Southern Bulgaria Research Articles

PHYSICOCHEMICAL AND MICROBIOLOGICAL RESULTS FROM HOT MINERAL WATER IN THE VILLAGE OF VARVARA, DISTRICT OF PAZARDZHIK, BULGARIA

There are 225 mineral springs in Bulgaria, and out of them, 148 are in southern Bulgaria and 77 in northern Bulgaria. The region with mineral water “Varvara” is located in Rhodope mountains, Pazardzhik region, Bulgaria. Physicochemical and microbiological research of two springs from the village of Varvara is presented in the article. The springs are “Drilling No. 3 - Varvara” and “Drilling No. 5 – Varvara”. The physicochemical research of mineral waters showed that it is characterized as hydrothermal, mineralized, hydrocarbon-sulphate, sodium, silicon-rich and fluoride waters. The hyperthermal mineral spring “Drilling No. 3 – Varvara” is with t=79.9°С. The hyperthermal mineral spring “Drilling No. 5 – Varvara” is with t=83.7°С. The presence of single spores of species of genus Bacillus (Bacillus subtilis, Bacillus licheniformis), phylum Bacillota were found in the tested mineral waters. B. subtilis is a Gram-positive bacterium that forms heat-resistant spores. B.
 licheniformis is a Gram-positive, mesophilic bacterium and its optimal growth temperature is around 50°С. B. licheniformis can survive at higher temperatures. Geobacillus stearothermophilus also was registered in the tested mineral waters. It is a rod-shaped, Gram-positive bacterium, a member of the phylum Bacillota.
 The results show that the waters from both examined sources in Varvara are useful for human health according to their physicochemical composition. The content of silicon and calcium is a prerequisite for their application in strengthening the musculoskeletal system. The rich fluoride content allows their controlled use for reduction in dental caries. The waters from “Drilling No. 3 - Varvara” and “Drilling No. 5 - Varvara” did not show any sanitary- chemical and microbiological signs of contamination. This reveals opportunities for balneological therapy and tourism in this region. Bottling these waters would allow for their wider use.

Topographic factor of water erosion – analysis of watershed morphometry and RUSLE LS factor in GIS environment

Soil erosion is the most serious soil degradation factor on the territory of Bulgaria. Nearly 66 % of its area have slopes in a range greater than 3°. The predominant hilly-mountainous relief and high slope degrees are prerequisites for development of water erosion. The properties of the topographic surface as a conditioning factor of erosion processes are evaluated in the current study on the example of the Dzhebelska River watershed (Southern Bulgaria). The following morphometric parameters are considered: basin relief, Melton index, slope and stream power index (SPI). Slope length and steepness factor (LS factor) is calculated using the slope degree and specific contributing area. The values vary between 0 and 43.36. The results of the analysis of the morphometric parameters indicate high erosion susceptibility in the upper and the middle part of the watershed but active erosion can be observed too in the low part of the watershed, where first order streams (Strahler’s method) flows directly to the river of fifth order. The current study is done in GIS environment on the base of 12 m digital elevation model.

Radiation status of soils from the region of the Eastern Rhodopes (Southern Bulgaria)

Local values of natural radiation background in soils from unexplored regions in the Eastern Rhodopes were established. The impact of anthropogenic activity as a potential risk for increase in radiation background was assessed. Soil samples from areas near the liquidated lead-zinc mines – Madzharovo, gold mine – Ada Tepe, Krumovgrad, lead-zinc complex – Kardzhali, Neochim – Dimitrovgrad, deposits for extraction of gneiss, marble quarries, etc. were analyzed to study possible contamination. Specific activity of natural radionuclides 210Pb, 238U, 226Ra, 235U, 232Th, 40K and technogenic 137Cs in the studied samples was determined by gamma spectrometric analysis with Multichannel analyzer DSA 1000, production of CANBERRA and HPGe-detector.

