The changes in land use and land cover (LULC) are among the primary drivers of global environmental changes in many developing countries. In this study, LULC changes were assessed on Phu Quoc Island, located in Kien Giang province, Vietnam, from 2001 to 2022. The study utilized remote sensing and Geographic Information System (GIS) technology using Landsat images for the years 2001, 2009, and 2022. Image classification for each year was conducted through supervised classification using a maximum likelihood classifier, with the main LULC classes being forests, bare land, agricultural areas, water bodies, and built-up areas. The accuracy of the classification was evaluated using the kappa coefficient, achieving values consistently above 0.8 for all three images. Over the 20-year period (2001-2022), the area of forest, agriculture, and water bodies decreased by 14.90 km2, 30.96 km2, and 0.64 km2, respectively. Meanwhile, the areas of bare land and built-up areas increased by 22.22 km2 and 24.28 km2, respectively. Additionally, this study employed the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Built-up Index (NDBI) to quickly assess LULC changes, obtaining results consistent with the supervised classification. The findings underscore the importance of closely monitoring LULC changes to facilitate effective natural resource management and maintain a sustainable environment.

The present paper considers the results of long-term (up to 17 years) in situ and laboratory research carried out on oiled French, Spanish, and Russian seacoasts. The objective of this research is to quantify the influence of geographical factors on the rates of natural transformation of the heavy fuel oil stranded ashore and to develop an empirical statistical model in order to evaluate the self-cleansing capacity of the coastal environment. In a number of field campaigns, 363 samples of weathered oil slicks and tar balls have been collected and analysed with the use of thin-layer chromatography combined with optical and gravimetric methods. The results obtained have been subjected to multiple nonlinear regression analyses. It has been shown that heavy fuel oil natural attenuation is more active in continental or estuarine environments influenced by nutrient-rich freshwater runoff and characterised by a higher number of sunny days, solar irradiation, and large temperature fluctuations. On the oceanic coasts, especially in sectors with low hydrodynamic energy, these processes take more time. The resulting model allows for the identification and mapping of the most vulnerable seacoasts, characterised by a low potential to degrade oil pollution. This information may be used in the contingency plans in order to optimise clean-up techniques and associated costs.

In recent decades, numerous oil spills have occurred worldwide and affected coastal environments. In the present paper, we analysed the results of long-term (up to 18 years) field and laboratory studies of temporal changes in the quantity and composition of oil slicks and tar balls in different geographical environments polluted by spilt fuel oil, including the Atlantic coasts of France and Spain, the coasts of the Sea of Azov and the Black Sea in Russia. The empirical statistical model developed in this research allowed us to identify the most significant environmental parameters during the oil pollution transformation process. We used these parameters to evaluate the potential rates of natural degradation of spilt oil stranded ashore and to develop a cartographic model. This is the first time a study offers quantitative maps of the potential of spilt oil natural transformation rates. These maps can be used to identify the most vulnerable seacoasts and to optimise the clean-up techniques.

The majority of researches of the Working group on the ‘Anthropocene’ of the International Commission on Stratigraphy (ICS) voted for the recognition of the Anthropocene as a formal chrono-stratigraphic unit characterized by profound alterations of several conditions and processes on Earth by human impact. It is also proposed to place its beginning and the end of the Holocene epoch in the mid-20th century, coinciding with the launch of nuclear weapon tests [1]. In contemporary sediment cores of the Sea of ​​Azov, the Don and the Kuban rivers, we will distinguish a "layer of anthropogenic impact", meaning the layer containing considerable quantities of technogenic material and (or) pollutants [2]. To reveal the chronology of its formation, its thickness, and boundaries, it is proposed to use the results of layer-by-layer determining of the Cs-137 and Am-241 specific activities, as well as the content of oil components, lead and mercury in the bottom sediments of the water bodies. The upper Cs-137 peak formed due to the Chernobyl accident and sometimes the lower Cs-137 and Am-241 peaks related to the global radioactive fallout in the 1950s and 1960s have been detected [3]. The decrease of mercury, lead, and oil components concentrations from the upper to the lower parts of sediment cores has also been observed. The results of analysis of technogenic radionuclides and priority pollutants distribution have proved that since the 1950s and 1960s in the bottom sediments of the Sea of ​​Azov and water bodies of its basin the “layer of anthropogenic impact" has been being formed. Its thickness varies from 20 to 50 cm and may even exceed 50 cm in areas characterized by high sedimentation rates. It has been found out that in the mid-20th century the ecosystem of the Sea of ​​Azov began to suffer from intense anthropogenic pressure, which reached its maximum in the 1970s and 1980s. It is proposed to consider the studied pollutants (technogenic radionuclides, mercury, lead, and oil components) as a possible set of priority markers of the Anthropocene epoch. The Holocene - Anthropocene boundary should be placed at the base of the identified “layer of anthropogenic impact”. The research was supported by the Russian Foundation for Basic Research, project no. 19-05-50097. Bibliography [1] Working Group on the ‘Anthropocene’. Results of binding vote by AWG. http://quaternary.stratigraphy.org/working-groups/anthropocene/ (last accessed 17 January 2021). [2] Kuznetsov A.N., Fedorov Yu.A., and Yaroslavtsev V.M. (2018) Technogenic and natural radionuclides in the bottom sediments of the Sea of Azov: regularities of distribution and application to the study of pollutants accumulation chronology. IOP Conference Series: Earth and Environmental Science 107, 012063. [3] Fedorov Yu.A., Kuznetsov A.N., and Trofimov M.E. (2008) Sedimentation rates in the Sea of Azov inferred from Cs-137 and Am-241 specific activity. Doklady Earth Sciences, vol. 423, no. 1, pp. 1333-1334.

