphered by petrographic studies, pseudosection modelling, and zircon dating. For the first time, omphacite has been found in the matrix of eclogites taken from a metamorphic mafic lens. Two groups of garnet have been identified in the Thongmön eclogites on the basis of major and rare earth elements and mineral inclusions. Core and intermediate sections of garnet represent Grt I, in which the major elements (Ca, Mg, and Fe) show a nearly homogenous distribution with little or weak zonation. This Grt I displays an almost flat chondrite‐normalized HREE pattern, and the main inclusions are amphibole, apatite, quartz, and abundant omphacite. Grt II, forms thin rims on large garnet grains, and is characterized by rim‐ward Ca decrease and Mg increase and MREE enrichment relative to HREE and LREE. No amphibole inclusions are found in Grt II, indicating the decomposition of amphibole contributed to its MREE enrichment. Two metamorphic stages, recorded by matrix minerals and inclusions in garnet and zircon, outline the burial of the Thongmön eclogites and progressive metamorphic processes to the pressure peak: (a) the assemblage of amphibole–garnet–omphacite–phengite–rutile–quartz, with the phengite interpreted as having been replaced by Bt+Pl symplectites, represents the prograde amphibole eclogite facies stage M1₍₁₎, (b) in the peak eclogite facies [stage M1₍₂₎], amphibole was lost and melting started. Based on the compositions of garnet and omphacite inclusions, M1₍₁₎ is constrained to 19–20 kbar and 640–660°C and M1₍₂₎ occurred at >21 kbar, >750°C, with appearance of melt and its entrapment in metamorphic zircon. SHRIMP U–Pb dating of zircon from two eclogite samples yielded consistent metamorphic ages of 16.7 ± 0.6 Ma and 17.1 ± 0.4 Ma respectively. The metamorphic zircon grew concurrently with Grt II in the peak eclogite facies. Thongmön eclogites characterized by the prograde metamorphism from amphibolite facies to eclogite facies were formed by the continuing continental subduction of Indian plate beneath the Euro‐Asian continent in the Miocene.  相似文献   

Assessing Collaborative Conservation: A Case Survey of Output,Outcome, and Impact Measures Used in the Empirical Literature     

Tomas M. Koontz  Nicolas W. Jager  Jens Newig 《社会与自然资源》2020,33(4):442-461

Abstract

Much existing research on collaborative conservation has focused on process, even as researchers have called for greater attention to explaining what results these processes yield. It is time to take stock of collaborative conservation research by mapping what kinds of variables researchers are including in analyses. Here we conduct a case survey from the SCAPE database of environmental decision-making cases. We include cases involving collaboration across government, environmental protection, and resource exploitation interests in western democratic countries. Results reveal patterns in what researchers include in their outputs, outcomes, and impacts measures of collaborative conservation. While there is little difference by publication type (peer-reviewed journals, scholarly book chapters, or gray literature) or over time, we find significant differences in explicit measures across variable types. In particular, variables more proximate to process in a logic chain are more often measured, as are social rather than ecological variables.  相似文献   

The tidal and wind induced hydrodynamics of the composite system Adriatic Sea/Lagoon of Venice     

Tomas Lovato  Alexey Androsov  Dmitry Romanenkov  Angelo Rubino 《Continental Shelf Research》2010

A shallow water hydrostatic 2D hydrodynamic numerical model, based on the boundary conforming coordinate system, was used to simulate aspects of both general and small scale oceanic features occurring in the composite system constituted by the Adriatic Sea and the Lagoon of Venice (Italy), under the influence of tide and realistic atmospheric forcing. Due to a specific technique for the treatment of movable lateral boundaries, the model is able to simulate efficiently dry up and flooding processes within the lagoon. Firstly, a model calibration was performed by comparing the results of the model, forced using tides and ECMWF atmospheric pressure and wind fields, with observations collected for a set of 33 mareographic stations uniformly distributed in the Adriatic Sea and in the Lagoon of Venice. A second numerical experiment was then carried out by considering only the tidal forcing. Through a comparison between the results obtained in the two experiments it was possible to assess the reliability of the estimated parameter through the composite forcing. Model results were then verified by comparing simulated amplitude and phase of each tidal constituent as well as tidal velocities simulated at the inlets of the lagoon and in the Northern Adriatic Sea with the corresponding observed values. The model accurately reproduces the observed harmonics: mean amplitude differences rarely exceed 1 cm, while phase errors are commonly confined below 15°. Semidiurnal and diurnal currents were correctly reproduced in the northern basin and a good agreement was obtained with measurements carried out at the lagoon inlets. On this basis, the outcomes of the hydrodynamic model were analyzed in order to investigate: (i) small-scale coastal circulation features observed at the interface between the adjoining basins, which consist often of vortical dipoles connected with the tidal flow of Adriatic water entering and leaving the Lagoon of Venice and with along-shore current fields connected with specific wind patterns; (ii) residual oscillations, which are often connected to meteorological forcing over the basin. In particular, it emerges that small-scale vortical features generated near the lagoon inlet can be efficiently transported toward the open sea, thus contributing to the water exchange between the two marine regions, and a realistic representation of observed residual oscillations in the area would require a very detailed knowledge of atmospheric as well as remote oceanic forcing.  相似文献   