Organic vs conventional farming of oil-bearing rose: Effect on essential oil and antioxidant activity

The aim of this study was to establish whether the type of the agricultural system has any influence on the essential oil production and antioxidant activity of industrial cultivated Rosa damascena Mill. in the Rose valley, Bulgaria. Six private farms from Kazanlak (Rose) Valley, Southern Bulgaria were included in the study conducted in the period 2019–2020. The first three selected farms are designated within the conventional farming and the other three are certificated as organic farms. GC/FID and GC/MS analyses were performed; the contents of total polyphenols and flavonoids in the methanol extracts from rose petals were determined. Additionally, the antioxidant activity of rose extracts was evaluated by four reliable methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2´-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), ferric reducing antioxidant power (FRAP), and cupric reducing antioxidant capacity (CUPRAC) assays. The impact of the agricultural system on the essential oil composition and antioxidant activity was evaluated by ANOVA statistical analysis. The results obtained showed that organic farming produced essential oil with a higher linalool and geraniol content and lower β-citronellol + nerol concentrations than conventional farming. It was found that organic farming production demonstrated a better antioxidant activity evaluated by the three DPPH, ABTS, and CUPRAC methods according to the averaged data for two years, 806.82, 797.66 and 1534.40 mM TE/g dw versus 510.34, 521.94 and 917.48 mM TE/g dw for CF, respectively, with high statistical significance for the DPPH and ABTS analyses. Consequentially, the rose extracts from the organic farming accumulated more phenolic compounds that corresponded to the higher antioxidant potential of the organic roses.

Correlation between bacterial abundance, soil properties and heavy metal contamination in the area of non-ferrous metal processing plant, Southern Bulgaria

In the present study, the correlation between bacterial abundance and soil physicochemical properties along the heavy metal contamination gradient in the area of non-ferrous metal processing plant was assessed. Our results showed that bacterial abundance (number of heterotrophic bacteria and number of 16S rRNA gene copies) decreased with 45–56% (CFU) and 54–87% (16S rRNA gene) along the Zn, Pb and Cd contamination gradient. The total bacterial abundance (16S rRNA gene) increased exponentially in contrast to the abundance of heterotrophic bacteria. The reduction of bacterial abundance in heavily contaminated soil indicated that the soil properties (soil pH, total organic carbon, inorganic ions, soil texture) could modify the effects of heavy metals and the response of microorganisms to that stress in long-term contaminated soils.

URANIUM AND 210PO RADIONUCLIDES IN DRINKING WATER IN SOUTHERN BULGARIA AND EXPECTED RADIATION DOSES.

The activity concentrations of the naturally occurring radionuclides 238U, 234U and 210Po have been determined for the first time in drinking water from certain sources in Southern Bulgaria using nuclear and radiochemical methods. The results obtained for the water samples vary in the intervals 0.6-678 mBq l-1 for 238U, 1.4-1484 mBq l-1 for 234U, <0.3-13.6 mBq l-1 for 210Po and 1.04-10.6 for the 234U/238U ratio. The annual effective dose from 238U, 234U and 210Po ranges from 1.09 to 44.1μSv y-1, 0.78 to 46.8μSv y-1 and 0.77 to 62.8μSv y-1 for infants, children and adults, respectively. The annual effective dose due to consumption of drinking water is below the individual dose criterion of 100μSv y-1 recommended by the World Health Organization. The natural radioactivity of the water sources investigated is below the national and international limits.

Exposure Due to Indoor Radon in Bulgarian Schools

Indoor radon exposure is the largest contributor to population dose from natural sources. Radon as a natural radioactive gas could accumulate to harmful levels in buildings, such as homes and buildings with public access. In order to assess the exposure due to radon in school the results of indoor radon measurements in 55 state school buildings in 7 municipalities located in one district in southern Bulgaria are considered in this paper. The survey was carried out with passive CR-39 etched track detectors. Radon concentrations ranged from 17 to 868 Bq m-3, with a geometric mean of 117 Bq m-3 and a geometric standard deviation of 1.78. The findings revealed that in 30% of the measured buildings the radon concentration was higher than the national reference level of 300 Bq m-3. The statistically significant difference in indoor radon concentrations between municipalities (KW, р < 0.001) was obtained. The research was also focused on parameters affecting radon concentration levels such as type of room and floor location. The estimated annual effective dose of 0.39 to 1.07 mSv y-1, applying the ICRP and UNSCEAR methodology, was calculated for students. The results of the measurements were provided to the administrative authorities and measures were proposed to improve the air in school buildings with high radon levels.

