On radioactive equilibrium in atmospheric aerosols at 700 and 1800 m a.s.l., as influenced by particle size and vertical mixing activity

Summary Data from simultaneous measurements of RaB and RaC concentration in atmospheric aerosols, taken at sites located roughly 700 and 1800 m a.s.l., are used to elucidate the relation of the ratio of the specific activities of RaB and RaC in aerosol particles on the one hand to the intensity of vertical mixing and the size of the aerosol particles on the other. The empirical relationships as found from a 15-month period of uninterrupted measurements are presented. Radioactive equilibrium is more nearly approached in aerosol particles of more than one micron in diameter than in smaller ones (including the smallest measurable sizes); this holds invariably — and for all height levels. The degree of approach to RaB/RaC equilibrium is the lowest for low altitude (700 m) and negligible vertical mixing: 65% to 75%. At the low-altitude site this figure increases to 80%–90% as the intensity of vertical mixing reaches higher levels. At 1800 m a.s.l., the degree of approach to RaB/RaC equilibrium is nearly 100% when vertical mixing is negligible, and declines with increased vertical mixing activity to a level of only 60–70% for conditions involving strong vertical mass exchange.

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Zusammenfassung Simultane Messungen der RaB- und RaC-Konzentration des atmosphärischen Aerosols an benachbarten Stationen in ca 700 und ca 1800 m a.s.l. werden benutzt um die Abhängigkeit des Verhältnisses der spezifischen Aktivitäten RaB/RaC auf Aerosolpartikeln von der Stärke des Vertikalaustausches, und von der Grösse der Aerosolpartikel abzuschätzen. Es werden die während einer 15-monatigen kontinuierlichen Meßperiode gesammelten empirischen Erfahrungen dargestelit. Die Annäherung an das radioaktive Gleichgewicht ist an Aerosolpartikeln vonD>1 m stets und unabhängig von der Seehöhe weiter fortgeschritten, als an den kleineren und kleinsten Partikeln. Der Grad der Gleichgewichtseinstellung RaB/RaC ist in niedriger Höhe (700 m) bei sehr schwachem Austausch am geringsten (65–75%) und steigt mit wachsender Austauschstärke bis zu einem Maximum von 80–90% an. Umgekehrt nimmt in 1800 m der Grad der Gleichgewichts-einstellung RaB/RaC von nahe 100% bei sehr schwachem Austausch bis auf 60–70% bei starkem Austausch ab.

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The research reported in this paper has been sponsored by the European Research Office, United States Army under Contract DAJA 37 67C 0254, and the Department of Defense of the Federal Republic of Germany.

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Physikalisch-Bioklimatische Forschungsstelle of the Fraunhofer Gesellschaft, in Garmisch-Partenkirchen. (Director: Dr.R. Reiter.)     

Synoptisch-luftelektrische Daueruntersuchungen im Hochgebirge im Dienste der Meteorologie

Zusammenfassung Zur Erforschung von Beziehungen zwischen luftelektrischen Phänomenen in verschiedenen Höhenstufen und zahlreichen meteorologischen Vorgängen wurden seit einigen Jahren im Alpenbereich Dauerregistrierungen des statischen luftelektrischen Feldes ausgeführt. Es dienten hierzu das StationspaarOberstdorf (815 m) undNebelhorn (1930 m) im Allgäu sowie die StationenGarmisch-Partenkirchen (705 m),Eibsee (1000 m),Riffelriss (1640 m) undZugspitze (2963 m) im Wetter-steingebirge. — Anhand von typischen Kurvenbeispielen werden folgende Beziehungen besprochen: 1)Untersuchungen von Lokaleffekten an den Tal- Hang- und Gipfelstationen, ausgelöst durch:a) verschiedene Aerosole (Staub, Rauch, Dunst, Nebel usw.);b) orographisch bedingte Windsysteme (Berg-Talwind, Hangwind);c) Föhnerscheinungen. — 2)Synoptisch-Luftelektrische Beobachtungen, und zwar:a) Verhalten des luftelektrischen Feldes über und unter Inversionsschichten, Dunstgrenzen und Konvektionsgrenzen zum Studium des Verhaltens der Grundschicht (Schneider-Carius);b) Erforschung der vertikalen Ladungsverteilung in stratiformer Bewölkung (Untersuchungen über polarisierte Wolkenschichten);c) Erforschung der vertikalen Ladungsverteilung in Turbulenzbewölkung zum Studium des elektrischen Aufbaus von Schauer- und Gewitterwolken unter Berücksichtigung ihrer zeitlichen Entwicklung;d) Studien über den vertikalen Luftmassenaustausch;e) Studien über das Verhalten des luftelektrischen Feldes bei Niederschlägen verschiedener Art insbesondere bei Phasenwechsel.

