scholarly journals Vertical electrical sounding of soils and permafrost of marine terraces of Gronfjord (Svalbard archipelago)

2016 ◽  
Vol 6 (2) ◽  
pp. 210-220 ◽  
Author(s):  
Ivan Alekseev ◽  
Evgeny Abakumov
Keyword(s):  
Electrical Resistivity ◽  
Active Layer ◽  
Field Work ◽  
Morphological Properties ◽  
Soil Morphology ◽  
Significant Information ◽  
Svalbard Archipelago ◽  
Resistivity Sounding ◽  
Marine Terraces ◽  
Profile Distribution

Vertical electrical resistivity sounding (VERS) of soil-permafrost strata has been performed during the field work within the sea terraces of Gronfjord (Svalbard archipelago, West Spitsbergen island). Vertical electrical resistivity sounding of soil-permafrost strata was performed by portable device LandMapper. Then these data have been analyzed via ZondIP software (1d model). Apparent electrical resistivity values on the soil-permafrost strata usually change rapidly. It was established that studied soils with different origin and morphological properties are referred to 2 trunks, 2 orders, 4 types and 7 subtypes. Histic Gleysols, Cryosols, Gleysols and their subtypes have been investigated within the key plots (Grendasselva, Aldegonda rivers and catena on the sea terrace in surroundings of Barentsburg aerodrome). Several trends in profile distribution of electrical resistivity values have been distinguished. The main is connected with monotonous increasing of electrical resistivity values with a depth. Values of apparent electrical resistivity increase rapidly on the border of active layer-permafrost layer. The contrasts in profile distribution of electrical resistivity values are caused mainly by differences in water content, texture class and degree of strata heterogeneity (due to cryogenic processes). The depths of active layer-permafrost boundary have been distinguished using ZondIP software. Regional differences in this indicator may be explained not only by local differences in thermal regime of soil and permafrost layers, but also by different character of anthropogenic influence on key plots. Vertical electrical resistivity sounding method provides significant information for understanding soil electrical properties without any mechanical disturbances of soil cover. The data obtained is clearly coincided with field work data on soil morphology.

scholarly journals Electrical resistivity measurements on Ice Stream B, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 129-136
Author(s):  
S. Shabtaie ◽  
C.R. Bentley
Keyword(s):  
Electrical Resistivity ◽  
Theoretical Models ◽  
Electrode Spacing ◽  
High Resistivity ◽  
Resistivity Sounding ◽  
Basal Ice ◽  
A Value ◽  
Ice Stream ◽  
Ice Stream B ◽  
The Antarctic

Electrical resistivity sounding using the four-electrode Schlumberger array was carried out at station UpB on Ice Stream B to an electrode spacing of 3 km. Measured apparent resistivities were compared with theoretical models based on known relations between resistivity, density and temperature. Densities were measured in a pit and two coreholes; temperatures were measured in the upper 200 m of the ice stream and have been calculated for greater depth from an ice-stream temperature model. The resistivity, after correction for density and temperature, increases with depth down to 650-700 m. Below that is a marked decrease over the next 100m or so that we correlate with the Holocene-Wisconsin transition zone. Still deeper there is an orders-of-magnitude increase to a value, in the basal ice, of 30 MΩ m or more. This extremely high resistivity is similar to that reported for temperate glaciers and deep in the Antarctic ice sheet elsewhere. We attribute it to the destruction, by extensive metamorphism, of impurity-conduction paths at two-grain boundaries

Multi-methodological investigation of a retrogressive thaw slump in the Richardson Mountains, Northwest Territories, Canada

2020 ◽  
Author(s):  
Julius Kunz ◽  
Christof Kneisel ◽  
Tobias Ullmann ◽  
Roland Baumhauer
Keyword(s):  
Electrical Resistivity ◽  
Active Layer ◽  
Geophysical Methods ◽  
Three Dimensional ◽  
Active Layer Thickness ◽  
Permafrost Degradation ◽  
Low Resistivity ◽  
Permafrost Table ◽  
Retrogressive Thaw Slump ◽  
Richardson Mountains

<p>The Mackenzie-Delta Region is known for strong morphological activity in context of global warming and permafrost degradation, which reveals in a large number of retrogressive thaw slumps. These are frequently found along the shorelines of inland lakes and the coast; however, this geomorphological phenomenon also occurs at inland ​​streams and creeks of the Peel Plateau and the Richardson Mountains, located in the southwest of the delta. Here several active retrogressive thaw slumps are found of which some have reached an extent of several hectares, e.g. the mega slump at the Dempster Creek.</p><p>In this study we investigated a recent retrogressive thaw slump at the edge of the Richardson Mountains close to the Dempster Highway to determine the subsurface properties using non-invasive geophysical methods. We performed three-dimensional Ground Penetrating Radar (GPR) surveys, as well as quasi-three-dimensional Electrical Resistivity Tomography (ERT) surveys in order to investigate the subsurface characteristics adjacent to the retreating headwall of the slump. These measurements provide information on the topography of the permafrost table, ice content and/or water pathways on top, within or under the permafrost layer. Additionally, we performed manual measurements of the active layer thickness for validation of the geophysical models. The approach was complemented by the analysis of high-resolution photogrammetric digital elevation models (DEM) that were generated using in situ drone acquisitions.</p><p>The measured active layer depths show a strong influence of the relief and especially of small creeks on the permafrost table topography. Likely, this influence also is the primary trigger for the initial slump activity. In addition, the ERT measurements show strong variations of the electrical resistivity values in the upper few meters, which are indicative for heterogeneities, also within the ice-rich permafrost body. Especially noticeable is a layer of low resistivity values in an area adjacent to the slump headwall. This layer is found at depths between 4m to 7m, which approximately corresponds to the base of the headwall. Here, the low resistivity values could be indicative for an unfrozen or water-rich layer below the ice-rich permafrost. Consequently, this layer may have contributed to the initial formation of the slump and is important for the spatial extension of the slump.</p><p>These results present new insights into the subsurface of an area adjacent to an active retrogressive thaw slump and may contribute to a better understanding of slump development.</p>

