Ecological Engineering and Environment Protection

Abstract: COVID-19 (declared as a pandemic by the WHO) has become a global health problem with serious economic consequences for more than 200 countries on six continents. The etiological agent SARS-CoV-2 is an RNA virus that is highly contagious and is transmitted mainly by airborne droplets, and not only symptomatic but also asymptomatic people are a source of infection. Currently, the prevalence and mortality are growing exponentially, which requires regular and mass testing with reliable tests to identify and isolate individuals infected with COVID-19.
Numerous scientific data have been presented confirming the ability of coronaviruses to adapt to new tissues and show sustainable tissue tropism, to overcome the evolutionarily constructed barriers of individual host animal species and to acclimatize successfully in different ecological niches. They clarify to a large extent the question of the origin of SARS-CoV-2 and support the hypothesis of its natural origin. COVID-19 is also seen in the light of the WHO's One Health concept, which makes it clear that human health is closely linked to animal health and environmental health.
The main epidemiological characteristics of Covid-19 are presented and emphasis is placed on standard methods of diagnosis and the urgent need for a vaccine and specific drugs for the control and prevention of this dangerous disease.
Keywords: COVID-19

INVESTIGATION OF ATMOSPHERIC RADIOACTIVITY IN BULGARIA IN APRIL 2020

Nina Nikolova, Dimitar Tonev, Elena Geleva, Dobromir Dimitrov, Hristo Angelov,Stefan Georgiev, Vladimir Bashev, Hristo Protohristov

Abstract. The present article describes a scientific study of the atmospheric radioactivity related to the fire that spread in the vicinity of the Chernobyl nuclear power plant in the beginning of April 2020. In the article are presented results from the measurements of natural and technogenic radioactivity of aerosol filters from the area of Musala Peak in the Base Ecological Observatory “Musala” and the gamma background on the territory of the Institute for Nuclear Research and Nuclear Energy at the Bulgarian Academy of Sciences and in the area of Musala Peak.
As a result from the processed data and the prepared analysis for the measured level of radioactivity in the period from 01.04.2020 to 20.04.2020, it could be reliably concluded that the fire in the area of the Chernobyl nuclear power plant did not lead to an increase in the level of radioactivity on the territory of Bulgaria.
Key words: Chernobyl nuclear power plant, fire, radioactivity, Musala Peak

FOREST FIRES IN BULGARIA
Alexander Alexandrov
Abstract: During the XX century there were three periods of forest fires in the country: First period - from the beginning of the century till fiftieth years when fires destroyed several dozens to hundreds dka of forests; Second period - from fiftieth years till 1991 when their number and area were significantly smaller and they nearly reached about 10 000 dka per year; Third period - after 1991, occupied with great forest fires. At the beginning of XX century appeared big fires - 270 000 dka (1903) predominantly in the Rhodope Mts., Rila Mt. and Pirin Mt. The forest fires in the last decade were extremely huge - 172 640 dka (1993), 142 530 dka (1994) and 574 060 dka (2000) (the biggest area). The new XXI century began with high levels of burned down forests: 201 520 dka (2001), 430 000 dka (2007).
Analyzing the percentages of forest fires per area unit for the period 2016-2020 it was found that in the state forests they were twice less than those of municipal and private forests. For the same period the percentage of forest fires due to negligence was 73.7%, followed by fires of unknown origin - 18.5%, with premeditation - 5.0% and by natural origin - 2.8%. The ground fires strongly dominated with 90.3 % while tree-top fires were 2.8%.
Key words: forest fire, natural disaster, ground fire, tree-top fire.

THE PROBLEM “SAFETY – SECURITY” IN THE FIGHT AGAINST FOREST FIRES

Hristo Tsakov, Olympia Roeva, Veselin Marinov, Dafina Zoteva, Alexandar Delkov

Abstract: Forest fires disrupt the structure of entire mountain areas, impair the forest protective functions, destroy flora and fauna, infrastructure, homes and sites affected by the fire.Economic and fire-fighting measures conducted to preserve the forest territories raise questions like “Are we doing things right? Are we doing the right things to prevent forest incineration?”.
The paper discusses the legal protection, the safety and the causes of forest fires, as well as the silvicultural, cultivation and firefighting activities and plans to reduce the risk, the damage and the loss of forest resources.
Keywords: forest fire, legal framework, forestry activities, causes of fires.

