Cation exchange capacity of loess and overlying soil in the non-carbonate loess sections, North-Western Croatia

The adsorption properties in terms of cation exchange capacity and their relation to the soil and sediment constituents (clay minerals, Fe-, Mn-, and Al-oxyhydroxides, organic matter) were investigated in loess, soil-loess transition zone, and soil at four loess-soil sections in North-Western Croatia. Cation exchange capacity of the bulk samples, the samples after oxalate extraction of Fe, Mn and Al, and after removal of organic matter, as well as of the separated clay fraction, was determined using copper ethylenediamine. Cation exchange capacity (pH～7) of the bulk samples ranges from 5 to 12 cmol _c /kg in soil, from 7 to 15 cmol _c /kg in the soil-loess transition zone, and from 12 to 20 cmol _c /kg in loess. Generally, CEC values increase with depth. Oxalate extraction of Fe, Mn, and Al, and removal of organic matter cause a CEC decrease of 3–38% and 8–55%, respectively, proving a considerable influence of these constituents to the bulk CEC values. In the separated clay fraction (<2 μm) CEC values are up to several times higher relative to those in the bulk samples. The measured CEC values of the bulk samples generally correspond to the clay mineral content identified. Also, a slight increase in muscovite/illite content with depth and the vermiculite occurrence in the loess horizon are concomitant with the CEC increase in deeper horizons, irrespective of the sample pretreatment.     

http://www.sciencedirect.com/science/article/pii/S167498711400067X

The Proterozoic Bamble Sector, South Norway, is one of the world＇s classic amphiboliteto granulite- facies transition zones. It is characterized by a well-developed isograd sequence, with isolated ＇granulite-facies islands＇ in the amphibolite-facies portion of the transition zone. The area is notable for the discovery of C02-dominated fluid inclusions in the granolite-facies rocks by Jacques Touter in the late 1960＇s, which triggered discussion of the role of carbonic fluids during granulite genesis. The aim of this review is to provide an overview of the current state of knowledge of the Bamble Sector, with an emphasis on the Arendal-Froland-Nelaug-Tvedestrand area and off shore islands （most prominantly Tromay and Hisoy） where the transition zone is best developed. After a brief overview of the history of geological research and mining in the area, aspects of sedimentary, metamorphic and magmatic petrology of the Bamble Sector are discussed, including the role of fluids. Issues relevant to current geotectonic models for SW Scandinavia, directly related to the Bamble Sector, are discussed at the end of the review.     

Sandstone alterations triggered by fire-related temperatures

The aim of the study was to identify and describe changes in two different sandstone types when undergoing different environmental and extreme temperature regimes to assess the possibility of finding insolation weathering and how these sandstones would behave during and after a fire. The first step was the simulation in the laboratory of temperature regimes up to 60 °C which would correspond to extreme events that could be found in insolation cycles even in Central Europe and the second one was the temperature above 200 °C simulating in laboratory conditions the thermal regime of a potential fire situation at temperatures up to 200, 400, 600 and 800 °C. Heating the samples above 400 °C led to gradual changes in mineral composition, colour, surface roughness and physical properties reaching, eventually, total rock breakdown through spalling and granular disaggregation. The different behaviour of sandstones exposed to high temperatures is mainly caused by their different mineral composition with various ratios of minerals that are more or less chemically stable at high temperatures as well as by the differences in the porosity.     

Vulnerability to natural disasters in Serbia: spatial and temporal comparison

The frequency of natural disasters and the extent of their consequences at a global level are constantly increasing. This trend is partially caused by increased population vulnerability, which implies the degree of population vulnerability due to high-magnitude natural processes. This paper presents an analysis of vulnerability to natural disaster in Serbia in the second half of the twentieth and the early twenty-first century. Vulnerability changes were traced on the basis of demographic–economic indicators derived from statistical data for local government units (municipalities) provided by the Statistical Office of the Republic of Serbia. Calculations were performed in the geographical information system environment. The results of the study show that spatial and temporal vulnerability variations are causally correlated with changes in the selected components. Significant rise of vulnerability is related to urban areas, while lower values are characteristic for other areas of Serbia; this is primarily a consequence of different population density.     

