Coastal aquifer assessment based on geological and geophysical survey,northwestern Crete,Greece

Groundwater preservation comprises a major problem in water policy. The comprehension of the groundwater/hydraulic systems can provide the means to approach this problem. Generally, drilling is expensive and time-consuming. On the other hand, new techniques have been applied during the last few decades that provide useful information on the depth and quality of aquifers. Among them, transient electromagnetic method (TEM) is an appealing method that provides fast results with minimum field crew and solves several hydrogeological problems. Many portable systems for single-site measurements are commercially available. The TEM-Fast 48HPC was used for acquiring 106 soundings in the northwestern Crete in Greece for defining the hydrogeological characteristics of the study area, since there were no available data from boreholes. Detailed geological, hydrolithological and tectonic survey was applied prior to the geophysical measurements. All the data were integrated to produce a secure and reliable hydrogeological model for the study area prior to any future hydrowell. Specifically, geometrical and hydraulic data of the study area groundwater were acquired. Two unconnected aquifers were detected and their possible contamination due to saltwater intrusion was analyzed and eliminated. Moreover, a location for borehole construction and groundwater pumping based on the potential of the aquifer system was proposed. Finally, the contribution of TEM (and electrical resistivity tomography) geophysical methods in studying complex coastal aquifers is shown by this work.     

Chemical and physical properties of Žďár nad Sázavou L chondrite and porosity differentiation using computed tomography

A very bright and long bolide was observed over the eastern part of the Czech Republic during late local evening on December 9, 2014. This bolide was recorded by professional instruments in the Czech part of the European Fireball Network. Three meteorites weighing in total 87 g were found in the predicted area and were named ??ár nad Sázavou. The complete material composition of the meteorite was obtained from one cut‐off piece using petrography, mineralogy, and scanning electron microscopy (together with X‐ray energy dispersive spectroscopy and wavelength dispersive spectroscopy). X‐ray computed tomography (CT) was applied on all pieces for the determination of their grain and bulk density, digitization of shape, and examination of the structural homogeneity. CT has proved its important role for nondestructive exploration of brecciated meteorites formed by distinct lithologies or petrological types. In this article, we discuss its limits in terms of structural and material resolution based on the correlation of state‐of‐the‐art CT data and SEM images. Furthermore, we introduce a new way of air cavity quantification, which distinguishes the natural porosity of meteorite and cracks related to erosion processes. This helps to discuss the presence of weathering products based on comparison of the meteorite pieces found at different times after impact.     

A New Bolide Station at the High Tatra Mountains

The European Fireball Network (EN) is operating since 1963 and one of its stable stations, from the very beginning, is the station at the Skalnate Pleso Observatory in the High Tatras. The station is sited at a height of 1788 m. More than 2900 expositions has been made at the Skalnate Pleso station since 1964 and among them one significant and spectacular event was recorded––bolide Turji-Remety in 2001 followed by a fall of about 450 kg meteorite (Spurny and Porubcan [in: Warmbein (ed.) Asteroids Comets Meteors, 2002]). A systematic search for the meteorite was unsuccessful. The new station having an ideal horizon will be operating since July 2007 on the top of Lomnicky Stit (2636 m above the sea level). This station will be equipped with an Autonomous Fireball Observatory of the Astronomical Institute of the Czech Academy of Sciences, which are already utilized in the Czech part of the EN for several years.     

Intensity of vlf and elf phenomena in the outer ionosphere

Summary Spatial and temporal variability of natural ELF-VLF phenomena field intensity has been studied using data from Interkosmos satellites with apogees below 2000 km. The results show a distinct dependence of the diurnal variation and latitudinal intensity distribution on the magnetic activity. The L-value at which the maximum of plasmaspheric noise occurs, e.g., correlates better with the Dst-index than with other indicies.

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On the role of diffractions in velocity model building: a full-waveform inversion example

Studia Geophysica et Geodaetica - Imaging of small-scale heterogeneities is important for the geological exploration in complex environments. It requires a processing sequence tuned to...     

Population-level genotyping of coat colour polymorphism in woolly mammoth (Mammuthus primigenius)

Patterns in the spatial or temporal distribution of genotypes may be indicative of natural selection. Previous work on the woolly mammoth melanocortin-1 receptor (Mc1r) gene identified three polymorphic positions that suggest Pleistocene populations may have harboured both light- and dark-haired mammoths (Rompler et al., 2006, 313: 62). Here, we extend this work and present the first population-level analysis of a functional gene in an extinct species. We genotyped the Mc1r gene in 47 woolly mammoth samples excavated from sites across the central portion of the woolly mammoths’ former range to examine the extent of variation of this polymorphism through time and across space. Only one individual was found to be heterozygous, indicating that the frequency of the ‘light’ mutant allele was very low. We conclude that light-coloured woolly mammoths would have been very rare, and may even have been non-existent if the ‘light’ mutant allele was strongly selected against in its homozygotic form. With the increasing availability of large-scale sequencing technologies, population-level datasets capable of identifying local adaptation will become increasingly attainable.     

Numerical treatment of the kinematic dynamo model

Summary Since the initial equations are complicated, the treatment of the kinematic dynamo model requires the use of numerical methods. In applying them to the given problem difficulties are encountered, which are not easy to overcome. This paper deals with the analysis of the experience acquired in treating the model of a nearly symmetric dynamo. Three different methods were employed (stationary, oscillatory and general non-stationary), because a combination of several solutions will yield more comprehensive information about the model being studied. Although the results are based on the study of a single particular model, similar problems also occur in other excercises and, therefore, the conclusions have a more general validity.     

Contamination of some reservoirs and lakes in Republic of Bulgaria by microcystins

This paper presents the results from analyses of water samples from 15 Bulgarian reservoirs and lakes for detection of microcystins presence by high‐performance liquid chromatography (HPLC) coupled to a ultraviolet (UV) and photo diode array (PDA) detector. In 3 of the studied drinking water reservoirs cyanobacterial blooms were not detected. Cyanobacterial blooms were observed in 6 of 12 investigated water bodies used for fishing and water sports. Microcystis was the dominant cyanobacterial genus. The concentration of total microcystins in the biomasses ranged from 8 to 1070 μg g^–1 (d.w.). Microcystin‐LR and microcystin‐RR were the predominant microcystins, followed by microcystin‐YR. Presence of dissolved microcystins was obtained in one water sample with concentration of total microcystins 1.64 μg L^–1. Presence of microcystin‐LF and ‐LW or unknown peaks possessing characteristic microcystin‐like UV‐spectra were not detected. Those first results for occurrence of microcystins in some Bulgarian reservoirs and lakes are a contribution to the knowledge on their distribution.