Spatial Distribution Of Magnetic Susceptibility Research Articles

Investigation of geothermal resources using a geophysical potential field in the Hurghada area, Egypt

Egypt's need for clean and renewable energy is pressing for numerous reasons, such as unpredictable fuel prices, diminishing fossil fuel resources, and growing concern about environmental degradation. Harvesting untapped geothermal resources could meet domestic electricity needs besides enabling Egypt to export electricity. The location of Egypt confirms that it has suitable geothermal energy potential areas in some provinces around the country, especially along the Gulf of Suez, the Red Sea, and the Western Desert. The Red Sea coast and the coasts of the Gulf of Suez exhibit several surface manifestations (hot springs and thermal water wells), indicating the presence of geothermal systems in these areas. The objective of this paper is to investigate the geothermal resources and obtain a full image of the geothermal potential of the Hurghada area along the Red Sea coast using geophysical potential field data. Aeromagnetic and aerogravity data were used to identify the most promising target regions for geothermal potentiality. Power spectral analysis of the aeromagnetic data was utilised to appraise the Curie point depth (CPD) and obtain geothermal gradient and heat flow maps of the Hurghada area, whereas a 3-D inversion of gravity data was utilised to estimate the depths to the Precambrian basement rocks. In addition to 3-D inversion of magnetic data to evaluate the spatial distribution of magnetic susceptibility. This study found no direct relationship between basement depths and the CPD, where basement rock outcrops at some locations correlate to a decrease in the Curie surface, while at others, they correspond to an increase.

Environmental effects of potentially toxic elements and the magnetic susceptibility distribution in the surface bottom sediments in the Vistula estuary (Gulf of Gdańsk, Poland)

PurposeThis study is aimed at analyzing the spatial distribution of magnetic susceptibility and the content of potentially toxic elements (PTEs) in the surface layer of bottom sediments in the Vistula estuary (Gulf of Gdańsk, Poland) in relation to local sedimentary conditions. We also assessed the usefulness of magnetic susceptibility measurements to identify changes in sediment properties caused by anthropogenic factors.Materials and methodsBottom sediments were collected along three transects using the Van Veen grab sampler. The following properties were determined: granulometric composition, organic matter and carbonate content, pH, electrical conductivity, and heavy metal content (Cd, Cr, Cu, Fe, Ni, Pb, and Zn). Specific (mass) magnetic susceptibility (χ) was measured using the MS2 Bartington® laboratory magnetic susceptibility meter. To characterize the conditions of the sedimentary environment in the study area, statistical analysis was performed on selected parameters of grain size distribution, such as mean grain diameter (Mz) and sorting (σ1) indices.Results and discussionThe research showed significant differences in the sedimentary environment (erosion vs. deposition processes) along the studied transects which were controlled by the wave regime, sea currents, and river water inflow. Open-water sediments were richer in organic matter and more saline than deltaic sediments, which in turn were characterized by higher pH and higher carbonate content. The highest mean total content of Pb, Cu, Ni, and Zn and the highest magnetic susceptibility (χ) were determined in open-water sediments, while the highest Fe and Cr values were obtained for deltaic sediments. Statistically significant differences between these sediments were found only for organic matter (LoI), Pb, Cu, and Cd content. Magnetic susceptibility showed a moderate correlation with Pb, Cu, Cd, and Zn (rs 0.4–0.6).ConclusionPTE content and magnetic susceptibility of sediments showed a very high heterogeneity within the study area, depending mainly on the location (delta vs. open waters), grain size composition, and organic matter content. Our results demonstrated that magnetic susceptibility analysis is an easy method that can be used to complement the identification of technogenic changes in the marine environment.

Age-Related Changes in the Spatial Variation of Magnetic Susceptibility of Human Articular Cartilage.

