Upper Silesia Research Articles

Spatial and Temporal Volatility of PM2.5, PM10 and PM10-Bound B[a]P Concentrations and Assessment of the Exposure of the Population of Silesia in 2018-2021.

Air pollution both indoors and outdoors is a major cause of various diseases and premature deaths. Negative health effects are more frequently observed in a number of European countries characterized by significant pollution. In Poland, especially in Upper Silesia, the most serious problem is the high concentration of particulate matter (PM) and PM10-bound benzo[a]pyrene (B[a]P). The main source of these two pollutants is so-called "low emissions" associated with the burning of solid fuels mainly in domestic boilers and liquid fuels in road traffic. This study examined the variability in the PM and PM10-bound B[a]P concentrations and their relationships with meteorological parameters, i.e., atmospheric pressure, air temperature and wind speed, in 2018-2021 at 11 monitoring stations. In many Silesian cities, the average annual concentrations of PM10, PM2.5 and B[a]P were much higher than those recorded in other European countries. At each station, the average daily PM10 concentrations were exceeded on 12 to 126 days a year. Taking into account the WHO recommendation for PM2.5, the highest recorded average daily concentration exceeded the permissible level by almost 40 times. The same relationships were observed in all measurement years: PM10 concentrations were negatively correlated with air temperature (R = -0.386) and wind speed (R = -0.614). The highest concentrations were observed in the temperature range from -15 °C to -5 °C, when the wind speed did not exceed 0.5 m·s-1. The calculated lifetime cancer risk (LCR) associated with the exposure to B[a]P in the Silesian Voivodeship suggested 30-429 cases per 1 million people in the heating season depending on the scenario used for the calculations (IRIS, EPA or WHO).

Factors influencing the temporal variability of atmospheric methane emissions from Upper Silesia coal mines: a case study from the CoMet mission

Abstract. Methane is a powerful greenhouse gas responsible for around 20 % of radiative forcing (relative to the pre-industrial era) caused by all long-lived greenhouse gases (WMO, 2021). About 60 % of the global emissions are from anthropogenic sources, and coal mining is one of the largest contributors. Emissions are either estimated by bottom-up approaches (based on inventories) or top-down approaches (based on atmospheric measurements). Combining those with an accurate error estimation allows us to better characterise model errors e.g. caused by transport mechanisms. Here we provide a detailed description of factors influencing the coal mine methane emission variability. We use high-frequency (up to hourly) temporal data from seven coal mines in the Upper Silesian Coal Basin during the Carbon dioxide and Methane (CoMet 1.0) mission from 14 May to 13 June 2018. Knowledge of these factors for the individual ventilation shaft is essential for linking the observations achieved during the CoMet 1.0 mission with models, as most publicly available data in the bottom-up worldwide inventories provide annual emissions only. The methane concentrations in examined shafts ranged from 0.10 % to 0.55 %±0.1 % during the study period. Due to the changing scope of mining works performed underground, they were subjected to a significant variation on a day-to-day basis. The yearly methane average emission rate calculated based on 1 month's set of temporal data of the analysed subset of mines was of the order of 142.68 kt yr−1 (σ=18.63 kt yr−1), an estimate 27 % lower than the officially published State Mining Authority (WUG) data and 36 % lower than reported to the European Pollutant Release and Transfer Register (E-PRTR). We also found that emissions from individual coal mine facilities were over- and underestimated by between 4 % to 60 %, compared to the E-PRTR, when short-term records were analysed. We show that the observed discrepancies between annual emissions based on temporal data and public inventories result from (1) the incorrect assumption that the methane emissions are time-invariant, (2) the methodology of measurements, and lastly, (3) the frequency and timing of measurements. From the emission monitoring perspective, we recommend using a standardised emission measurement system for all coal mines, similar to the Methane Fire Teletransmission Monitoring System (SMP-NT/A). Legal safety requirements require all coal mines to implement this system. After an adaptation, the system could allow for gas flow quantification, necessary for accurate and precise estimations of methane emissions at a high temporal resolution. Using this system will also reduce the emission uncertainty due to factors like frequency and timing of measurements. In addition, it would be beneficial to separately identify the emissions from individual ventilation shafts and methane drainage stations. That would bridge the gap between bottom-up and top-down approaches for coal mine emissions. The intermittent releases of unutilised methane from the drainage stations are currently not considered when constructing regional methane budgets.

