Airborne Electromagnetic and Radiometric Peat Thickness Mapping of a Bog in Northwest Germany (Ahlen-Falkenberger Moor)

Knowledge on peat volumes is essential to estimate carbon stocks accurately and to facilitate appropriate peatland management. This study used airborne electromagnetic and radiometric data to estimate the volume of a bog. Airborne methods provide an alternative to ground-based methods, which are labor intensive and unfeasible to capture large-scale (>10 km2) spatial information. An airborne geophysical survey conducted in 2004 covered large parts of the Ahlen-Falkenberger Moor, an Atlantic peat bog (39 km2) close to the German North Sea coast. The lateral extent of the bog was derived from low radiometric and elevated surface data. The vertical extent resulted from smooth resistivity models derived from 1D inversion of airborne electromagnetic data, in combination with a steepest gradient approach, which indicated the base of the less resistive peat. Relative peat thicknesses were also derived from decreasing radiation over peatlands. The scaling factor (µa = 0.28 m−1) required to transform the exposure rates (negative log-values) to thicknesses was calculated using the electromagnetic results as reference. The mean difference of combined airborne results and peat thicknesses of about 100 boreholes is very small (0.0 ± 1.1 m). Although locally some (5%) deviations (>2 m) from the borehole results do occur, the approach presented here enables fast peat volume mapping of large areas without an imperative necessity of borehole data

Научные основы землеустройства снежных отвалов на примере г. Томска

Цель работы - теоретическое обоснование необходимости обустройства снежных отвалов. Для достижения поставленной цели проведены исследования химического и морфологического состава почв на территории снежных отвалов в г. Томске, применены методы использования данных ДЗЗ для мониторинга снежных отвалов, произведена оценка временной изменчивости площадей снежных отвалов и даны прогнозы, изучен видовой состав растительности снежных отвалов, выявлены закономерности произрастания, дана комплексная оценка загрязнения почв и техноземов на территории снежных отвалов, введен официальный термин "снежный отвал", произведено совершенствование нормативной правовой базы.The purpose of the work is theoretical substantiation of the necessity of arrangement of snow dumps. To achieve this goal, the chemical and morphological composition of soils in the territory of the snow dumps in Tomsk was studied, the methods of using remote sensing data for monitoring snow dumps were applied, the temporal variability of the snow dump areas was estimated and forecasts were given, the species composition of the snow dumps was studied, A comprehensive assessment of pollution of soils and technozems in the territory of snow dumps, an official term "snow dump" was introduced, Improvement of the regulatory framework

Comparison of novel semi-airborne electromagnetic data with multi-scale geophysical, petrophysical and geological data from Schleiz, Germany

In the framework of the Deep Electromagnetic Sounding for Mineral EXploration (DESMEX) project, we carried out multiple geophysical surveys from regional to local scales in a former mining area in the state of Thuringia, Germany. We prove the applicability of newly developed semi-airborne electromagnetic (EM) systems for mineral exploration by cross-validating inversion results with those of established airborne and ground-based investigation techniques. In addition, supporting petrophysical and geological information to our geophysical measurements allowed the synthesis of all datasets over multiple scales. An initial regional-scale reconnaissance survey was performed with BGR's standard helicopter-borne geophysical system deployed with frequency-domain electromagnetic (HEM), magnetic and radiometric sensors. In addition to geological considerations, the HEM results served as base-line information for the selection of an optimal location for the intermediate-scale semi-airborne EM experiments. The semi-airborne surveys utilized long grounded transmitters and two independent airborne receiver instruments: induction coil magnetometers and SQUID sensors. Due to the limited investigation depth of the HEM method, local-scale electrical resistivity tomography (ERT) and long-offset transient electromagnetic (LOTEM) measurements were carried out on a reference profile, enabling the validation of inversion results at greater depths. The comparison of all inversion results provided a consistent overall resistivity distribution. It further confirmed that both semi-airborne receiver instruments achieve the bandwidth and sensitivity required for the investigation of the resistivity structure down to 1 km depth and therewith the detection of deeply seated earth resources. A 3D geological model, lithological and geophysical borehole logs as well as petrophysical investigations were integrated to interpret of the geophysical results. Distinct highly-conductive anomalies with resistivities of less than 10 Omega rn were identified as alum shales over all scales. Apart from that, the petrophysical investigations exhibited that correlating geophysical and geological information using only one single parameter, such as the electrical resistivity, is hardly possible. Therefore, we developed a first approach based on clustering methods and self-organizing maps (SOMs) that allowed us to assign geological units at the surface to a given combination of geophysical and petrophysical parameters, obtained on different scales. (C) 2020 The Author(s). Published by Elsevier B.V