Quantitative susceptibility mapping (QSM) has shown great potential for revealing the layer structure of articular cartilage based on the laminar susceptibility difference at different depths. However, more information is needed on the effects of age on the spatial distribution of magnetic susceptibility in human cartilage. To assess the ability of QSM to quantify the age-related differences in depth-wise cartilage susceptibility values in healthy populations. Prospective. A total of 94 healthy asymptomatic subjects in three age cohorts: 19-30 (n=36, 20 males), 31-50 (n=45, 27 males), and 51-66 years (n=13, 7 males). 3D gradient echo sequences at 3.0 T. Four cartilage compartments were analyzed, including the central lateral/medial femur (cLF/cMF) and the lateral/medial tibia (LT/MT). The spatial susceptibility profile and the corresponding 95% confidence interval (CI) of each age cohort were obtained as functions of the normalized distance from the bone-cartilage interface to the cartilage surface (cartilage depth from 0.0 to 1.0). The relationship between age and cartilage thickness of each cartilage subregion was tested by Pearson correlation with P < 0.05 considered significant. Cartilage depths with separations of 95% CIs were considered to have significant susceptibility differences between two age cohorts with a Bonferroni-corrected P < 0.05. The cartilage thickness did not change significantly with age (P value range: 0.06-0.85). Susceptibilities were significantly higher in the 51-66-year-olds compared with the 31-50-year-olds in the deep layer of cMF (cartilage depth: 0.0-0.22) and LT (0.05-0.28). Susceptibilities were significantly higher in the 51-66-year-olds compared with the 19-30-year-olds near the cartilage-bone interface of cMF (0.0-0.34), cLF (0.0-0.28), and LT (0.0-0.58). There were also significantly higher susceptibilities in the 31-50-year-olds compared with the 19-30-year-olds in the deeper regions of cMF (0.26-0.57), cLF (0.0-0.40), and LT (0.07-0.80). Age-related susceptibility changes in the deeper regions of knee cartilage were observed using QSM. 2 TECHNICAL EFFICACY: Stage 2.

Preliminary Investigation of Soil and Sediments Using Magnetic Susceptibility Method in Kogi State, Nigeria

Over the years, there has been significant increase in population and urbanization in Kogi State as a result of rural - urban migration. This has become a major threat to soil sustainability which is a natural non-renewable resource. The aim of this research is to carry out magnetic susceptibility mapping on the surface and subsurface soil of Kogi State using environmental magnetism techniques and geochemical analysis. The susceptibility test on rock samples and background soil samples within the study area shows an average of about 112.0 × 10^-5 SI. The magnetic susceptibility measurement on soil from Kogi State shows magnetic susceptibility enhancement of about (450.0 - 700.0) × 10^-5 SI. These values were dominant along the major towns, road pavements and commercial areas at the surface to a depth of about 50.0 cm in soil profiles. The 2D spatial distribution of magnetic susceptibility with depth reveals that these magnetic grains are distributed in the subsurface as a result of anthropogenic loading. The frequency-dependence of magnetic susceptibility (χfd%) values are very low (2 - 10.0 %) in most of the areas on the surface soil. These values indicate that the magnetic properties are predominantly contributed by the coarse multi-domain (MD) and stable single-domain (SSD) grains of anthropogenic origin. Atomic Absorbtion Spectrometer (AAS) analysis of these soil samples indicates the presence of Lead (300.0 - 900.0) mg/l and Cadmium (20.0 - 60.0) mg/l in large concentration at the surface soil in most part of the Kogi State. While Chromium show relatively low concentration on the surface soil. From the statistical correlation analysis, Lead and Cadmium show high positive correlation with magnetic susceptibility. These results suggests that the high enhancement of magnetic susceptibility on the surface and sub-surface soil in most part of Kogi State arise from anthropogenic activities rather than lithological and pedogenic processes and most likely cause by high concentration of Lead and Cadmium.

Single-step calculation of susceptibility through multiple orientation sampling.