Silesian Language or Dialect: Why Do We Need a Standard?

The article’s goal is to reflect on the history of the regional identity of the Upper Silesian region of Poland. Although historical, political, and cultural aspects are considered, the focus is on the linguistic dimension, since language is one of the most important elements of collective identity. The article opens with a short historical overview, starting with the period of the Industrial Revolution, which was the crucial moment for the formation of the so-called Upper Silesian mixed code which is the subject of reflection in this article. Next, we analyse the status of the Silesian ethnolect and the possibility of raising it to the rank of a regional language. The investigation is conducted from the point of view of Polish linguistics, but based on a wider perspective of European minority language politics.

„Verblassen des Staatsgedankens“ und „Totengesang“: Gesundheitskrise und Spanische Grippe in Oberschlesien

Upper Silesia was characterized by the struggle between two conflicting national movements, German and Polish/Silesian, the dominance of the Catholic Church and the accelerated industrialization since the second half of 19th century. It experienced a fast population growth, accompanied by the spread of infectious diseases. The First World war caused even more social disturbances and finally led to the erosion of the state’s legitimacy. In autumn 1918 the more serious second wave of the Spanish Flu caused death and severe illness. The provincial administration mostly stood by its own and struggled with the identification of the disease and the collection of verifiable numbers.

Udział Kościoła w odbudowie niepodległej Polski

During the partitions of Poland, the Catholic Church took care of Polish history and tradition. Moreover, during the First World War, the clergy asked themselves what ways should be followed to regain freedom and what the new state would look like. The Church was closest to the program of the National League (later National Democracy) of Roman Dmowski. The priests not only served as moral and charitable help, but also served as chaplains in the newly-formed army, including Pilsudski’s legions, the army of General Józef Haller and the Polish Rifle Division. They also undertook political activities, eg the Primate of the Kingdom of Poland, Archbishop Aleksander Kakowski, became a member of the Regency Council, and a number of clergymen became members of the Legislative Sejm. The church also played an important role during the struggle for the unification of Polish lands and the borders of the reborn homeland, which lasted for six years. The priests got primarily involved in propaganda activities, supporting the Wielkopolska Uprising and plebiscite activity in Warmia and Mazury (East Prussian plebiscite) as well as in Upper Silesia and Cieszyn Silesia. The entire nation was involved in regaining independence, but the Catholic Church was a part that played a special role in that process.

Stratigraphy and Sedimentary Record of the Ordovician System in Poland: a Review

Abstract This report provides insight into the main stratigraphic and sedimentary aspects of the Ordovician System in major tectonic units of Poland: (1) East European Craton, (2) Pomeranian Block, (3) Łysogóry Block, (4) Małopolska Block, (5) Upper Silesian Block, and (6) the Sudetes. The first studies of the Ordovician rocks in Poland were conducted as early as the second half of the nineteenth century in outcrops of the Holy Cross Mountains (SE Poland). Moreover, the Ordovician rocks are exposed in the Sudetes, where they are incorporated into the tectonostratigraphic units accreted during the Variscan orogeny. Significant progress has been made since the 1950s in the recognition of the Ordovician stratigraphic and facies architecture due to numerous drilling cores, which have been mostly made in NE Poland (East European Craton). The temporal and spatial facies pattern in the Polish part of the East European Craton indicate that in the Early and Middle Ordovician this area was a part of large, epicontinental carbonate platform replaced in the Late Ordovician by fine-grained clastics of distal shelf. The Ordovician sedimentary record in the Łysogóry and Małopolska blocks (SE Poland) reveals numerous similarities to the facies architecture in the neighbouring East European Craton, especially its marginal localities. Thus, it is possible to distinguish the same eustatic events in these units corresponding to sea-level changes reported in Baltica, although locally a regional tectonic activity masked their effects. The evolution of the sedimentary basin in NW Poland (Pomeranian Block) was influenced by the collision of Baltica with Avalonia in the Late Ordovician, which resulted in the development of the Caledonian fold-and-thrust belt.