The paper examines the results of twelve-year (2007 to 2019) observations of spatial distribution and temporal changes in the concentrations of petroleum components in the coastal waters and sediment cores, as well as in the quantity and composition of oil slicks and tar balls on the beaches, cliffs and solid constructions of the Black Sea coast in the area of the city of Novorossiysk, which is the most important oil seaport of Russia, and in the Kerch Strait. 165 samples of seawater, 24 sediment cores up to 50 cm long split layer-bylayer into 108 samples, and 102 samples of oil slicks and tar balls were taken and analyzed with the use of thin layer and column chromatography, optical and gravimetric methods. The evidences of high level and chronic character of oil pollution of the studied coastal sectors are presented. Much attention is given to the dynamics of the natural transformation of oil slicks and tar balls found on the shore. It is shown that over time, under the influence of natural factors of attenuation, the oil slicks stranded ashore undergo an exponential decrease of the ratio between relatively labile hydrocarbons and conservative asphaltic components in their composition. The rate of the process may vary considerably depending on the size of oil pollution traces, their location on the coastal zone profile, as well as on the climatic, hydrological, and geomorphological conditions. An empirical statistical model is developed on the base of this data. This model makes it possible to classify and to map seacoasts according to their ability to degrade oil pollution using the information on the principal environmental parameters of attenuation.

The chapter considers the results of 12 years (2007–2019) of field observations examining spatial distribution and temporal changes in the quantity and composition of oil pollution traces on the beaches, cliffs, coastal waters, and sediment cores in the Black Sea coastal zone near the city of Novorossiysk and in the Kerch Strait, Russia. Novorossiysk is the most important oil seaport of Russia. The Kerch Strait is a significant transitory route for petroleum export and is an area where a huge fuel oil spill happened in November 2007. 165 samples of seawater, 246 samples of oil slicks, and 24 sediment cores up to 50 cm thick were taken and analyzed with the use of thin layer and column chromatography, together with optical and gravimetric methods. Evidence of high levels and the chronic character of oil pollution in the studied sector of the coastal zone are presented. Much attention is given to the analysis of distribution and dynamics of natural destruction of oil slicks found on the shore. Over time, the findings of this chapter demonstrate an exponential diminution of the ratio between the relatively labile and conservative components of those oil slicks. The rates of natural attenuation processes vary depending on the environmental factors (mainly thermohaline and hydrodynamic), as well as on the pollutant position in the coastal zone and its dispersity determining the contact area with seawater, fresh air, and substrate.

The article presents the results of work on dismantling the large installation equipment of Research Building B at the Bochvar High-technology Research Institute of Inorganic Materials (Bochvar Institute). The works were carried out as part of Building B preparation for decommissioning. The purpose of dismantling the large-sized capacitive equipment was to reconstruct the large installation site for managing radioactive waste generated during Building B decommissioning. The works on decommissioning a radioactively contaminated building within a densely populated district of megalopolis were carried out for the first time. The characteristics of the large-sized capacitive equipment are presented. Radioactive contamination of the capacitive equipment is determined by long-lived a-emitting isotopes: 235U, 238U, 239Pu. The sequence of works on dismantling the radiation-contaminated capacitive equipment includes preparatory work, dismantling the tank piping, localizing radioactive contamination of the external surface of the equipment as well as dismantling and moving it into a transport container. Dismantling and decontamination of the large-sized capacitive equipment was carried out by the Bochvar Institute Decommissioning Department. The following tools were used during the works: (1) a mobile foam decontamination facility to perform decontamination works and (2) a mobile high pressure facility to apply localizing and decontaminating film coatings. The tanks were dismantled by means of low-spark tools, i.e., reciprocating saws. Crane runways were made in order to move the dismantled equipment into transport containers: the movement was carried out with the help of a winch. The main results of dismantling and decontaminating the radioactively contaminated tanks are the dismantling of four units of long-length column-type equipment with heights from 4.2 to 6.4 m and 26 units of capacitive equipment (maximum capacity = 8 m3) as well as decontamination of the internal surfaces of radiation-contaminated equipment (decontamination factor = 25–70). As a result, the activity of the accumulated radioactive waste was reduced (the RW class was changed from 3 to 4). The main conclusion regarding the managment of large-sized radiation-contaminated tanks during Building B decommissioning is as follows: the works were organized and carried out at a high technical level, using modern decontamination and dismantling equipment and modern methods to ensure work safety at the Bochvar Institute site in the city of Moscow.

