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  Subjects -> GEOGRAPHY (Total: 493 journals)
Showing 401 - 277 of 277 Journals sorted alphabetically
Revista de Geografia (Recife)     Open Access  
Revista de Geografia e Ordenamento do Território     Open Access  
Revista de Geografía Norte Grande     Open Access   (Followers: 1)
Revista de la Asociacion Geologica Argentina     Open Access  
Revista de Teledetección     Open Access  
Revista del Museo de La Plata     Open Access  
Revista do Instituto de Estudos Brasileiros     Open Access  
Revista Eletrônica : Tempo - Técnica - Território / Eletronic Magazine : Time - Technique - Territory     Open Access  
Revista Espinhaço     Open Access  
Revista Estudios Hemisféricos y Polares     Open Access  
Revista Geama     Open Access  
Revista Geoaraguaia     Open Access  
Revista Geográfica de América Central     Open Access  
Revista Geonorte     Open Access  
Revista Interamericana de Ambiente y Turismo     Open Access  
Revista Intercontinental de Gestão Desportiva     Open Access  
Revista Interdisciplinar da Mobilidade Humana     Open Access  
Revista Latinoamericana de Antropología del Trabajo     Open Access  
Revista Tamoios     Open Access  
Revista Tocantinense de Geografia     Open Access  
Revista Universitaria de Geografía     Open Access  
Revista Uruguaya de Antropología y Etnografía     Open Access  
Revue archéologique du Centre de la France     Open Access   (Followers: 1)
Revue de géographie historique     Open Access   (Followers: 1)
RIEM : Revista Internacional de Estudios Migratorios     Open Access  
Rocznik Toruński     Open Access  
Rural & Urbano     Open Access  
San Francisco Estuary and Watershed Science     Open Access  
Sasdaya : Gadjah Mada Journal of Humanities     Open Access  
Saúde e Meio Ambiente : Revista Interdisciplinar     Open Access  
Scandinavistica Vilnensis     Open Access  
Scientific Annals of Stefan cel Mare University of Suceava. Geography Series     Open Access  
Scottish Geographical Journal     Hybrid Journal   (Followers: 4)
Scripta Nova : Revista Electrónica de Geografía y Ciencias Sociales     Open Access  
Sémata : Ciencias Sociais e Humanidades     Full-text available via subscription  
Seoul Journal of Korean Studies     Full-text available via subscription   (Followers: 4)
Singapore Journal of Tropical Geography     Hybrid Journal   (Followers: 6)
Social Dynamics: A journal of African studies     Hybrid Journal   (Followers: 3)
Social Geography Discussions (SGD)     Open Access   (Followers: 7)
Sociedade & Natureza     Open Access  
South African Geographical Journal     Hybrid Journal   (Followers: 1)
South African Journal of Geomatics     Open Access   (Followers: 2)
South Asian Diaspora     Hybrid Journal   (Followers: 3)
South Australian Geographical Journal     Open Access  
Southeastern Europe     Hybrid Journal   (Followers: 3)
Southeastern Geographer     Full-text available via subscription   (Followers: 2)
Southern African Journal of Environmental Education     Open Access  
Sport i Turystyka : Środkowoeuropejskie Czasopismo Naukowe     Open Access  
Sriwijaya Journal of Environment     Open Access  
Standort - Zeitschrift für angewandte Geographie     Hybrid Journal   (Followers: 3)
Studia Universitatis Babes-Bolyai, Geologia     Open Access  
Studies in African Languages and Cultures     Open Access   (Followers: 1)
Technology and Technique of Typography     Open Access  
Tectonics     Full-text available via subscription   (Followers: 15)
Terra     Open Access  
Terra Brasilis     Open Access  
Terrae Incognitae     Hybrid Journal   (Followers: 1)
Territoire en Mouvement     Open Access  
The Canadian Geographer/le Geographe Canadien     Hybrid Journal   (Followers: 8)
The Geographic Base     Open Access   (Followers: 7)
The Geographical Journal     Hybrid Journal   (Followers: 17)
The South Asianist     Open Access   (Followers: 2)
Third Pole: Journal of Geography Education     Open Access  
Tidsskrift for Kortlægning og Arealforvaltning     Open Access  
Tiempo y Espacio     Open Access  
TRaNS : Trans-Regional-and-National Studies of Southeast Asia     Full-text available via subscription   (Followers: 4)
Transactions of the Institute of British Geographers     Hybrid Journal   (Followers: 28)
Transmodernity : Journal of Peripheral Cultural Production of the Luso-Hispanic World     Open Access   (Followers: 4)
Treballs de la Societat Catalana de Geografia     Open Access  
TRIM. Tordesillas : Revista de investigación multidisciplinar     Open Access  
Turystyka Kulturowa     Open Access  
UD y la Geomática     Open Access  
UNM Geographic Journal     Open Access   (Followers: 1)
Urban Climate     Hybrid Journal   (Followers: 4)
Urban Geography     Hybrid Journal   (Followers: 36)
Urban History Review / Revue d'histoire urbaine     Full-text available via subscription   (Followers: 7)
Urban Research & Practice     Hybrid Journal   (Followers: 19)
Vegueta : Anuario de la Facultad de Geografía e Historia     Open Access  
Visión Antataura     Open Access   (Followers: 6)
Water International     Hybrid Journal   (Followers: 19)
Watershed Ecology and the Environment     Open Access  
Wellbeing, Space & Society     Open Access   (Followers: 4)
Yearbook of the Association of Pacific Coast Geographers     Full-text available via subscription   (Followers: 2)
Załącznik Kulturoznawczy / Cultural Studies Appendix     Open Access  

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Journal Prestige (SJR): 2.568
Citation Impact (citeScore): 6
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1313-2644 - ISSN (Online) 1313-2652
Published by Pensoft Homepage  [58 journals]
  • Potential risk resulting from the influence of static magnetic field
           upon living organisms. Numerically simulated effects of the static
           magnetic field upon fatty acids and their glycerides

    • Abstract: BioRisk 19: 1-24
      DOI : 10.3897/biorisk.19.96250
      Authors : Wojciech Ciesielski, Henryk Kołoczek, Zdzisław Oszczęda, Jacek A. Soroka, Piotr Tomasik : Background: We attempt to recognise the effects of static magnetic field (SMF) of varying flux density on flora and fauna. For this purpose, the influence of static magnetic field is studied for molecules of octadecanoic (stearic), cis-octadec-9-enoic (oleic), cis,cis-octadec-9,12-dienoic (linoleic), all cis-octadec-6,9.12-trienoic (linolenic), trans-octadec-9-enoic – (elaidic), cis-octadec-11-enoic (vaccenic) and all trans-octadec-6,9,12-trienoic (trans-linolenic) acids as well as 1- and 2-caproyl monoglycerides, 1,2- and 1,3-caproyl diglycerides and 1,2,3-caproyl triglyceride. In such a manner we attempt to develop an understanding of the interactions of living cells with SMF on a molecular level. Methods: Computations of the effect of real SMF 0.0, 0.1, 1, 10 and 100 AMFU (Arbitrary Magnetic Field Unit; here 1AMFU > 1000 T) flux density were performed in silico (computer vacuum), involving advanced computational methods. Results: SMF polarises molecules depending on applied flux density It neither ionises nor breaks valence bonds at 0.1 and 1 AMFU. In some molecules under consideration flux density of 10 and 100AMFU some C-H and C-C bonds were broken. Some irregularities were observed in the changes of positive and negative charge densities and bond lengths against increasing flux density. They provide evidence that molecules slightly change their initially fixed positions with respect to the force lines of the magnetic field. The length of some bonds and bond angles change with an increase in the applied flux density providing, in some cases, polar interactions between atoms through space. Conclusions: SMF destabilizes lipid acids and caproyl glycerides irregularly against increasing flux density. That irregularity results from the ability of those molecules to twist out of the initially established SMF plain and squeeze molecules around some bonds. In some molecules SMF flux density of 10 AMFU and above breaks some valence bonds and only in case of elaidic acid the trans-cis conversion is observed. Depending on the structure and applied flux density SMF either stimulates or inhibits metabolic processes of the lipids under study. HTML XML PDF
      PubDate: Mon, 6 Mar 2023 17:29:21 +0200
  • The first evidence of microplastics in plant-formed fresh-water
           micro-ecosystems: Dipsacus teasel phytotelmata in Slovakia contaminated
           with MPs

    • Abstract: BioRisk 18: 133-143
      DOI : 10.3897/biorisk.18.87433
      Authors : Katarína Fogašová, Peter Manko, Jozef Oboňa : Tiny pieces of plastic, or microplastics, are one of the emerging pollutants in a wide range of different ecosystems. However, they have, thus far, not been confirmed from phytotelmata – specific small water-filled cavities provided by terrestrial plants. The authors confirmed microplastics (141 μm – 2.4 mm long fibres of several colour and blue and orange fragments with diameters of 9–81 μm) in quantities from 101 to 409 per ml in Dipsacus telmata from two different periods. The phytotelmata, therefore, appear to be possible indicators of current and future microplastic pollution of the environment. However, further research is needed to obtain accurate information and verify the methodology for possible assessment of the local environmental burden of microplastics. HTML XML PDF
      PubDate: Tue, 30 Aug 2022 09:38:17 +030
  • Potential risk resulting from the influence of static magnetic field
           upon living organisms. Numerically simulated effects of the static
           magnetic field upon metalloporphyrines

