Unmanned systems provide significant prospects for improving the efficiency of electromagnetic geophysical exploration in mineral prospecting and geological mapping, as they can significantly increase the productivity of field surveys by accelerating the movement of the measuring system along the site, as well as minimizing problems in cases where the pedestrian walkability of the site is a challenge. Lightweight and cheap UAV systems with a take-off weight in the low tens of kilograms are unable to carry a powerful current source; therefore, semi-airborne systems with a ground transmitter (an ungrounded loop or grounded at the ends of the line) and a measuring system towed on a UAV are becoming more and more widespread. This paper presents the results for a new generation of semi-airborne technology SibGIS UAV-TEMs belonging to the “line-loop” type and capable of realizing the transient/time-domain (TEM) electromagnetics method used for studying a uranium object of the paleovalley type. Objects of this type are characterized by a low resistivity of the ore zone located in relatively high-resistivity host rocks and, from the position of the geoelectric structure, can be considered a good benchmark for assessing the capabilities of different electrical exploration technologies in general. The aeromobile part of the geophysical system created is implemented on the basis of a hexacopter carrying a measuring system with an inductive sensor, an analog of a 50 × 50 m loop, an 18-bit ADC with satellite synchronization, and a transmitter. The ground part consists of a galvanically grounded supply line and a current source with a transmitter creating multipolar pulses of quasi-DC current in the line. The survey is carried out with a terrain drape based on a satellite digital terrain model. The article presents the results obtained from the electromagnetic soundings in comparison with the reference (drilled) profile, convincingly proving the high efficiency of UAV-TEM. This approach to pre-processing UAV–electrospecting data is described with the aim of improving data quality by taking into account the movement and swaying of the measuring system’s sensor. On the basis of the real data obtained, the sensitivity of the created semi-airborne system was modeled by solving a direct problem in the class of 3D models, which allowed us to evaluate the effectiveness of the method in relation to other geological cases.

The purpose of the study is to present the research results of the capabilities of modern portable rapid X-ray fluorescence analyzers when solving problems of geological and geochemical prospecting. On example of the applied SciAps X200 analyzer, the metrological indicators for the analysis results by portable instruments have been studied. The accuracy assessment results of analytical studies according to state standard reference samples are shown. Reproducibility of the analysis results is calculated on the basis of samples from promising gold sites of the Bodaibo synclinorium. The method is proved to be of high precision, and measurement errors in many cases are many times lower than the permissible certified values. The reproducibility is shown as 0,5–20 % depending on the element, which in most cases is significantly lower than the methodology permits. The results of interlaboratory comparative tests confirming the comparability of the analytical results of stationary and portable X-ray fluorescence analyzers are presented. For a number of significant elements, the authors have substantiated the lack of need to refine the results of the field rapid X-ray fluorescence analysis using labor-intensive and expensive methods with acid decomposition - atomic emission and atomic absorption spectroscopy. It has been proved that introduction of portable express equipment into geological prospecting works will make it possible to conduct real-time “on site” analytical studies.