Quantitative susceptibility mapping (QSM) was developed to estimate the spatial distribution of magnetic susceptibility from MR signal phase acquired using a gradient echo (GRE) sequence. The field-to-susceptibility inversion in QSM is known to be ill-posed and needs numerical stabilization through either regularization or data oversampling. The calculation of susceptibility through the multiple orientation sampling (COSMOS) method uses phase data acquired at three or more head orientations to achieve a well-conditioned field-to-susceptibility inversion and is often considered the gold standard for in vivo QSM. However, the conventional COSMOS approach, here named multistep COSMOS (MSCOSMOS), solves the dipole inversion from the local field derived from raw GRE phase through multiple steps of phase preprocessing. Error propagations between these consecutive phase processing steps can thus affect the final susceptibility quantification. On the other hand, recently proposed single-step QSM (SSQSM) methods aim to solve an integrated inversion from unprocessed or total phase to mitigate such error propagations but have been limited to single orientation QSM. This study therefore aimed to test the feasibility of using single-step COSMOS (SSCOSMOS) to jointly perform background field removal and dipole inversion with multiple orientation sampling, which could serve as a better standard for gauging SSQSM methods. We incorporated multiple spherical mean value (SMV) kernels of various radii with the dipole inversion in SSCOSMOS. QSM reconstructions with SSCOSMOS and MSCOSMOS were compared using both simulations with a numerical head phantom and in vivo human brain data. SSCOSMOS permitted integrated background removal and dipole inversion without the need to adjust any regularization parameters. In addition, with sufficiently large SMV kernels, SSCOSMOS performed consistently better than MSCOSMOS in all the tested error metrics in our simulations, giving better susceptibility quantification and smaller reconstruction error. Consistent tissue susceptibility values were obtained between SSCOSMOS and MSCOSMOS.

Technogenic Magnetic Particles in Soils and Ecological–Geochemical Assessment of the Soil Cover of an Industrial City in the Ural, Russia

The work is devoted to the study of pollution by technogenic magnetic particles and heavy metals of soils in the city of Gubakha, Middle Ural (Russia). The aim of the work is the ecological and geochemical assessment of the elemental chemical composition of the soils of the city of Gubakha, and the establishment of the geochemical role of technogenic magnetic particles (TMPs). For the first time, the regularities of the spatial distribution of magnetic susceptibility in the soils of the city of Gubakha were revealed, and the morphology, elemental and mineralogical compositions of magnetic particles in the soils of an industrial city in the Middle Urals were characterized using the methods of the chemical extraction of iron compounds, magnetic separation, ESEM/EDS, and Mössbauer spectroscopy. The magnetic phase of soils contains magnetite/maghemite, hematite, pyrrhotite, intermetallic alloys and chromite. Spherical magnetic particles are hollow, and have a magnetite shell and a varied surface texture. The crystal lattice of magnetite is characterized by low stoichiometry. The heavy metals Zn, Cu, Ni and Cr are concentrated in magnetic particles and have a high correlation coefficient with magnetic susceptibility. The level of contamination of Cu, Ni, Zn, Cr and Mn in the soils of a residential zone of Gubakha, estimated by the value of the pollution load index (PLI), was high. The Igeo index for Fe ranges from 6.2 to 12.2, for Cu–1.1 and Ni–1.1. The combination of methods for measuring magnetic susceptibility, determining the mineralogical composition of iron compounds, and determining the elemental chemical composition by X-ray fluorescence, has shown the effectiveness of an integrated approach for carrying out an ecological–geochemical assessment of the soil cover of Gubakha.

The estimation of an anthropogenic depth boundary using the magnetic susceptibility method in Kogi State, North-Central Nigeria