    • Abstract: BioRisk 18: 115-132
      DOI : 10.3897/biorisk.18.86616
      Authors : Wojciech Ciesielski, Tomasz Girek, Zdzisław Oszczęda, Jacek A. Soroka, Piotr Tomasik : Background: An attempt to recognize the effects of a static magnetic field (SMF) of varying flux density on flora and fauna.. For this purpose the influence of static magnetic field upon molecules of Mg(II), Fe(II), Fe(III), Co(II), Co(III) and Cu(II) metalloporphyrins is studied. Methods: Computations of the effect of real SMF 0.0, 0.1, 1, 10 and 100 AFU (Arbitrary Magnetic Field Unit; here 1AMFU > 1000 T) flux density were performed in silico (computer vacuum) involving advanced computational methods. Results: The static magnetic field (SMF) decreased the stability of the metalloporphyrine molecules. This effect depended on the situation of the molecule in respect to the direction of the SMF of the Cartesian system. An increase in the value of heat of formation was accompanied by an increase in the dipole moment. It was an effect of deformations of the molecule which involved pyrrole rings holding the hydrogen atoms at the ring nitrogen atoms and the length of the C-H and N-H bonds. As a consequence, that macrocyclic ring lost its planarity. Conclusions: SMF even of the lowest, 0.1 AMFU flux density influences the biological role of metalloporphyrines associated with their central metal atoms. This effect is generated by changes in the electron density at these atoms, its steric hindering and polarization of particular bonds from pure valence bonds possibly into ionic bonds. HTML XML PDF
      PubDate: Tue, 23 Aug 2022 14:07:13 +030
  • A study of the microbiology of the intestinal tract in different
           species of Teleost fish from the Black Sea

    • Abstract: BioRisk 18: 105-113
      DOI : 10.3897/biorisk.18.80357
      Authors : Sevginar Ibryamova, Stephany Toschkova, Borislava Pavlova, Elitca Stanachkova, Radoslav Ivanov, Nikolay Natchev, Nesho Chipev, Tsveteslava Ignatova-Ivanova : This paper presents a study on the microbial status of different fish species and their habitats in the Bulgarian Black Sea area. The samples were collected in the period of January 2021 until March 2021. The fish species we used in this study were Black Sea turbot (Scophthalmus maximus), round goby (Neogobius melanostomus), shore rockling (Gaidropsarus mediterraneus) and European anchovy (Engraulis encrasicolus). The BIOLOG system was used for microbiological determination. From the different fish species, different species of microorganisms were isolated (using selective nutrient media). From the torbut, we isolated species Enterococcus villorum with 24 × 103 cells in 1 ml, Moraxella nonliquefaciens with 70 × 103 cells in 1 ml and Pseudomonas synxantha with 123 × 103 cells. Pseudomonas putida was isolated from the round goby with 20 × 103 cells in 1 ml. The species Streptococcus entericus with 123 × 103 cells in 1 ml was isolated from the shore rockling. Pseudomonas fulva with 60 × 103 cells in 1 ml was isolated from the European anchovy. A total of 223 × 103 cells in 1 ml of Pseudomonas agarici were isolated from Trachinus draco. Pseudomonas tolaasii with 145 × 103 cells in 1 ml were isolated from Merlangius merlangus. A different species of bacteria of the genus Pseudomonas was found for each of the investigated species of Black Sea fish. Apparently, the species Pseudomonas is characteristic of marine Teleostei and is important for the life and metabolism of these vertebrates. These microorganisms probably are resident species and developed not as result of pollution or environmental change. HTML XML PDF
      PubDate: Thu, 4 Aug 2022 11:55:28 +0300
  • Potential risk resulting from the influence of static magnetic field
           upon living organisms. Numerically simulated effects of the static
           magnetic field upon porphine

    • Abstract: BioRisk 18: 93-104
      DOI : 10.3897/biorisk.18.80607
      Authors : Wojciech Ciesielski, Tomasz Girek, Zdzisław Oszczęda, Jacek A. Soroka, Piotr Tomasik : Background: Recognizing effects of static magnetic field (SMF) of varying flux density on flora and fauna is attempted. For this purpose the influence of SMF upon the porphine molecule is studied. Methods: Computations of the effect of static magnetic field (SMF) of 0.0, 0.1, 1, 10 and 100 AFU (1 AFU > 1000 T) flux density were performed in silico for SMF changes distribution of the electron density in that molecule. HyperChem 8.0 software was used together with the AM1 method for optimization of the conformation of the molecule of porphine. The computations of polarizability, charge distribution, potential and dipole moment for molecules placed in SMF were performed for molecule situated subsequently in the x-y, y-z and x-z planes of the Cartesian system. The computations involved the DFT 3-21G method. Results: Static magnetic field (SMF) decreased stability of the porphine molecule. This effect depended on the situating the molecule in respect to the direction of SMF of the Cartesian system. An increase in the value of heat of formation was accompanied by an increase in dipole moment. Conclusions: Observed effects resulted from deformations of the molecule which involved pyrrole rings holding the hydrogen atoms at the ring nitrogen atoms and the length of the C–H and N–H bonds. In a consequence that macrocyclic ring lost its planarity. HTML XML PDF
      PubDate: Thu, 30 Jun 2022 23:56:05 +030
  • Potential risk resulting from the influence of static magnetic field
           upon living organisms. Numerically simulated effects of the static
           magnetic field upon simple alkanols

    • Abstract: BioRisk 18: 35-55
      DOI : 10.3897/biorisk.18.76997
      Authors : Wojciech Ciesielski, Tomasz Girek, Zdzisław Oszczęda, Jacek A. Soroka, Piotr Tomasik : Background: Recognising effects of static magnetic field (SMF) of varying flux density on flora and fauna is attempted. For this purpose, the influence of static magnetic field upon molecules of lower alkanols i.e. methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, S-butan-2-ol, isobutanol and tert-butanol is studied. Methods: Computations of the effect of real SMF 0.0, 0.1, 1, 10 and 100 AFU (Arbitrary Field Unit; here 1AFU > 1000 T) flux density were performed in silico (computer vacuum), involving advanced computational methods. Results: SMF polarises molecules depending on applied flux density, but it neither ionises nor breaks valence bonds. Some irregularities in the changes of positive and negative charge densities and bond lengths provide evidence that molecules slightly change their initially fixed positions with respect to the force lines of the magnetic field. Length of some bonds and bond angles change with an increase in the applied flux density, providing, in some cases, polar interactions between atoms through space. Conclusions: Since SMF produced and increase in the negative charge density at the oxygen atom of the hydroxyl group and elongated the –O-H bond length, these results show that SMF facilitates metabolism of the alkanols. HTML XML PDF
      PubDate: Mon, 6 Jun 2022 14:23:41 +0300
  • Potential risk resulting from the influence of static magnetic field upon
           living organisms. Numerically-simulated effects of the static magnetic
           field upon carbohydrates

    • Abstract: BioRisk 18: 57-91
      DOI : 10.3897/biorisk.18.77001
      Authors : Wojciech Ciesielski, Tomasz Girek, Henryk Kołoczek, Zdzisław Oszczęda, Jacek A. Soroka, Piotr Tomasik : Background: Recognising effects of static magnetic field (SMF) of varying flux density on flora and fauna is attempted. For this purpose, the influence of SMF upon molecules of α- and β-D-glucose, α- and β-D-galactose, α- and β-fructopyranoses, α- and β-fructofuranoses and α- and β-D-xylofuranoses and α and β-D-xylopyranoses is studied. Methods: Computations of the effect of static magnetic field (SMF) of 0.0, 0.1, 1, 10 and 100 AFU (1 AFU > 1000 T) flux density were performed in silico for SMF changes distribution of the electron density in these molecules. Hyper-Chem 8.0 software was used together with the AM1 method for optimisation of the conformation of the molecules of monosaccharides under study. Then polarisability, charge distribution, potential and dipole moment for molecules placed in SMF were calculated involving DFT 3-21G method. Results: Application of SMF induced polarisability of electrons, atoms and dipoles, the latter resulting in eventual re-orientation of the molecules along the applied field of the molecules and the electron density redistribution at particular atoms. Increase in the field strength generated mostly irregular changes of the electron densities at particular atoms of the molecules as well as polarisabilities. Energy of these molecules and their dipole moments also varied with the SMF flux density applied. Conclusions: Saccharides present in the living organisms may participate in the response of the living organisms to SMF affecting metabolism of the molecules in the body fluids by fitting molecules to the enzymes. Structural changes of saccharide components of the cell membranes can influence the membrane permeability. HTML XML PDF
      PubDate: Mon, 6 Jun 2022 14:23:21 +0300
  • Studies on the Bulgarian members of the family Chenopodiaceae s.
           stricto: a review

    • Abstract: BioRisk 18: 17-34
      DOI : 10.3897/biorisk.18.78548
      Authors : Vanya Stoyanova Boneva, Nadezhda Traycheva Petkova : The Bulgarian members of Chenopodiaceae are mainly ruderal and weed species; another part are halophytes. Over the last two decades, phylogenetic molecular studies have led to a number of taxonomic changes in the above mentioned family. Changes have also occurred in one of the largest genera – Chenopodium. The aim of the present study is to review the research on Bulgarian members of the Chenopodiaceae family. The data available in the literature on the taxonomic composition, chorology, morphological features and karyological variability of the species from their Bulgarian populations has been studied. A review of the phytochemical studies of Chenopodiaceae plants from their Bulgarian populations has been made. The systematized data is presented in chronological order, which allows for tracing the current level of study on the family in Bulgaria and opportunities for new research. HTML XML PDF
      PubDate: Wed, 27 Apr 2022 11:25:04 +030
  • Relocation and formation of new local population of Viola pumila Chaix
           – an endangered species in Europe and identification of measures for
           improvement of its habitat

