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This study presents an evaluation of a pulse height condensation particle counter (PH-CPC) and an expansion condensation particle counter (E-CPC) in terms of measuring ambient and laboratory-generated molecular and ion clusters. Ambient molecular cluster concentrations were measured with both instruments as they were deployed in conjunction with an ion spectrometer and other aerosol instruments in Hyytiälä, Finland at the SMEAR II station between 1 March and 30 June 2007. The observed cluster concentrations varied and ranged from some thousands to 100 000 cm -3. Both instruments showed similar (within a factor of ~5) concentrations. An average size of the detected clusters was approximately 1.8 nm. As the atmospheric measurement of sub 2-nm particles and molecular clusters is a challenging task, we conclude that most likely we were unable to detect the smallest clusters. Nevertheless, the reported concentrations are the best estimates to date for minimum cluster concentrations in a boreal forest environment.
We report the first atmospheric observations of the Chlorofluorocarbons (CFCs) trifluorochloroethene, 3-chloropentafluoropropene and 4,4-dichlorohexafluoro-1-butene by means of Gas Chromatography with Electron Capture and Mass Spectrometric detection (GC-ECD-MS) in air samples taken at the Taunus Observatory operated by the University of Frankfurt (Main) and the Jungfraujoch High Altitude Research Station in Switzerland. These substances belong to a class of CFCs containing a double bond and are suspected to originate from the production and thermal degradation of widely used fluoropolymers like polychlorotrifluoroethene (PCTFE). Their atmospheric lifetimes are expected to be rather short. A quantitative calibration could only be derived for trifluorochloroethene but not for the other species by now. Thus, we use a relative sensitivity method to get a first indication of the observed atmospheric abundances. Identification was possible because of an air plume containing high concentrations of these substances. We suggest that the abundances found on this occasion originated from a local source. However, we have also observed the novel CFCs in air masses representative of background conditions, though with much lower concentrations. These species and some of their degradation products are toxic and could also be relevant for stratospheric and tropospheric ozone depletion.
Assessment of ecologically relevant hydrological change in China due to water use and reservoirs
(2008)
As China’s economy booms, increasing water use has significantly affected hydro-geomorphic processes and thus the ecology of surface waters. A large variety of hydrological changes arising from human activities such as reservoir construction and management, water abstraction, water diversion and agricultural land expansion have been sustained throughout China. Using the global scale hydrological and water use model WaterGAP, natural and anthropogenically altered flow conditions are calculated, taking into account flow alterations due to human water consumption and 580 large reservoirs. The impacts resulting from water consumption and reservoirs have been analyzed separately. A modified “Indicators of Hydrologic Alteration” approach is used to describe the human pressures on aquatic ecosystems due to anthropogenic alterations in river flow regimes. The changes in long-term average river discharge, average monthly mean discharge and coefficients of variation of monthly river discharges under natural and impacted conditions are compared and analyzed. The indicators show very significant alterations of natural river flow regimes in a large part of northern China and only minor alterations in most of southern China. The detected large alterations in long-term average river discharge, the seasonality of flows and the inter-annual variability in the northern half of China are very likely to have caused significant ecological impacts.
The present paper deals mith the results of an environniental isotopic study in western Thessaly valley, carried out during the period 1968 - 1971. The isotopes used are 18O, D, Tritium, 18C and 14C. By the interpretation and evaluation of these resiilts useflil informations as regards the soiirce of recharge, the recharge mechanisrn and the dynamics of the flow system of the valley are provided.
In a joint enterprise, the ground water supplies in some Oases in UAR (namely El Kharga, El Dakhla, El Baharia and Siwa), in Wadi El Natrun (to the west of the Nile Delta), in Ayoun Mousa (West Sinai) and in some places along the Mediterranean Littoral, have been investigated. According to the dating of the water by the C14 method, the age of the artesian water from the Oases is between 25,000 and 40,000 years and the origin is obviously from rain water which fell and infiltrated within the "Nubian Sandstone" layers, occupying almost entirely the southern portion of the western Desert (the water underwent some evaporation before it disappeared in the subsurface as indicated from the loss of the 016). This process took place during one or more of the Pluvial periods which followed (and were not coincident with) the last "Würm" eustatic lowering of the Mediterranean. No infiltration water have presumably recharged the layers in question, so almost entirely fossil water reserves are tapped at present. The quantities of such reserves are unknown. More ancient waters, however, may be expected to the north of El Kharga and El Dakhla Oases. Such waters may- to their greater portions - enter these two oases from that direction. On the other hand, little or almost no water is expected to feed the reservoir from the opposite direction.