Magnetic susceptibility measurements remain one of the most reliable methods used to investigate the pollution of both surface and subsurface soil from metallic anthropogenic sources. Most of the geological rocks within the study area increase the susceptibility of the soil; however, knowing the natural background susceptibility of the parent rocks will give an idea of the anthropogenic influence on the susceptibility of the soil. This study was carried out in Kogi State, North Central Nigeria, with the aim of determining the depth of the boundary between the anthropogenic influences on soil magnetic susceptibility from those of a lithogenic origin. Magnetic susceptibility measurements were carried out on 1,760 soil samples, collected from 220 soil profiles at a depth of 80.0 cm and at intervals of 10.0 cm. From the spatial distribution of magnetic susceptibility maps at different depths, the boundary between the basement complex and the sedimentary basin was clearly demarcated. The result further shows the highest magnetic susceptibility values of 350–650 × 10−5 SI, which dominates the surface soil to a depth of 40.0 cm. At the depth of 40–50 cm, the result indicates the combination of a natural anthropogenic influence on soil magnetic susceptibility with an average of 250 × 10−5 SI. Furthermore, no evidence of layering along the depth sections was observed, suggesting that the soil profiles indicate areas mainly covered by anthropogenically influenced susceptibility, which were localized and restricted to commercial places within the state. This study reveals that the average depth of soil affected by anthropogenic pollutants is between 40–50 cm in commercial places and 20–30 cm in other places with less commercial activities.

Quantitative Susceptibility Mapping: Technical Considerations and Clinical Applications in Neuroimaging.

Quantitative susceptibility mapping (QSM) is a novel magnetic resonance imaging (MRI) technique for quantifying the spatial distribution of magnetic susceptibility within an object or tissue. Recently, QSM has been widely used to study various dominant magnetic susceptibility sources in the brain, including iron and calcium. In addition, the method enables mapping of the cerebral metabolic rate of oxygen, which could act as a new metabolic biomarker for diseases that involve disruption of the brain's oxygen supply. Thus, the clinical applications of QSM are wide-reaching and hold great promise as imaging biomarkers for studying several neurological diseases. This review aims to summarize the physical concepts and potential clinical applications of QSM in neuroimaging. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 2.

Quantitative susceptibility map analysis in preterm neonates with germinal matrix-intraventricular hemorrhage.

Germinal matrix-intraventricular hemorrhage (GMH-IVH) is a common form of intracranial hemorrhage occurring in preterm neonates that may affect normal brain development. Although the primary lesion is easily identified on MRI by the presence of blood products, its exact extent may not be recognizable with conventional sequences. Quantitative susceptibility mapping (QSM) quantify the spatial distribution of magnetic susceptibility within biological tissues, including blood degradation products. To evaluate magnetic susceptibility of normal-appearing white (WM) and gray matter regions in preterm neonates with and without GMH-IVH. Retrospective case-control. A total of 127 preterm neonates studied at term equivalent age: 20 had mild GMH-IVH (average gestational age 28.7 ± 2.1 weeks), 15 had severe GMH-IVH (average gestational age 29.3 ± 1.8 weeks), and 92 had normal brain MRI (average gestational age 29.8 ± 1.8 weeks). QSM at 1.5 Tesla. QSM analysis was performed for each brain hemisphere with a region of interest-based approach including five WM regions (centrum semiovale, frontal, parietal, temporal, and cerebellum), and a subcortical gray matter region (basal ganglia/thalami). Changes in magnetic susceptibility were explored using a one-way analysis of covariance, according to GMH-IVH severity (P < 0.05). In preterm neonates with normal brain MRI, all white and subcortical gray matter regions had negative magnetic susceptibility values (diamagnetic). Neonates with severe GMH-IVH showed higher positive magnetic susceptibility values (i.e. paramagnetic) in the centrum semiovale (0.0019 versus -0.0014 ppm; P < 0.001), temporal WM (0.0011 versus -0.0012 ppm; P = 0.037), and parietal WM (0.0005 versus -0.0001 ppm; P = 0.002) compared with controls. No differences in magnetic susceptibility were observed between neonates with mild GMH-IVH and controls (P = 0.236). Paramagnetic susceptibility changes occur in several normal-appearing WM regions of neonates with severe GMH-IVH, likely related to the accumulation of hemosiderin/ferritin iron secondary to diffusion of extracellular hemoglobin from the ventricle into the periventricular WM. 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1199-1207.

