Editorial Note: Rhodopes Mountains - a fairy tale in green – Part I (Eastern Rhodopes)

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In this study we developed thermodynamic models for solid-liquid equilibrium for mixed systems HF-NaF-H2O and HF-KF-H2O up to 2 m HF at T = 25oC. Models are developed on the basis of Pitzer ion interactions approach. The recommendations on mean activity coefficients (<italic>γ</italic>±) have been used to construct the model for HF-H2O system. The models for binary systems NaF-H2O and KF-H2O are taken from our previous study in the same journal [Donchev et al. ASN (2021) 8(2), 1-15]. To parameterize models for ternary systems we used the available solubility data, i.e. on the basis of solubility approach. The thermodynamic solubility products (as ln Kosp) of precipitating in mixed systems double salts [NaF.HF(cr), and KF.HF(cr)] have been determined on the basis of evaluated model ion interaction parameters and using experimental m(sat) solubility data. The model is in a good agreement with experimewnt solubility data in the systems HF–NaF–H2O and HF–NaF–H2O up to maximum HF molality of 2 mol·kg−1. At higher acid molality the model predicts much higher solubility of double salts (NaF.HF(cr) and KF.HF(cr) for both mixed systems. It was concluded that not a correct raw data for binary HF–H2O system used in parameterization are the main reason for concentration restriction of mixed HF models presented here.
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Thermodynamic solid-liquid equilibrium model for mixed systems HF-NaF-H2O and HF-KF-H2O up to 2 m HF at T = 25oC

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The purpose of the present study was to gather information about the effects of the herb Levisticum officinale (lovage) and of its phenolic ingredients and to elucidate the potential health benefits of the plant in relation to its polyphenolic content. The study was performed by searching different internet-based databases (Google Scholar, ScienceDirect, PubMed, etc.).
Levisticum officinale (lovage) is a perennial aromatic plant from the Apiaceae family. This herb is rich in essential oil and is widely used as a seasoning for culinary purposes. Lovage contains up to 860 mg GAE/100 g fresh weight phenolic substances as well. Polyphenols in L. officinale belong to the classes of flavonoids (quercetin, rutin, kaempferol and anthocyanins) and phenolic acids (chlorogenic, neochlorogenic, ferulic, gallic, ellagic). They contribute to potent antioxidant properties of the plant. Anti-inflammatory, anticancer, neuroprotective, antidiabetic, antibacterial, hepatoprotective and other properties of L. officinale extracts have also been demonstrated. Phenolic substances abundant in lovage have shown to be protective in models of osteoporosis and different cardiovascular diseases as well.
The information confirms our assumption that Levisticum officinale is not only an useful and pleasant-tasting Mediterranean-cuisine seasoning but also a herb that can contribute to the healthy lifestyle.
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Potential health benefits of the plant <italic>Levisticum officinale</italic> (lovage) in relation to its polyphenolic content

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Opuntia fragilis (Nutt.) Haw. (Cactaceae) is the smallest and most cold-hardy species of genus Opuntia in North America. In Bulgaria it is grown as an ornamental plant, but in 2019 a population of this species was discovered by other researchers in natural habitats in Lozenska Mt (Western Bulgaria) at 630–660 m a.s.l. on an area (extent of occurrence) of ca. 100 m2. In July 2020, we established a population of this species on the Black Sea coast near the town of Primorsko (Eastern Bulgaria) at 5 m a.s.l. on an area of ca. 300 m2. The distance between the two populations is 360 km in a straight line and their origins are independent of each other. The two localities of this species are so far the only ones described not only for the territory of Bulgaria, but also for Europe.
Data are given on the conditions characterizing each of the localities. The possible reasons for the appearance in natural habitats of this alien plant species for the Bulgarian flora are considered. The impacts and threats this species may have on biodiversity in natural habitats are indicated. Measures have been proposed to control the populations of the species.
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<italic>Opuntia fragilis</italic> (Nutt.) Haw. (Cactaceae) in the Bulgarian flora

