Assessing the Vibrational Frequencies of the Holweide Hospital in the City of Cologne (Germany) by Means of Ambient Seismic Noise Analysis and FE modelling

Ambient seismic noise measurements were conducted inside the Holweide Hospital (Cologne) for checking whether its frequencies of vibration fall into the range where soil amplification is expected. If this is the case, damage might increase in case of an earthquake due to an amplified structural response of the building. Two different techniques were used: the ratio between the horizontal and vertical components of the spectra recorded at stations located inside the building and the ratio between the corresponding components of the spectra recorded simultaneously inside the building and at a reference station placed outside. While the former method might be preferred because of less equipment involved, the latter has the advantage of producing more stable results and deleting automatically the influence of the sedimentary cover, which might obscure some eigenfrequencies of vibration of the building. An independently performed finite-element analysis of the hospital showed a good correlation between measured and calculated eigenmodes.     

Influence of chemical composition and microstructure on the hygroscopic growth of pyrogenic aerosol

The hygroscopic properties of a model smoke aerosol series including ammonium sulfate, levoglucosan, and oxalic and humic acids were investigated. The condensation growth of particles and the relative humidity of direct and inverse particle-droplet phase transitions were measured with a tandem differential mobility analyzer. The data were obtained in the range of relative humidity from 4 to 95% at 298 K. Experimental growth factors were compared to the results of Koehler theory by using contemporary models of water activity in particles. It was shown that the hygroscopic properties of the aerosols were substantially different from the hygroscopic properties of the corresponding bulk phases. It was found that a complex microstructure of nanoparticles resulted in excess volume absorption of water, in some cases causing their full deliquescence at lower relative humidities than in macrosystems of identical composition. From the measurement data, a parametrization of hygroscopic particle growth was performed. The results of parametrization can be used to construct refined models of a smoke aerosol.     

Letter to the Editor

Mathematical Geosciences -     

Snow cover as an indicator of cumulative man-made pollution in the area of influence of cities and roads

It is known that, as a section of land hydrology, hydrography studies concrete water bodies characterizing both qualitatively and quantitatively their location, regime, and local conditions. Thus, estimating the size of contaminated land within the river systems, lake and ocean basins is also a task of hydrography. The studies were conducted in the period from 1972 to 2012.     

Renhold Süring †

Ohne Zusammenfassung     

Gold mineralisation at the Lady Bountiful Mine,Western Australia: An example of a granitoid-hosted Archaean lode gold deposit

The Lady Bountiful granitoid-hosted lode gold deposit, located in the mid-greenschist facies metamorphosed Ora Banda greenstone sequence, is hosted predominantly by the late-tectonic Liberty Granodiorite. Gold mineralisation is localised along quartz-veined, sinistral, brittle fault-zone(s) that transect the boundary between the Liberty Granodiorite and Mt Pleasant sill. Quartz vein textures indicate two stages of a single gold-related vein-development event, with high-grade gold mineralisation restricted to the second stage. Ore minerals include pyrite, chalcopyrite, pyrrhotite, galena, sphalerite, Au−Ag−Bi−Pb-tellurides, and native gold. Fluid infitration has resulted in narrow (<1 m) bleached wallrock alteration envelopes to the fault zones comprising albite-K-mica ±chlorite±calcite±rutile assemblages. Temperature-pressure conditions varied from Stage I (300°±50°C, ≈2 kbar) to Stage II (250°±50°C, ≈0.5 to 2 kbar), with the hydrothermal fluid in both stages characterised by X(CO₂)≤0.15 and moderate salinity (≈1.28 m NaCl). Intermittent phase separation of Stage II mineralising fluids, initiated by pressure fluctuations in dilational sites, and/or fluid-dominated fluid: wallrock interaction, are invoked as the dominant depositional mechanisms. The granitoid-hosted Lady Bountiful lode gold deposit shares many features with other granitoid-hosted lode gold deposits in the Yilgarn Craton and the Superior Province. Granitoid-hosted lode gold deposits, such as the Lady Bountiful deposit, provide additional evidence that the dominant control on the localisation of gold mineralisation within a granitoid host is structure, with competency contrasts playing a significant role. Furthermore, the hydrothermal wallrock alteraction and orefluid chemistry characteristics of the granitoid-hosted lode gold deposits are comparable to those established for greenstone-hosted lode gold mineralisation.     

Biogeochemical Modelling of a Seasonally Anoxic Lake: Calibration of Successive and Competitive Pathways and Processes in Lake Aydat,France

A reactive transport model was developed to describe seasonal variations of biogeochemical and physical processes in Lake Aydat. The model includes physical processes such as vertical mixing, sedimentation and advection related to inflows into the lake and biogeochemical conversion processes in the water column and in the sediment surface layer. The reactions described in the model include primary redox reactions such as primary production, aerobic and anaerobic respiration, methanogenesis and secondary reactions established between oxidants and reducers produced by the primary reactions. After adjusting various kinetic constants, the model reasonably reproduced the main features of seasonal variations of dissolved oxygen and nitrate depth profiles and pH. The reactive transport model was also used to quantify the relative importance of different biogeochemical pathways. For instance, ferrous denitrification seems to play an important role when stratification is increasing.