Structural, Morphological and Mechanical Characterisation of Molybdenum Nitride Thin Films Deposited by a Plasma Focus Device

2017 ◽  
Vol 41 (12) ◽  
pp. 699-704
Author(s):  
Mohammad Taghi Hosseinnejad ◽  
Mehdi Ettehadi-Abari ◽  
Naser Panahi
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
Plasma Focus ◽  
Photoelectron Spectroscopy ◽  
Plasma Focus Device ◽  
Morphological Properties ◽  
Degree Of Crystallinity ◽  
Root Mean Square Roughness ◽  
Molybdenum Nitride ◽  
X Ray

This research focuses on the characterisation of nanostructured molybdenum nitride (MoN) thin films deposited on glass substrates at room temperature using a low-energy (1.1 kJ) plasma focus device. The nanostructure, surface morphology, electrical resistivity and mechanical properties of MoN thin films were studied in terms of the number of shots required to prepare them. X-ray diffraction (XRD) analysis indicated that all of the deposited layers were polycrystalline in nature, possessing the γ-Mo2N (fcc) structure. The XRD results also revealed that the degree of crystallinity and residual stress of the thin films were strongly dependent on the number of shots. X-ray photoelectron spectroscopy showed the Mo 3d3/2, Mo 3d5/2, Mo 3p3/2 and N 1s peaks for all of the thin films, confirming the formation of the γ-Mo2N structure. Scanning electron microscopy images showed the growth of granular structures and then the formation of larger-sized agglomerates on the surfaces of the samples with increasing numbers of shots. Atomic force microscopy indicated that grain sizes on surface layers as well as the average and root mean square roughness increased for samples deposited with more shots. Furthermore, the variations in hardness and electrical resistivity of the deposited MoN thin films were qualitatively explained on the basis of the morphological properties of the samples.

scholarly journals Synthesis and Characterization of Conductive Polypyrrole: The Influence of the Oxidants and Monomer on the Electrical, Thermal, and Morphological Properties

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Abdirahman Yussuf ◽  
Mohammad Al-Saleh ◽  
Salah Al-Enezi ◽  
Gils Abraham
Keyword(s):  
Electrical Resistivity ◽  
Room Temperature ◽  
Oxidative Polymerization ◽  
Sodium Dodecyl ◽  
Conductive Polymer ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structural Formation ◽  
Pyrrole Monomer

Conductive polymer, polypyrrole (PPy), was synthesized by chemical oxidative polymerization technique for a period of four hours at room temperature using pyrrole monomer (mPPy) in aqueous solution. Different oxidants such as ferric chloride (FeCl3) and ammonium persulphate (N2H8S2O8) and surfactant sodium dodecyl sulphate (C12H25NaO4S) were used. The produced PPy samples were characterized by using different techniques such as the electrical resistivity by four probe technique, thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The performance of the oxidants has been investigated and compared. It was found that both oxidants, FeCl3 and N2H8S2O8, have decreased electrical resistivity as a function of temperature, which means increased conductivity. However, FeCl3 has achieved better performance than N2H8S2O8, where it has achieved a lower resistivity of about 60 ohms at room temperature, which indicates higher conductivity of PPy samples with FeCl3 as an oxidant. Similarly, further investigation of FeCl3 oxidant has been conducted by varying its concentration, and its influence on the final properties was reported. It has been observed that the morphology of PPy samples has a significant influence on the conductivity. It was found that 0.1 M and 0.05 M concentrations of FeCl3 oxidant and monomer, respectively, have achieved better thermal stability, which is FeCl3/mPPy ratio of 2 as an optimum value. FTIR and XRD results confirmed the structural formation of polypyrrole from pyrrole monomer during the synthesizing process.

scholarly journals A Comparison of Frequency Domain Electro-Magnetometry, Electrical Resistivity Tomography and Borehole Temperatures to Assess the Presence of Ice in a Rock Glacier

2020 ◽  
Vol 8 ◽  
Author(s):  
Jacopo Boaga ◽  
Marcia Phillips ◽  
Jeannette Noetzli ◽  
Anna Haberkorn ◽  
Robert Kenner ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Frequency Domain ◽  
Layer Thickness ◽  
Active Layer ◽  
Electrical Resistivity Tomography ◽  
Temperature Data ◽  
Active Layer Thickness ◽  
Rock Glacier ◽  
Resistivity Tomography ◽  
Borehole Temperature

Alpine permafrost is currently warming, leading to changes such as active layer deepening and talik formation. Frequency domain electro-magnetometry (FDEM) measurements were tested as a simple and efficient method to investigate ground characteristics along two transects on the ice-rich Schafberg rock glacier in the Eastern Swiss Alps. The results were compared with electrical resistivity tomography (ERT) and ground temperature data acquired simultaneously in boreholes. FDEM provides information on the electrical properties of the ground, allowing to investigate ground-ice distribution. Our device allowed measurements to a depth of around 7 m. In ice-rich permafrost, FDEM can provide an approximation of the active layer thickness, and ice-free zones within the permafrost such as intra-permafrost taliks can be identified. This rapidly applicable geophysical method can be used to monitor ground ice distribution easily and efficiently, making it an ideal complement to borehole temperature data, which only provide point information and are costly to install and maintain. At the Schafberg site the three methods FDEM, electrical resistivity tomography and borehole temperature measurements provided similar results, with regard to active layer thickness and the presence of unfrozen zones within the ice-rich permafrost.

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