    • Abstract: BioRisk 18: 1-16
      DOI : 10.3897/biorisk.18.76114
      Authors : Maria Zh. Kaschieva, Nikolay P. Nedyalkov : The meadow violet (Viola pumila Chaix) is an endangered species which is regionally extinct in many European countries. This is a stenobiontic species with a very limited distribution in Bulgaria. Only a few populations have been detected, and they consist of several tens to several hundreds of specimens. The meadow violet has limited reproductive abilities and weak competitiveness. The species is exposed to various anthropogenic threats, as the most significant of them are related to ploughing, conversion of the mesophilic meadows into arable lands, changes in the water regime of the habitats, the expansion of highly competitive species from the group of tufted cereal grasses and infrastructure construction. To date, information concerning the relocation of rare and endangered plant species in Bulgaria is rather scarce. In the present study we provide a protocol on our activities during a successful establishment of a new locality as part of our effort to successfully relocate one particular population of the meadow violet. The observations made after the relocation of the species over a two-year period (2020 and 2021) provided data on the successful relocation, and the creation of a new locality for the species. We discuss the conservation measures needed for this rare and endangered species, and efforts to increase its population, as well as the measures needed for effective management of the habitats of V. pumila (mainly 6510 “Lowland hay meadows”). HTML XML PDF
      PubDate: Wed, 27 Apr 2022 11:24:36 +030
  • Development of accurate chemical thermodynamic database for geochemical
           storage of nuclear waste. Part III: Models for predicting solution
           properties and solid-liquid equilibrium in cesium binary and mixed systems

    • Abstract: BioRisk 17: 407-422
      DOI : 10.3897/biorisk.17.77523
      Authors : Tsvetan Tsenov, Stanislav Donchev, Christomir Christov : The models described in this study are of high importance in the development of thermodynamic database needed for nuclear waste geochemical storage as well as for technology for extracting cesium resources from saline waters. In this study we developed new not concentration restricted thermodynamic models for solution behavior and solid-liquid equilibrium in CsF-H2O CsOH-H2O and Cs2SO4-H2O systems at 25 °C. To parameterize models we used all available experimental osmotic coefficients data for whole concentration range of solutions and up to saturation point. The new models are developed on the basis of Pitzer ion interactions approach. The predictions of new developed here models are in excellent agreement with experimental osmotic coefficients data (ϕ) in binary solutions from low to extremely high concentration (up to 21.8 mol.kg-1 for CsOH-H2O and up to 35.6 mol.kg-1 for CsF-H2O). The previously developed by Christov by Christov and co-authors and by other authors Pitzer approach based thermodynamic models for five (5) cesium binary systems (CsCl-H2O CsBr- H2O CsI-H2O CsNO3-H2O and Cs2SeO4- H2O) are tested by comparison with experimental osmotic coefficients data and with recommendations on activity coefficients (γ±) in binary solutions. The models which give the best agreement with (ϕ)- and (γ±) -data from low to high concentration up to m(sat) are accepted as correct models which can be used for solubility calculations in binary and mixed systems and determination of thermodynamic properties of precipitating cesium solid phases. The thermodynamic solubility products (ln Kosp) and the Deliquescence Relative Humidity (DRH) of solid phases precipitating from saturated cesium binary solutions (CsF(cr) CsCl(cr) CsBr(cr) CsI(cr) CsOH(cr) CsNO3(cr) Cs2SO4(cr) and Cs2SeO4(cr)) have been determined on the basis of evaluated and accepted binary parameters and using experimental solubility data. The reported mixing parameters [θ(Cs M2+) and ψ(Cs M2+ X)] evaluated by solubility approach for 15 cesium mixed ternary systems (CsCl-MgCl2-H2O CsBr-MgBr2-H2O CsCl-NiCl2-H2O CsBr-NiBr2-H2O CsCl-MnCl2-H2O CsCl-CoCl2-H2O CsCl-CuCl2-H2O CsCl-CsBr-H2O CsCl-RbCl-H2O Cs2SO4-CoSO4-H2O Cs2SeO4-CoSeO4-H2O Cs2SO4-NiSO4-H2O Cs2SeO4-NiSeO4-H2O Cs2SO4-ZnSO4-H2O and Cs2SeO4-ZnSeO4-H2O) are tabulated. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:36 +030
  • Development of accurate chemical thermodynamic database for geochemical
           storage of nuclear waste. Part II: Models for predicting solution
           properties and solid-liquid equilibrium in binary nitrate systems

    • Abstract: BioRisk 17: 389-406
      DOI : 10.3897/biorisk.17.77487
      Authors : Stanislav Donchev, Tsvetan Tsenov, Christomir Christov : The main purpose of this study is to develop new thermodynamic models for solution behavior and solid-liquid equilibrium in 10 nitrate binary systems of the type 2–1 (Mg(NO3)2-H2O, Ca(NO3)2-H2O, Ba(NO3)2-H2O, Sr(NO3)2-H2O, and UO2(NO3)2-H2O), 3–1 (Cr(NO3)3-H2O, Al(NO3)3-H2O, La(NO3)3-H2O, Lu(NO3)3-H2O), and 4–1 (Th(NO3)4-H2O) from low to very high concentration at 25 °C. To construct models, we used different versions of standard molality-based Pitzer approach. To parameterize models, we used all available raw experimental osmotic coefficients data (φ) for whole concentration range of solutions, and up to supersaturation zone. The predictions of developed models are in excellent agreement with φ-data, and with recommendations on activity coefficients (γ±) in binary solutions from low to very high concentration. The Deliquescence Relative Humidity (DRH), and thermodynamic solubility product (as ln K°sp) of 12 nitrate solid phases, precipitating from saturated binary solutions have been calculated. The concentration-independent models for nitrate systems described in this study are of high importance for development of strategies and programs for nuclear waste geochemical storage. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:35 +030
  • Pre-monitoring geochemical research of the river sediments in the area
           of Ada Tepe gold mining site (Eastern Rhodopes)

    • Abstract: BioRisk 17: 379-387
      DOI : 10.3897/biorisk.17.77466
      Authors : Dimitar Zhelev, Rumen Penin : The article depicts the geochemical properties of the landscapes in the Ada Tepe gold mine area before its launching. The research is conducted by examining the heavy metals (Cu, Pb, Zn, Co, Cr, Mn and Ni) content in samples of river sediments in the local landscapes. The research aims to analyse the concentration of heavy metals before the launch of gold mining. The study implements the coefficient of Clarke concentration. The deviation from the background concentrations is a ratio between the element concentration in the collected environmental samples and the Clarke value of the element. The coefficient has a scale from 0 to a particular positive value, corresponding to the level of enrichment of the sample in comparison to the background Clarke value. The values corresponding to the Clarke concentration are equal to 1, the lower values are between 0 and 1 (dispersion) and any value higher than 1 is a case of concentration (enrichment). The obtained results display the researched territory as a natural background area. The content of heavy metals in the river sediments of the researched area (mg/kg, median value) by chemical elements is Cu (15), Zn (72), Pb (17), Mn (461), Ni (35), Co (8) and Cr (60). That is the reason it could be defined as not impacted by human activities and it is not influenced by natural geochemical anomalies. Heavy metals do not pollute the researched landscapes before mining. This outcome is obtained by the geochemical content of the investigated heavy metals in the river sediments. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:34 +030
  • Forests of Breznik municipality

    • Abstract: BioRisk 17: 367-377
      DOI : 10.3897/biorisk.17.77388
      Authors : Borislav Grigorov, Nikolay Velev, Assen Assenov, Momchil Nazarov, Beloslava Genova, Kiril Vassilev : The current study aims to uncover the forest habitat diversity of Breznik municipality, following the EUNIS Classification. Initial data was collected from the Ministry of Environment and Water and the Forestry Management Plans. Forest habitat polygons were spatially processed with the use of the ArcGIS 10.8.1 software package. Field studies were performed to add more detailed information to the analysis. The phytocoenoses of the forest habitats are dominated by Quercus dalechampii, Q. frainetto, Fagus sylvatica, Carpinus betulus. Some artificial plantations with Pinus nigra and P. sylvestris were also present, as well as with non-native species, such as Robinia pseudacacia and Quercus rubra. The results of this study could be used for more in-depth research of the Breznik municipality vegetation. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:33 +030
  • Comparative determination of antimicrobial activity of the Balkan
           endemic species Stachys thracica Davidov during the process of ex situ

    • Abstract: BioRisk 17: 357-365
      DOI : 10.3897/biorisk.17.77484
      Authors : Desislava Mantovska, Detelina Petrova, Lybomira Yocheva, Zhenya Yordanova : Stachys thracica Davidov – Thracian woundwort is a Balkan endemic plant included in The Red Data Book of Bulgaria with conservational status “rare”. The plants from genus Stachys have a long history of use to treat various diseases, inflammatory conditions, coughs, ulcers, genital tumors, and infected wounds. Due to its limited distribution the information on the biological activity and chemical composition of S. thracica is rather scarce. The aim of the present research is the comparative determination of the antimicrobial activity of methanolic extracts obtained from in situ wild, in vitro cultivated and ex vitro adapted S. thracica plants. The in vitro shoot culture of the Thracian woundwort was maintained in hormone-free MS medium under controlled environmental conditions. The methanolic extracts from in situ, in vitro cultivated and ex vitro adapted S. thracica plants were active mainly against Gram-negative bacteria. All three extracts showed equal activity against Acinetobacter calcoaceticus. The establishment of in vitro shoot culture and its subsequent adaptation in ex vitro conditions was an appropriate alternative approach for the ex situ conservation of S. thracica as well as for the study of its biological activity. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:32 +030
  • Influence of some environmental factors on the distribution of
           zooplankton complexes in Mandra Reservoir, in Southeastern Bulgaria