Integration of soil magnetometry and geochemistry for assessment of human health risk from metallurgical slag dumps

The main objective of the study was an assessment of the pollution level of agricultural land located close to dumps of industrial waste remaining after former Zn and Pb ore processing in Poland. The integrated geophysical-geochemical methods were applied for assessment of soil quality with respect to trace element pollution. Additionally, human health risk induced by the contaminated arable soil and dusting slag heap was estimated. The investigations pointed out that soils in the vicinity of the metallurgical slag dump in Piekary were heavily polluted. Spatial distribution of magnetic susceptibility corresponding well with distribution of the content of potentially toxic elements indicated the local “pollution hotspots.” Proper geophysical and geochemical data interpretation supported by statistical factor analysis enabled identification of three different sources of pollution including metallurgical slug dump as a main source, but also traffic pollution influencing the area located along the busy road and relatively strong influence of the geochemical background. Computed health hazard index revealed no adverse health effect to the farmers cultivating arable soil, but in the direct vicinity of dusting, slag dump health risk occurred, caused mostly by very toxic elements as As and Tl. In the future, investigation should be focused on contribution of different sources to the heavy metal pollution in soil-crop system in this area. It should be highlighted that a site-specific approach should be taken in order to redevelop this kind of area in order to reduce ecological and human health threat. The study proved the integrated two-stage geophysical-geochemical method to be a feasible, reliable, and cost-effective tool for identification of the extent of soil pollution and areas at risk.

Magnetic characteristics and trace elements concentration in soils from Anthemountas River basin (North Greece): discrimination of different sources of magnetic enhancement

The magnetic minerals (e.g., iron oxides) that are present in soils can be easily identified by using rock-magnetic techniques. Increased magnetic susceptibility of soils may reflect particles rich in iron oxides of anthropogenic, lithogenic, and pedogenic origin. Therefore, reliable discrimination of these sources is required, especially in areas where neither of them is dominant. The aim of the present study is to assess the lithogenic and anthropogenic contributions to iron-oxide mineralogy of soils in the area of the Anthemountas River basin in the southeast part of Thessaloniki city. Previous investigations within the study area, based on spatial distribution of magnetic susceptibility, revealed the presence of two magnetically enhanced regions. Therefore, the present study is focused on these two areas, in order to characterize the origin of magnetic enhancement. Detailed magnetic analyses include properties reflecting the type, concentration, and relative grain-size distribution of magnetic particles. Moreover, trace element concentration is determined with an aim to establish the link between low-field mass-specific magnetic susceptibility and concentration of Fe, Cr, Ni, Mn, Pb, Zn, and Ti. These findings are supported by descriptions of the micromorphology performed by scanning electron microscopy and determination of elemental composition by energy-dispersive spectrometer analyses in selected points. Finally hierarchical cluster analysis is applied to classify the soil samples into appropriate groups according to their magnetic properties. The results reveal that magnetic measurements provide a useful tool for the discrimination between different magnetic sources responsible for the enhancement of magnetic susceptibility in soils. Low-field mass-specific magnetic susceptibility reflects increased concentration of trace elements, while its combination with other magnetic measurements clearly differentiates the origin of magnetic enhancement in both parts of the study area.

Quantitative Susceptibility Mapping: Contrast Mechanisms and Clinical Applications.

Quantitative susceptibility mapping (QSM) is a recently developed magnetic resonance imaging (MRI) technique for quantifying the spatial distribution of magnetic susceptibility within biological tissues. It first uses the frequency shift in the MRI signal to map the magnetic field profile within the tissue. The resulting field map is then used to determine the spatial distribution of the underlying magnetic susceptibility by solving an inverse problem. The solution is achieved by deconvolving the field map with a dipole field, under the assumption that the magnetic field results from a superposition of the dipole fields generated by all voxels and that each voxel has its own unique magnetic susceptibility. QSM provides an improved contrast-to-noise ratio for certain tissues and structures compared with its magnitude counterpart. More importantly, magnetic susceptibility directly reflects the molecular composition and cellular architecture of the tissue. Consequently, by quantifying magnetic susceptibility, QSM is becoming a quantitative imaging approach for characterizing normal and pathological tissue properties. This article reviews the mechanism that generates susceptibility contrast within tissues and some associated applications.

