Soil Magnetic Susceptibility Research Articles

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.

Soil magnetic susceptibility and its relationship with naturally occurring processes and soil attributes in pedosphere, in a tropical environment

Soil magnetic susceptibility (κ) has potential to be used as a pedoenvironmental indicator from which mineralogy, pedogeochemical, pedogeomorphological and pedogenic processes can be inferred. It can be used in pedosphere studies, as an auxiliary information for appropriate and sustainable soil use and management. This research aimed to analyze how pedogenesis and geochemical processes affect the κ and some of its attributes, as well as its potential use in discriminating soil great groups, following the digital soil mapping approach. The study area is located in São Paulo State - Brazil. Soil samples were collected for physical–chemical analysis from 79 locations (0–20 cm depth). At these sites, magnetic susceptibility was measured with a portable field instrument and analyzed in terms of geology, relief and soil class. The results showed that geology strongly affects κ, mainly in diabase derived soils, followed by metamorphosed siltstone and siltstone. In fluvial sediments, the κ exhibits different behaviors due to different sediments deposited by the Capivari River. In less evolved soils, such as Cambisols, lithology is a more important contributor to κ than pedogenesis. In more evolved soils, pedogenesis increases κ, whereas argilluviation/ferralitization reduces it. The κ values did not decrease significantly or even increase downslope, due to the presence of diabase on the lower parts. Differences in κ where observed between diabase bedrock located in different parts of the study area, indicating more of an influence by geomorphic processes rather than lithology. With respect to soil attributes, positive correlations between κ and base saturation, cation exchange capacity, organic matter, and iron and clay content were found, whereas a negative correlation was found between κ and sand content. The κ correlates with changes in lithology and soil class demonstrating its application as a potential tool for the discrimination of soil great groups and digital soil mapping.

Soil and dust magnetism in semi-urban area Truskavets, Ukraine

The objective of this paper was to study pollution in the semi-urban area of Truskavets (Ukraine) using low-cost and energy-efficient magnetic measurements. Soil magnetic properties were measured near a railway station (transect) and near a road (transect and grid). To compare the magnetic properties of the soils from the urban areas, we sampled in a forest area located 2–3 km from Truskavets. Additionally, ten dust samples were taken 150 cm above the ground from the smooth surface of the tree bark. Near the Stebnyk Ring (the end of the second transect), we established a grid (20 × 20 m) and measured the soil magnetic susceptibility MS (mass-specific χ, and volume κ). There were taken 55 soil samples within the upper 0–5 cm of the topsoil. The results showed that low-frequency MS of the natural soil was within the range of 8–10 × 10–8 m3/kg, a low value for the Ukraine soils. The urban soils collected near the roadway and the railway had high MS values. Soil pollution was confirmed by the frequency dependence of magnetic susceptibility: χfd = 2–3%. Our results, based on the thermomagnetic, hysteresis, isothermal (IRM), and anhysteretic remanent magnetization (ARM) measurements, suggested that magnetite is responsible for the increase in the magnetic signal of the urban soils. Natural soils normally contain a single domain (SD) grains. It has also been found that the high coercivity haematite and goethite are stable pedogenic minerals in the Truskavets natural soil. Overall, the magnetic measurements have proven to be a rapid, low cost, non-destructive and efficient technique for soil monitoring and air quality assessment.

Patterns in soil contamination across an abandoned steel and iron plant: Proximity to source and seasonal wind direction as drivers

Via magnetic susceptibility and X-ray fluorescence spectrometry, we examined soil heavy metal contents across an abandoned steel and iron plant that has been in production for 50 years. Soil magnetic susceptibility and heavy metal contents similarly decreased with increasing distance from the plant's industrial, central area. Results indicate that the mean value of soil magnetic susceptibility was 2727 × 10−8 m3·kg−1 and the max peak was 100 m from the plant's center. Frequency dependent susceptibility values less than 2%, suggest the presence of coarse grains from industrial activities. A significant positive correlation occurs between magnetic susceptibility and Mn, Fe, Cu and Pb. Irregular-shaped and non-spherical aggregates are the main morphology of technogenic magnetic particles found in soil samples. Our results indicate that the North, Northeast and East sampling areas generally have the highest pollutants values and these directions correspond with prevailing wind directions at differing times of the year. Mapping the spatial distribution of metals could lead to high-resolution risk targeting areas for remediation and land use planning.

