The main soil properties, concentrations of selected elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn), and the chemical speciation of each element were determined in urban soil samples taken from ...urban parks in four Serbian cities (Belgrade, Pančevo, Obrenovac, and Smederevo) exposed to different sources of pollution. Pollution indices (PI, PI
N
) and factors (MF, ICF, GCF) also were evaluated. The study revealed As and Cd concentrations below the detection limit, whereas the content of Cr, Cu, Fe, Mn, Ni, Pb, and Zn at some sites exceeded the limits established by local regulations, as well as the background values, which may represent an environmental threat. Sequential extraction results show that Fe, Cr, Cu, and Ni were predominantly in the residual fraction at most sites; however, Ni from Pančevo and Smederevo also was bound to the reducible fraction. The presence of Pb at all sites and Zn in Smederevo and Belgrade was mainly associated with the reducible and residual fractions. The highest Mn content was found in the reducible fraction, followed by the acid soluble/exchangeable and residual fractions. Based on the obtained indices and factors, the overall soil status at the selected sampling sites was found to range from the warning limit to slightly polluted, whereby Smederevo had the highest risk, and Pančevo and the control site the lowest risk of contamination by toxic metals.
In recent years, the IMF has released a growing number of reports and other documents covering economic and financial developments and trends in member countries. Each report, prepared by a staff ...team after discussions with government officials, is published at the option of the member country.
This study focuses on age and evolution of the Oligocene quartz latite of the Rogozna Mts. (Central Balkan Peninsula), in order to better understand the link between magmatism and formation of ...Pb–Zn±Ag mineralization. New 40Ar/39Ar biotite and amphibole plateau ages suggest that the Rogozna Mts. quartz latite originated through a continuous volcanic episode from 27.3±0.1 to 29.5±0.1Ma which was immediately followed by a hydrothermal phase. The quartz latites are hypocrystalline porphyritic with phenocrysts and microphenocrysts (~60vol.%) of plagioclase (An37–49), biotite Mg# 100×Mg/(Mg+Fetot)<50, calcic amphibole, quartz, sanidine clinopyroxene and phlogopite (Mg#=79 to 84). The rocks display numerous disequilibrium textures, such as: sieved plagioclase phenocrysts, dissolution effects on quartz, phlogopitized biotite and amphibole crystals, and phlogopite microphenocrysts showing effects of incomplete growth (or dissolution?) and biotitization. The Rogozna Mts. quartz latites are shoshonitic in character with Na2O/K2O<1, high LILE/HFSE ratios, strong depletions at Nb and Ti and K, Pb and U peaks on primitive mantle-normalized diagrams. They are similar to other potassic/ultrapotassic rocks in this region, in particular to those of Veliki Majdan and Rudnik (West Serbia), which are also related to Pb–Zn deposits. The evolution of the Rogozna Mts. quartz latite is modeled using a trace element binary mixing model adopting a lamproite magma and a dacite-like calc-alkaline melt as end-members. The model implies that a fractionating magma chamber (~4.5–9.5km) undergoes cooling in the range of >850°C–~720°C and injection of lamproite-like melts. The injection causes an increase of temperature and a decrease of viscosity of the resulting hybrid magma, facilitating its upwelling and triggering pyroclastic eruptions. The addition of new volatiles by lamproitic melts most probably established the conditions for a hydrothermal phase above the magma chamber that was previously degassed explosively. This implies that magma mixing processes can be of great importance for the formation of Pb–Zn deposits. Similar processes are likely to have occurred in other areas with economically significant Pb–Zn–Ag±other metal mineralization in the region of the Central Balkan Peninsula (Veliki Majdan, Rudnik, Golija, Kopaonik, Avala, etc.).
► Rogozna quartz latite formed 27.3±0.1–29.5±0.1Ma ago from hybridized melts. ► Hybridization originated by mixing of dacite calc-alkaline and K to ultra-K melt. ► Prior to hybridization crystallized amphibole, plagioclase, biotite at 5–10km. ► Phlogopite and disequilibrium textures formed after injection of K to ultra-K melt. ► Pb–Zn–Ag deposits formed synchronous with quartz latite.
Loess correlations – Between myth and reality Marković, Slobodan B.; Stevens, Thomas; Mason, Joseph ...
Palaeogeography, palaeoclimatology, palaeoecology,
11/2018, Letnik:
509
Journal Article
Recenzirano
Odprti dostop
The correlation of loess sequences across global, hemispheric, regional and local scales is one of the most fundamental aspects to loess research. However, despite recent progress in stratigraphic ...and chronometric methods, the correlation of many loess sequences is often still based on untested assumptions over loess deposition, preservation, soil type and age. As such, the aim of this overview is to provide an adequate framework for evaluation of the accuracy of loess correlations applied on different temporal and spatial scales across Eurasia. This opens up possibilities for detailed temporal and spatial environmental reconstructions across the huge loess provinces of the Eurasia and provides a framework for future extension of this to North America. Additionally, we evaluate the potential development of appropriate sub-millennial scale loess correlations, as well as essentially important chronological approaches for establishing valid correlations between different loess records, such as current improvements in tephrochronology, 14C and luminescence dating techniques.