Magnetic classification of stony meteorites: 2. Non‐ordinary chondrites     

Pierre ROCHETTE  Jérôme GATTACCECA  Lydie BONAL  Michèle BOUROT‐DENISE  Vincent CHEVRIER  Jean‐Pierre CLERC  Guy CONSOLMAGNO  Luigi FOLCO  Matthieu GOUNELLE  Tomas KOHOUT  Lauri PESONEN  Eric QUIRICO  Leonardo SAGNOTTI  Anna SKRIPNIK 《Meteoritics & planetary science》2008,43(5):959-980

Abstract— A database of magnetic susceptibility (χ) measurements on different non‐ordinary chondrites (C, E, R, and ungrouped) populations is presented and compared to our previous similar work on ordinary chondrites. It provides an exhaustive study of the amount of iron‐nickel magnetic phases (essentially metal and magnetite) in these meteorites. In contrast with all the other classes, CM and CV show a wide range of magnetic mineral content, with a two orders of magnitude variation of χ. Whether this is due to primary parent body differences, metamorphism or alteration, remains unclear. C3–4 and C2 yield similar χ values to the ones shown by CK and CM, respectively. By order of increasing χ, the classes with well‐grouped χ are: R << CO < CK ≈ CI < Kak < CR < E ≈ CH < CB. Based on magnetism, EH and EL classes have indistinguishable metal content. Outliers that we suggest may need to have their classifications reconsidered are Acfer 202 (CO), Elephant Moraine (EET) 96026 (C4–5), Meteorite Hills (MET) 01149, and Northwest Africa (NWA) 521 (CK), Asuka (A)‐88198, LaPaz Icefield (LAP) 031156, and Sahara 98248 (R). χ values can also be used to define affinities of ungrouped chondrites, and propose pairing, particularly in the case of CM and CV meteorites.  相似文献   

A spectral analysis of geoid undulation and gravity anomaly data computed with Pratt's isostasy theory applied to Moho depth variations in Fennoscandia     

Tomas Nord  Lars E. Sjöberg 《Geophysical Journal International》1992,111(1):179-184

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Steady-state kinetics and equilibrium between ground water and granitic rock     

Tomas Paces 《Geochimica et cosmochimica acta》1973,37(12):2641-2663

A hypothesis is presented that the dissolution of albite includes the exchange of sodium for hydrogen ion in a surface layer of the mineral and the structural collapse of the residual anionic lattice of the layer. The ion exchange is described by the first law of diffusion (D_25°C = 3 × 10^?22 and 1.5 × 10^?20 cm²sec^?1 at P_CO2 = 0 and 26.2 atm, respectively). The surface residual layer reaches a steady-state thickness ranging from n × 10^?8 to n × 10^?5 cm according to the temperature and P_CO2. The increase in aqueous sodium with time in a continuous ground-water system is described by a simple exponential equation. The equation is used to estimate the percolation time of ground water from the data on the chemical composition of a water sample. The probable times range from 14 to 3840 days for various ground-water systems and are compared to the times of percolation calculated from the geothermal and hydraulic data. Both estimates are found to be in general agreement. The concentrations of Al and Si in cold water from granitic rocks are shown to be controlled by the chemical equilibrium with respect to an aged aluminosilicate. The aluminosilicate precipitates from ground water as an amorphous isoelectric solid. Its chemical composition is represented by a simplified stoichiometric formula [Al(OH)₃](_1?x)[SiO₂]_x and varies linearly with pH of the solution. The atoms of Al, O and H tend to occupy a fixed position in the solid given by the gibbsite structure upon aging in the field. The solubility product of the solid is estimated from the published data on experimental and field research into the dissolution of feldspars: logK = (1 ? x) × log [Al³⁺] + xlog [H₄SiO₄] ? (3 ? 3x) log [H⁺] = 8.56 ? 11.26x, where x is the molar fraction of silica in the aluminosilicate.  相似文献