As part of proactive geoecological research, the purpose of which was to assess the impact of waste from the industrial site of the Vostsibelement plant on the ecosystem of the town of Svirsk (Irkutsk region), the authors discovered anomalies with strong arsenic and polymetallic contamination located 200 m north-west from the boundary of the industrial site of the “Vostsibelement” plant. Part of the contaminated site is the former industrial site of the Angarsk Metallurgical Plant, which was successfully remediated in 2009–2013. This raised the questions of a detailed study of the current environmental and geochemical situation at the site and identification of the processes causing the presence of significant contamination on the previously successively reclaimed site. To estimate the current geochemical state of the site, an environmental-geochemical survey, which was four times more detailed than the requirements of the state standard, was carried out, accompanied by rapid X-ray fluorescence analysis of samples. As a result, it was found out that on the area of more than 30 hectares,13 hectares of which belong to the former industrial site of the Angarsk Metallurgical Plant, the present pollution exceeded the standards for arsenic, lead, copper and zinc by tens and hundreds of times. At the same time, it was determined that the nature of pollution and the spatial localization of the main anomalies had changed relative to the initial situation in 2009: currently, pollution is concentrated in the peripheral areas of the industrial site and beyond and is chaotic in nature (pollutant concentrations in neighboring samples, even taken over a mesh of 50×50 m, may differ by hundreds of times). The sites reclaimed with soil removal feature no significant contamination. For a retrospective analysis of changes in the situation at the site during reclamation works in 2009–2013 and after their completion, until the summer of 2022, the analysis of Landsat and Sentinel satellite multispectral sensing data was applied. With a time resolution of no worse than one image per month, the materials in the visible and near-infrared range were analyzed. The normalized differential vegetation biomass index (NDVI) was chosen to be the main informative indicator as it clearly reflects the facts of changes in the surface type of the industrial site and allows to assess the vegetation development on the site, which is an important indirect indicator of the environmental and geochemical situation. As a result, a good convergence of geochemical and remote sensing data was established and it was shown that reclamation measures had been carried out to the required extent and gave a noticeable result: the measures taken to remove the polluted soil and deliver conditionally clean and conditionally fertile soil are clearly recorded. A positive geobotanical effect from these measures is noticeable since there is the change in the vegetation type and biomass increase in the reclaimed areas compared to peripheral areas left for self-overgrowth by native vegetation. It is shown that with the time this effect disappears and a single type of vegetation is formed on the area. However, no obvious facts of significant technogenic impact on the industrial site after the end of monitoring activities in 2016 according to multispectral satellite data were revealed. There was not any soil removal or delivery of large volumes of waste on the site. The vegetation developed synchronously with the background areas. Thus, the study reliably confirmed the fact of pollution and described it in detail, tracked the progress of reclamation measures and proved the presence of positive environmental effects. It also refuted the hypothesis about the possibility of secondary pollution as a result of obvious anthropogenic influence. At the same time, it is shown that geochemical studies of such objects conducted in accordance with current state standards can distort understanding about their condition, while greater methodological freedom of scientific research compared to the work within the framework of government assignments allows to reveal the chaotic nature of pollution in the peripheral areas of the area and beyond. But even the achieved detailed description definitely does not allow us to consider the ecological and geochemical characteristics of the object presented in the article as final as it seems necessary to thicken the sampling mesh at least by four times. The degree of probable “soft” gradual pollution of the industrial site due to the transfer and migration of pollutants from nearbyт objects (up to II hazard class), which can be sources of additional secondary pollution with all detected elements, also remains unexplored. Thus, the data obtained indicate the need for an additional set of engineering and environmentalт work that goes far beyond the scope of the proactive scientific research. The methodological conclusion from the work is the proof of the applied approach effectiveness and applicability to geoecological research, which can make it possible to assess the current situation quickly, reliably and at low cost as well as to analyze, confirm or refute the hypotheses about the development of the situation and therefore can be successfully used in other similar cases.

Gravitational processes on cut slopes located close to infrastructure are a high concern in mountainous regions. There are many techniques for survey, assessment, and prognosis of hazardous exogenous geological processes. The given research describes using UAV data and GIS morphometric analysis for delineation of hazardous rockfall zones and 3D modelling to obtain an enhanced, detailed evaluation of slope characteristics. Besides the slope geomorphometric data, we integrated discontinuity layers, including rock plains orientation and fracture network density. Cloud Compare software 2.12 was utilised for facet extraction. Fracture discontinuity analysis was performed in QGIS using the Network GT plugin. The presented research uses an Analytical Hierarchy Process (AHP) to determine the weight of each contributing factor. GIS overlay of weighted factors is applied for rockfall susceptibility mapping. This integrated approach allows for a more comprehensive GIS-based rockfall susceptibility mapping by considering both the structural characteristics of the outcrop and the geomorphological features of the slope. By combining UAV data, GIS-based morphometric analysis, and discontinuity analysis, we are able to delineate hazardous rockfall zones effectively.