    • Abstract: BioRisk 17: 343-355
      DOI : 10.3897/biorisk.17.77368
      Authors : Eleonora Fikovska, Dimitar Kozuharov, Marieta Stanachkova : The aim of the present study was to trace the influence of some environmental factors (w.temperature, wind, transparency, depth) on the distribution of zooplankton communities in the system Reservoir Mandra and the ecotone zones formed at the confluence of rivers Fakiyska, Sredetska, Izvorska and Rusokastrenska. Four samplings were performed at seven sites between February 2020 and January 2021. After determining the species composition and abundance, the results were subjected to structural analysis and Canonical Correspondence Analysis (CCA). A total of 67 taxa were identified, constituting about 48% of the Rotifera group, 27% of Cladocera and 19% of the Copepoda and only 6% from Protozoa. The Shannon-Weaver index for individual species diversity was between 2.37 and 0.62. The positive and negative correlation of zooplankton distribution in CCA shows that the relative abundance of any species depends on specific environmental variables. Analysis showed that temperature and wind had the strongest impact on the distribution of zooplankton. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:31 +030
  • Pteromalid fauna (Hymenoptera, Pteromalidae) in oilseed rape (Brassica
           napus L.) fields in Bulgaria – species composition and perspectives for
           biological control

    • Abstract: BioRisk 17: 329-342
      DOI : 10.3897/biorisk.17.77454
      Authors : Ivaylo Todorov, Toshko Ljubomirov, Vlada Peneva : Parasitoid wasps belonging to the family Pteromalidae are widespread and abundant members of the insect communities in the temperate regions of the world. As many other chalcids do, pteromalids serve as natural enemies of the pests in various crops and play an important role in the biological control of these harmful insects. Here we present the results of a field study in Bulgaria which was focused on the diversity of family Pteromalidae in ten oilseed rape fields. All samples were collected by sweep netting on the border line or inside the crop field. A total of 93 pteromalid specimens belonging to 26 taxa were gathered. The most abundant genus was Mesopolobus – 67% of the sampled pteromalids. The most numerous species in the samples was Mesopolobus morys – a well-known key parasitoid of the cabbage seed weevil, Ceutorhynchus obstrictus, in Europe. One species – Halticoptera patellana, is recorded for the first time in Bulgarian fauna. Clearfield oilseed rape fields had relatively higher parasitoid abundance and richness than the fields treated by conventional technology. In the present work we discuss the overall species composition of Pteromalidae obtained from the studied areas and present our point of view on the perspectives for biological control of oilseed rape pests. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:30 +030
  • Monitoring bumblebee pollinator visits to the medicinal plant Gentiana
           asclepiadea L. (Gentianacese) – a comparison between the periods
           1990–1994 and 2017–2020

    • Abstract: BioRisk 17: 317-327
      DOI : 10.3897/biorisk.17.76577
      Authors : Ekaterina Kozuharova, Vasil Simeonov : Ever increasing data continue to indicate the decline of bumblebee populations. The key factors causing declines in their abundance and diversity are: 1) habitat destruction, 2) loss of floral resources, 3) emerging diseases, 4) increased use of pesticides (particularly neonicotinoids). The aim of this study is to monitor bumblebee visits to Gentiana asclepiadea L, recording pollinator species, and taking measurements of seed set. This plant species is chosen for two reasons: 1) similar data is available from our previous research in the 1990’s and 2) this montane plant species is supposed to be less exposed to hazards from pesticides and habitat destruction. Three study sites were chosen in Mt. Vitosha (SW Bulgaria) where natural populations of G. asclepiadea occur in 1990. The observations of bumblebee activity in the flowers of G. asclepiadea were conducted during the flowering seasons (August and September) of 2017 – 2020 at the same study sites and compared to the data obtained in the previous period (1990–1994). The free pollination fruit set was tested by monitoring of 100 G. asclepiadea flowers each year for development of fruit capsules. The seed set was tested by counting the matured seeds and non-fertilised ovules of 10 fruit capsules each year. A slight decline in bumblebee activity was recorded in 2017 – 2020 in comparison to 1990–1994. This is reflected in the fruit set and the seed set. Our data demonstrates that even in a mountain habitat, where there are fewer direct hazards to bumblebees, that pollination effectiveness has been suppressed over time. This corresponds to a research study which provides evidence that insect biomass fell by 76% in German nature reserves between 1989 and 2016. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:29 +030
  • Plant products with acetylcholinesterase inhibitory activity for
           insect control

    • Abstract: BioRisk 17: 309-315
      DOI : 10.3897/biorisk.17.77052
      Authors : Borislav Georgiev, Milena Nikolova, Ina Aneva, Anatoli Dzhurmanski, Boriana Sidjimova, Strahil Berkov : Acetylcholinesterase (AChE) inhibitors are widely used in Alzheimer’s treatment, but they are also crucial for their action on organophosphorus insecticides. The latter exert their toxicity by inhibiting the AChE enzyme in insects, leading to their death. Amaryllidaceae alkaloids have been proven to be potent AChE inhibitors. In the present study methanolic extracts and essential oils being obtained from species of Asteraceae, Lamiaceae, Brassicaceae and Amaryllidaceae were evaluated in vitro for AChE inhibitory activity. Ellman’s colourimetric method, with modifications, was used for AChE activity evaluation. According to the activity level, the tested plant products were divided into three categories. First: plant products with strong activity comparable to that of galanthamine; second: plant products with medium activity, with IC50 value about 1 mg/ml and the last group with low activity, with IC50 value greater than 1 mg/ml. Essential oils of Origanum vulgare subsp. hirtum Ietswaart., Satureja pilosa Vel., Monarda fistulosa L., Thymus longedentatus (Degen & Urum.) Ronniger and the methanolic extract of Leucojum aestivum L. showed the most potent activity and were referred to as the first group. Carvacrol was identified as the main component of the most active essential oils. In L. aestivum extract, galanthamine was found as the main alkaloid. The obtained results indicate that essential oils and alkaloid-rich plant extracts possess the strongest AChE inhibitory activity. This gives us a reason to recommend these plant products to be tested for insecticidal activity in the future. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:28 +030
  • Pollinators of Lavandula angustifolia Mill., an important factor for
           optimal production of lavender essential oil

    • Abstract: BioRisk 17: 297-307
      DOI : 10.3897/biorisk.17.77364
      Authors : Hristo Valchev, Zdravko Kolev, Bilyana Stoykova, Ekaterina Kozuharova : Lavender essential oil is widely used in pharmacy, perfumery and the food industry. It is one of the key essential oils in aromatherapy due to its valuable pharmacological properties. The producers of lavender essential oil are well aware that the greatest quantity of oil is obtained near the end of the inflorescence anthesis and that oil quantity is correlated with the pollination as unpollinated flowers drop down. In addition, it has been demonstrated that oil quality is also highest at the end of the flowering period, related to the gradual increase of monoterpenes (particularly the valuable linalool) and the decrease of sesquiterpenes during flower ontogenesis. The aim of this preliminary study was to measure the occurrence of spontaneous self-pollination in Lavandula angustifolia Mill. and to identify external pollinators. The field experiments were performed in a lavender plantation near Gorna Lipnitza Village, north Bulgaria and in the ex-situ lavender collection in the experimental plot of the Botanical Garden of Sofia University. It was revealed that spontaneous self-pollination did not occur in flowers from which external pollinators had been excluded. Exposed flowers were pollinated by polylectic insects, such as honeybees, several species of bumblebees and butterflies. Wild pollinators (particularly bumblebees) dominated over honeybees at both study sites. Our observations showed that all pollinators actively collected nectar. The pollen baskets of most bees were full, indicating the active consolidation of pollen adhering to the pollinators’ bodies. Although lavender growers tend to place beehives in the fields for optimal essential oil production, it is also crucial to conserve wild pollinators. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:27 +030
  • Evaluation of viral infection levels in intensive and organic
           poultry farming

    • Abstract: BioRisk 17: 287-296
      DOI : 10.3897/biorisk.17.77398
      Authors : Plamen M. Kirov, Radostina I. Alexandrova : Whereas early organic farming was mainly focused on plant production, in the last decade, the number of organically-managed poultry farms within the European Union has increased significantly. Similar to organic crop production, organic animal farming is based on the same principles: welfare-friendly, sustainable production and resource utilisation without or with very little addition of synthetic substances, such as antibiotics and antiparasitic treatments. These practices, as well as the access to wild animals, make the free-range poultry production systems predisposed to different viral diseases and, thus, associated with potentially higher public health risks or reduction in production quality. On the other hand, intensive farming amplifies the impact of viral diseases due to high density, low genetic diversity and elevated immunodeficiency. The aim of this analytical study is to compare free-range with intensive poultry systems and the occurrence of different viral diseases in these types of farms in the EU over the past decade. The research is based on official data from the statistical office of the European Union, as well as official data from the Member countries. The results were similar in each country and demonstrate that free-range production has a higher incidence of viral diseases with high zoonotical potential. This makes year-round surveillance absolutely necessary, as well as the need for implementation of additional criteria and requirements towards free-range systems. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:26 +030
  • Organic vs conventional farming of oil-bearing rose: Effect on
           essential oil and antioxidant activity

