Microphysical, chemical and optical aerosol properties in the Baltic Sea region

The microphysical structure, chemical composition and prehistory of aerosol are related to the aerosol optical properties and radiative effect in the UV spectral range. The aim of this work is the statistical mapping of typical aerosol scenarios and adjustment of regional aerosol parameters. The investigation is based on the in situ measurements in Preila (55.55° N, 21.00° E), Lithuania, and the AERONET data from the Gustav Dalen Tower (58 N, 17 E), Sweden.Clustering of multiple characteristics enabled to distinguish three aerosol types for clear-sky periods: 1) clean maritime–continental aerosol; 2) moderately polluted maritime–continental aerosol; 3) polluted continental aerosol. Differences between these types are due to significant differences in aerosol number and volume concentration, effective radius of volume distribution, content of SO₄⁻ ions and Black Carbon, as well as different vertical profiles of atmospheric relative humidity. The UV extinction, aerosol optical depth (AOD) and the Ångstrom coefficient α increased with the increasing pollution. The value α = 1.96 was observed in the polluted continental aerosol that has passed over central and eastern Europe and southern Russia. Reduction of the clear-sky UV index against the aerosol-free atmosphere was of 4.5%, 27% and 41% for the aerosol types 1, 2 and 3, respectively.     

Combined Sr,Nd, Pb and Li isotope geochemistry of alkaline lavas from northern James Ross Island (Antarctic Peninsula) and implications for back-arc magma formation

We present a comprehensive geochemical data set for a suite of back-arc alkaline volcanic rocks from James Ross Island Volcanic Group (JRIVG), Antarctic Peninsula. The elemental and isotopic (Sr, Nd, Pb and Li) composition of these Cenozoic basalts emplaced east of the Antarctic Peninsula is different from the compositions of the fore-arc alkaline volcanic rocks in Southern Shetlands and nearby Bransfield Strait. The variability in elemental and isotopic composition is not consistent with the JRIVG derivation from a single mantle source but rather it suggests that the magma was mainly derived from a depleted mantle with subordinate OIB-like enriched mantle component (EM II). The isotopic data are consistent with mantle melting during extension and possible roll-back of the subducted lithosphere of the Antarctic plate. Magma contamination by Triassic–Early Tertiary clastic sediments deposited in the back-arc basin was only localized and affected Li isotopic composition in two of the samples, while most of the basalts show very little variation in δ⁷Li values, as anticipated for “mantle-driven” Li isotopic composition. These variations are difficult to resolve with radiogenic isotope systematics but Li isotopes may prove sensitive in tracking complex geochemical processes acting through the oceanic crust pile, including hydrothermal leaching and seawater equilibration.     

The 6dF Galaxy Survey: final redshift release (DR3) and southern large-scale structures

We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky  (| b | > 10°)  . Its 136 304 spectra have yielded 110 256 new extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with  ( K , H , J , r _F, b _J) ≤ (12.65, 12.95, 13.75, 15.60, 16.75)  . The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with   z ≤ 0.1  , showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS .     

Relationship between mn nodule abundance and other geological factors in the northeastern pacific: Application of gis and probability method

The aims of this study are 1) to construct a database using geostatistics and Geographic Information System (GIS), and 2) to derive the spatial relationships between manganese nodule abundance and other geological factors such as metal grade, slope, water depth, topography, and acoustic characteristics of the sub-bottom. Using GIS, it is possible to analyze a large amount of data efficiently, and to maximize the practical application, to increase specialization, and to enhance the accuracy of the analyses. The greater the copper and nickel grade, the higher the rating. The distribution pattern of nickel grade is similar to that of copper grade. The slopes are generally less than 3° except for seamounts and cliff areas. The rating shows no correlation with slope. The rating is highest for slopes between 2.5 and 3.5° in block N1 and between 4.0 and 4.5° in block N3. The topography is classified into five groups: seamount, hill crest, hill slant, hill base or plain, and seafloor basin or valley. The rating proves lowest for seamount and hill crest. Our results show that the rating increases with the water depth in the study area. Nodule abundance dose not show any significant relationship with the thickness of the upper transparent layer in the study area.     

Internal recycling of particle reactive organic chemicals in the Chesapeake Bay water column

Hydrophobic organic contaminants (HOCs) may be used as tracers of particle dynamics in aquatic systems. Internal cycling of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were studied in the mesohaline Chesapeake Bay to assess the role of resuspension in maintaining particle and contaminant inventories in the water column, and to compare settling and suspended particle characteristics. Direct measurements of sediment resuspension and settling conducted in conjunction with one of the sediment trap deployments indicate reasonable agreement between measurements of particle flux using the two different methods. Organic carbon and PCB concentrations in settling solids collected in near-surface sediment traps were remarkably lower than concentrations in suspended particles collected by filtration during the trap deployments, but higher PAH concentrations were found in the settling particles. The different behaviors of PAHs and PCBs in the settling particles are due to their different source types and association to different types of particles. Sediment trap collections in near bottom waters were dominated by resuspension. Resuspension fluxes of HOCs measured 2 m above the bay bottom were as high as 2.5 μg/m² day for total PCBs and 15 μg/m² day for fluoranthene, and were 25 and 10 times higher than their settling fluxes from surface waters, respectively. HOC concentrations in the near bottom traps varied much less between trap deployments than HOC concentrations in the surface traps, indicating that the chemical composition of the resuspended particles collected in the near bottom traps was more time-averaged by repeated resuspension than the surface particles.     