Albert Schmidts Schrift über "Die Wupper" erschien zunächst in den Jahren 1902 / 1903 und beinhaltete neben zahlreichen Messtabellen einen knapp gehaltenen Text. Die heute meist zitierte zweite Auflage stammt aus dem Jahr 1913. Sie erschien wie ihre Vorgänger bei der in der bergisch-preußischen Kreisstadt Lennep (Rheinl.) ansässigen Buchhandlung Richard Schmitz. Sie umfasst zahlenmäßig vermehrte Messtabellen des Wupperstandes, graphische Darstellungen und auch einige Fotografien aus bereits realisierten bzw. geplanten Talsperrenprojekten. Das Werk gilt als Pionierschrift des deutschen Talsperrenbaus. Der Baumeister, Architekt und Ingenieur Albert Schmidt aus Lennep (1841-1932) schuf für die technischen Talsperrenkonstruktionen des Aachener Professors Dr. Otto Intze (1843-1904) im Bergischen Land die notwendigen Grundlagen, indem er aufgrund seiner Niederschlagsmessungen im künftigen Talsperrengebiet Aussagen über die notwendige Fassungsgröße ermöglichte. Prof. Intze und Albert Schmidt werden bis heute als die Väter der deutschen Talsperren bezeichnet. Die Schrift über "Die Wupper", von ihrer Entstehung im Oberbergischen bei Marienheide bis zur Mündung in den Rhein in Leverkusen, schildert den "schwarzen Fluss" u.a. als durch die Industrialisierung extrem verseuchtes Gewässer und entwickelt Methoden seiner biologischen Reinigung durch sog. Rieselfelder. Insofern wird der Autor heute nicht nur als Kenner der damaligen Verhältnisse, sondern auch als ein "früher Alternativer" oder "Grüner" bezeichnet.
Jurassic accretionary complex of the Tamba terrane, southwest Japan, and its formative process
(1993)
A graph theoretical approach to the analysis, comparison, and enumeration of crystal structures
(2008)
As an alternative approach to lattices and space groups, this work explores graph theory as a means to model crystal structures. The approach uses quotient graphs and nets - the graph theoretical equivalent of cells and lattices - to represent crystal structures. After a short review of related work, new classes of cycles in nets are introduced and their ability to distinguish between non-isomorphic nets and their computational complexity are evaluated. Then, two methods to estimate a structure’s density from the corresponding net are proposed. The first uses coordination sequences to estimate the number of nodes in a sphere, whereas the second method determines the maximal volume of a unit cell. Based on the quotient graph only, methods are proposed to determine whether nets consist of islands, chains, planes, or penetrating, disconnected sub-nets. An algorithm for the enumeration of crystal structures is revised and extended to a search for structures possessing certain properties. Particular attention is given to the exclusion of redundant nets and those, which, by the nature of their connectivity, cannot correspond to a crystal structure. Nets with four four-coordinated nodes, corresponding to sp3 hybridised carbon polymorphs with four atoms per unit cell, are completely enumerated in order to demonstrate the approach. In order to render quotient graphs and nets independent from crystal structures, they are reintroduced in a purely graph-theoretical way. Based on this, the issue of iso- and automorphism of nets is reexamined. It is shown that the topology of a net (that is the bonds in a crystal) constrains severely the symmetry of the embedding (that is the crystal), and in the case of connected nets the space group except for the setting. Several examples are studied and conclusions on phases are drawn (pseudo-cubic FeS2 versus pyrite; α- versus β- quartz; marcasite- versus rutile-like phases). As the automorphisms of certain quotient graphs stipulate a translational symmetry higher than an arbitrary embedding of the corresponding net would show, they are examined in more detail and a method to reduce the size of such quotient graphs is proposed. Besides two instructional examples with 2-dimensional graphs, the halite, calcite, magnesite, barytocalcite, and a strontium feldspar structures are discussed. For some of the structures it is shown that the quotient graph which is equivalent to a centred cell is reduced to a quotient graph equivalent to the primitive cell. For the partially disordered strontium feldspar, it is shown that even if it could be annealed to an ordered structure, the unit cell would likely remain unchanged. For the calcite and barytocalcite structures it is shown that the equivalent nets are not isomorphic.