금산지구 항공 자력탐사 자료의 3차원 역산

금산지역 항공 자력자료에 대하여 2차원 수치모델링 및 역산조합으로 구한 사전정보를 이용하는 3차원 자력역산을 수행하고 지질정보와 대비하여 함우라늄 층과 여타 옥천누층군 단위 암상에 대응하는 자기감수율의 공간적 분포특성을 고찰하였다. 체적당 자기감수율 분포 및 수평 슬라이스 시각화를 통해 흑색셰일형 함우라늄층인 흑색 점판암과 대응하는 자력이상 값은 우라늄 광화대와 전체적으로 양호한 상관관계를 보여주었다. 회색 혼펠스층 우라늄 광화대의 간접 지시자인 마전리층 및 암회색 점판암층 역시 석영반암 경계에서부터 동남쪽으로 발달하는 자력선구조 특성을 잘 보여주었다. 인접한 강한 자기감수율 이상을 보여주는 암회색 점판암과 분리하여 인지 가능한 함우라늄 흑색 점판암층의 최대 깊이는 고도 306m 기준으로 약 150m 안팎으로 판단하였다. 한편, 흑색 점판암층 남쪽의 마전리층은 다소 높은 자기감수율 분포를 보여주나 자기감수율의 공간적 변동이 심한 특징을 보이며 관입암인 주라기 화강암은 낮은 자기감수율 특성을 보여주는 반면, 백악기 화강암은 상대적으로 높은 자기감수율 특성을 나타내었다. 3D magnetic inversion, based on the assemblage of 2D forward modeling and inversion as a practical technique to reflect the a priori information, was conducted to investigate the spatial distribution features of black-shale related and pyrometamorphic uranium deposit and several lithological units of Ogcheon Super Group in an area of Geumsan. By using the 3D visualization technique with suitable susceptibility interval and horizontal slice map, the spatial distribution of magnetic susceptibility corresponded to the black shale related uranium bearing lithological units, Black Slate member was well coincided with a information of uranium deposit. Also, even though it is indirect indicator for the detetction of uranium deposits interbedded in Gray Hornfels member, spatial susceptibility distribution which shows the south-east magnetic linearment corresponding to the Majeon-ri formation and Dark Gray Slate were matched well. From this investigation, we inferred that maximum depth extension which Black Slate member can be separately recognized with respect to adjacent Dark Gray Slate with strong magnetic susceptibility anomaly is about 150m with reference elevation level of 306m. In addition, Majeon-ri formation located south of Black Slate member revels relatively high magnetic susceptibility range but shows high spatial susceptibility fluctation. And, as an intrusive rocks, Jurassic Biotite Granite shows relatively low magnetic susceptibility characteristics. On the contrary, Cretaceous granite distributed in soutthern part of the study area shows the relatively high susceptibility distribution.

Vertical zonation of the Barcroft granodiorite, White Mountains, California: Implications for magmatic processes