Bottom sediments formed in the water bodies under the technogenic impact are important environmental factors affecting water quality and hydrobiota. Usually they consist of natural and technogenic material and differ from natural formations by their morphology, chemical and lithological composition, physicochemical and biochemical properties. In the present paper we use the term “sediment layer of anthropogenic impact” to define the sediment layer containing technogenic material and/or chemical pollutants. The determination of its location in the sediment cores, its thickness and accumulation chronology is an important scientific problem. In the paper the results of layer by layer study of Cs-137, Am-241, Pb-210 specific activities as well as concentrations of petroleum components, lead and mercury in 48 sediment cores of the Sea of Azov and the Don River are examined. The sediment core layers are dated by radiological methods. In all the sediment cores the peak of Cs-137 specific activity related to the Chernobyl accident was detected. In the Sea of Azov, this peak is located in the upper sediment layer up to 10 cm thick, however, in the delta and in the near-delta part of the Don River, where the sedimentation rates are more important, it is found at 20 to 40 cm depth. Also in certain sediment cores the second peak of Cs-137 related to the global nuclear fallout of the 1960s was found. The most of petroleum components, lead and mercury quantities are concentrated in the upper sediment layer formed in the last 50 to 70 years, i.e. in the period of the most important anthropogenic pressure. So, this complex approach based on the data on the vertical distribution of technogenic radionuclides and common pollutants in the sediment cores made it possible to identify and delineate the sediment layer of high anthropogenic impact as well as to assess the duration of this impact.

The sea coasts are especially exposed to the oil pollution harmful influence as they frequently suffer from oil spills relating to the tanker accidents, port and off-shore activities. The objective of the present research is to examine the rates of spilled fuel oil natural destruction on geographically different seacoasts and to evaluate their relationship with principal environmental factors such as climatic and hydrological conditions, coast exposure and geomorphology, sediment types, intensity of biogeochemical cycles. For this purpose, a number of contaminated sectors of the Atlantic coasts of France and Spain (areas of “Erika” and “Prestige” tanker accidents), the Strait of Kerch (“Volgoneft-139” tanker accident) and the Black Sea coast in Russia (area of Novorossiysk sea port) were studied. Long-term (from 6 to 15 years) field observations were carried out there. The oiled samples were analyzed with the use of thin layer and column chromatography, optical and gravimetric methods. The results show that in the course of time, the oil slicks demonstrate an exponential diminution in their size, number and in the ratio of labile hydrocarbons content to conservative asphaltic components content. The half-period of this diminution varies from less than 1 to 12 years, subject to the forms of fuel oil traces and geographical conditions. On the Strait of Kerch coast washed by shallow, slightly salted and highly bio-productive waters of the Sea of Azov the spilled fuel oil tends to disappear twice as rapidly as on French and Spanish coasts of the Atlantic Ocean. The joint examination of the observed rates of oil pollution natural destruction and the geographical conditions of studied sites shows that temperature and seawater salinity are the crucial environmental factors of self-cleaning process.

