A simple non‐linear analytical relationship between aerosol accumulation number and sub‐micron volume, explaining their observed ratio in the clean and polluted marine boundary layer

We propose an analytical expression for the relation between aerosol accumulation number and sub‐micron volume over the marine boundary layer (MBL), based on a simple balance equation. By providing appropriate source and sink terms which account for entrainment, coagulation, in‐cloud scavenging and condensational growth, the model is able to reproduce the observed ratio between MBL particles larger than 80 nm diameter (as a proxy for accumulation mode number) and submicron aerosol volume, from freshly polluted to background conditions. Entrainment and coagulation are essential in predicting the observed ratio. Budget and lifetime calculations show that, due to relatively low source rates of oceanic non‐sea‐salt‐sulfate and sea‐salt, the anthropogenic signature in aerosol volume remains significant even after 8 days of MBL transport.     

Identifying factors of influence in the spatial distribution of domestic fires

Domestic fires at the city level, being causes for casualties and causing significant material damages, are stored as a point pattern in a GIS. In this paper we apply a statistical point pattern analysis to derive major causes from related layers of information. We fit a G-function to analyse neighbourhood relations and a Strauss process for inferring causal relations. Using open-source software we find significant differences in patterns and explaining factors between the different parts of the day, in particular for different building types and income groups. We conclude that a quantitative spatial model can be fitted and that this provides a useful opportunity for fire brigades to improve planning their efforts.     

Structure, Composition and Evolution of the South Indian and Sri Lankan Granulite Terrains from Deep Seismic Profiling and Other Geophysical and Geological Investigations: A LEGENDS Initiative

We here argue the need for a multidisciplinary, integrated geophysical/geological survey across southern India and Sri Lanka, part of the largest exposed Neoproterozoic high-grade metamorphic terrain in the world. The purpose is to stimulate deep seismic profiling and other geophysical and geological investigations in order to better understand the structure, composition and evolution of a keystone of Precambrian continental crust and the role it played in the amalgamation and subsequent break-up of the Gondwana supercontinent. Of particular importance is that this lithospheric fragment records a 2 billion year long history of magmatism, sedimentation, deformation and metamorphism and now exposes at the surface rocks that once formed at depths of 30 km or more and that record unusually high metamorphic temperatures of up to 1000°C. Modern geophysical data should help to determine what lies underneath these high-T surface rocks and whether the terrain consists of structural distinct subunits separated by (now hidden) sutures. It is likely that the crustal-scale structures generated during the formation of the SGT may extend to other, now dispersed, segments of the Gondwana landmass and their identification in geophysical data will provide a fresh basis for reconstructing the process of supercontinent assemblage and break-up.     

Thermochronometry and palaeomagnetism of the Archaean Nelshoogte Pluton, South Africa

²⁰⁷Pb/²⁰⁶Pb single-grain zircon, ⁴⁰Ar/³⁹Ar single-grain hornblende and biotite, and ⁴⁰Ar/³⁹Ar bulk-sample muscovite and biotite ages from the Nelshoogte trondhjemite pluton located in eastern Transvaal, South Africa, show that this granitoid had a protracted thermal history spanning 3213±4  Ma to about 3000  Ma. Whole-rock ⁴⁰Ar/³⁹Ar ages from cross-cutting dolerite dykes indicate that these were intruded at about 1900  Ma. There is no evidence of this or other, later events significantly affecting the argon systematics of the minerals from the pluton dated by the ⁴⁰Ar/³⁹Ar method.
  The pluton has a well-defined palaeomagnetic pole which is dated at 3179±18 (2 σ ) Ma by ⁴⁰Ar/³⁹Ar dating of hornblende. This pole (18°N, 310°E, A ₉₅=9°) yields a palaeolatitude of 0°, significantly different from other Archaean poles from the Kaapvaal Craton. The palaeolatitude difference implies that there was significant apparent polar wander during the Archaean. A second, overprinting magnetization seen in the pluton is also seen in the lower-Proterozoic dolerite dykes, and is consistent with other lower-Proterozoic (2150–1950  Ma) poles for southern Africa.     

Polycyclic aromatic hydrocarbons as evidence of hydrocarbon migration in marine and lagoon sediments of a recent rift zone (Skjálfandi and Öxarfjörður), Iceland

Polycyclic aromatic hydrocarbons (PAHs) content and distribution was studied in the northern part of modern rift zone. All samples analysed represent slightly altered clastic deposits and hot water discharging in springs and from wells. To study PAH in present-day gas emission traps with diatomite absorbent were installed in the Skógalón geothermal field. All samples were analysed by the method of Shpol'sky spectroscopy. Hydrothermally altered deposits show the highest amount of PAH. Data obtained allow to believe that the distribution of PAH is closely associated with the dynamics of the hydrothermal environment. The fissure formation and temperature fluctuation in hydrothermal systems can govern both the processes of PAH synthesis and sorption. The evidences of PAH migration up through the Skjálfandi and Öxarfjörður sedimentary basins show that hydrocarbons associate mainly with hydrothermal minerals and deep ground waters. Studying PAH associations can be used as an indicator of hydrocarbons distribution, ways of migration and possible zones of accumulation in the land and marine sedimentary basins in active and ancient rift zones of Iceland.     

Vorläufige Ergebnisse von Gefügeuntersuchungen in den Kitzbühler Alpen

Ohne ZusammenfassungMit 4 Diagrammen.     