Petrological and geochemical variations within plutons reflect their magmatic and emplacement histories. Here we present new magnetic susceptibility ( K m ) data on the ~163 Ma Barcroft granodiorite pluton in eastern California, which is exceptionally well exposed, especially in the vertical dimension. The Barcroft pluton offers exposures over a total of 2560 m of elevation and is an appropriate target to investigate variations of magnetic susceptibility. In ferromagnetic plutonic rocks, K m reflects mainly the abundance of magnetite, whereas in paramagnetic plutonic rocks it reflects primarily the abundance of mafic silicates. Magnetic susceptibility is also determined by magmatic processes such as crystal fractionation and by intensive parameters such as oxygen fugacity. Other magmatic processes, including magma replenishment, hybridization, and host-rock assimilation, may also influence K m variations. A first data set is based on 622 core samples that were measured in the laboratory. Our second data set comes from 1960 field measurements collected at 196 stations between ~1600 and 4000 m elevation. Detailed surveys were performed at the outcrop scale to evaluate the impact of the ~100 Ma McAfee Creek intrusion on the Barcroft background magnetic susceptibility. The combined data sets display a broad positive correlation between K m and elevation. Pluton mineralogy also appears to vary with elevation but is more difficult to quantify. At the outcrop scale, small dikes of the McAfee Creek granite transect the pluton and are responsible for a decrease in K m of the host granodioritic rocks toward the dikes due to late-stage magmatic or hydrothermal alteration. A contour map of K m shows a high degree of correlation with local topographic features such as deep canyons. Magnetic susceptibility of the Barcroft mafic rocks varies at the outcrop scale as a result of presence of petrological heterogeneities. However, these small-scale variations are embedded in a broader magnetic susceptibility trend due primarily to elevation, which reflects petrologic stratification of the pluton. The late-magmatic and hydrothermal alterations described in previous studies do not affect the spatial distribution of magnetic susceptibility. We propose that vertical increase of K m was primarily caused by crystal fractionation or another magmatic differentiation mechanism rather than by an externally driven increase in oxygen fugacity toward the roof of the intrusion.

Testing the Indicative Value of Magnetic Susceptibility Measurements for Concluding on Site Potentials and Risks Provoked by Fly Ash Deposition

The article presents results of testing the indicative value of magnetic susceptibility for fly ash deposition and its effects on forest site properties. Base saturation and concentrations of Ca and Mg were used as indicators for nutrient pools resulting from fly ash deposition. Concentrations of Fe, Al, Mn, Cd and Black Carbon were used as indicators for risks of leaching. The correlation of magnetic susceptibility with concentrations of nutrient, acidic cations, heavy metals, base saturation and Black Carbon was calculated. Additionally, we tested the suitability of magnetic susceptibility as a parameter in a linear regression based model to predict the concentrations of Ca, Mg, Fe, Al, Mn, Cd and Black Carbon. We were able to show a positive correlation between magnetic susceptibility and the selected indicators. In contrast to previous studies, we were also able to demonstrate the suitability of magnetic susceptibility to predict the size of fly ash deposition influenced nutrient pools mainly for humus layers, especially for Oa horizons. The spatial distribution of magnetic susceptibility showed also a positive correlation with regionalized base saturation. However, because of the data base and other factors impacting the measurement and modeling results, some shortcomings of using a linear regression model must be noted. From these results, we concluded that magnetic susceptibility might be a valuable parameter in a multiple regression based approach, but should not be used alone for predicting effects of fly ash deposition.

Spatial Distribution of Magnetic Susceptibility and Ore Elements, and Cause of Local Reduction on Magnetite-series Granitoids and Related Ore Deposits at Chichibu

Spatial Distribution of Magnetic Susceptibility and Ore Elements, and Cause of Local Reduction on Magnetite-series Granitoids and Related Ore Deposits at Chichibu

Mineralogy and Magnetic Properties of Basaltic Substrate Soils: Kaho'olawe and Big Island, Hawaii

Magnetic behavior of soils can seriously hamper the performance of geophysical sensors. Currently, we have little understanding of the types of minerals responsible for the magnetic behavior, as well as their distribution in space and evolution through time. This study investigated the magnetic characteristics and mineralogy of Fe‐rich soils developed on basaltic substrate in Hawaii. We measured the spatial distribution of magnetic susceptibility (χlf) and frequency dependence (χfd%) across three test areas in a well‐developed eroded soil on Kaho'olawe and in two young soils on the Big Island of Hawaii. X‐ray diffraction spectroscopy, x‐ray fluorescence spectroscopy (XRF), chemical dissolution, thermal analysis, and temperature‐dependent magnetic studies were used to characterize soil development and mineralogy for samples from soil pits on Kaho'olawe, surface samples from all three test areas, and unweathered basalt from the Big Island of Hawaii. The measurements show a general increase in magnetic properties with increasing soil development. The XRF Fe data ranged from 13% for fresh basalt and young soils on the Big Island to 58% for material from the B horizon of Kaho'olawe soils. Dithionite‐extractable and oxalate‐extractable Fe percentages increase with soil development and correlate with χlf and χfd%, respectively. Results from the temperature‐dependent susceptibility measurements show that the high soil magnetic properties observed in geophysical surveys in Kaho'olawe are entirely due to neoformed minerals. The results of our studies have implications for the existing soil survey of Kaho'olawe and help identify methods to characterize magnetic minerals in tropical soils.

