Biomarker distributions as indicators for the depositional environment of lacustrine sediments in the Valjevo-Mionica basin (Serbia)

In this study, the molecular composition and biomarker distribution of lacustrine sediments from Val-1 drillhole in the central zone of the western part of the Valjevo-Mionica basin were investigated at depth interval of 0–400 m. Former investigations have shown that the core material can be separated into six depth intervals based on bulk geochemical, mineralogical and sedimentological characteristics. Concerning the quality of organic matter, presence of specific minerals, and high salinity and anoxicity, or alkalinity, three zones are of highest interest, defined at depth intervals of 15–75 m (A), 75–200 m (B) and 360–400 m (F). The first aim of the study was to identify which biomarkers characterize these specific intervals. The second aim, addressing the transitions zones of these intervals, was to extend the changes in the characteristics of the organic substance, to reflect the changes of conditions in the depositional environment as well as to define biomarker parameters which are the most sensitive sedimentological indicators.The sediments from the hypersaline anoxic and alkaline environment show high contribution of algal precursor biomass, what is in accordance with the good quality of organic substances in the sediments from these zones. High squalane content and low content of regular isoprenoid C₂₅ are typical for hypersaline anoxic environment, whereas sediments from alkaline environment have high regular isoprenoid C₂₅ content.Transition to specific sedimentation zones is characterized by change in total organic matter content, and of both free and pyrolysis-derived, and change in hydrogen index value. In the biomarker distributions, more significant changes were detected in distributions of n-alkanes and isoprenoids, compared to polycyclic alkanes. The most intensive changes in alkane distribution are reflected in changes in n-C₁₇ content compared to n-C₂₇, and phytane compared to n-C₁₈. In addition, significant sensitivity was seen in ratios between squalane and n-alkane C₂₆ (hypersaline depositional environment), or isoprenoid C₂₅ and n-alkane C₂₂ for high alkalinity environment.This study showed that Sq/n-C₂₆ ratio can be used to assess the quality of organic substance in immature lacustrine sediments.     

A finite element model for seismic response analysis of deformable rocking frames

A new finite element model to analyze the seismic response of deformable rocking bodies and rocking structures is presented. The model comprises a set of beam elements to represent the rocking body and zero‐length fiber cross‐section elements at the ends of the rocking body to represent the rocking surfaces. The energy dissipation during rocking motion is modeled using a Hilber–Hughes–Taylor numerically dissipative time step integration scheme. The model is verified through correct prediction of the horizontal and vertical displacements of a rigid rocking block and validated against the analytical Housner model solution for the rocking response of rigid bodies subjected to ground motion excitation. The proposed model is augmented by a dissipative model of the ground under the rocking surface to facilitate modeling of the rocking response of deformable bodies and structures. The augmented model is used to compute the overturning and uplift rocking response spectra for a deformable rocking frame structure to symmetric and anti‐symmetric Ricker pulse ground motion excitation. It is found that the deformability of the columns of a rocking frame does not jeopardize its stability under Ricker pulse ground motion excitation. In fact, there are cases where a deformable rocking frame is more stable than its rigid counterpart. Copyright © 2016 John Wiley & Sons, Ltd.     

Rock-slides on road cuttings in the Dinaric karst of Croatia: processes and factors

The northern Adriatic coast, which forms part of the Dinaric karst system, is bordered by high mountains. Here, the occurrence of rock-slides and rock-falls in road sections with high cuttings excavated in recent times and more than one century ago has been documented. Some of these old slopes were stable for a long time before rock-slides started to occur. We propose that these mass movements are favoured by karstification processes acting along joints in the exposed rock mass. The stress changes induced by overburden removal (excavation) cause dilation in the mass joint systems reducing the rock mass strength and facilitating the circulation of aggressive water. Changes in water pressure and temperature, wetting and drying cycles, and corrosion processes along discontinuity planes entail a reduction through time of the shear strength of potential failure surfaces.     