The purpose of the article is to present the research results on the application of concentration methods to hazardous waste from the industrial site of the former Vostsibelement battery plant located in the town of Svirsk, Irkutsk region (Russia), which is the facility of accumulated environmental damage. The previous studies have identified significant contents of heavy metals and arsenic that exceed standard values by hundreds and thousands of times in the industrial site soils. This fact determines soil high hazard class – II and III. To reduce the hazard class and decrease the volume of hazardous waste it is proposed to use a recuperative approach, that means to recover some metals and arsenic in order to return them in economic circulation. A spiral concentrator, a shaking table and a centrifugal concentrator were used for gravity concentration of metals and arsenic. The best results were obtained using a shaking table. The latter made it possible to increase the lead content in the concentrate by 22 times as compared to the content in the original sample, arsenic content by 7.7 times, and iron content by 16.7 times. Magnetic concentration of the shaking table middlings made it possible to obtain a concentrate with a high content and recovery of iron, copper and zinc. Despite the fact that the soil waste contains a significant amount of organic matter unlike the case of ore processing, the possibility of successful metal recover and significant reduction of metal concentrations in soil is shown. The proposals for a further waste-recycling scheme are made on the basis of the data obtained.

The subject of the study is the problem of the decline degree of the information content of geophysical data when switching from land surveys to low-altitude geophysical survey using unmanned aerial vehicles. The research involves a comparative analysis of the information content of the unmanned aerial vehicle survey results and those of the land magnetic survey. The conducted research allowed to present the observed values of the magnetic field obtained by both survey methods within the same area as well as the final information products in the form of the results of filtering and three-dimensional data inversion. It is shown that visual analysis of maps of the full vector of magnetic field strength gives the impression of a lower information content of magnetic survey performed by unmanned aerial vehicles. However, the data having been processed create final information products of identical information content. This concerns both the results of three-dimensional modeling of the effective magnetic susceptibility, and maps and plots of the anomalous magnetic field after filtering in a sliding window. The negative impact of geological interference from morainic deposits on ground data is also shown. Local magnetic anomalies based on unmanned aerial vehicle survey results can confidently correlate with land survey anomalies, whereas the data collected during low-altitude aeromagnetic survey using unmanned aerial vehicles have a lower error probability. The conclusions refer to a specific case and cannot be unambiguously applied to any geological situation, however, the authors believe in the typicality of this example.

The article presents the results of transient electromagnetic (TEM) prospecting surveys using an unmanned aerial system carried out at Lake Baikal, which is a unique geoelectrical setting where low-resistivity lacustrine sediments are located under a relatively isotropic water body. The task was to investigate the possibility of using a drone-based TEM survey to delineate the electrical stratigraphy of the subsurface at depths between 50 and 300 m, separated into layers and blocks. A new version of the SibGIS UAV-TEM unmanned system was used, significantly improved compared to the prototype previously described in the literature. The current switch providing bipolar current pulses connected to a grounded electrical line was the source of the electromagnetic field in the geological environment. The hexacopter carrying a measuring system consisting of 18-bit ADC and sensor—analog of 50 × 50 loop, was the receiving system. We measured survey data of 16 traverses over the Baikal going from the shore to the depths. Significant attention is being paid to a new approach to data inversion. For fast interpretation of the TEM data, we used the Sτ-method, which allows for tracing the change in the apparent longitudinal conductivity with depth. It is shown that thanks to the new sensor and current switch, the data quality has increased significantly; now, the UAV system can register sounding curves up to 1 ms. As a result, new data on the geological structure of the shelf zone of Lake Baikal were obtained. They had a good fundamental agreement with the predecessor data obtained from terrestrial measurements (from ice cover), allowing us to conclude that the UAV-TEM technology can already replace conventional ground-based electromagnetic surveys.

Summary Nowadays magnetic and gamma surveys using UAV technologies are widely used in the practice of geological exploration. However, until now electromagnetic sounding in the UAV version is practically not used, but is very promising. In this paper, we consider the results of testing the UAV-TDEM technology. This technology is a time-domain transient electromagnetic sounding on a lightweight UAV. A measuring system with an inductive sensor (receiving loop) is towed by a UAV, and a galvanically grounded power transmitter is on the ground and connected to a pulse generator. The testing place was not chosen by chance: Baikal Lake is a unique geological formation with a rather simple one-dimensional geoelectric model at first glance: a fresh water layer with a resistivity of about 200 Ohm m, under which there are low-resistivity bottom sediments. 3D modeling, performed taking into account bathymetry, has shown that under a water layer with a thickness of 200–300 m a high-resistance objects are found in conductive sediments to a depth of at least 200 m. Some of them are extensions of coastal geological structures. As a result, the depth of the UAV-TDEM technology in these geoelectric conditions is estimated of about 500 m.