Magnetic susceptibility measurement and heavy metal pollution at an automobile station in Ilorin, North-Central Nigeria

Magnetic susceptibility measurement was carried out on 26 top-soil samples randomly collected from the study area and 5 selected top-soil samples outside the station, using the Bartington MS meter linked to a computer operated using Multisus2 software. The Measurements was done at both low (0.47 kHz) and high (4.7 kHz) frequency susceptibilities which was further used to calculate the frequency dependent susceptibility (ΧFD). The values for low frequency mass magnetic susceptibility ranges between 96.6 × 10−5 m3 kg−1 and 146 × 10−5 m3 kg−1 with an average value of 117.35 × 10−5 m3 kg−1 and standard deviation of 12.22 × 10−5 m3 kg−1. The result reveal high magnetic susceptibility values at the station compared with the values observed outside the station which ranges between 53.0 × 10−5 m3 kg−1 and 72.3 × 10−5 m3 kg−1 with an average value of 63.2 × 10−5 m3 kg−1 and standard deviation of 7.01 × 10−5 m3 kg−1. This significant magnetic enhancement indicates high concentration of ferrimagnetic minerals in the soil and thus evidence of pollution due to the activities at the station which implies that the magnetic enhancement is of anthropogenic source than pedogenic and lithogenic. Analysis of the heavy metals also reveals higher values at the station. The correlation analysis between the mass specific magnetic susceptibility and the heavy metals concentrations (i.e. Cu (R = 0.92), Fe (R = 0.88), Cr (R = 0.85), Zn (R = 0.83), Cd (R = 0.79), Mg (R = 0.72), Mn (R = 0.60), Pb (R = 0.67)) which was conducted to further investigate the relationship between the soil magnetic susceptibility values and elemental variations, demonstrated magnetic susceptibility can be used as a proxy method for assessing the pollution of these heavy metals.

Using magnetic susceptibility for predicting hydrocarbon pollution levels in a petroleum refinery compound in Isfahan Province, Iran

Nowadays through the world as well as in Iran, petroleum hydrocarbons have majority contribution in environmental ricks for human and other organisms. Therefore, this study evaluates hydrocarbon pollution effects on soil chemical properties, as well as soil magnetic susceptibility on a petroleum refinery compound in Isfahan province, Iran. It also examines the efficacy of using magnetic signatures to predict hydrocarbon pollution of soils. Two sites (polluted and unpolluted) with similar intrinsic soil properties and environmental attributes were selected. A total of 120 soil samples were collected at two depths of 0–10 and 10–30 cm. Laboratory analysis included measurement of electrical conductivity (EC), pH, aqua regial extractable Fe (FeA), dithionite extractable Fe (Fed), magnetic susceptibility at low frequency (χlf), total petroleum hydrocarbon (TPH), as well as powdery X-ray characterization. Polluted soils by petroleum hydrocarbons had significantly higher EC, χlf, FeA and Fed and lower pH values compared to the unpolluted soils. Positive significance (r = 0.88, p < .01) was obtained between TPH and magnetic susceptibility. Enhancement of magnetic susceptibility presumably attributed to formation of ferrimagnetic minerals such as magnetite because of degradation of hydrocarbon compounds. A multiple linear regression model was developed between magnetic susceptibility and TPH, and the results showed that the developed pedotransfer function could explain 86% of the variability of TPH in the studied area, and provided a reliable function to predict TPH in polluted soils, as a cost-effective and fast technique to be implemented in the polluted sites by petroleum hydrocarbons. It seems that inclusion of additional magnetic measures may improve the accuracy of the predictive model.