Sur les changements du gradient vertical de temperature dans le brouillard de Rayonnement

Résumé Des sondages aérologiques, par ballon captif équipé d'un météorographe, au sein d'une couche de brouillard de rayonnement dense et particulièrement persistante (épaisseur 300 m, durée 11 jours) ont permis à l'auteur de mettre en évidence d'importants changements internes du gradient de température. Il les décompose en trois phases d'évolution successives suivant la densité du brouillard: 1) inversion; 2) isothermie et 3) gradient approximatif de l'adiabatique saturée. De plus, il met en évidence l'existence éphémère de tranches d'air à gradient thermique nettement suradiabatique se formant au sommet de la couche nuageuse par suite du rayonnement et de l'évaporation vers l'espace. On émet l'hypothèse que ces tranches instables sont mobiles vers le bas et servent à refroidir l'ensemble de la couche de brouillard d'où, par la suite, changement progressif du gradient thermique interne.

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Summary During a long period of dense radiation fog (11 days, 1000 ft. thick), a meteorograph attached to a captive balloon was used to investigate the vertical temperature-lapse-rate. The records reveal three consecutive phases in the development of the fog: i. inversion; ii. isothermal state; iii. approximately saturated-adiabatic lapserate.Owing to radiation and evaporation, the top layer often shows instability. The results of the observations seem to support the author's hypothesis that the instable layer gradually spreads downward while the temperature decreases in the whole fog.

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Zusammenfassung Während einer besonders lang andauernden Nebelperiode (11 Tage) waren in der dichten Nebelschicht (300 m) aerologische Sondierungen mit Hilfe eines an einem Fesselballon befestigten Meteorographen durchgeführt worden, die erlaubt hatten, grundlegende Veränderungen des Temperaturgradienten festzustellen. Je nach Dichte des Nebels können 3 Entwicklungsstufen beobachtet werden: 1. Inversion; 2. Isothermie und 3. beinahe Feuchtadiabate. Ueberadiabatische Gradienten, die sich an der Nebeloberfläche durch Ausstrahlung und Verdunstung gegen die freie Atmosphäre bilden, werden besonders hervorgehoben. Es wird vermutet, dass sich diese instabilen Luftpakete nach unten bewegen, die ganze Nebelschicht auskühlen und somit eine progressive interne Aenderung des Temperaturgradienten hervorrufen.

     

Zur Genese des elementaren Schwefels im Gips von Weenzen (Hils)

Zusammenfassung In der Hilsmulde tritt bei Weenzen ein Salzstock durch Kreide- und Tertiärsedimente zutage. Dieser Gips führt an einigen Stellen elementaren Schwefel. Durch Isotopenanalysen wurde festgestellt, daß der elementare Schwefel gegenüber dem Ausgangssulfat an³⁴S verarmt und der Schwefelm Restsulfat entsprechend angereichert wurde. Schwefelfreie Bereiche des Gipses zeigen den für Zechsteinevaporite üblichen ³⁴S-Wert. Der Isotopenunterschied von durch-schnittlich 26% deutet auf bakteriellen Ursprung des Schwefels, weil eine anorganische Reduktion des Sulfates unter den vorauszusetzenden Temperaturen nicht möglich ist. Es wird angenommen, daß während des Aufstieges des Salzstockes ein geringfügiger Zutritt von Erdöl Lebensbedingungen für anaerobe Bakterien schuf, was zur Reduktion des Sulfats zu H₂S führte. Der dabei freiwerdende Schwefelwasserstoff wurde durch Reaktion mit SO ₄ ^2– in elementaren Schwefel umgewandelt. Da sich die Reduktion in den einzelnen Bereichen des Gipses sicher in Abhängigkeit von der Intensität der Bakterientätigkeit vollzog, hat sie primär wohl nicht zu homogener Verteilung der Schwefelisotope im Schwefelwasserstoff bzw. im Restsulfat geführt. Während für den elementaren Schwefel die nachträgliche Homogenisierung wegen der Beweglichkeit des Schwefelwasserstoffes verständlich ist, kann sie im Restsulfat so erklärt werden, daß dieses während der Neokomtransgression von oben her stärker der Lösung ausgesetzt war und umkristallisierte, wodurch sich die anfangs wahrscheinlich stärkeren Unterschiede in der Isotopenzusammensetzung des Gipses verwischten.

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Native sulphur is encountered occasionally within the gypsiferous cap-rock of a Permian salt dome in the Hils syncline, in the environs of Weenzen (see map, Fig. 1). A number of sulphur isotope analysis demonstrated that the native sulphur originated out of the primary sulphates, had been depleted in³⁴S, causing a relative enrichment of the remaining sulphate in³⁴S. Those parts of gypsum which are entirely devoid of native sulphur, exhibit a³⁴S value typical of Zechstein (upper Permian). The average enrichment of³²S in native sulphur of about 26% suggests its bacteriological origin, since under the temperatures usually prevailing during the origin of a salt dome, a sulphate cannot be reduced by petroleum. During the rise of the salt dome, the sulphates became contaminated with a small amount of petroleum as a result of which a congenial ecological condition for the development of the sulphate reducing bacterias was produced. The³⁴S depleted H₂S, produced by these bacterial, reacted with the sulphate, thus giving rise to native sulphur (Feely andKulp, 1957).The activity of the sulphate-reducing bacterial leads to different stages of fractionation in the different biochemical environments owing to the varying intensity of the bacterial growth, as well as to the variable ratios of reduced sulphate to primary sulphate. The highly mobile H₂S was homogenized already before the precipitation of native sulphur, whereas the homogenisation of the sulphate is viewed in the solution and recrystallisation processes taking place just below the Neocomian transgression horizon.