It was known long ago that in certain sectors of the Sea of Azov and the Black; Sea coasts the beach sediments accumulate minerals (monazite and others) containing natural radionuclides U-238, Th-232, and their decay products. In these sectors often situated in the highly populated and resort areas the ionizing radiation intensity may be dozens of times higher than the normal background level. Among the sources of natural radionuclides in the studied area the coal dust and the products of fossil fuel combustion should also be mentioned. The Sea of Azov accumulates freshwater runoff from a vast drainage basin including not only the areas of radioactive minerals denudation, but also numerous on-land and underwater mud volcanoes, coal mines, petroleum extraction areas, and highly developed industrial centers. Therefore, the study of regularities of U-238, Th-234 and Th-232 specific activities distribution along the Don River - the Gulf of Taganrog - the Sea of Azov transect is of particular interest. In the Sea of Azov basin, a series of expeditions was carried out in the period from 2006 to 2010. The samples of water and sediment cores were taken and analyzed by the method of direct gamma spectrometry. In these samples the specific activities of natural (U-238, Th-232, K-40, Ra-226, Pb-210) technogenic radionuclides (Cs-137, Am-241), and such short-lived radionuclides as Th-234 (sic) Pb-212 were measured. It is shown that U-238, Th-232 and Th-234 specific activities increase both in water and superficial layer of bottom sediments in the direction: the Don River -> the Gulf of Taganrog -> the south-eastern part of the Sea of Azov. The role of different sources of the considered radionuclides in the system of the Sea of Azov drainage basin is to be specified in further investigations.

In the Sea of Azov a series of scientific expeditions were carried out. The samples of water and sediment cores were taken and analyzed by the method of direct gamma spectrometry in the Center of radioecology and technology of Southern Federal University. The sediment cores were extracted by a 1 m long metal coring tool and sampled layer-by-layer. For the first time the specific activities of U-238, Th-232, K-40, Ra-226, Pb-210, Cs-137, Am-241, and such short- lived radionuclides as Th-234. Pb-212 were measured in these samples. The regularities of lateral and vertical distribution of natural and technogenic radionuclides in the bottom sediments are revealed. The results of radioecological investigations of the Sea of Azov are considered. It is found out that in most sediment cores the Cesium-137 and Americium-241 specific activities show up two distinct peaks: one of them corresponds to the Chernobyl accident in 1986 and the other was formed by global radioactive fallout from above-ground testing of thermonuclear weapons in 1950s and 1960s. It is proved that since 1960s the Sea of Azov and its catchment area undergo the pollution by technogenic radionuclides transported due to the atmospheric circulation.

The paper is devoted to the comparative analysis of results of long-term field observations carried out on geographically different sea coasts contaminated by spilled fuel oil. Such investigations are of particular interest as they make it possible to assess the rates of oil pollution natural transformation as well as their correlation with principal geographical factors such as climatic and hydrological conditions, coast exposure and geomorphology, sediment types, intensity of biogeochemical cycles. For these purposes, the authors have chosen three zones where the accidental oil spills occurred in the last years: on the north-western coast of France (tanker “Erika” accident in December 1999; accident at an oil refinery in the Loire River Estuary in March 2008), on the north-western coast of Spain (tanker “Prestige” accident in November 2002) and in the Strait of Kerch (tanker “Volgoneft-139” accident in November 2007). The duration of long-term observations ranged from 5 to 13 years. The present investigation included visual assessment and sampling of oil slicks and sediment cores. The analysis of samples were carried out with the use of thin layer and column chromatography, optical and gravimetric methods making possible to determine separately the sum of saturated, mono- and di-aromatic hydrocarbons (HC), the sum of polycyclic aromatic hydrocarbons (PAH) and the sum of asphaltic components (AC) as well as the presence of hydrocarbons of contemporary biological origin. The obtained results show that even 10 to 13 years after the oil spills their weathered traces are still present in the coastal zone, especially in its upper part. In the course of time an exponential diminution in the oil pollution level and the ratio between hydrocarbons and asphaltic components (HC/AC) was revealed. In the studied cases, the half-periods of fuel oil natural transformation varied from 1 to 5 years. The highest activity of the self-cleaning process was observed for small fuel oil traces on the rocky substrate exposed to the influence of fresh air, solar radiation, storm waves and surf action. On the Strait of Kerch coasts influenced by shallow, slightly salted and highly bio-productive waters of the Sea of Azov the spilled fuel oil tends to disappear more rapidly than on French and Spanish coasts washed by the Atlantic Ocean.

The data given are the results of many-year studying the distribution of the concentrations of main oil components (hydrocarbons, surfactants, and asphaltene-tarry substances) in the water mass, vertically settling particulate matter, and bottom sediment cores taken from the section Lower Don-The Gulf of Taganrog-Russian sector of the Sea of Azov in summer and autumn periods in 2006–2011. Spatial and seasonal regularities in the distributions of the total concentration of oil components and the values of their ratios in water, as well as the spatial and annual features of their accumulation in bottom sediments have been established. Radiological methods have been used for layer-by-layer dating of bottom sediment cores and determine the thickness of the layer that had formed under the maximal anthropogenic impact on ecosystems. The presence of considerable amounts of hydrocarbons of modern biological origin has been revealed in all components of examined aquatic complexes.