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Summary In order to investigate the relations between atmospheric electric phenomena in different altitudes and various meteorological processes, continuous automatical recordings of the statical atmospheric potential gradient have been performed in the alpine region since several years. — Two stations in the Allgäu Mountains:Oberstdorf (815 m) andNebelhorn (1930 m) and four stations in the Wetterstein Mountains:Garmisch-Partenkirchen (705 m),Eibsee (1000 m),Riffelriss (1640 m) andZugspitze (2963 m) serve to this purpose. — Using typical curves, we demonstrate the results of the study of the following problems: 1) Local effects at both valley stations and mountain stations, caused bya) various aerosols (dust, smoke, vapour, fog, etc.),b) winds, conditioned by orographical circumstances,c) foehn; 2) Synoptical problems of the atmospheric electricity:a) the behaviour of the atmospheric potential gradient both above and below inversions and superior limits of convection in order to study the status of the fundamental layer of the atmosphere («Grundschicht»,Schneider-Carius),b) the vertical variation of the electric charge in sheet clouds (polarisations of sheet clouds),c) the vertical variation of electric charge in shower and thunderstorm clouds in order to study their electric structure and chronologic development.d) vertical exchange of air masses,e) the behaviour of the atmospheric potential gra- dient during various forms of precipitation, especially if there is a change of the phase.

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Vortrag gehalten auf der 3. Internationalen Tagung für Alpine Meteorologie in Davos, April 1954.     

Cold seep deposits of Beauvoisin (Oxfordian; southeastern France) and Marmorito (Miocene; northern Italy): microbially induced authigenic carbonates

The relation of two well-known ancient carbonate deposits to hydrocarbon seepage was confirmed by this study. Archaea are found to be associated with the formation of Oxfordian seep carbonates from Beauvoisin and with a Miocene limestone from Marmorito ("tube-worm limestone"). Carbonates formed due to a mediation by archaea exhibit extremely positive or extremely negative δ¹³C_carbonate values, respectively. Highly positive values (+15‰) reflect the use of ¹³C-enriched CO₂ produced by methanogenesis. Low δ¹³C values of the Marmorito carbonates (–30‰) indicate the oxidation of seepage-derived hydrocarbons. Likewise, the δ¹³C content of specific tail-to-tail linked isoprenoids, biomarkers for archaea, was found to be strikingly depleted in these samples (as low as –115‰). The isotopic signatures corroborate that archaea were involved in the cycling of seepage-derived organic carbon at the ancient localities. Another Miocene limestone ("Marmorito limestone") shows a strong imprint of methanotrophic bacteria as indicated by δ¹³C values of carbonate as low as –40‰ and biomarker evidence. Epifluorescence microscopy and field-emission scanning electron microscopy revealed that bacterial biofilms were involved in carbonate aggregation. In addition to lucinid bivalves previously reported from both localities, we infer that sponges from Beauvoisin and tube worms from Marmorito depended on chemosynthesis as well. Low δ¹³C values of nodules related to sponge taphonomy (–27‰) indicate that sponges might have been linked to an enhanced hydrocarbon oxidation. Tube worm fossils from Marmorito closely resemble chemosynthetic pogonophoran tube worms from Recent cold seeps and are embedded in isotopically light carbonate (δ¹³C –30‰). Received: 13 October 1998 / Accepted: 5 February 1999     

Cosmic-ray-induced fission of heavy nuclides: Possible influence on apparent U-fission track ages of extraterrestrial samples

The rates of cosmic-ray-induced fission of U, Th, Bi, Pb, and Au in mineral samples as a function of burial depth in the lunar surface layer are calculated using the available experimental particle flux and cross section data. Theoretical correction factors are given for apparent fission track ages of extraterrestrial samples of different burial depths which were exposed to cosmic rays for various time fractions of their solidification age. Samples having typical lunar heavy element contents can yield apparent fission track ages which are too high by a factor of up to 13 due to cosmic-ray-induced fission. The interference may be neglected, if the ratio of exposure age to solidification age remains 5 × 10⁻³. The calculations show, that the induced fission of Bi, Pb, and Au which are known to have high meteoritic abundances may dominate spontaneous ²³⁸U-fission in long-time exposed meteorites of low U and Th contents.     

The propagation effect of commuting to work in the spatial transmission of COVID-19

Journal of Geographical Systems - This work is concerned with the spatiotemporal dynamics of the coronavirus disease 2019 (COVID-19) in Germany. Our goal is twofold: first, we propose a novel...     