    • Abstract: BioRisk 17: 271-285
      DOI : 10.3897/biorisk.17.77488
      Authors : Mima Todorova, Ana Dobreva, Nadezhda Petkova, Neli Grozeva, Mariya Gerdzhikova, Petya Veleva : 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. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:25 +030
  • Sexually-manifested variations in pigmentation of Boeckella poppei
           (Copepoda, Calanoida) from Livingston Island (Maritime Antarctica)

    • Abstract: BioRisk 17: 263-269
      DOI : 10.3897/biorisk.17.75988
      Authors : Ivan Pandourski, Vesela Evtimova, Lyubomir Kenderov : Antarctic environments are exposed to high levels of ultraviolet radiation (UVR) that are often detrimental to their biota. Recent studies suggest that the genus Boeckella (Copepoda, Calanoida) has a high level of plasticity in terms of its reaction to UVR, which enables its wide distribution in various water bodies in Antarctica. Boeckella poppei is common in freshwater habitats of all three main biogeographic regions in Antarctica: sub-Antarctic islands, maritime and continental. We present for the first time a specific photoprotective response in populations of B. poppei from Livingston Island, Maritime Antarctica. In non-ovigerous females and in males, we observed uniform distribution of carotenoids in the body, while these pigments were almost entirely concentrated in the ovisacs of mature females. We consider this as a means of progeny protection from the teratogenic influence of the high level of UVR in Antarctic environments. Unequivocally, such adaptation would facilitate the expansion of B. poppei on the continent through colonisation and survival in shallow freshwater habitats. Given that the Antarctic environment is dynamically changing over the past decades and the accelerated retreat of permanent ice cover is a premise for the formation of shallow ponds, B. poppei could be a suitable indicator for reflecting the ongoing global environmental changes in Antarctica. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:24 +030
  • Seasonal variations of the microflora of wedge clam Donax trunculus
           (Linnaeus, 1758) from the region of Arkutino (Bulgarian Black Sea

    • Abstract: BioRisk 17: 253-262
      DOI : 10.3897/biorisk.17.77097
      Authors : Sevginar Ibryamova, Borislava Pavlova, Elitca Stanachkova, Seniha Salim, Aysel Lyatif, Dimitar Dimitrov, Darina Bachvarova, Nesho Chipev, Nikolay Natchev, Tsveteslava Ignatova-Ivanova : The main goal of the present study was to investigate the impact of the state of the environment on the microbiota of the wedge clam Donax trunculus (Linnaeus, 1758) from the region of Arkutino (Bulgarian Black Sea aquatory). The species Enterococcus hirae was isolated during the summer (from May to August). The species P. mendocina prefers the warmer months and the species P. alcaligenes the colder ones. The temperature followed a course of decrease during the period September 2020 to January 2021, followed by a slow increase from February 2021. Comparing May 2020 with May 2021, it became evident that in 2021 the temperature was 1.5 °C lower. We can say that the number of the species P. alcaligenes was twice as high in May 2021. It is likely that this species preferred lower optimum temperatures and constant other parameters. For the species Enterococcus hirae such dependence was not observed - the number remained constant in May, but with increasing temperature the number of microorganisms decreased during the summer months. The species seemed to preferably develop at pH 7.78. The species A. gyllenbergii preferably grows at temperatures between 20.3–25.7 °C and the optimal temperature was 25.7 °C. For C. farmeri the optimum conditions were temperature 26.2 °C and pH 7.3. The species E. vulneris was probably related not only to the increase in water temperature, but also to the anthropogenic factor, as it was found only in July. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:23 +030
  • Seasonal changes in the pro/antioxidant status of mussels Mytilus
           galloprovincialis (Lamarck, 1819) from Bulgarian Black Sea coastal

    • Abstract: BioRisk 17: 241-251
      DOI : 10.3897/biorisk.17.77279
      Authors : Elina Tsvetanova, Almira Georgieva, Nesho Chipev, Albena Alexandrova : The pro/antioxidant status of marine macrozoobentic organisms is being increasingly applied in environmental monitoring and conservation programs. The oxidative stress level in marine bivalves can provide valuable information not only on the health of the organisms and their populations, but also on the current state of habitats and ecosystems. The aim of the present study was to make the first comprehensive investigation of the seasonal changes in the antioxidant activity in different organs (gills, digestive gland and foot) of M. galloprovincialis from representative Bulgarian Black Sea coastal habitats. The lipid peroxidation and glutathione levels, as well as activities of the antioxidant enzymes catalase, superoxide dismutase, glutathion peroxidase, glutathion reductase, glucose-6-phosphate dehydrogenase and glutathione-S-transferase of the organs were measured spectrophotometrically. Our hypothesis was that enhanced environmental pressure during the summer season, induced by multiple factors (biogenic, abiogenic and anthropogenic) led to weakening of the antioxidant protection in mussels at the beginning of autumn. The reaction of the mussel organism to the multiple stress factors was specific for the target organ and the type of the biomarker. Significant differences were present in the activity of the antioxidant system in mussels from the northern and southern coastal locations. The seasonal changes in the pro/antioxidant status of mussels were primarily due to specific seasonal changes in factors concerning the marine environment at the concrete locality. Further research is obviously needed to confirm the present results and provide a more complete data of seasonal and spatial changes in the antioxidant defense system of mussels from the Bulgarian Black Sea coastal area and their implementation in biomonitoring programs. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:22 +030
  • Influence of proline and methyl jasmonate priming on in vitro seed
           germination and seedling development of Chelidonium majus L

    • Abstract: BioRisk 17: 227-240
      DOI : 10.3897/biorisk.17.77465
      Authors : Iva Doycheva : Drought, salinization and heavy metal pollution of soils are main stress factors with an increasing impact on the deterioration of soil quality, yield and crop quality. Seed priming shows good results in improving seed germination, seedling growth and plant development. Proline (Pro) and metyl jasmonate (MeJA) show stimulating activity and help plants overcome stress. The study investigated the effect of Pro, MeJA and hydropriming on seeds sown on water agar supplemented with different concentrations of heavy metals (Cd, Pb, Zn) (HM), NaCl or Polyethylene glycol 6000 (PEG 6000). Chelidonium majus is a medicinal species which is grown as a crop in some parts of Europe. It is an ingredient in some remedies and is becoming an increasingly popular object of research regarding its biological activities. The low concentrations of all heavy metals applied increased the germination of all variants of seeds – control, hydroprimed and those which were Pro and MeJA primed. Seed priming with Pro and MeJA promoted high germination percentage of seeds germinated on water agar with NaCl. PEG 6000 at its higher concentration (5%) slightly increased the seed germination of all variants. The growth of roots and hypocotyls was inhibited by HM and NaCl. However, PEG 6000 slightly influenced their growth. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:21 +030
  • Light and auxin treatments affect morphogenesis and polyphenolics
           productivity in Artemisia alba Turra cell aggregates in vitro

    • Abstract: BioRisk 17: 213-225
      DOI : 10.3897/biorisk.17.77452
      Authors : Dobrina Pecheva, Kalina Danova : Artemisia alba Turra is an essential oil-bearing shrub, with a Euro-Mediterranean distribution widespread in the south-eastern parts of Europe. Phytochemical investigations have evidenced the presence of volatile mono- and sesquiterpene derivatives, as well as non-volatile sesquiterpenoids, flavonoids and phenolic acids contributing to the anti-inflammatory, antimicrobial, antioxidant and pro-apoptotic activity of different preparations, obtained from the plant. The current research aims at elucidation of the potential for biotechnological polyphenolic compounds productivity of non-differentiated cell lines of the plant. For this purpose, non-differentiated cell aggregates were initiated from either leaf or root explants of the sterile grown plant. They were cultivated either in the dark or at 16/8 h photoperiod in liquid media, supplemented with N6-benzyladenine (BA) as auxin. The cytokinin effects of indole-3-butyric acid (IBA) and 1-naphthalene acetic acid (NAA) were compared. It was established that NAA supplementation was superior to IBA and light treatment – to dark growth conditions in terms of polyphenolics productivity. In addition, NAA supplementation led to better expressed compaction and larger size of the cell aggregates as compared with IBA. The results of the present experiment indicate that secondary metabolites productivity in vitro is a dynamic process closely related to the plant’s growth and development and is in close relation to the interactions of the plant with its environmental conditions. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:20 +030
  • Screening of Amorpha fruticosa and Ailanthus altissima extracts for
           genotoxicity/antigenotoxicity, mutagenicity/antimutagenicity and