Using of fluctuating asymmetry in adult Pelophylax ridibundus (Amphibia: Anura:Ranidae) meristic traits as a method for assessing developmental stability of populationand environmental quality of their habitat: industrial area in southern Bulgaria

One way to assess the impacts of toxicants on populations of anurans is through developmental stability (DS) - the ability to buffer stresses during development stages. To assess the extent of possible perturbations in DS of frogs that inhabit a polluted industrial area east of Plovdiv city, Bulgaria, we applied analysis of fluctuating asymmetry (FA) in ten morphological traits in P. ridibundus. As a control group, we used animals inhabiting a less disrupted site. Based on the FA levels obtained for the frogs from both sites, we evaluate the state of their habitat. In the contaminated site, the mean FAMI (frequency of asymmetric manifestation of an individual) index for P. ridibundus individuals was 0.87 and in the reference site, it was 0.37, respectively. In our opinion, these results are evidence that in the population inhabiting the industrial area, there are very serious disorders in DS. We believe that they are the result of the chronic effects of stress agents of anthropogenic origin, whose negative effects affect all stages of the life of individuals. The results show that changes in the levels of asymmetry in the meristic morphological features in adults and sexually mature individuals of P. ridibundus are a very reliable method for bioindication.

Ground beetle (Coleoptera: Carabidae) communities and microhabitat diversity in a mountain village house yard – a case study from the Western Rhodope Mountains in Bulgaria

This study explores the ground beetle (Coleoptera: Carabidae) diversity from an uncultivated house yard in a mountain hamlet in the Western Rhodope Mountains in southern Bulgaria. The sampling site was located at an altitude of 1340 m. A total of 2512 carabid specimens of 76 species were collected with only six pitfall traps between May 2016 and April 2021. They belong to 31 genera, 13 tribes, 21 zoogeographical categories and 15 life forms. Two species (Olisthopus rotundatus and Ophonus brevicollis) are new for the Rhodope Mountains. The findings reveal new highest altitude records for two species (Ophonus brevicollis and Philorhizus notatus). Along with the typical montane forest fauna, many ecotone and open habitat species were found. Nevertheless, carabid life forms and wing morphology structure indicate a stable environment in comparison with other regions in Bulgaria. Furthermore, this research demonstrates that even small natural habitat patches can keep a remarkable carabid diversity. Over the five-year study period, the carabid fauna in the studied house yard experienced some, both qualitative and quantitative, impoverishment, indicating some ecological “exhaustion”.

Groundwater Quality Dynamics from Field Experiments on Watershed Level in Southern Bulgaria

Groundwater Quality Dynamics from Field Experiments on Watershed Level in Southern Bulgaria

Determination of the content of natural radionuclides in rock materials used in the buildings

The negative impact of natural inorganic building materials on people during their life cycle can be potentially significant, in case of presence of radionuclides, due to the very long period of negative radioactive impact. International experience shows that effective prevention of public health and reduction of exposure involves a wide range of actions, which has been achieved through the development and preparation of a strategy at the national level. The content of natural radionuclides in rock materials for construction purposes, taken from different buildings in Southern Bulgaria, has been determined. The obtained data are in norms under the Bulgarian legislation, but for some samples with values close to the maximum permissible concentrations.

Cases of contemporary re-Islamization among Roma in Bulgaria

Since the beginning of the 1990s, various religious processes can be observed among the Roma community and other ethnic minorities in Bulgaria. In parallel with the conversion of Orthodox Christian and Sunni Muslim Roma to evangelical Christianity, processes of re-Islamization have also been taking place. Based on a series of legislative and judicial decisions taken by local and state institutions, cases of re-Islamization have been presented to the public as examples of the spread of radical Islam, a trend that could lead to ethnic conflicts and to the perception that the Roma are a threat to national security. Contrary to this already popular notion, the results of my ethnological study (2018-2020) among various local Roma Islamic groups in Southern Bulgaria led to a different conclusion. This paper draws attention to small groups of newly converted Turkish-speaking Roma and focuses on the emic perspective of the members of the studied groups regarding the interpretation of the new religious ideas they more or less adhere to.

Chronological Modelling of the Chalcolithic Settlement Layers at Tell Yunatsite, Southern Bulgaria

This article publishes a new series of radiocarbon dates from Tell Yunatsite, Southern Bulgaria. Context-based excavations undertaken over a large surface area, as well as a small test trench, provided a long stratigraphic sequence (11 ‘building levels’) covering a large part of the Chalcolithic period in Thrace (5th millennium BCE). Bayesian statistics and Gaussian Monte Carlo Wiggle Matching were employed to achieve a fine chronology for the multilayered tell. Implications and problems on the application of the calibration curve for the Late and Final Chalcolithic in Bulgaria are also discussed.