A Mass Balance Approach to Resolving LNAPL Stability

This article explores the hypothesis that natural losses of light nonaqueous phase liquids (LNAPLs) through dissolution and evaporation can control the overall extent of LNAPL bodies and LNAPL fluxes observed within LNAPL bodies. First, a proof‐of‐concept sand tank experiment is presented. An LNAPL (methyl tert‐butyl ether) was injected into a sand tank at five constant injection rates that were increased stepwise. Initially, for each injection rate the LNAPL bodies expanded quickly. With time the rate of expansion of the LNAPL bodies slowed and at extended times the extent of the LNAPL became constant. Attainment of a stable LNAPL extent is attributed to rates of LNAPL addition being equal to rates of LNAPL losses through dissolution and evaporation. Secondly, analytical solutions are developed to extrapolate the processes observed in the proof‐of‐concept experiment to dimensions and time frames that are consistent with field‐scale LNAPL bodies. Three LNAPL body geometries that are representative of common field conditions are considered including one‐dimensional, circular, and oblong shapes. Using idealized conditions, the solutions describe volumetric LNAPL fluxes as a function of position in LNAPL bodies and the overall extent of LNAPL bodies as a function of time. Results from both the proof‐of‐concept experiment and the mathematical developments illustrate that natural losses of LNAPL can play an important role in governing LNAPL fluxes within LNAPL bodies and the overall extent of LNAPL bodies.     

Cladoceran community composition in tropical semi-arid highland reservoirs in Tigray (Northern Ethiopia): A metacommunity perspective applied to young reservoirs

A field survey of zooplankton communities was carried out in 32 recently established tropical semi-arid reservoirs in the highlands of Northern Ethiopia with the aim to identify to what extent environmental factors determine species composition of the cladoceran community in such isolated and young reservoirs. To address seasonal variation, the survey was carried out both at the beginning and the end of the dry season. A total of 15 species of cladocerans were identified. Daphnia was the most abundant cladoceran genus, and was present in all reservoirs. Using presence-absence data, no association between cladoceran community composition and geographic distance was found. RDA results indicate that the set of environmental variables that explained cladoceran community composition differed among seasons. Depth, altitude and fish biomass showed a significant association with cladoceran community composition during the wet season, whereas variation in cladoceran community structure was associated with phytoplankton biomass in the dry season. The relative abundance of Daphnia was much higher in the pelagic than in the littoral zone of our study systems. Two key groups of pelagic filter-feeding cladocerans, Diaphanosoma and Daphnia, showed a clear pattern, in which one or the other tended to strongly dominate the community. In addition, we observed a negative association between dominance of Daphnia in the zooplankton community and dominance of cyanobacteria in the phytoplankton community.     

The intensity of the earth's magnetic field in the past derived from the archaeomagnetic data

a n¶rt;u¶rt; amuu amua uuu anmuaum n a n¶rt;u 8500 m nm um au aam m uuu m naama. ¶rt;u u ¶rt;a ¶rt; u ¶rt; m¶rt; mumu auu nau nuu aau mama [1–3] (Puc. 1.B). nma aau auau (Puc.2) mnaua m m m¶rt;a, ¶rt; au n¶rt; amu u, m n¶rt;u 2- ma m, mmu naa auu nu¶rt; n¶rt;a 1000 m u 350 m, au a aumu, mmm 80%- mmu. am au ¶rt;a u anmu ¶rt; m¶rt; mumu (mum) naa auu u¶rt; ma u ¶rt; m naama[5] (Puc. 3). uma a mam nma aaua naaa auu nu¶rt; n¶rt;a 750 m, 200 m u a — 300 m. (Puc. 4.) nmu u ¶rt;a nma amua an¶rt;u n¶rt;u n u ma m (au) auumu m ¶rt;m m (Puc. 5). aa a m¶rt;m nu naamaum n aam ¶rt;uu mu au, anum¶rt;a m uua nm m¶rt;a.

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Dedicated to Academician Alois Zátopek on His 65th Birthday     

Meteorological microseisms and stratospheric warmings

Summary The meteorological microseisms recorded at Prague are found to be essentially independent of the occurrence of the major midwinter stratospheric warmings. This finding contributes to studying the downward propagation mechanism of some extraterrestrial influences.     

The relation between the heat flow field and the distribution ofP n -wave velocities for the European continent

Summary The dependence of P_n-wave velocities on the heat flow, temperature at the crustmantle boundary and the thickness of the Earth's crust in Europe was investigated in relation to the problem of lateral inhomogeneities in the upper mantle. A map was constructed of the distribution of P_n-wave velocities on the territory of Europe. The relations these investigations yielded, were compared with the results of laboratory experiments and all the results are discussed from the physical point of view. The conclusion drawn is that that temperature and pressure effect provide a sufficient explanation of the observed regional changes of P_n-wave velocities for the European continent.

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auum ¶rt;auu mu n¶rt; ¶rt; nmu uua (P_n) u mn nm, mnam a nmu amuu u m a mumuu n a u¶rt;aa u numa ¶rt;¶rt;m amuu. mumuu n a maa a uu m P_n- a nmu uua. u¶rt;u umam ¶rt;a mama aam u¶rt;au uuu m n¶rt; amuu u u ¶rt;au u mnam mmmm mama n¶rt;aa am. ¶rt;a ¶rt;, m ua uu m P_n- a n mum ¶rt;mam um uuu mnam u ¶rt;au a nmu uua.