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The concept of sustainable development can play a key role for various knowledge-based sectors, a major factor in the educational system, focused on addressing the problems that exist and preventing new social, economic and environmental ones.
The article examines the definition of sustainability, the point of learning aimed at environmental sustainability. The new European Sustainability Competence Framework that outlines the competencies necessary for the ecological transition, including critical thinking, initiatives, conservation of nature and taking responsibility for the negative impact of everyday actions and decisions on the environment and climate worldwide, has been examined here.
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Learning for sustainability - competences and expectations

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Humanity continues to degrade natural capital, threatening its long-term sustainability. This more and more categorically imposes the need to create a specific green infrastructure - a response to the natural solutions to the accumulating problems (environmental pollution, floods, natural disasters and cataclysms). The failure of decisions to pay sufficient attention to ecological consequences and to apply systematic measures of high quality are among the main reasons for the current situation in most ecosystems. The fast-paced and highly mechanized way of life of modern man creates the illusion of remoteness from the natural world. Yet all human activity depends entirely on ecosystems and their functions and at the same time has (threatening) impacts on them. Therefore, the achievement of greater efficiency in the use of natural resources and the creation of suitable ecological living conditions are critically important goals both for Europe and for the whole world. Green Infrastructure (GI) is a successfully tested tool for providing environmental, economic and social benefits through environmentally sound solutions. Such a tool helps to understand the values provided by nature to human society and mobilizes investments for their maintenance and growth.
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Green infrastructure - the smart interpreting of natural capital

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Bulgaria is a country with an extremely diverse nature. Unlike a number of European countries, Bulgarian nature is relatively well preserved. For the purposes of its protection, a network of protected areas was created, which occupy 5.3% of the country’s territory. Bulgaria also participates in a number of international initiatives, which put about 1/3 of the territory of Bulgaria under protection of the natural environment. According to the Protected areas Act in Bulgaria, 6 categories are distinguished - national parks, natural parks, reserves, maintained reserves, protected localities, natural attractions. Among them, important resources for the development of tourism are national parks, natural parks, protected localities and natural attractions. They represent unique sites for the development of alternative forms of tourism such as ecological, cultural-cognitive, route-cognitive tourism, etc. On the other hand, reserves and maintained reserves prohibit tourism activities. The network of protected areas is unevenly developed throughout the country. It is better represented in the mountainous areas, and in the plain parts of the country it is more limited due to the strong anthropogenic changes and the pressure from various human activities. In connection with the preserved nature, the mountains are preferred sites for tourism. The contribution of the protected areas in this regard is significant.
Stara planina tourist region is among the country’s tourist areas with well-defined mountainous characteristics. This is an important prerequisite both for the preservation of nature and for the formation of a suitable environment for recreation and tourism, and the mentioned directions are mutually bound.
The purpose of this article is to valorize the protected areas in Stara Planina tourist region and to highlight the possibilities for their current and future use for the development of tourism.
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Bishop Konstantin Preslavsky University of Shumen

Department for Information, Qualifications and Continuing Education

Protected areas in the Stara planina tourist region – current state and prospects for tourism development

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Tourism is one of the fastest growing industries of the new millennium. Bulgaria is a destination with an extremely large variety of natural and anthropogenic tourism resources and a relatively well-developed tourism sector of the economy, which brings significant income to the country’s economy. Varna tourist region is one of the leaders in the development of tourism, both for sea vacations and specialized types of tourism. Despite the great potential of the country and the researched tourist areas in particular, there are a number of problems related to uneven tourist development, seasonality, deteriorated tourist infrastructure and the quality of the services offered. The purpose of this paper is to study the current state of tourism and the opportunities for its development in the region.
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Tourism in Varna Black sea area – current situation and prospects for development

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The report reveals the impact of tourism on changing national identity. The interaction between tourism and cultural identity as social phenomena is noted. Globalization as a prerequisite for cultural disorientation is examined. The concept of anthropotok, as a mass self-sustaining process of identity change, is examined.
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Tourism as a prerequisite for changing the national identity