Geochemical comparison of the subvolcanic appinite suite of the British Caledonides and the durbachite suite of the Central European Hercynides: evidence for associated shoshonitic and Granitic Magmatism

Summary Subvolcanic pyroxenite-hornblendite-kentallenite-diorite-granodiorite masses of the appinite suite that are spatially and temporally associated with the much more voluminous granitic plutons of the British Caledonides have major element proportions and REE patterns indicative of shoshonitic affinities. Hornblendite-monzonite-syenogabbro-pyroxene melasyenite-durbachite-biotite-rich syenite-biotite-rich granite masses of the plutonic durbachite suite of the Bohemian Massif of the Central European Hercynides, that also are spatially and temporally associated with much more voluminous granitic plutons, have geochemical characteristics that generally correspond with those of the appinite suite. Compositionally both suites resemble lamprophyres emplaced during the latter parts of the respective episodes.Both the appinite and durbachite suites show independence of K/Rb and SiO₂ with the two suites having mainly different but somewhat overlapping K/Rb ratios. Other geochemical characters, as shown by fields and trends on K vs Rb, AFM and other plots, point to the durbachite suite representing generally more evolved products of shoshonitic magma than members of the appinite suite. However, there are different geochemical characteristics, including higher Cr/Ni ratios in the durbachite suite and Co present in lower proportions in the appinite suite. These differences are the result of different histories of freezing, remelting and partial separation and remixing of fractionation products and reflect the explosive subvolcanic vs plutonic regimes of the appinitic and durbachitic suites, respectively. Support for this petrogenesis is provided by mineral compositions and comparison of compositions of mineral phases and the rocks in which they occur.

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Ein geochemischer Vergleich der subvulkanischen Appinite der Britischen Kaledoniden und der Durbachite der Mitteleuropäischen Herzyniden: Hinweise für assoziierten shoshonitischen und granitischen Magmatismus

Zusammenfassung Subvulkanische Pyroxenit-Hornblendit-Kentallenit-Diorit-Granodioritmassen der Appinit-Gruppe, die räumlich und zeitlich mit den viel umfangreicheren Granitplutonen der Britischen Kaledoniden assoziiert sind, haben Hauptelementverteilungen und SEE Gehalte, die auf Beziehungen zu Shoshoniten hinweisen. Hornblendit-Monzonit-Syenogabbro-Pyroxen-Melasyenit-Durbachit-Biotit-reiche Syenite-Biotit-reiche Granitmassen der plutonischen Durbachitabfolge des Böhmischen Massivs der Mitteleuropäischen Herzyniden, die auch räumlich und zeitlich mit viel umfangreicheren Granitplutonen assoziiert sind, haben geochemische Charakteristika, die im allgemeinen mit denen der Appinit-Gruppe übereinstimmen. Beide Gruppen sind in ihrer Zusammensetzung Lamprophyren ähnlich, die in späteren Abschnitten der magmatischen Episoden Platz genommen haben.Sowohl in den Appinit-, wie in den Durchbachit-Abfolgen sind K/Rb und SiO₂ voneinander unabhängig, beide Gruppen haben aber verschiedene, wenn auch zum Teil einander überlappende K/Rb Verhältnisse. Andere geochemische Parameter, wie K vs Rb, AFM und andere, weisen darauf hin, daß die Durbachit-Abfolge im allgemeinen weiter entwickelte Produkte shoshonitischen Magmas darstellt, als die Mitglieder der Appinit-Gruppe. Es gibt jedoch verschiedene geochemische Charakteristika, wozu auch höhere Cr/Ni Verhältnisse in den Durbachiten und niedrige CoGehalte in den Appiniten gehren. Diese Unterschiede sind das Ergebnis verschiedener Abkhlung, Aufschmelzung und teilweiser Trennung- und Wiedermischung von Fraktionierungs-Produkten und weisen auf die explosiven subvulkanischen bzw. plutonischen Regimes der beiden Gruppen hin. Diese petrogenetische Interpretation wird durch Mineralzusammensetzungen und deren Vergleich mit den Muttergesteinen unterstützt.

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With 6 Figures     

Phase transformation studies on a synthetic hedenbergite up to 26 GPa at 1200° C

Phase transformations in a synthetic hedenbergite (CaFeSi₂O₆) have been observed with X-ray diffraction up to 26 GPa at 1200° C in a diamond anvil cell with a YAG laser heating system. Hedenbergite first decomposes into spinel, stishovite, and cubic perovskite phases at 16 GPa, and spinel further decomposes into wüstite and stishovite at 19 GPa. Between 19 GPa and 26 GPa, the phase assemblage is wüstite + stishovite+ perovskite. On decompression to 0.1 MPa, all the highpressure phases are retained except the cubic perovskite, which reverts to a retrogressive phase of CaSiO₃. A comparison of the results of this study with those from a previous study on a natural hedenbergite suggests that the garnet phase formed from natural hedenbergite is stabilized by manganese.     

Study of clusters of galaxies by correlation analysis

We present preliminary results of the application to real data of a new method for studying the structure of groups and clusters of galaxies. The new method is able to produce reliable results for structures with a small number of galaxies. The 6 clusters whose number density and velocity dispersion profiles are determined, could have hardly been studied with classical methods. These new results are particularly significant, especially in what concerns the velocity dispersion profile, since little is known so far on its characteristics.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Active tuned liquid column damper with propellers

The active control of a Tuned Liquid Column Damper (TLCD) with two propellers is presented. A single‐degree‐of‐freedom system with a passive or active TLCD is used as an example to set up the basic equation of motion. The Optimal Control Theory is applied to establish the control law and to calculate the control force generated by these two propellers installed inside the TLCD. A simple pendulum‐like model test is carried out to study the dynamic characteristics of the passive and active TLCDs and the effectiveness of the vibrational control. Comparison of the experimental result with the analytical one shows a good agreement. Finally, the analytical results of the seismic response are also included as an example for demonstration and application. Copyright © 2003 John Wiley & Sons, Ltd.