Deep-lying sites of the house-cricket Acheta domesticus (Linnaeus, 1758) (Orthoptera: Gryllidae) in coal mines in Upper Silesia (Poland)

The report provides information about the occurrence of the house-cricket Acheta domesticus in 2021 in the area of the hard coal mines "Budryk" (Ornontowice) and "Pniówek" (Pawłowice). The species was recorded at depths of 900, 1050 and 1290 m ("Budryk") and 1050 m beneath the surface ("Pniówek"). The information provided testifies high adaptability of the species and encourages its search in other Polish mines.

Resentment Barriers to Innovation Development of Small and Medium Enterprises in Upper Silesia

The first aim of the article is to diagnose the barriers of agency (including resentment ones) that occur during the implementation of innovations in the selected Silesian small and medium-sized enterprises. The second goal is to explain how the structural and cultural resentment contexts and the type of reflexivity undertaken by the employees determine an innovative activity in the state of morphostasis (contextual continuity) and morphogenesis (contextual discontinuity) at selected companies. The theoretical basis of the research is Margaret Archer’s morphogenetic theory of structure and agency and her scheme of causal analysis. Based on this and using the qualitative analysis of data obtained during focus group interviews (FGI), a diagnosis is made regarding the presence of agency barriers in the innovation processes. A morphogenetic causal analysis of the emergence of agency barriers limiting the course of innovation processes in a business reality burdened with resentment contexts has been presented. On the theoretical and empirical level, the usefulness of the morphogenetic schema in the study of organizational behavior in small and medium enterprises was verified. Conducting diachronic causal analyzes among employees of selected SMEs made it possible to show the conditions between the scope of the existing resentment barriers (structural and cultural), the type of dominant reflexivity among their members, and the possibilities of innovation in these organizations. It has been shown that in organizational contexts burdened with group resentments, the agency of staff is mainly morphostatic. The dominant type of reflexivity (communicative, not autonomous) is focused on maintaining the existing contextual continuity and not on changing it. The results obtained from the research will allow the implementation of educational and implementation projects (research in action) in the future, adequate to the needs of the small and medium enterprise sector in terms of eliminating resentments in the structure and organizational culture. These aims will be implemented through the participation of external expert groups in the following areas of innovation of a given company: pro-innovative attitudes, competencies, processes, and strategies, perception of the environment, customer orientation, or branding.

Application of long-reach directional drilling boreholes for gas drainage of adjacent seams in coal mines with severe geological conditions

This study aimed to demonstrate the application of Long Reach Directionally Drilled Boreholes (LRDD) for gas drainage of adjacent seams before and during the longwall face operations of low permeability-high gas content coals Staszic-Wujek Hard Coal Mine in the Upper Silesia Coal Basin (Poland). Five LRDD Boreholes (TM1a-TM5) with a length of 300 and 400 m were located over coal seam 501 in the fractured zone and monitored over six months of longwall face operations. LRDD Boreholes were combined with Cross-Measured Boreholes. Reservoir characterization and geological modeling supported the results obtained from gas drainage. The drainage efficiency of LRDD Boreholes was the approximately 70% level, while conventional Cross-Measured Boreholes were only 30%. The highest goaf gas quality (94% methane concentration) was reported for TM4, placed at an average elevation of 41 m above coal seam 501. The highest goaf gas production (average 6.2 m3/min) was reported for LRDD Borehole TM3. This borehole was placed within the fracture zone (average elevation of 24.4 m) and drilled through the sandstone lithotype with the best reservoir properties, enhancing drainage performance. LRDD Boreholes TM2 and TM4 achieved similar performance. These three LRDD Boreholes were drilled close to the maximum principal horizontal stress direction, providing borehole stability during under-mining. The lowest goaf gas production was reported for LRDD Boreholes TM1a and TM5. Both Boreholes were placed in the rubble zone.