    • Abstract: BioRisk 17: 201-212
      DOI : 10.3897/biorisk.17.77327
      Authors : Teodora Todorova, Krassimir Boyadzhiev, Aleksandar Shkondrov, Petya Parvanova, Maria Dimitrova, Iliana Ionkova, Ilina Krasteva, Ekaterina Kozuharova, Stephka Chankova : The aim of the present study was to evaluate the potential genotoxic/antigenotoxic, mutagenic/antimutagenic, and carcinogenic/anticarcinogenic effect of Amorpha fruticosa (AF) fruit, Ailanthus altissima bark hexane (AAEH) and methanol (AAEM) extracts on a model system Saccharomyces cerevisiae. Plants were identified and extracted by Ekaterina Kozuharova. Three concentrations of each extract were tested – 10, 100 and 1000 µg/ml. In vitro pro-oxidant/antioxidant activities were evaluated by DPPH and DNA topology assay. The potential genotoxic/antigenotoxic, mutagenic/antimutagenic and carcinogenic/anticarcinogenic effects were revealed in vivo by: Zimmermman’s test on Saccharomyces cerevisiae diploid strain D7ts1, and Ty1 retrotransposition test on S. cerevisiae haploid strain 551. Zeocin was used as a positive control. Based on the in vitro antioxidant activity the extracts could be arranged as follows: AF>AAEM>AAEH. AAEH possessed moderate oxidative potential. No genotoxic and mutagenic capacity was obtained in vivo for extracts tested. The levels of total aberrants, convertants and revertants were comparable with the control ones. No Ty1 retrotransposition was induced by extracts treatment. Further, the extracts possessed well-expressed antigenotoxic, antimutagenic and anticarcinogenic activity. Significant reduction of the total aberrants, reverse point mutations and Ty1 retrotransposition was obtained. Only the AF extract was found to reduce the levels of zeocin-induced mitotic gene conversion. The three extracts did not possess any genotoxic, mutagenic and carcinogenic effect on Saccharomyces cerevisiae. Based on their protective activity, they can be arranged as follows: AF>AAEM>AAEH which corresponds well with their phytochemical composition. Further experiments could provide more detailed information concerning the mode of action of extracts, as well as their main constituents. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:19 +030
  • Polar and non-polar fraction from Origanum vulgare spp. hirtum
           methanolic extract – differences in their bioactivity on Chlamydomonas
           reinhardtii test system

    • Abstract: BioRisk 17: 191-200
      DOI : 10.3897/biorisk.17.78169
      Authors : Maria Dimitrova Todorova, Petya Nikolaeva Parvanova, Teodora Ivanova Todorova, Milena Tihomirova Nikolova, Strahil Hristov Berkov, Stephka Georgieva Chankova : Aim: To compare the bioactivity of both polar and non-polar fraction of Origanum vulgare spp. hirtum methanolic extract on Chlamydomonas reinhardtii. Material and methods: The polar and non-polar fractions were derived from aerial parts of Origanum vulgare ssp. hirtum, collected during the flowering stage from the ex-situ collection of IBER-BAS. GC/MS analysis of both fractions was done following the standard protocol. The measured mass spectra were deconvoluted by the Automated Mass Spectral Deconvolution and Identification System (AMDIS), before comparison with the databases. Chlamydomonas reinhardtii 137C+ (WT) was used as a test system. Spot-test, cell survival fraction (SF), test of “visible mutations” and CFGE (for measurement of induced DNA double-strand breaks (DSBs)) were applied. Results: The polar fraction did not possess genotoxic, mutagenic as well as DNA-damaging effect. The situation with the non-polar fraction was quite different. Even at the lowest concentration of 250 ppm, cell survival was decreased by 60% (SF = 0.41 ± 0.08). Treatment with concentrations equal to/or greater than 500 ppm resulted in around 100% lethality. A mild mutagenic effect was obtained for the concentration of 250 ppm non-polar fraction (IM = 4.83 ± 0.004). Well-expressed and concentration-dependent induction of DSBs for even the strong DNA fragmentation was observed after the treatment with the non-polar fraction. Conclusions: The different bioactivity of the two fractions correlated well with their different chemical composition. The polar fraction, rich in sugars, organic acids and flavonoid glycosides, did not possess genotoxic and mutagenic potential. The strong genotoxic potential of the non-polar fraction might be related to carvacrol content (37.08%), which is not present in the composition of the polar fraction. To the best of our knowledge, this study provides the first information that the carvacrol-rich non-polar fraction of Origanum vulgare spp. hirtum methanolic extract possesses genotoxic, mutagenic and DNA damaging effect on some low eukaryotes, such as C. reinhardtii. Further experiments with carvacrol should be done in order to clarify the exact mechanism of action. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:18 +030
  • On the mode of action of Origanum vulgare spp. hirtum methanolic
           extract and essential oil on Chlamydomonas reinhardtii

    • Abstract: BioRisk 17: 179-190
      DOI : 10.3897/biorisk.17.77313
      Authors : Maria D. Todorova, Petya N. Parvanova, Teodora I. Todorova, Georgi D. Dronchev, Milena T. Nikolova, Strahil H. Berkov, Stephka G. Chankova : Aim: To reveal whether methanolic extract and essential oil from Origanum vulgare subsp. hirtum in doses causing even low levels of mortality in aphids, would have harmful effects on plants-genotoxic, mutagenic and/or DNA damaging. Materials and methods: Aerial parts of Origanum vulgare ssp. hirtum from the ex-situ collection of IBER, BAS during flowering were collected. Extraction and isolation procedures, as well as GC/MS analysis of essential oil and methanolic extract were performed by standard protocols. The components were identified by comparing their relative retention times to the retention times of authentic standards, and with mass spectra with the NIST. Test system: Chlamydomonas reinhardtii strain 137 C+ (WT). Endpoints: “clonal” assay, the test of “visible mutations”, constant field gel electrophoresis. Statistics: GraphPad Prism version 6.04 (San Diego, USA) and One-way Analysis of Variance ANOVA with multiple comparisons using the Tukey method. Results: A good correlation was observed between chemical composition of essential oil and methanolic extract, and their mode of action. Our genotoxic and double strand breaks results demonstrated mild genotoxic and statistically non-significant DNA damaging potential of methanolic extract and concentration-dependent well - expressed genotoxic and DNA damaging potential of essential oil. A good relationship between increased double strand breaks levels and decreased survival might be related to one of the main constituents of essential oil, suspected to be carvacrol. No mutagenic effect for ME and EO was found. Conclusion: Well-expressed toxic/genotoxic capacity of essential oil, as well as its capacity to damage DNA inducing double strand breaks, but the absence of mutagenic potential, could be considered as a good reason to recommend Origanum vulgare subsp. hirtum essential oil as a promising candidate for purposes of “green” technologies. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:17 +030
  • State of the antioxidant defense system in wedge clams from Bulgarian
           Black Sea as a measure of resistance to environmental impacts

    • Abstract: BioRisk 17: 169-178
      DOI : 10.3897/biorisk.17.77384
      Authors : Almira Georgieva, Elina Tsvetanova, Nesho Chipev, Albena Alexandrova : Pollution and climate change can induce oxidative stress (OS) in aquatic organisms. Reduced activity or incoordination between antioxidant enzymes in marine bivalves may cause cellular impairment with effects on higher levels of ecological organization. The present study aims to assess the condition factor and the activity of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione concentration (GSH) in soft tissues of Donax trunculus (Linnaeus, 1758) as indicators of the state of marine ecosystems along the Bulgarian Black Sea coast. The wedge clams were sampled manually from different localities in June and in September. The activity of antioxidant enzymes and GSH concentrations varied both seasonally and among localities. Higher values of GSH, SOD and GPx were registered in wedge clams collected in autumn compared to those collected in summer. In wedge clams higher activity of the major phase II detoxification enzyme GST was observed in summer at localities with intensive tourism, suggesting an activation of the cell detoxification processes, presumably in response to increased environmental pressure. In conclusion, the observed presence of elevated enzyme activities suggested activation of the antioxidant protection system of the wedge clams in response to environmental pressure, indicating their ability to cope with induced OS and adapt to local conditions, and thus maintain ecosystem health. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:16 +030
  • Application of residual sludges from wastewater treatment technologies for
           construction of biofertiliser

    • Abstract: BioRisk 17: 157-168
      DOI : 10.3897/biorisk.17.77463
      Authors : Mihaela Belouhova, Dobromira Yaneva, Yana Topalova : To stimulate plant development in phytoremediation or in the cultivation of non-food crops in potentially contaminated soils, a biotechnologically created product could be applied. The aim of this study was to explore the possibility of creation of biofertiliser, based on activated sludge combined with bacterial strain with detoxifying and plant growth promoting properties. The presented study is focused on the effect of phenol in the following concentrations: 5 mg/l, 100 mg/l, 250 mg/l, 500 mg/l and 1000 mg/l on the metabolic activity of Brevibacillus laterosporus BT271. The gradual increased concentration of phenol was used to study the metabolic activity of mineralised activated sludge and B. laterosporus BT271. The CTC/DAPI staining showed high activity of the bacteria even at the highest concentration. The greatest amount of biomass was accumulated at 5 mg/l phenol (4.44 × 107 cells/ml). At this toxicant concentration, a total dehydrogenase activity of 5.72 × 10-4 μg H+/ml*min was found. Studies of the metabolic activity of microorganisms in experiments involving a combination of mineralised activated sludge, B. laterosporus BT271 and phenol at three concentrations (5 mg/l, 250 mg/l and 1000 mg/l) showed the highest value for dehydrogenase activity in the variant with average phenolic concentration (up to 6.39 × 10-6 μg H+/ml*min. The results proved the detoxification potential of B. laterosporus BT271 when different concentrations of phenol were present. The combination of a mineralised activated sludge and selected highly active biodegrading B. laterosporus BT271 showed valuable properties of detoxification and metabolic activity and keep these potentials up to 1000mg/l phenol. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:15 +030
  • Natural zeolites as detoxifiers and modifiers of the biological effects of
           lead and cadmium in small rodents: A review