Deep Structure and Dynamics of the Central Balkan Peninsula from Seismic Data

—Analysis of P- and S-receiver functions for 19 seismic stations on the Balkan Peninsula has been performed. Half of the stations are in Bulgaria. The crustal thickness varies from 28–30 to 50 km. The ratio of longitudinal and shear wave velocities in the upper crust reaches 2.0 in some places. In the southwest of the study area, the 410-km seismic boundary is uplifted by 10 km relative to nominal depth. The elevation may be caused by hydration and/or cooling of the mantle transition zone under the influence of the Hellenic subduction zone. A low S-wave velocity layer related to the 410-km boundary may be located atop this boundary. In the northwestern part of the study area this layer is present in spite of the absence of the 410-km boundary. A similar paradox has been previously noted in central Anatolia. Indications of a low-velocity layer are present at a depth exceeding 410 km. The simultaneous inversion of the receiver functions of the two types (P and S) and the Rayleigh wave phase velocities reveals a large (7–9%) decrease in the S-wave velocity in the upper mantle of southern Bulgaria and northern Greece. The thickness of the low-velocity layer (asthenosphere) is about 50 km. The lithosphere-asthenosphere boundary (LAB) is at depths of 40 to 60 km. In terms of tectonics, this zone is characterized as the South Balkan extension system. To the north of 43° N, the S-wave velocity in the upper mantle is usually at least 4.4 km/s and the LAB is not detected or is detected at a depth of over 80 km. The SKS analysis of azimuthal anisotropy reveals lateral zoning in the upper mantle that is correlated to velocity zoning. Probably, the mechanically weak low-velocity mantle of the South Balkan system is easily deformed, and the azimuth of the fast direction of anisotropy (20°) indicates the direction of extension. At the northern stations, the fast direction (about –30°) may be a reflection of an older process.

Metasomatism and cyclic skarn growth along lithological contacts: Physical and geochemical evidence from a distal Pb[sbnd]Zn skarn

Distal skarns form by the metasomatic reactions of a host rock induced by far-traveled hydrothermal fluids. Physical and structural characteristics and geochemical patterns of distal PbZn skarn bodies were studied at the Petrovitsa deposit in southern Bulgaria. Skarn bodies formed from the interaction of hydrothermal fluids with reactive host lithologies (marble and gneiss). These fluids were transported along sub-vertical feeder structures and lithological contacts. Epidote skarn developed in gneiss protolith, and pyroxene (johannsenite) skarn developed in marble. Detailed geological mapping, complimented by measurements of the internal structure of the skarn body using pyroxene growth versors, quantifies the propagation direction of the skarn body: 1) away from the major local fluid conduit (feeder structure), and 2) away from lithological contacts between aluminosilicate rock and marble. Such growth suggests that fluid flow was generally orthogonal to the skarn front propagation direction in the pyroxene skarn.Textural, mineralogical and geochemical data from skarn samples reveal multiple growth generations of major skarn calc-silicates epidote and pyroxene. The epidote skarn is characterized by limited spatial distribution and fine-grained epidote/clinozoisite growth associated with massive replacement and sulfide mineralization. The pyroxene skarn consists of acicular clinopyroxene crystals which form spheroidal aggregates with discrete growth banding. These bands are the physical representation of the cyclic fluid pulses which resulted in rhythmic skarn growth marked by geochemical banding. In situ geochemical analyses in the epidote skarn reveal early Al-rich epidote overprinted by Fe-rich epidote associated with higher Mn and Sr contents and irregular compositional banding. Clinopyroxene (Jo60–95) shows general increase in Na, Al, Mn, and REE + Y with distance from the feeder structure and lithologic contacts. These elements correlate with the distance traveled by the hydrothermal fluid from the feeder to the site of skarnification, which we define using a proxy based on the Al content of pyroxene crystals. This reflects an increasing degree of fluid “contamination” by interaction with the aluminosilicate host rocks and functions as a proxy for fluid transport distance. The spatial distribution of trace-elements in pyroxene on an outcrop scale is indicative of discrete pulses of hydrothermal fluid resulting in precipitation of skarn calc-silicates along the increasingly tortuous fluid pathway between the feeder structure and the skarn front, resulting in both the macro- and micro-scale chemical and textural variability of the skarn body.

Lipoprotein (a) in patients with a genetic diagnosis of familial hypercholesterolaemia in Southern Bulgaria

Background and Aims: Lipoprotein (a) (Lp (a) is one of the main reasons for the large residual risk in patients with Familial hypercholesterolemia (FH). The goal of the study was to analyse the Lp (a) levels in 300 patients with a genetically proven hetero-FH.