Twenty years of coal mining-induced subsidence in the Upper Silesia in Poland identified using InSAR

The paper presents the results of terrain subsidence monitoring in Poland’s Upper Silesian Coal Basin (USCB) mining area using Differential Interferometry Synthetic Aperture Radar (DInSAR) and Persistent Scatterer Interferometry (PSI). The study area accounts for almost three million inhabitants where mining which started in the 19th century, has produced severe damage to buildings and urban infrastructures in past years. The analysis aimed to combine eight different datasets, processed in two techniques, coming from various sensors and covering different periods. As a result, a map of areas that have been exposed to subsidence within 3045 square kilometers was obtained. The map covers a period of twenty years of intensive mining activities, i.e. 1992–2012. A total of 81 interferograms were used in the study. The interferograms allowed not only to determine subsidence troughs (basins) formed from 1992 to 2012 but also to observe subsidence development over time. The work also included five sets of PSI processing, covering different temporal and spatial ranges, which were used to determine zones of residual subsidence. Based on InSAR datasets, an area of 521 square kilometers under the influence of mining activities were determined. Within the subsiding zones, an area of 312.5 square kilometers of the rapid increase in subsidence was identified on the interferograms. The study of combined different InSAR datasets provided large-area and long-term information on the impact of mining activities in the Upper Silesia Coal Basin.

Seismic activity and flooding of hard coal mines in the Ostrava-Karvina Coalfield

The termination of mining activities often results in post-mining problems and risks. One of these issues is the flooding of mines. Long-term mining in the Ostrava and Petrvald sub-basins in the Upper Silesian Coal Basin finished in 1994. Tens of coal seams were mined here, and the depth of mining reached more than 1000 m below the surface. Flooding of the Ostrava sub-basin started in 1994. The Ostrava and Petrvald sub-basins were flooded from one half only to prevent water from flooding into the Karvina sub-basin, where mining continued. The continual pumping of water has been carried out ever since. Only low-energy seismic events (up to 103 J) were recorded during the periods of flooding and water pumping. Only one high-energy seismic event was recorded here (108 J, magnitude of 3.5, 12 December 2017). This study presents the natural and mining conditions regarding the process of mine flooding; and the induced seismicity registered during the flooding of mines and the preservation of water at the stated level. Analysis of the flooding of mines in connection to the registered seismicity is presented. Probable reasons for the low seismic activity during the flooding of mines are also discussed.

Tree-ring records of surface displacements in a coal-mining subsided region and their links to hypsometric changes and extreme precipitation

Tree-ring records from sites affected by underground mining provide valuable data on the long-term development of subsidence troughs. However, due to complexity of local conditions, it is unclear whether the surface displacements are actually the result of mining operations or shallow landslides caused by extreme rainfall. This paper compares surface movements at two nearby sites in the Upper Silesian Coal Basin (Central Europe) that have been affected by underground coal mining. Dendrogeomorphic data on subsidence-related movements were obtained from 360 increment cores (90 trees) of European larch (Larix decidua Mill.). Subsidence between 1966 and 2013 was calculated from the corresponding digital elevation models and the actual morphometric parameters of the sites were related to tree-ring records. The effect of precipitation on surface displacements was evaluated using logistic regression models incorporating rainfall data from a nearby meteorological station and dendrogeomorphic event years. The subsidence at the edges of subsidence troughs (study sites) between 1966 and 2013 reached 4–9 m, which is relatively low compared to nearby (5 km radius) directly undermined sites with subsidence up to 22 m. Most events were dated to the 1930s, 1970s, 1990s, and late 2000s with a peak of activity in 1973 and other noteworthy events in 1986, 1995, and 2009. Event years at the site with a flatter topography, and more waterlogged and clay soils are well explained by higher triennial precipitation and higher Simple daily intensity index, suggesting a possible influence of near-surface displacements on the chronology of recorded events, whereas the elevated site with step-block topography showed no relationship between precipitation extremes and event years. We concluded that not only the time of mining operation, but also the site-specific conditions are crucial for characterization of surface displacements in the forested post-mining landscape.

