Boško Gajić

Heavy metals in soils: distribution, relationship with soil characteristics and radionuclides and multivariate assessment of contamination sources.

The study is dealing with the distribution and the origin of heavy metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) in soils from a priori non-polluted areas. Positive correlations with organic matter and clay content but not with pH have been observed for most of elements analyzed in this study. Correlations of some metals (Cr, Pb and Zn) and radionuclides (238U and 137Cs) observed for analyzed soils could be explained by their common affinity for clay minerals. Enrichment factor (EF) analysis and cluster analysis (CA) highlighted the lithogenic origin of Cr, Cu, Mn, Ni, Pb and Zn and pointed out the primary input of Cd from anthropogenic sources. It also revealed the need for detailed geochemical surveys in the future in order to decrease the uncertainty of discrimination between lithogenic and anthropogenic origin of metals of interest.

Quantification of transfer of 238U, 226Ra, 232Th, 40K and 137Cs in mosses of a semi-natural ecosystem

There is a lack of appropriate data on transfer of some radionuclides on many terrestrial biota groups. To expand the available data concentration ratios of (238)U, (226)Ra, (232)Th, (40)K and (137)Cs in mosses are presented in this paper. The relationship between concentration ratios of radionuclides and physicochemical characteristics of the underlying soil was also investigated. The data on concentration ratios obtained here will provide a useful addition to the currently used database of transfer parameters, particularly for natural radionuclides.

Trace Metals in Soils and Several Brassicaceae Plant Species from Serpentine Sites of Serbia

Abstract Serpentine soils from 16 sample points in Serbia as well as the roots and shoots of eight Brassicaceae family species: Aethionema saxatile, Alyssum montanum, Alyssum repens, Cardamine plumieri, Erysimum linariifolium, Erysimum carniolicum, Isatis tinctoria, Rorippa lippizensis, were analyzed with regard to their concentrations of P, K, Fe, Ca, Mg, Ni, Zn, Mn, Cu, Cr, Cd, and Pb. Most of the soil samples were typical of ultramafic sites with low concentrations of P, K and Ca and high concentrations of Mg, Fe, Ni and Zn. Ca/Mg ratio was <1 in most soil samples and Brassicaceae plants. Only in A. montanum, A. repens, E. linariifolium and R. lippizensis was the Ca/Mg ratio >1. The levels of P, K, Fe and Zn were high, Mn and Cu occurred in low amounts, whereas Cr, Cd, Co and Pb were only traceable. In the roots and shoots of A. montanum and A. repens the measured concentrations of Ni were 657 mg kg-1 and 676 mg kg-1 respectively, which is the first instance that such high concentrations of Ni were detected in these two species.

Contamination of local water supply systems in suburban Belgrade

In suburban Belgrade, there are some 200 local water supply systems which are not connected to either the Belgrade Water Supply System or to supply systems operated by municipal utilities. The small systems in Belgrade suburbs are either operated by local municipality (local government) or even by the group of local citizens who have neither technical capability nor financial resources to do it properly. Roughly 200,000 of Belgrades inhabitants obtain their drinking water from these water supply systems. The water quality delivered by these local water supply systems is often compromised in terms of microbiological, physical and/or chemical compliance with drinking water standards in addition to the general lack of strategy on water safety plans and risk assessment. WHO Guidelines on water quality standards as well as the recommendations on safety plans and whole risk assessment are strictly respected in the main (central) Water Supply System in Belgrade. Most frequently, elevated concentrations of ammonia, nitrites, nitrates and iron lead to lack of chemical compliance, while elevated counts of aerobic mesophilic bacteria and the presence of bacteria indicative of faecal pollution tend to be behind microbiological lack of compliance with drinking water standards. In most cases, failure to meet drinking water standards can be attributed to groundwater pollution. No sewer system exists in these areas, and wastewater from septic tanks, in practice infiltration wells, is in direct contact with groundwater. Of a total of 72 laboratory-tested drinking water samples, 51.3% failed to meet physical and/or chemical standards, and 73.6% failed to meet microbiological standards. Groundwater pollution can only be prevented if wastewater disposal system is provided for all households and all suburban residential areas which obtain their water supply from local water supply systems. Some possible mitigation measures have been indicated. In the interim period, water must be disinfected continually, and the feasibility of ozonation or UV irradiation, in addition to chlorination, should be assessed.

The Influence of Edaphic Factors on Spatial and Vertical Distribution of Radionuclides in Soil

This chapter summarises the edaphic factors affecting radionuclide spatial and vertical distribution in different soil types, with special emphasis on typical soil types in Serbia. The correlations between radionuclide and stable element content in soil and soil characteristics (particle size fractions, pH, carbonate content, organic matter content, cation exchange capacity, saturated hydraulic conductivity, specific electrical conductivity) are presented. These results provide insight into the main factors that affect radionuclide migration in the soil, which contributes to knowledge about radionuclide behaviour in the environment and factors governing their mobility within terrestrial ecosystems.

Aggregate composition and stability of structural aggregates of non-calcareous rendzinas in Eastern Serbia

The present study includes the results of comparative investigations of aggregate composition and water stability of structural aggregates in humus horizons of non-calcareous rendzina under native forest and pasture vegetations and the same rendzina utilized long-term as arable field. The results show that aggregate composition and water stability of structural aggregates in the cultivated non-calcareous rendzina are significantly impaired due to a long-term anthropogenization. In the cultivated rendzinas the content of agronomically most valuable aggregates (0.25-10 mm) significantly decreased, while the percentage of cloddy aggregates (>10 mm) was increased about 1.5 to 3.5 times in comparison with the rendzina under pasture and forest vegetations. The structure coefficient of cultivated soils was lower (2.61) than in forest (4.63) and pasture (10.47) rendzinas. The cultivated non-calcareous rendzina had lower (59.12%) aggregate water stability than rendzina under pasture (82.66%) and forest (91.92%). Mean weight diameters of water stable agregates was higher in forest (1.44 mm) and pasture (1.20 mm) than in cultivated (0.65 mm) rendzina.

Reactive power compensation and loss reduction in large industrial enterprises

Abstract This paper considers the reactive power compensation and the active power and energy loss reduction of large radial power networks in the Serbian mine and smeltery industry. It gives an efficient optimization procedure for positioning and sizing capacitors in large industrial systems, that is integrated with a simple network analysis method.

Impact of Deficit Irrigation on Yield and Chemical Properties of Soybean Seeds in Temperate Climate

Summary The goal of this research is to determine the effects of different levels of water deficit (I100: full irrigation, I65: 35% deficit, I40: 60% deficit and I0: no irrigation) on yield and chemical composition of soybean [Glycine max (L.) Merr.] grown in Srem region of Serbia. Water deficit significantly affected the yield and chemical composition of soybean seeds. The lowest (1.63 t/ha) and the highest (3.21 t/ha) seed yields were obtained from I0 and I65 treatments, respectively. Furthermore, the highest protein (1092 kg/ha) and oil (563 kg/ha) yields were observed in I65 treatment. Lower and higher irrigation levels from I65 decreased the protein and oil yields. Our data indicated that irrigation generally increased K, P, Mg, Mn, Cu, Zn and B concentrations and decreased Ca and Fe concentrations in soybean seed. It was clearly observed that full-watered treatment (I100) provided no potential benefit in terms of soybean yield and chemical composition. For higher economic yield and good nutritional quality, water-saving treatment I65 could be suitable in soybean management in Srem region of Serbia as in other regions with similar soil and climate conditions.