•Examination of cyanobacterial compounds as a paleoclimate reconstruction biomarker.•Usage of double-centered interaction matrix analysis and heat-map visualization.•SWE compounds were observed in ...the loess sediment and BLCs samples.•Potential establishment of SWE as a proxy for UV irradiance.•Potential establishment of MWE as a proxy for general stressful conditions.
Loess is the most important archive of Quaternary palaeoclimate evolution, with more thorough and systematic investigations carried out in the past two decades in the Carpathian Basin. Application of novel proxies in loess research could improve the state of knowledge of the past climatic changes. In order to examine the feasibility of cyanobacterial pigments to be used as biomarkers in paleoclimate reconstruction and thereby substantiate the presence of cyanobacterial community during loess accumulation, geochemical evidence of cyanobacteria-specific biomarkers in the sediment is required. In this study structurally different cyanobacterial metabolites were examined for their potential to be used as biomarkers. These compounds included scytonemin wavelength equivalent (SWE) and mycosporine wavelength equivalent (MWE) compounds.
The effect of various physico-chemical factors (pH value, temperature and light source) on the production of SWE and MWE compounds in correlation with the nitrogen content of the growth medium was studied. SWE compounds were observed in 8 out of 15 soil and aquatic cyanobacterial strains, while MWE compounds were found in all 15 strains. The results show that exposure to UV light induced a higher synthesis of both pigments.
Moreover, the presence of SWE compounds was confirmed in cyanobacterial cultures isolated from biological loess crusts (BLCs) as well as in BLC and loess sediment samples. The potential application of these pigment groups as biomarkers in paleoenvironmental and paleoclimatic reconstruction is discussed.
Construction of the Danube Iron Gate Dam for hydroelectricity, 943km from the mouth of the Danube River, is changing sediment transport due to its retention in the Iron Gate Reservoir (IGR), ...potentially causing heavy metal enrichment, re-distribution within the solid phase, exchange or re-suspension on sediment–water interface. The concentrations of heavy metals (Cu, Zn, Pb and Cd) in water and sediment during a five-year period along the IGR were determined. The fluxes of heavy metals from river water to sediment due to sedimentation were determined, as well as their fluxes from the bottom sediment to the sediment–water interface due to sediment re-suspension at high flow rate, when fluvial erosion takes place and removes part of the previously deposited sediment from the river bed, in a yearly amount between 2 and 9%, depending on the hydraulic regime in the IGR.
•Surface sediment and water of Iron Gate Reservoir on heavy metals were analyzed.•The fluxes of heavy metals were determined.•The fluvial erosion provokes the resuspension of h.m. from sediments into the water.•Reservoir sediment is accumulating at men rate of 6cm/yr.
•Two periods (1987–1994; 2000–2003) were characterized by long and severe droughts.•The 2000year was the driest year during the observed period.•The significant increasing trend was at Negotin in ...spring and at Novi Sad in autumn.•The significant increasing trend in annual precipitation data was detected at Sombor.•No significant trend was detected in the SPI-12 series at the 5% significance level.
Precipitation and Standardised Precipitation Index (SPI) trends were analyzed by using linear regression, Mann–Kendall and Spearman’s Rho tests at the 5% significance level. For this purpose, meteorological data from 12 synoptic stations in Serbia over the period 1980–2010 were used. Two main drought periods were detected (1987–1994 and 2000–2003), while the extremely dry year was recorded in 2000 at all stations. The monthly analysis of precipitation series suggests that all stations had a decreasing trend in February and September, while both increasing and decreasing trends were found in other months. On the seasonal scale, there were the increasing trends in autumn and winter precipitation series, while on the annual scale the most of the stations had no significant trends. Besides, the decreasing trend was found at the Belgrade and Kragujevac stations, while the other stations had the increasing trend for the SPI-12 series.
In Serbia, as elsewhere in postsocialist Europe, the rise of “civil society” was expected to support a smooth transformation to Western models of liberal democracy and capitalism. More than twenty ...years after the Yugoslav wars, these expectations appear largely unmet. Frontiers of Civil Society asks why, exploring the roles of multiple civil society forces in a set of government “reforms” of society and individuals in the early 2010s, and examining them in the broader context of social struggles over neoliberal restructuring and transnational integration.
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