Development and actualization of brownfields database with the use of unmanned aerial vehicles - the case of Upper Silesia, Poland

This paper presents the assumptions and the preliminary results of the project entitled “Extension of the system for management of post-mining areas in the Silesian province - OPI TPP 2.0”. The overall objective of the project is to develop and implement a new e-service in the form of an open-access information system on post-mining areas in the Silesia Voivodeship. The range of information and tools planned to be made available is dedicated to assessing the possibilities and potential for economic and social reuse of these areas. The basic and extremely important stage of the project was to identify and collect data on post-industrial sites located in the Silesia Province. The information contained in this article illustrates the activities that were carried out in the initial phase of the project in which unmanned aerial vehicles (UAV) were used to identify and acquire information on brownfields (including post-mining sites) entered into the developed common database. The article assesses the possibility of using drones in an enterprise of such a large scale and also points out the advantages of using this method. The article describes the methodology and scope of work related to the acquisition of data that can be collected using unmanned aerial vehicle (UAV) covering surface infrastructure and land use of brownfields, allowing for the identification of negative phenomena on their site as well as monitoring of naturally occurring processes. Based on fieldworks experience and the results of numerous analyses carried out for different types of brownfields (e.g. post-mining areas, former transport bases, settling ponds, etc.), paper presents the advantages and benefits of drones (UAN) over other data sources used to monitor changes in an area. The article is based on the results of an inventory of over 600 brownfields located in Upper Silesia region (Silesia Voivodeship, Poland).

Silesia – Silentium: Silesian Women in Anna Dziewit-Meller’s Prose

This article aims to present the image of the Silesian women emerging from the novels by Anna Dziewit-Meller (Góra Tajget [Mount Taygetus], Od jednego Lucypera [All Because of One Lucifer]). The analysis and interpretation focused on the category of silence inscribed in the studied text allow the author to draw conclusions about the complicated family relationships of women, marked by the twentieth-century history of Upper Silesia. In the article, the author posits a thesis about silence as an immanent trait of Dziewit-Meller’s protagonists, and asks whether they have a chance of breaking out of the circle of traumas passed down in their families.

Atmospheric deposition and trajectories of antimony in Central Europe

Antimony (Sb) concentrations were measured in wet atmospheric deposition at 10 high-elevation sites in the Czech Republic (Central Europe) during three winter seasons (2009–2011). Soluble and insoluble Sb forms were quantified in snow (vertical deposition) and rime (horizontal deposition) on mountain summits located equidistantly near the Czech borders with Austria, Germany and Poland. The highest Sb concentrations were found in the soluble form in rime (0.47 μg L−1), while the lowest Sb concentrations were those in the insoluble form in snow (0.017 μg L−1). The estimated average Sb deposition rate in Central Europe amounted to 1.3. 10−4 g m−2 yr−1. Most Sb was deposited in the soluble form in snow (7.9. 10−5 g m−2 yr−1), followed by the soluble form in rime (3.5. 10−5 g m−2 yr−1). The corresponding insoluble fraction contained less Sb, namely 1.2. 10−5 g m−2 yr−1 in snow and 2.3. 10−6 g m−2 yr−1 in rime. The average Sb deposition in Central Europe, measured at an altitude of 1000 m a.s.l., was by six orders of magnitude higher compared to Sb deposition in the Arctic (7. 10−10 g m−2 yr−1), and by four orders of magnitude lower compared to Sb deposition in a Sb–Hg mining district in China (7 g m−2 yr−1). Using the HYSPLIT model, backward trajectories of air masses indicated that the Sb sources were predominantly situated in Upper and Lower Silesia.