Dynamics of Trojan asteroids with large orbital inclination: A preliminary report

Some Trojans have a remarkably large inclination. This fact raises the question whether or not these asteroids are dynamically different from Trojans with an inclination, say smaller than 10°. In this paper the author investigates the dynamics of selected Trojans. Common properties and differences between highly inclined orbits and practically planar ones are discussed.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

The lithospheric transition between the Delamerian and Lachlan orogens in western Victoria: new insights from 3D magnetotelluric imaging

The magnetotelluric (MT) method was used to image the crust and upper mantle beneath the Delamerian and Lachlan orogens in western Victoria, Australia. During the Cambrian time period, this region changed from being the extended passive margin of Proterozoic Australia into an Andean-style convergent margin that progressively began to accrete younger oceanic terranes. Several broadband MT transects, which were collected in stages along coincident deep (full crust imaging) seismic reflection lines, have now been combined to create a continuous 500 km east–west transect over the Delamerian–Lachlan transition region in the Stawell Zone. We present the electrical resistivity structure of the lithosphere using both 3D and 2D inversion methods. Additionally, 1D inversions of long-period AusLAMP (Australian Lithospheric Architecture Magnetotelluric Project) MT data on a 55 km regionally spaced grid were used to provide starting constraints for the 3D inversion of the 2D profile. The Delamerian to Lachlan Orogen transition region coincides with the Mortlake Discontinuity, which marks an isotopic discontinuity in Cenozoic basalts, with higher strontium isotope enrichment ratios in the Lachlan Orogen relative to the Delamerian Orogen. Phase tensor ellipses of the MT data reveal a distinct change in electrical resistivity structure near the location of the Mortlake Discontinuity, and results of 3D and 2D inversions along the MT profile image a more conductive lower crust and upper mantle beneath the Lachlan Orogen than the Delamerian Orogen. Increased conductivity is commonly ascribed to mantle enrichment and thus supports the notion that the isotope enrichment of the Cenozoic basalts at least partially reflects an enriched mantle source rather than crustal contamination. Fault slivers of the lower crust from the more conductive Lachlan region expose Cambrian boninites and island arc andesites indicative of subduction, a process that can enrich the mantle isotopically, and also electrically, by introducing carbon (graphite) and water (hydrogen).     

Spatial scan statistics in vulnerability assessment: an application to mountain hazards

In the European Alps, the concept of risk has increasingly been applied in order to reduce the susceptibility of society to mountain hazards. Risk is defined as a function of the magnitude and frequency of a hazard process times consequences; the latter being quantified by the value of elements at risk exposed and their vulnerability. Vulnerability is defined by the degree of loss to a given element at risk resulting from the impact of a natural hazard. Recent empirical studies suggested a dependency of the degree of loss on the hazard impact, and respective vulnerability (or damage-loss) functions were developed. However, until now, only little information is available on the spatial characteristics of vulnerability on a local scale; considerable ranges in the loss ratio for medium process intensities only provide a hint that there might be mutual reasons for lower or higher loss rates. In this paper, we therefore focus on the spatial dimension of vulnerability by searching for spatial clusters in the damage ratio of elements at risk exposed. By using the software SaTScan, we applied an ordinal data model and a normal data model in order to detect spatial distribution patterns of five individual torrent events in Austria. For both models, we detected some significant clusters of high damage ratios, and consequently high vulnerability. Moreover, secondary clusters of high and low values were found. Based on our results, the assumption that lower process intensities result in lower damage ratios, and therefore in lower vulnerability, and vice versa, has to be partly rejected. The spatial distribution of vulnerability is not only dependent on the process intensities but also on the overall land use pattern and the individual constructive characteristics of the buildings exposed. Generally, we suggest the use of a normal data model for test sites exceeding a minimum of 30 elements at risk exposed. As such, the study enhanced our understanding of spatial vulnerability patterns on a local scale.     

Tectonic evolution of the southern Gawler Craton,South Australia,from electromagnetic sounding

Long-period natural-source electromagnetic data have been recorded using portable three-component magnetometers at 39 sites in 1998 and 2002 across the southern Eyre Peninsula, South Australia that forms part of the Gawler Craton. Site spacing was of order 5 km, but reduced to 1 km or less near known geological boundaries, with a total survey length of approximately 50 km. A profile trending east – west was inverted for a 2D electrical resistivity model to a depth of 20 km across the southern Eyre Peninsula. The main features from the models are: (i) on the eastern side of the Gawler Craton, the Donington Suite granitoids to the east of the Kalinjala Shear Zone are resistive (>1000 Ωm); (ii) the boundary between the Donington Suite granitoids and the Archaean Sleaford Complex, which has much lower resistivity of 10 – 100 Ωm, is almost vertical in the top 10 km and dips slightly westwards; and (iii) two very low resistivity (<1 Ωm) arcuate zones in the top 3 km of Hutchison Group sediments correlate with banded iron-formations, and are probably related to biogenic-origin graphite deposits concentrated in fold hinges. Such features suggest an extensional regime during the time period 2.00 – 1.85 Ga. We suggest that the resistivity boundary between the Donington Suite and the Archaean Sleaford Complex represents a growth fault, typical for rift systems that evolve into a half-graben structure. In the graben basin, low-resistivity shallow-marine Hutchison Group sediments were deposited. Folding of the sediments during the Kimban Orogeny between 1.74 and 1.70 Ga has led to migration of graphite to the fold hinges resulting in linear zones of very low resistivity that correlate with banded iron-formation magnetic anomalies.