Enrichment of the local plant gene fund for providing a resource base for priority agro-food systems

Plant genetic resources are a link between environment, agriculture and food systems, so their conservation requires cooperation within the different sectors of bio-economy. The existing diversity in local genetic resources is an initial base in crop breeding corresponding with the new challenges such as climate change, plant health and food quality. As a result from the activities of the National Research Program “Healthy foods for a strong bio-economy and quality of life” 63 accessions from different regions of Southern Bulgaria were collected through several collecting missions. Each accession was described by passport data including: taxonomic description under the nomenclature of the GRIN system, date of registration in the collection, donor, ecological and geographical characteristics of the explored area, biological status, etc., according to the International descriptor of FAO/Bioversity. The greatest diversity of old varieties and local forms has been found in the legumes and vegetable crops. The seeds are usually inherited in families or passed between neighbours and they are intended for household or local market. The collected plant materials were evaluated by morphological and agro-biological characteristics. Evaluation data from accessions of bean showed high variability of morphological traits as height of plants, number of pods and seeds per plant. The results obtained from this study will be useful in breeding programs and interspecific crosses, for selection and introduction of desired traits through pre-breeding programs, for research and direct use of farmers.

Effect of irrigation rate on Sudan grass yield, grown as a second crop

Abstract. The aim of the present study was to establish the effect of irrigation rate on the yield of Sudan grass variety Engje-1, grown as a second crop for silage on meadow-cinnamon soil for the region of Southern Bulgaria. For this purpose, an experiment with Sudan grass variety Endje-1 on the experimental field of the Agricultural Institute – Stara Zagora, after its predecessor barley, was conducted. The Sudan grass was harvested in the brooming stage. Five variants were explored: Variant 1 – without irrigation (control); Variant 2 – with optimal irrigation, 75-80% of field capacity (FC); Variant 3 – irrigation as Var.2 but with removal of the first watering; Variant 4 – irrigation as Var.2 but with removal of the second watering; Variant 5 – irrigation as Var.2, but with removal of the third watering. It was found that the efficiency of 1m3 of irrigation water was the highest at the optimum variant (Var.2), where 5.36 kg of dry mass (DM) were produced by 1 m3 of water. With the removal of the second irrigation (Var.4), the yield on the dry mass decreased by 6.4% compared to the optimal variant (Var.2), and with the removal of the first irrigation (Var.3) the losses on the dry mass reached, 12.3%, respectively. The highest values of this indicator were obtained by varying the second irigation (Vаr.4) – 7.53 kgDM/m3 water. The coefficient of efficiency of the irrigation rate, representing the ratio between the increase of the yield (in comparison with the version without irrigation – Vаr.1), and the size of the realized irrigation norm had the highest value in the version without second irrigation (Vаr.4) and the lowest values for the version without first irrigation (Vаr.3).

TBE in Bulgaria

First cases of probable tick-borne encephalitis (TBE) were reported in 1961 by Andonov et al. in eastern regions of Bulgaria.1 Possible TBE cases with the typical two-wave fever, originating from consumption of raw goat milk, were described back in 1953 by Vaptzarov et al. in southern Bulgaria.2 Investigations in the 1960s were able to isolate 3 tick-borne encephalitis virus (TBEV) strains from Haemaphysalis punctata and 1 from Dermacentor marginatus ticks from goats and sheep in the district of Plovdiv.3 The antigenic properties of these 4 virus strains were identical to the highly virulent strain “Hypr” of the European subtype of TBEV (TBEV-EU).

Investigation of 238U, 234U And 210Po Content in Selected Bulgarian Drinking Water

The radioactivity of selected sources of drinking water in Southern Bulgaria was investigated using 238U, 234U and 210Po activity measurements and dose calculation, respectively. The activities of 238U, 234U and 210Po varied from 226 to 826 mBq/L, 274 to 1623 mBq/L and &lt; 0.6 to 25.5 mBq/L, respectively, being lower then derived concentrations for radioactivity in water intended for human consumption of the considered radionuclides, given in EC Directive 2013/51/EURATOM. In some drinking waters the mass concentration of natural uranium exceeded the set maximum chemical concentration level of 0.030 mg/L. A radioactive disequilibrium between 234U and 238U in water was detected. Based on the radionuclide activity concentrations total annual effective ingestion doses for adults, as well as contribution of each particular radionuclide to the total doses, were assessed and discussed. Тhe lowest contribution to the annual effective doses was found for 210Po and the highest for 234U. The results show that the annual effective doses of residents are below the reference level of 100 μSv/y according to the recommendations of the World Health Organization. The obtained new results are used to assess the radiation status of the investigated water.