Forecasting hourly particulate matter concentrations based on the advanced multivariate methods

In this study, several multivariate methods were used for forecasting hourly PM₁₀ concentrations at four locations based on SO₂ and meteorological data from the previous period. According to the results, boosted decision trees and multi-layer perceptrons yielded the best predictions. The forecasting performances were similar for all examined locations, despite the additional PM₁₀ spatio-temporal analysis showed that the sites were affected by different emission sources, topographic and microclimatic conditions. The best prediction of PM₁₀ concentrations was obtained for industrial sites, probably due to the simplicity and regularity of dominant pollutant emissions on a daily basis. Conversely, somewhat weaker forecast accuracy was achieved at urban canyon avenue, which can be attributed to the specific urban morphology and most diverse emission sources. In conclusion to this, the integration of advanced multivariate methods in air quality forecasting systems could enhance accuracy and provide the basis for efficient decision-making in environmental regulatory management.     

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.     

2D geological–geophysical model of the Timok Complex (Serbia,SE Europe): a new perspective from aeromagnetic and gravity data

The study reports new aeromagnetic and gravity data for the northern part of the Timok Magmatic Complex (TMC), East Serbia. The TMC is part of the Tethyan Eurasian metallogenic zone well known for hosting large copper and gold deposits. The complex formed by continuous volcanic activity 90–78 Ma ago, that developed in roughly three phases: Turonian andesites, Santonian–Campanian andesites/basaltic andesites (both mostly volcanic) and Campanian latites/monzonites (mostly shallow intrusive). The aeromagnetic measurements included acquiring total magnetic intensity data that were corrected for diurnal variations, leveling, microleveling, calculated normal field values, calculated anomaly values of total magnetic field intensity and reduction to the pole. The gravity measurements were carried out in an irregular grid with relative gravity values obtained using a Worden gravity meter. 2D modeling reveals that the subsurface extension of the Campanian Valja Str? pluton is ten times larger than it is indicated by its surface outcrops. This implies that the area south and southeast from the pluton can be interesting in terms of finding new porphyry systems. The model indicates that this intrusive body should not be considered as a deeply dissected pluton. This sheds new light onto its potential with respect to epithermal gold mineralization, as well. The model also suggests that there are larger non-exposed bodies of Santonian–Campanian volcanics and near-surface hydrothermally altered rocks than it is inferred from geological maps. The results of our study suggest that further interdisciplinary investigations in the TMC, in particular those integrating geophysics and geology, may have potential of advancing the existing exploration models.     

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.     

Late cretaceous radiolarians and age of flyschoid sediments in the Struganik section (Western Serbia)

The succession of radiolarian assemblages in the Struganik section of western Serbia is described for the first time. The following radiolarian beds are defined in carbonate flyschoid sequences represented by thin-platy limestones with calcarenite and bentonite clay intercalations (from the base upward): Theocampe urna-Dictyomitra koslovae (presumably lower Santonian); Afens perapediensis-Clathropyrgus titthium (presumably uppermost lower Santonian-basal upper Santonian); Alievium gallowayi-Crucella espartoensis (upper Santonian). The examined assemblages are characterized by high taxonomic diversity. The upper Santonian Alievium gallowayi-Crucella espartoensis Assemblage exhibits significant similarity with the coeval radiolarian assemblage of the Crimean Mountains (Ukraine). Archaeocenosphaera (?) karamatai sp. nov. is described.     

Some foundation stability problems of the railway bridge over the Mala Rijeka

SummarySome Foundation Stability Problems of the Railway Bridge over the Mala Rijeka The authors presented an outlay of problems occurring in estimating the stability of rocky slopes loaded by large vertical forces. General attitudes, kept by the authors during the stability analysis for an actual case — foundation of piers No. 3 and 4 of the railway bridge across the Mala Rijeka, are also presented. The results of calculation as well as the advantages of the approach applied are outlined in the paper. Finally, general conclusions are drawn regarding the method to be kept in solving the stability of slopes loaded by large artificial loading.With 7 Figures     

Numerical model for quantitative precipitation forecasting

Summary A numerical model for the quantitative precipitation forecasting has been formulated. In this model precipitation is computed as a function of the vertical velocity and humidity distribution in the atmosphere. The orographic influence on the vertical velocity was taken into consideration. Further, the relation between vertical velocity and static stability of the atmosphere has been considered and, as an important factor in the condensation process, was introduced into the equation of the model. This numerical model for the precipitation forecasting has been applied in the North Adriactic Sea region, which is characterized by a strong vertical gradient of the specific humidity and pronounced orographic influence. The results achieved show that this model could successfully be used as an objective method in the routine forecasting of the amount of precipitation.