The article considers an example of solving the problem of a detailed and rapid geoecological assessment of a technogenically disturbed site through the use of a set of recent achievements in the field of geochemical, airborne and ground geophysical, ecotoxicological, and geoinformation methods, as well as near-surface drilling. The object is the industrial site of the former ``Vostsibelement'' battery plant in Svirsk (Eastern Siberia, Russia), which was closed more than 20 years ago. The object is localized within the Baikal natural territory - a UNESCO World Heritage Site. Significant excesses of the total content of lead were revealed by express XRF analysis - up to several thousand times, and hundreds of times for arsenic, copper, zinc and nickel. Concentration maps were constructed. Using the drilling, the depth of penetration of toxicants into the depth of the soil profile has been found. Terrestrial and UAV gamma survey methods have established increased radioactivity of building materials of some buildings within and outside the industrial site. For the first time, biotesting methods revealed areas of the territory with waste of II and III hazard classes. As a result of ecotoxicological experiments, it was found that, despite the fact that lead anomalies have the maximum contrast, arsenic poses the greatest environmental hazard. Aerial lidar and photogrammetry data have made it possible to estimate the amount of waste located on the surface. Drilling data allow us to estimate the amount of contamination in the near surface part of the section. It is shown that a dangerous object of accumulated harm to the environment was identified, it needs to be immediately liquidated. One of the main conclusions is the substantiation of the need to conduct significantly more detailed geoecological studies, in comparison with the accepted state standards of Russia, otherwise the results of the geoecological assessment of such complex objects will be unreliable.

Summary In order to successfully prospect for new deposits, in most cases it is necessary to use a set of geophysical methods that allow both studying the surface, and creating models of the deep structure of the near surface part of the earth’s crust. The classic universal combination is the «triad» of methods “magnetic prospecting+gamma-spectrometry+electromagnetic prospecting”, this option is used in most geophysical systems based on manned helicopters. In recent years, magnetic prospecting and gamma survey methods have already been widely used in the UAV version, so UAV-based electromagnetic soundings are of maximum interest at this stage of geophysics. In this paper, we consider a case of combining all three UAV-based methods in the case of prospecting for blind deposits of sandstone-type uranium, with special attention being paid to the use of the current version of SibGIS UAV-TEM system for time-domain electromagnetic sounding, which is significantly improved compared to the first prototypes. According to the authors, this case proves that unmanned systems, which allow performing geophysical surveys with a set of methods at low altitudes and with precise terrain drape, make it possible to almost completely abandon ground-based surveys, at present - and in the case of transient electrical prospecting too.

Summary To create a complete set of UAV-based aerogeophysical methods, two lightweight UAV-electromagnetic systems were developed. The first one (VLF-type) is designed to first-stage geophysical mapping over large areas; it can be performed simultaneously with magnetic and gamma surveys on one UAV. In this case, the receiver with mutually orthogonal ferrite antennas provides measurement of the vertical and horizontal components of the electromagnetic field in the audio frequency range (10 – 48 kHz), at the far field region of the electromagnetic field of navigation radio stations. The second variant is the UAV-TEM, where the time-domain transmitter located on the ground and connected to a galvanically grounded line several kilometers long, and the receiver with coil is towed by the multirotor UAV. From one line placement, it is possible to perform surveys in areas up to several square kilometers. This variant is optimal for detailed electromagnetic soundings in local sites identified at the previous stage of geophysical mapping, it provides the possibility of data inversion to a depth more than 300 meters. Together with UAV-magnetic prospecting and gamma-spectrometry, the created systems provides a solution to a wide range of geological tasks in any complexity of landscape conditions.