    • Abstract: BioRisk 17: 147-155
      DOI : 10.3897/biorisk.17.77435
      Authors : Michaela Beltcheva, Peter Ostoich, Iliana Aleksieva, Roumiana Metcheva : The present investigation analyzes the literature about the toxicity of Cd and Pb in small rodents’ organisms and the role of natural zeolites as modifiers of the biological effects. An array of ecotoxicological, morpho-physiological, hematological, genetic and biochemical methods as most representative are under discussion as a basic point for further exploration of biological effects in laboratory mice. The review of existing results demonstrated that there is abundant data on the sorption of lead and cadmium by modified natural zeolites in water and soils. Nevertheless, there is insufficient data on the ion exchange capacity and biological effects of this sorbent in living organisms, especially regarding Cd detoxification. On the basis of the current review, it is possible to conclude that future investigations in this field will elucidate the potential of the use of zeolites as successful detoxifiers against heavy metals and other toxic elements in living organisms. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:14 +030
  • In vitro reconstitution of complexes of stress HliA protein with

    • Abstract: BioRisk 17: 139-146
      DOI : 10.3897/biorisk.17.77306
      Authors : Lubov Sharapova, Nadezhda Yurina : Proteins similar to Hli (high light inducible) proteins of cyanobacteria are present in all photosynthetic eukaryotes and are necessary for survival in various stressful conditions, although their exact function is not fully understood. In current study, the recombinant stress-induced protein HliA of cyanobacterium Synechocystis was isolated and characterised for the first time. The synthetic gene of HliA protein was created and cloned into plasmid for expression of recombinant protein with Hisx6-tag at the C-terminus in bacteria. Recombinant HliA protein of Synechocystis was isolated by metal-affinity chromatography. The HliA protein was reconstituted with chlorophyll a and carotenoids. Using circular dichroism spectroscopy, it was shown that chlorophyll a and carotenoids interact in vitro with the HliA protein. The binding of pigments to the HliA protein favours the protective function of this protein. Apparently, Hli proteins are involved in the coordinated delivery of pigments for the biogenesis of photosynthetic complexes, thereby reducing the risk of accumulation of phototoxic free chlorophyll molecules. Current results are important for understanding the processes of photoprotection in either cyanobacteria or algae and higher plants. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:13 +030
  • Cellular susceptibility and oxidative stress response to menadione of
           logarithmic, quiescent, and nonquiescent Saccharomyces cerevisiae cell

    • Abstract: BioRisk 17: 127-138
      DOI : 10.3897/biorisk.17.77320
      Authors : Polya Galinova Marinovska, Teodora Ivanova Todorova, Krassimir Plamenov Boyadzhiev, Emiliya Ivanova Pisareva, Anna Atanasova Tomova, Petya Nikolaeva Parvanova, Maria Dimitrova, Stephka Georgieva Chankova, Ventsislava Yankova Petrova : The aim of the present study was to compare cellular susceptibility and oxidative stress response of S. cerevisiae logarithmic (log), quiescent (Q), and non-quiescent (NQ) cell populations to menadione – a well-known inducer of oxidative stress. Three main approaches were used: microbiological – cell survival, molecular – constant field gel electrophoresis for detection of DNA double-strand breaks (DSB), and biochemical – measurement of reactive oxygen species (ROS) levels, oxidized proteins, lipid peroxidation, glutathione, superoxide dismutase (SOD) and catalase on S. cerevisiae haploid strain BY4741. The doses causing 20% (LD20) and 50% (LD50) lethality were calculated. The effect of menadione as a well-known oxidative stress inducer is compared in the log, Q, and NQ cells. Survival data reveal that Q cells are the most susceptible to menadione with LD50 corresponding to 9 µM menadione. On the other hand, dose-dependent DSB induction is found only in Q cells confirming the results shown above. No effect on DSBs levels is observed in log and NQ cells. Further, the oxidative stress response of the cell populations is clarified. Results show significantly higher levels of SOD and ROS in Q cells than in log cells after the treatment with 100 µM menadione. On the other side, higher induction of oxidized proteins, malondialdehyde, and glutathione is observed after menadione treatment of log cells. Our study provides evidence that Saccharomyces cerevisiae quiescent cells are the most susceptible to the menadione action. It might be suggested that the DNA damaging and genotoxic action of menadione in Saccharomyces cerevisiae quiescent cells could be related to ROS production. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:12 +030
  • Comparative study on the oxidative stress of commercially important fish
           species from localities with different ecological conditions along the
           Bulgarian Black Sea coast

    • Abstract: BioRisk 17: 117-126
      DOI : 10.3897/biorisk.17.77300
      Authors : Albena Alexandrova, Yordan Raev, Dimitar Dimitrov, Nesho Chipev, Elina Tsvetanova, Almira Georgieva, Violin Raykov : The aim of the present study was to perform a pilot assessment and analysis of the oxidative stress (OS) level in four commercially important fish species (round goby, red mullet, sprat and horse mackerel) from different localities of the Bulgarian Black Sea coast. The fish were sampled during trawl selectivity experiments. The OS level in the fish was assessed by measuring lipid peroxidation (LPO), glutathione concentration (GSH), activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST), as well as acetylcholine esterase (AChE) in gills and liver. Round goby and red mullet caught in the Nessebar Bay showed clear signs of OS with the highest levels of LPO and GST activities, accompanied by the lowest AChE activities in both liver and gills. On the contrary, round goby caught near Maslen Nos (a region with good ecological conditions) were least affected by OS with low LPO and high GSH concentrations and SOD activity. There were no significant differences in the OS bioindicators of horse mackerel from the different localities. Sprat caught in Nessebar Bay, compared to those caught from the other localities, showed presence of OS indicated by lower GSH levels and relatively higher CAT, GPx and GST activities, accompanied by low AChE activity in gills. It can be concluded that round goby and red mullet were more vulnerable to OS induced by marine environmental factors than the horse mackerel and sprat. However, their antioxidant defense system allows them to tolerate and adapt to the environment of their habitats. Further studies are needed for the assessment of OS in important fish species in the Bulgarian part of the Black Sea. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:11 +030
  • Saccharomyces cerevisiae yeast cells as a test system for assessing Zeocin

    • Abstract: BioRisk 17: 105-116
      DOI : 10.3897/biorisk.17.77227
      Authors : Polya Marinovska, Teodora Todorova, Anna Tomova, Emiliya Pisareva, Krassimir Boyadzhiev, Martin Dimitrov, Petya Parvanova, Maria Dimitrova, Stephka Chankova, Ventsislava Petrova : Having unique genetic machinery and a high degree of conservation with higher eukaryotes, the yeast Saccharomyces cerevisiae is recognised as a smart experimental system for studying the modes of chemical toxicity. The present study was undertaken to elucidate the changes in the intracellular redox homeostasis and key macromolecule structure following exposure to Zeocin. Cell populations of logarithmic, quiescent (Q) and non-quiescent (NQ) cells of Saccharomyces cerevisiae BY4741 were used as a model to examine the cytotoxic effect of this radiomimetic. The levels of endogenous ROS, oxidized lipids, carbonylated proteins, and glutathione were analysed after treatment with Zeocin (IC50). An increase in ROS production and respectively increased oxidative stress was detected in all three types of cell populations, with the highest degree being observed in proliferating S. cerevisiae BY4741 cells. The stress response of both proliferating and stationary phase (Q and NQ) cells to Zeocin included an overexpression of glutathione. The quiescent cells also showed very low DNA susceptibility to high Zeocin concentration (100–300 µg/ml), presented as no induced double-strand breaks (DSBs) in the macromolecule. Based on our research it could be concluded that the cellular physiological state is a critical factor determining the resistance to environmental stress with Q cells being the most robust. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:10 +030
  • Assessment of PAHs accumulation in Donax trunculus (Linnaeus, 1758)
           (Bivalvia, Donacidae) from the Bulgarian Black Sea Coast

    • Abstract: BioRisk 17: 95-104
      DOI : 10.3897/biorisk.17.77343
      Authors : Stanislava K. Georgieva, Mona D. Stancheva, Zlatina V. Peteva, Tsveteslava I. Ivanova, Albena V. Alexandrova : Anthropogenic pollution of marine ecosystems is one of the main sources of polycyclic aromatic hydrocarbons (PAHs). Marine bivalves are often used as bioindicators of environmental pollution due to their wide distribution and capability of xenobiotic bioaccumulation. The aim of the present study was to assess the presence of PAHs in soft tissues of wedge clams Donax trunculus (Linnaeus, 1758), collected from sublittoral sandy habitats at different locations off the Bulgarian Black Sea coast. Wedge clams from the different locations showed variations in the content of accumulated PAHs’ compounds. The concentrations of PAHs were measured by gas chromatography system with mass spectrometry detection. The total PAHs content (sum of 13 PAHs’ compounds) measured was in the range from 5.59 to 50.50 ng/g wet weight and was comparable with other European studies. The compounds phenanthrene and fluorene were most abundant in all analyzed samples. The results showed that low molecular weight (LMW) PAHs (2 and 3 aromatic rings) were predominant, accounting for 91% of the total PAHs levels, while high molecular weight (HMW) PAHs (4–5- and 6- rings) presence was 8.9% on average. The ratio LMW/HMW PAHs was higher than one, suggesting predominant pollution of petrogenic origin. The concentrations of benzo (a)pyrene did not exceed the limit set in EC Regulation although it was detected in 20% of the analyzed samples. In conclusion, maximum overall PAHs content was found in clams from Arkutino, while minimum PAHs content was present in samples from Elenite. The Sum PAH4 (sum of four polycyclic aromatic hydrocarbons: benzo[a]pyrene, chrisene, benzo[a]anthracene, and benzo[b]fluoranthene) in the wedge clams for all localities studied was below legislation limits. Data from the present research can be used for assessing pollution levels in the marine environment and also risk of human exposure to PAHs using D. trunculus as bioindicator species. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:09 +030
  • Heavy metal stress response of microalgal strains Arthronema africanum and
           Coelastrella sp. BGV