Mineralogy of the coal waste dumps from the Czech part of the Upper Silesian Basin: Emphasized role of halides for element mobility

Both unburning and burning coal mine dumps present serious hazards to the natural environment and human health. Bituminous coal has been produced in the Czech part of the Upper Silesian Basin since 18th century, with total production over 100 million metric tons of waste material (barren rock) deposited in dumps. Today, each dump has undergone remediation and reclamation works, and many of them were totaly removed. Only three dumps with signs of thermal activity (burning) remain, with the Heřmanice dump as the most important. The powder X-ray diffraction (XRD) in combination with electron dispersive spectroscopy (EDS) and backscattered electron (BSE) imaging were applied to identify and describe the products of both unburning and burning dumps. The ones without thermal activity released mostly sulfates such as jarosite group minerals, hexahydrite, ferrohexahydrite, gypsum, thenardite, konyanite, and baryte due to pyrite weathering processes, accompanied by ferrihydrite, schwertmannite, goethite, and aragonite. As expected, the mineral associations of thermally active dumps were more variable. Apart from hot gas vent products such as sulfur, salammoniac, and cryptohalite, we identified a zoned sulfate cap (crust) with an accumulation of newly formed phases (e.g., aluminopyracmonite, pyracmonite, godovikovite, mascagnite, koktaite, boussingaultite, and clairite). Both the gas vents and sulfate crust contained a number of rare and exotic phases, such as Bi, bismuthinite, demicheleite-(Br), demicheleite-(I), fluorite, selenium, NH4Br, NH4I, BiOCl, BiBr3, BiI3, native iodine, CdS, CdIn2S4, (NH4,K)AlF4, (NH4,K)3AlF6, Ce-dominant REE-sulfate, and others. Since coal ash and barren rock are not geochemicaly anomalous, the presence of such various phases could be atributed to the very effective leaching and transport of chemical elements by halide elements, which originated in brines in the roof of the Carboniferous rocks circulating in the strata prior to extraction and emplacement in the dump. This mineralization is to a great extent similar to that of natural volcanic vents, and must be studied by specific methods (low-vacuum electron microscopy with energy-dispersive detectors, use of natural unpolished samples). The composition of altered rock clasts within the dumps was monitored only occasionally, but newly formed feldspars (probably sanidine, albite, andesine), hematite, diopside to hedenbergite, cordierite, magnetite-magnesioferrite minerals, anhydrite, TiO2 microcrystals, Mg-rich fayalite, and in case of more intensively burnt rocks also wollastonite, barium feldspar (celsian-hyalophane series), and a phase of Ca-SiO4-PO4 system were also observed. It is clear that the burning of coal dumps presents a specific problem, and future steps towards understanding their potential environmental risks would require complex studies including the determination of their mass and chemical element balance, the estimation of the dump volume affected by the thermal mobilization of chemical elements, and the migration pathways of the potentially-hazardous elements. However, it is clear that the most problematic part incudes just the few uppermost meters with vents of hot gases and the sulfate cap, which are readily soluble in water after the end or lateral shift of burning.

Monitoring Subsidence Area with the Use of Satellite Radar Images and Deep Transfer Learning

Subsidence, especially in populated areas, is becoming a threat to human life and property. Monitoring and analyzing the effects of subsidence over large areas using in situ measurements is difficult and depends on the size of the subsidence area and its location. It is also time-consuming and costly. A far better solution that has been used in recent years is Differential Interferometry Synthetic Aperture Radar (DInSAR) monitoring. It allows the monitoring of land deformations in large areas with high accuracy and very good spatial and temporal resolution. However, the analysis of SAR images is time-consuming and involves an expert who can easily overlook certain details. Therefore, it is essential, especially in the case of early warning systems, to prepare tools capable of identifying and monitoring subsidence in interferograms. This article presents a study on automated detection and monitoring of subsidence troughs using deep-transfer learning. The area studied is the Upper Silesian Coal Basin (southern Poland). Marked by intensive coal mining, it is particularly prone to subsidence of various types. Additionally, the results of trough detection obtained with the use of convolutional neural networks were compared with the results obtained with the Hough transform and the circlet transform.