Magnetic mapping of fly-ash pollution and heavy metals from soil samples around a point source in a dry tropical environment

The Singrauli region in the southeastern part of Uttar Pradesh, India is one of the most polluted industrial sites of Asia. It encompasses 11 open cast coal mines and six thermal power stations that generate about 7,500 MW (about 10% of India's installed generation capacity) electricity. Thermal power plants represent the main source of pollution in this region, emitting six million tonnes of fly-ash per annum. Fly-ash is deposited on soils over a large area surrounding thermal power plants. Fly-ashes have high surface concentrations of several toxic elements (heavy metals) and high atmospheric mobility. Fly ash is produced through high-temperature combustion of fossil fuel rich in ferromagnetic minerals. These contaminants can be identified using rock-magnetic methods. Magnetic susceptibility is directly linked to the concentration of ferromagnetic minerals, primarily high values of magnetite. In this study, magnetic susceptibility of top soil samples collected from surrounding areas of a bituminous-coal-fired power plant were measured to identify areas of high emission levels and to chart the spatial distribution of airborne solid particles. Sites close to the power plant have shown higher values of susceptibility that decreases with increasing distance from the source. A significant correlation between magnetic susceptibility and heavy metal content in soils is found. A comparison of the spatial distribution of magnetic susceptibility with heavy-metal concentrations in soil samples suggests that magnetic measurements can be used as a rapid and inexpensive method for proxy mapping of air borne pollution due to industrial activity.

Magnetic susceptibility and ice-rafted debris in surface sediments of the Atlantic sector of the Southern Ocean

Spatial distribution of magnetic susceptibility and the gravel fraction in surface sediments in the Atlantic sector of the Southern Ocean were investigated to reconstruct source areas and recent transport pathways of magnetominerals and ice-rafted debris. Maxima of magnetic susceptibility were observed offshore from areas where mafic source rocks occur, e.g. Queen Maud Land and the northern Antarctic Peninsula. The glacigenic input of debris and subsequent redeposition of fine material by bottom and turbidity currents on the continental margins result in regional variations of the gravel and susceptibility values. In the deep sea, however, the mixing of ice-rafted debris and turbidites from distal source areas causes a homogenous distribution of the susceptibility signal. On submarine elevations such as Maud Rise and Astrid Ridge, dust input may be an additional source for magnetominerals.

Proxy mapping of fly-ash pollution of soils around a coal-burning power plant: a case study in the Czech Republic

The northern part of the Czech Republic ranks among the most industrially polluted areas of Europe due mainly to combustion of brown coal with high contents of pyrite and heavy metals. Fly ash produced through high-temperature combustion of fossil fuel is also rich in ferromagnetic minerals. These are also included in emissions, penetrate the soil, and can be identified using rock-magnetic methods. Magnetic susceptibility is directly linked to a concentration of ferromagnetic minerals and is dominated by high values of magnetite. This study reports on a method of monitoring the spatial distribution of pollution due to airborne solid particles based on measurements of magnetic susceptibility of the soil surface near a brown-coal-burning power plant. Areas with high emission levels and their maximum range are determined. A comparison of the spatial distribution of magnetic susceptibility with heavy-metal concentrations in soil samples suggests that magnetic mapping can be beneficially used as a rapid and inexpensive method to determine contamination due to industrial activity.