    • Abstract: BioRisk 17: 83-94
      DOI : 10.3897/biorisk.17.77483
      Authors : Zornitsa Karcheva, Zhaneta Georgieva, Alexander Tomov, Detelina Petrova, Miroslava Zhiponova, Ivanina Vasileva, Ganka Chaneva : The present study compared the stress response of two microalgal strains – Arthronema africanum (Cyanoprokaryota) and Coelastrella sp. BGV (Chlorophyta), after heavy metals’ treatment. Changes of algal growth, pigment and protein content were analyzed after adding Cu, Cd and Pb (50 µM and 100 µM) to the nutrition medium. It was found that Cd and Pb significantly inhibited growth and protein biosynthesis of microalgae, but the effect of Cu remained less pronounced. In both strains, a decrease of chlorophyll content was observed, while carotenoid content markedly increased, especially in Coelastrella sp. BGV biomass. The addition of 100 µM Cd and 100 µM Pb to the medium caused a strong enhancement of malondialdehyde in both microalgal strains, which corresponded to the significant increase of superoxide dismutase and catalase activity. The antioxidant enzymes appeared to be differently altered by heavy metals’ exposure. The activity of SOD in the Arthronema africanum cells was most strongly affected by Cd, in contrast to Coelastrella sp. BGV that was highly increased by 100 µM Pb. The application of 100 µM Cd and 100 µM Pb increased in a similar manner catalase activity in both microalgae. The strains that were studied showed a high absorption capacity for metal ions, especially for Pb, which was absorbed largely than Cd and Cu. For that reason, we assumed that both microalga and, in particular, Coelastrella sp. BGV, could be successfully used for treatment of contaminated water bodies. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:08 +030
  • Trace metal accumulation in tissues of wedge clams from sandy habitats
           of the Bulgarian Black Sea coast

    • Abstract: BioRisk 17: 73-81
      DOI : 10.3897/biorisk.17.77290
      Authors : Darina Bachvarova, Mona Stancheva, Tsveteslava Ignatova-Ivanova, Sevginar Ibryamova, Nesho Chipev, Albena Alexandrova : The aim of the present study was to carry out an initial screening of trace metals bioaccumulation in soft tissues of the wedge clam (Donax trunculus Linnaeus, 1758) from different localities of the Bulgarian Black Sea coastal area and to evaluate the bioindicator potential of this species. Wedge clams were collected in June and September 2020 from sublittoral sandy habitats at different localities of the Bulgarian Black Sea coast. Soft tissues of individual clams were digested with nitric acid followed by ICP-OES analytical determination. The content of trace metals in the wedge clams differed significantly amongst localities. Higher metal content was present in wedge clams from Sveti Vlas, Shkorpilovtsi, Slanchev Bryag, Ahtopol and Kranevo. The highest values of lead (Pb) (2.51 mg/kg) and cadmium (Cd) (0.32 mg/kg) were found in samples from Sveti Vlas and the highest concentration of copper (Cu) (34.12 mg/kg), iron (Fe) (269.52 mg/kg) and nickel (Ni) (0.32 mg/kg) were detected in wedge clams from Shkorpilovtzi. Maximum content of chromium (Cr) (0.58 mg/kg) was present in samples from Slanchev Bryag, together with high values of Fe. The highest concentration of zinc (Zn) (18.04 mg/kg) together with high values of Cr and Fe were measured in wedge clams from Irakli. In conclusion, the wedge clams from the localities known to have higher coastal inflows and touristic pressures, i.e. Varna, Shkorpilovtzi, Sveti Vlas, Slanchev Bryag and Ahtopol accumulated significantly higher metal elements in their tissues. Only few significant seasonal differences in the concentration of metal elements in wedge clams were present and the observed seasonal variations were probably connected to the hydrological parameters of the ecosystems. The wedge clam D. trunculus is a suitable bioindicator for assessment and monitoring of metal pollution in the Bulgarian Black Sea environment. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:07 +030
  • Environmental impact assessment of discharge of treated wastewater
           effluent in Upper Iskar sub-catchment

    • Abstract: BioRisk 17: 59-71
      DOI : 10.3897/biorisk.17.77381
      Authors : Veronika Yordanova, Yovana Todorova, Mihaela Belouhova, Lyubomir Kenderov, Valentina Lyubomirova, Yana Topalova : The upper Iskar sub-catchment is one of Bulgaria’s most important economic and socially significant water sources because of its role in supplying Sofia with drinking water. Among the critical factors that carry potential high-risk levels for water quality in this hydrosystem are the discharge from the Samokov Wastewater Treatment Plant (WWTP), diffuse pollution from agriculture, and the percolation of untreated sewage from the small villages. In this study, we assessed the effect of treated wastewater effluent on water quality, and on the ecological state and microbial communities in the river sector of Samokov’s WWTP discharge area. The assessment was based on the complex use of chemical and microbiological indicators and biological quality elements. The concentrations of organics, nutrients and microcomponents were determined with results confirming the expected increase for parameters associated with the discharge of urban wastewater. The ecological state, according to macrozoobenthos indicators, was “good” throughout the river sector but local deterioration was registered in a proximal location downstream of the WWTP outfall. The analysis of stream water and bed sediment microbial communities by a fluorescent technique showed the high metabolic activity and intensive transformation processes in addition to high abundance registered with standard cultivation methods. The importance of the studied sub-catchment for the functioning of the urban water cycle, and for the quality of Sofia’s drinking water, underlines the need to extend an existing monitoring program with a more detailed assessment of the environmental impact of wastewater discharge. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:06 +030
  • Radiation status of soils from the region of the Eastern Rhodopes
           (Southern Bulgaria)

    • Abstract: BioRisk 17: 45-57
      DOI : 10.3897/biorisk.17.77432
      Authors : Milena Hristozova, Radoslava Lazarova : 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. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:05 +030
  • Differences in bacterial functional profiles from loamy sand and clay loam
           textured soils under fungicide QuadrisR impact

    • Abstract: BioRisk 17: 31-43
      DOI : 10.3897/biorisk.17.76939
      Authors : Michaella Petkova, Anelia Kenarova, Silvena Boteva, Stela Georgieva, Christo Chanev, Galina Radeva : The non-target effect of the fungicide QuadrisR on the bacterial community from grassland loamy sand (LS) and cropland clay loam (CL) soils with unknown history of fungicide usage was investigated. QuadrisR was applied to soil mesocosms at 0.0 mg kg-1 (Az0), 2.90 mg kg-1 (Az1), 14.65 mg kg-1 (Az2) and 35.0 mg kg-1 (Az3) calculated towards the active ingredient azoxystrobin (Az). Response of bacterial communities to QuadrisR was investigated during a 120-day incubation experiment, evaluating the shifts in bacterial catabolic profiles by the community-level physiological profiling (CLPP) technique and Biolog EcoPlatesTM method. QuadrisR decreased the overall catabolic activity (AWCD) of soil bacterial communities and the rate of decrease was independent of soil type and fungicide concentration. Fungicide affected negatively the utilisation of amines and positively that of amino acids in both soil types, whereas the effects on other carbon guilds (carbohydrates, carboxylic acids and polymers) corresponded closely to the respective soil type and fungicide concentration. Results indicated the presence of non-target effects of QuadrisR on bacterial functioning; hence, it is important to address the fungicide side-effects on soil health. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:04 +030
  • Correlation between bacterial abundance, soil properties and heavy
           metal contamination in the area of non-ferrous metal processing plant,
           Southern Bulgaria

    • Abstract: BioRisk 17: 19-30
      DOI : 10.3897/biorisk.17.77458
      Authors : Radina Nikolova, Michaella Petkova, Nikolai Dinev, Anelia Kenarova, Silvena Boteva, Dimitar Berov, Galina Radeva : 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. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:03 +030
  • Ecocide – global consequences (pesticides, radionuclides, petroleum

    • Abstract: BioRisk 17: 7-18
      DOI : 10.3897/biorisk.17.77438
      Authors : Roumiana Metcheva, Peter Ostoich, Michaela Beltcheva : The problem of environmental pollution is becoming increasingly important on a global scale. Man has oversaturated the environment of his habitat with harmful and most often toxic waste. It is difficult to describe all the toxic substances, as a separate book can be written for each group. The term “ecocide” has been introduced, which reflects large-scale destruction of the natural environment. We will focus only on three classes of pollutants that are of particular concern, creating environmental conflicts. These are: • Pesticides are extremely toxic and create large amounts of non-degradable waste. It accumulates in tissues and organs of target organisms, becoming toxic and causing serious pathological changes in the body, mainly at the cellular and subcellular levels, causing various diseases and as a result, serious changes in the structure and functions of the populations and the whole ecosystem are increasingly observed. • Waste from the nuclear industry and radioactive fallout from nuclear explosions. It is especially dangerous that radioactive elements can be concentrated in certain organs. • Petroleum products - often large quantities end up in the seas and oceans, along with industrial waste of various kinds, impossible to compensate for by nature and they pose a serious threat to ecosystems, many of which have already been destroyed. At the submolecular level, chemical and physical effects can lead to genetic rearrangements (mutations); destructive ionization in the tissues of every living being, sometimes with completely unexpected consequences for humans. HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:02 +030
  • International seminar of ecology – 2021 “Current trends of

    • Abstract: BioRisk 17: 1-5
      DOI : 10.3897/biorisk.17.84978
      Authors : Stephka Chankova : none HTML XML PDF
      PubDate: Thu, 21 Apr 2022 19:00:01 +030
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