Revision of the Carboniferous medullosalean prepollen organs from the Upper Silesian Basin (Czech Republic)

Seven species of medullosalean prepollen organs were distinguished following a revision of the collections in the Ostrava Museum: Givesia media (Stockmans) Stockmans et Willière, Kotasotheca annaadamii Pacyna et Zdebska, Whittleseya cf. brevifolia White, W. concinna Matthew, W. dawsoniana White, W. delphinae Stockmans et Willière and W. desiderata White. All the specimens came from the Carboniferous (Yeadonian and Langsettian) Karviná Formation, Saddle, Suchá and Doubrava members. Prepollen grains are elliptical in outline, and have a single suture on the proximal surface, ornamented distally by two longitudinal grooves. These prepollen grains are assigned to Monoletes ovatus Schopf and were isolated from specimens of Whittleseya concinna, W. delphinae and W. desiderata. Different species have different prepollen size: Whittleseya concinna – 155–208 μm, W. delphinae – 198–228 μm, and Whittleseya desiderata– 195–288 μm long. Large prepollen grain size variability was probably because the four studied prepollen organs were of different stages of maturity. No attached fructifications were found, but based on evidence of association Whittleseya concinna probably belonged to Neuralethopteris larischii foliage, and Whittleseya desiderata to Neuropteris obliqua foliage. The other studied fructifications were not accompanied by pteridosperm foliage. Whittleseya delphinae and W. elegans have been considered as synonyms by some authors (Pacyna et Zdebska, 2010) but this problem may be resolvable by cuticular study.

A Method for the Identification of Critical Interstop Sections in Terms of Introducing Electric Buses in Public Transport

Among the activities that cities are taking to reduce the emissions of harmful substances emitted by conventional engine-powered vehicles is replacing the fleet with electric vehicles in public transport that can operate in urban areas. Fleet conversion is a process in which one of the decisions that must be made is the choice of lines that should be served in the first place by electric buses. Due to the specificity of the battery charging process, the routes of lines serviced by electric vehicles should run through sections that are as little exposed to disruptions as possible, which can adversely affect the travel time of these sections. The main goal of the article was to develop a method that supports the search for bus lines that are characterized by the highest level of reliability and punctuality and therefore also by the stability of the travel time between stops. The proposed method makes it possible to indicate critical interstop sections that have the greatest impact on the sensitivity of the line to disturbances. It was assumed that the more critical sections of the route, the greater the risk of bus delay, which may be disadvantageous in the case of electric vehicles due to the need to reach the battery charging station in time. The method was implemented on the example of selected lines in the Upper Silesian region (Poland) for data covering four years (2016–2019). The proposed approach allowed for the development of the ranking of lines, corresponding to the order in which the conventional fleet should be changed to electric.

Mercury and methylmercury in Baltic Sea sediments, and Polish and Lithuanian soils

We review the current environmental pollution by mercury in the soils of Poland and Lithuania and in the sediments of the Baltic Sea. Mercury is documented to have many negative impacts on the environment as a toxic trace element. In many different chemical forms, it is being released into the environment by both geogenic and anthropogenic activities, with most being released from anthropogenic sources. Methylmercury is considered one of the most toxic forms found in the environment. Mercury levels in sediment and various point sources increased after World War II in the Baltic Sea, which was used as a dumpsite. Previous studies show noticeable differences in total mercury in the Baltic Sea. In the Warta and Odra rivers in Poland, mercury levels are also higher than the background value, though recent findings suggest that river sediments are not the main source of mercury to marine sediments. Concentrations in soils in Poland and Lithuania were below the level of limit values (1 and 1.5 mg/ kg −1 respectively), but Upper Silesia showed concentrations (up to 4.01 mg·kg −1 ) above the limit values. Furthermore, between 1992 and 2006, mercury levels in Wrocław dropped dramatically. The dominant trees in the area can affect mercury accumulation. No data were available for comparison with the soils in Estonia and Latvia.