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Acta Scientifica Naturalis

 Acta Scientifica Naturalis is the official journal of the Konstantin Preslavsky University of Shumen and has been published with no major interruptions since 1973 under the name of the Annual of the Konstantin Preslavsky University- Chemistry, Biology, Physics, Geography.   The main objective of Acta Scientifica Naturalis is to publish original research findings in the fields of the Natural Sciences and related sciences:    Chemistry - Atmospheric Chemistry, Bioinorganic Chemistry, Bioorganic Chemistry, Catalysis, Combinatorial Chemistry, Computational Chemistry, Coordination Chemistry, Geochemistry, Inorganic Chemistry, Macromolecular Chemistry, Materials Science, Medicinal Chemistry, Ocean Chemistry, Organic Chemistry, Organometallic Chemistry, Physical Chemistry, Polymer Chemistry, Supramolecular Chemistry, Theoretical Chemistry.   Biology and Ecology - Animals Physiology, Anthropology, Applied Ecology, Biochemistry, Bioecology,　Biophysics, Botany, Cell Biology, Embryology, Entomology, General Ecology, Genetics, Helminthology, Human Physiology, Hydrobiology, Immunology, Microbiology, Molecular Biology, Molecular Genetics, Morphology, Mycology, Neurobiology, Parasitology, Plant Physiology, Radiobiology, Virology, Zoology.   Plant Growing and Plant Protection - Biological Plant Protection, Cereals, Entomology, Fruit growing, Herbology, Horticulture, Integrated Plant Protection, Legumes, Phytopathology, Technical crops, Vegetable production, Viticulture.   Physics - Atomic and Molecular Physics, Condensed Matter Physics, Electromagnetism, Gas Discharge and Plasma Physics, High Energy Physics, Hydrodynamics, Interdisciplinary Physics, Mathematical Physics, Medical Physic, Neutron Physics and Nuclear Reactor, Nuclear Physics, Particle Physics, Radiophysics and Electronics, Theoretical Physics, Thermal Physics, Wave Physics.   Astronomy and Astrophysics - Applied Geophysics, Astrophysics and Stellar Astronomy, Atmospheric Physics, Earth Magnetism and Gravimetry, Geophysics, Heliophysics, Meteorology, Near-Earth Space Physics, Oceanic Physics, Seismology, Stellar Mechanics.   Earth Sciences - Cartography, Climate Change, Geodemography, Geography of Tourism, Geomorphology, GIS, Hydrology, Morphostructurs, Morphotectonic, Paleogeography, Quaternary Movements, Risk, Social Geography.　   Tourism - Cognitive Tourism, Ecotourism, Extreme Tourism, Mountain Tourism, Recreational Tourism, River Tourism, Rural Tourism, Sea Tourism, etc.      The abbreviated title of the journal is ASN, which should be used in bibliographies, footnotes and bibliographical references strips.   Article Publication Charges (APC)   To publish in Acta Scientifica Naturalis, authors are required to pay an article processing charge (EUR 120). It includes our maintenance, publication and submission to global indexing and tracking organizations and archiving to allow instant access to the article and associated supplementary documents for each user.   Archiving   Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.   Plagiarism Policy   The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process.   Open Access License   This journal provides immediate open access to its content under the Creative Commons BY 3.0 license. Authors who publish in this journal agree to the terms of the Creative Commons BY 3.0 license. 

Acta Scientifica Naturalis

Volume 10 (2023): Issue 1 (March 2023)

Editorial Note: Rhodopes Mountains - a fairy tale in green – Part I (Eastern Rhodopes)

Thermodynamic solid-liquid equilibrium model for mixed systems HF-NaF-H2O and HF-KF-H2O up to 2 m HF at T = 25^oC

Potential health benefits of the plant Levisticum officinale (lovage) in relation to its polyphenolic content

Opuntia fragilis (Nutt.) Haw. (Cactaceae) in the Bulgarian flora

Learning for sustainability - competences and expectations

Green infrastructure - the smart interpreting of natural capital

Protected areas in the Stara planina tourist region – current state and prospects for tourism development

Tourism in Varna Black sea area – current situation and prospects for development

Tourism as a prerequisite for changing the national identity

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