ECONOMIC IMPORTANCE OF THE PINE SAWFLIES FOR THE BULGARIAN FORESTS
Gergana Zaemdzhikova
Abstract. According to data of the Executive Forest Agency (EFA), during the period 2013-2019, the еconomic importance of pine sawflies for the Bulgarian forests was studied. On the report of the EFA, economically significant damage in the pine forests is mainly caused by Neodiprion sertifer, against which 78% of all attacks in the country are reported. Diprion pini is also found in small areas, which participates with 21% in the attacked area. The presence of the other two species Acantholyda hieroglyphica and Acantholyda erythrocephala is insignificant – less than 1%. Almost 100% of the control measures during the period were directed against N. sertifer and D. pini, against which almost all forest attacks were registered.
The attacked area by the pine sawflies is lower than that of the pine processionary moth, but their economic importance may be even greater, because they cause more severe damage. So far, there is no practical metod for determining the economic importance of pests in the country, but the experience of specialists from the State Forest Enterprises and Forest Protection Stations shows, that the pine sawflies problem may have been underestimated.
Key words: Diprionidae, Pamphiliidae, damage, pest control.

ASSESSMENT OF THE EDIFICATORY SPECIES CONVERTIBILITY IN TREE AND SCHRUB VEGETATION ON THE TERRITORY OF LOZENSKA MOUNTAIN
Abstract. The paper represents the final stage (Stage 3) of a series of studies related to the ecological-phytogeographic analysis of the Lozenska mountain dendroflora. The main edificatory species in the forest communities from the mountain territory were evaluated and compared in terms of their convertibility. The results show that the closest in value to the reference species are Carpinus orientalis Mill, Fraxinus ornus L. Quercus cerris L. and Quercus frainetto Arn. The classification of the species is evidence not so much of an established tendency for xerophytisation on the territory of the Lozenska mountain, but of suitable complex conditions for the increased invasiveness of the eastern hornbeam in the furrow and for the greater tolerance of the oaks to the changes of the environment.
Key words: dendroflora, adaptation, plasticity, ecological-phytogeographic analysis

Economic and ecological effects from wastewater use in agriculture
Bozhidar Ivanov, Svetla Marinova, Hrabrin Bachev, Veselka Georgieva
Abstract: The use of wastewater in agriculture is a technology known and applied worldwide for decades. It is considered to be one of the cheapest and appropriate ways of recovering waste from Wastewater Treatment Plants. At the same time, there are various issues related to the use of the sludge in agriculture, which concern environmental, production, sanitary, social aspects, along with also economic ones that are essential to achieve long-term practicing, relevance and usefulness. The aim of the study is to analyze and appraise the economic and environmental effects of the use of Wastewater Treatment Plans sludge in agriculture. The appraisal of economic effects is made on the basis of comparing the efficiency and effectiveness in the use of the two alternative methods of fertilization - with mineral fertilizers and with wastewater. The analysis shows that the economic results of wastewater treatment of maize are higher than those of mineral fertilizers, which allows the technological costs of obtaining sludge suitable for use in agriculture without changing the economic advantages of this practice over the basic one.
Keywords: economic efficiency, effectiveness, wastewater, agriculture, fertilization.

ATTEMPT TO ESTIMATE YIELD OF MAIZE WITH TEMPERATURES AND PRECIPITATIONS DURING VEGETATION PERIOD
Maria Ivanova, Alexander Sadovski
Abstract: The estimation of yields today is possible through many methods and models. In our study, we experimented on whether yields could only be assessed by the climatic characteristics of average monthly temperature and precipitations during the growing season. Many scientific papers look at changes in average yields, while there is a growing interest in yield variability due to extreme conditions. Using the fully fuzzy linear regression (FFLR) method, significant correlations were found in temperatures between April - August (T4 - T8) and June - July (T6 - T7), while no significant correlations were found in precipitation between April - September. The selected temperature and precipitation indicators can be considered almost independent in the regression analysis of maize yield. As a result of the application of the method for self-organization of models, two empirical regression equations with coefficients and statistical characteristics are obtained. Comparing the two models for estimating maize yield, it was found that Model 1 of the first empirical regression equations better described the actual yields. The two models are compared using the Akaike Information Criterion (AIC). A t-test was used to compare the mean maize yields and the results obtained from the center of the fuzzy regression solution. The results confirm the possibilities for using the method of completely fuzzy linear regression in the estimates of the yields response depending on the temperatures and precipitations during the vegetation period.
Key words: maize, estimating yields, temperature, precipitation, fuzzy linear regression

OBSERVATIONS ON CHANGES IN THE PARAMETERS OF THE “HOME” COMPOSTING PROCESS. PART 2 – CHEMICAL AND BIOLOGICAL PARAMETERS
Metodi K. Mladenov
Abstract: The subject of research in current development is the process of "home" composting of two main categories of bio-wastes: "green" and "brown", when composting them at "home" conditions. Sampling of the raw materials and the two compostable masses were carried out, differing in the type of brown waste incorporated into them, in order to observe the change in the content of the major nutrients (K, N, P) and C, and to determine the C/N ratio. The values of these elements and their changes during the composting process for both composts, were determined. The occurrence of various living organisms, which usually serve as an indicator of the proper occur of the composting process in the compost masses, has also been traced, and the concrete species are identified.
Key words: „home“ composting, major nutrients, ratio C/N, biological species

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