Nowadays in solving geological problems, the technologies of UAV-geophysics, primarily magnetic and gamma surveys, are being increasingly used. However, for the formation of the classical triad of airborne geophysics methods in the UAV version, there was not enough technology for UAV-electromagnetic sounding, which would allow studying the geological environment at depths of tens and hundreds of meters with high detail. This article describes apparently the first technology of UAV-electromagnetic sounding in the time domain (TDEM, TEM), implemented as an unmanned system based on a light multi-rotor UAV. A measuring system with an inductive sensor—an analogue of a 20 × 20 or 50 × 50 m receiving loop is towed by a UAV, and a galvanically grounded power transmitter is on the ground and connected to a pulse generator. The survey is carried out along a network of parallel lines at low altitude with a terrain draping at a speed of 7–8 m/s, the maximum distance of the UAV’s departure from the transmitter line can reach several kilometers, thus the created technology is optimal for performing detailed areal electromagnetic soundings in areas of several square kilometers. The results of the use of the unmanned system (UAS) in real conditions of the mountainous regions of Eastern Siberia are presented. Based on the obtained data, the sensitivity of the system was simulated and it was shown that the developed technology allows one to collect informative data and create geophysical sections and maps of electrical resistivity in various geological situations. According to the authors, the emergence of UAV-TEM systems in the near future will significantly affect the practice of geophysical work, as it was earlier with UAV-magnetic prospecting and gamma-ray survey.

Summary Ancient iron-making complexes are in many places on the western coast of the central part of Lake Baikal. The objects are located in the folded frame of the Siberian platform, represented by deeply metamorphosed rocks of the Olkhon crystalline complex. The possibilities of terrestrial and UAV magnetic surveys and electrical resistivity tomography (ERT) are considered to optimize searches and study archaeological sites with minimizing excavating by applying. They use 3D inversions of geophysical surveys’ data to localize and estimate parameters of physical-geological models of archeological and geological near-surface objects. Comparing the modeling results on a well-known archaeological site has given a chance to estimate the effectiveness of the methods used. Inversion of magnetic fields using vector scanning and elastic net regression allows receiving a geometrical image, spatial distribution of susceptibility, and remanent of furnaces by terrestrial and UAV magnetic surveys data and distinguish object artificial and geological origins.

Unmanned aerial systems (UAS) for airborne gamma-ray surveys in radioecological and geological research are being increasingly used, since they provide radiation safety for personnel and high survey performance. Improvement of detection modules is one of the main directions in which UAS-gamma is developing. Semiconductor detectors are used increasingly as they have a small mass and are convenient for light unmanned aerial vehicles (UAVs). Simultaneously, in our opinion, the potential of traditional scintillation detectors is not exhausted because they are cheaper and more affordable. Radiometric and spectrometric detection modules based on scintillation detectors can even be created at home. The main disadvantage of scintillation detectors is the need for large crystals with significant mass to obtain high data quality. Traditional aerial gamma surveys with operated aircraft systems use scintillation detectors with a volume of tens or hundreds of litres. In this paper, we present the comparison result of radiometric and spectrometric surveys with small volume detectors made at different altitudes and ground surveys. We prove that with properly designed and applied ultralight UAS for aerial gamma spectrometry it is possible to obtain high-quality and informative data.

Summary In 1977, on the western coast of Lake Baikal, near the village of Shara-Togot, Olkhon region, a monument to the ancient metallurgy of iron Barun-Khal II was unveiled. According to the radiocarbon method, the age of the monument is 2180-1750 years. The area, promising for the detection of objects related to ancient metallurgical centers, is quite large, several tens of kilometers in length and several kilometers in width. In this regard, the search for new archaeological sites by traditional methods is difficult. A possible way to optimize searches, as well as study archaeological sites without excavating them, are geophysical methods - magnetic prospecting and electrical prospecting. In this case, surveys were carried out on the reference object by methods of ground and UAV magnetic prospecting and electrical prospecting. Also, modern 3D-inversion of magnetic and electromagnetic imaging was performed. This made it possible to evaluate the effectiveness of each of the methods, to compare the reliability and information content of the observed data and the resulting 3D models of the hidden object. In this work, on the example of one of the objects of the Barun-Khal II monument, the results of a complex of geophysical research are analyzed, including ground and UAV-magnetic surveys, electrotomography (Skala-64 equipment).

Summary To create a complete set of UAV-based aerogeophysical methods, two lightweight UAV-electromagnetic systems were developed. The first one is designed to first-stage geophysical mapping over large areas; it can be performed simultaneously with magnetic and gamma surveys on one UAV. In this case, the receiver with mutually orthogonal ferrite antennas provides measurement of the vertical and horizontal components of the electromagnetic field in the audio frequency range (10 - 48 kHz), at the far field region of the electromagnetic field of navigation radio stations. The second variant is the UAV-TEM, where the time-domain transmitter located on the ground and connected to a galvanically grounded line several kilometers long, and the receiver with coil is towed by the multirotor UAV. From one line placement, it is possible to perform surveys in areas up to several square kilometers. This variant is optimal for detailed electromagnetic soundings in local sites identified at the previous stage of geophysical mapping, it provides the possibility of data inversion to a depth of 600 meters. Together with UAV-magnetic prospecting and gamma-spectrometry, the created systems provides a solution to a wide range of geological tasks in any complexity of landscape conditions.

The investigation of hard-to-reach areas that are prone to landslides is challenging. The research of landslide hazards can be significantly advanced by using remote sensing data obtained from an unmanned aerial vehicle (UAV). Operational acquisition and high detail are the advantages of UAV data. The development of appropriate automated algorithms and software solutions is necessary for quick decision-making based on the received heterogeneous spatial data characterising various aspects of the environment. This article introduces the first phase of a long-term study about landslide detection and prediction that aims to develop an automatic algorithm for detecting potentially hazardous landslide areas, using data obtained by UAV surveys. As a part of the project, the selection of appropriate techniques was implemented and a landslide susceptibility (LS) map of the study site was developed. This paper presents the outcomes of the applied indirect heuristic approach of landslide susceptibility assessment using an analytical hierarchy process (AHP) in a GIS environment, based on UAV data. The results obtained have been tested on a real-world entity.

Low-attitude remote Earth sensing (RES) performed by unmanned aerial vehicles (UAV) helps run geological surveys more efficiently; aeromagnetic surveys have been on rise recently. UAV surveying can be made significantly more informative and cost-effective by switching from monomethod surveying to integrated efforts that combine multiple complementary methods. However, how to run such surveys efficiently is a question barely covered in special literature. This paper uses evidence from a site in Bodaybinsky District (Eastern Siberia, Russia), a promising black-shale gold mineralization site, to analyze a typical geological exploration case, namely additional exploration of underexplored areas near a known deposit. It considers a method for integrated UAV geophysical surveying and its interpretation; this multi-method approach comprises aeromagnetic surveys, gamma radiometry, and multispectral photography. Emphasis is made on how important correct interpretation of geophysical data is for the latter. The paper shows that such photography is necessary for identifying man-affected segments in the area and for assessing the distribution of vegetation in it; this helps adjust the gamma background charts. Use of integrated low-altitude surveys taken from UAVs helps quickly and cheaply identify potential gold-bearing sites by a set of indirect features. Exploratory drilling has proven the approach effective.

Major types of mineralization distinguished at the Krasniy deposit: (a) dispersed idiomorphic pyrite crystals, (b) a veinlet with pyrite and pyrrhotite, (c) veinlets of milky-white quartz bearing fine cubic pyrite, (d) a vein of brownish quartz with pyrite pocket.

The subject of the article is the development of a laboratory tester for the study of the effectiveness of propeller-engine groups (PEG) of electric unmanned aerial vehicles (UAV). The need to create such solutions is due to the fact that the development and testing of unmanned platforms in the format of prototypes and their flight tests are time-consuming and expensive processes, it is not possible to assess the limit parameters of motors and their electronic speed controllers (ESC). Hardware devices and software for testing PEG separately can reduce the cost and speed up this process, as well as make the result more optimal both in terms of technical parameters and in terms of economic efficiency. A solution has been developed that allows to measure the motor amperage, the generated thrust of PEG, the voltage on the battery, the temperature of the motor, and then calculate PEG effectiveness indicators on their basis, visualize them in graphs, and thus compare the thrust and energy efficiency of various engine-propeller groups with propellers up to 30” ‘in size’. It is shown how the test results allow you to choose the optimal solution for assembling propeller-motor groups for light and medium UAV, and optimally design unmanned platforms for airborne geophysical prospecting.