Low CO2 levels of the entire Pleistocene epoch

Quantifying ancient atmospheric pCO2 provides valuable insights into the interplay between greenhouse gases and global climate. Beyond the 800-ky history uncovered by ice cores, discrepancies in both the trend and magnitude of pCO2 changes remain among different proxy-derived results. The traditional paleosol pCO2 paleobarometer suffers from largely unconstrained soil-respired CO2 concentration (S(z)). Using finely disseminated carbonates precipitated in paleosols from the Chinese Loess Plateau, here we identified that their S(z) can be quantitatively constrained by soil magnetic susceptibility. Based on this approach, we reconstructed pCO2 during 2.6–0.9 Ma, which documents overall low pCO2 levels (<300 ppm) comparable with ice core records, indicating that the Earth system has operated under late Pleistocene pCO2 levels for an extended period. The pCO2 levels do not show statistically significant differences across the mid-Pleistocene Transition (ca. 1.2–0.8 Ma), suggesting that CO2 is probably not the driver of this important climate change event.

Comparative analysis of soil magnetic susceptibility and concentration of rare earth elements in soil of problematic areas

Abstract Soil contamination with rare earth metals (REE) can have both direct and indirect connection with industrial activity and ore-exploration. In the studies conducted so far, the presence of rare earth elements in coal seams, coal combustion waste as well as fly ash was found. It is important that detailed studies of the REE content in soil were not carried out in Poland. Until now, in a few studies, a high content of cerium and lanthanum was found in relation to the average content of the torn ones in the world. This work focuses on the areas under the influence of the industry associated with the extraction and combustion of hard coal, but also with other types of industry. Analyzes of REE content in soil were conducted in selected areas of the Upper Silesian Industrial Region and Norway, located near the Bjornevatn mine. In study areas, soil samples were collected and used for chemical and magnetometric measurements. Firstly, concentrations of REE were determined, and after that soil samples were used to measure soil magnetic susceptibility. Finally, statistical analyses were performed in order to check the correlation between REE concentrations in soil and soil magnetic susceptibility.

Assessment of areal water and tillage erosion using magnetic susceptibility: the approach and its application in Moroccan watershed.

Soil erosion constitutes a serious threat for sustainable agriculture in many countries. Magnetic susceptibility of soil is a fast, cheap, and non-destructive technique that could be used to quantify soil erosion or soil redistribution on a long-term scale. This study attempts to analyze the variation of magnetic susceptibility in soil profiles having the same lithology and climatic conditions, but different land uses and slope gradients in a subcatchment in northern Morocco. Soil cores were collected on forested, cultivated, and pasture lands. Each core was associated to a field unit (also called a homogeneous unit) characterized by a set of four cited erosion factors. The samples were measured for mass-specific low-frequency magnetic susceptibility (χlf) and frequency-dependent magnetic susceptibility (χfd). The linear correlation of χlf and χfd indicates the homogeneity of magnetic population in soil. It supports the use of empirical models based on comparisons of χlf to predict the value of magnetic parameter after tillage homogenization and removal of soil material from the surface, and to estimate soil erosion or redeposition. The study built a methodology improving these empirical models and enabling a quantitative approach of the phenomenon. Two models, namely "tillage homogenization" (as improved in this study) and the proposed "simple correlation" result in globally similar estimates of erosion, while another model, the "simple proportional" model, underestimates it. The results give an estimate of long-term erosion (deposition) in sampled units and allow drawing of an areal soil redistribution map in the watershed.

Towards magnetometric characterization of soil pollution with rare-earth elements in industrial areas of Upper Silesian Industrial Area, Southern Poland

The paper presents systematic study concentrations of selected rare-earth elements, namely La and Ce in soils of highly industrialized regions using geochemical and magnetometric measurements as well as geostatistical methods. Soil magnetometry was used to determine if the concentrations of La and Ce in soil could be a result of anthropogenic pollution or natural soil properties. Results of analyses revealed that the highest concentrations of La and Ce were observed near a waste heap of the plant producing and processing batteries, and in the region of the Jizera Mountains, natural REE-rich minerals are very common. It was also found that the lowest concentrations of La and Ce in soil were observed in forested areas of where the dominant type of pollution sources was associated with the metallurgical industry. Distributions of magnetic susceptibility in soil profiles collected in areas with predominant industrial influence showed visible peak in topsoil, what confirmed anthropogenic origin of La and Ce in soil. In areas where large volumes of wastes were deposited in past, industrial activity, vertical distributions of soil magnetic susceptibility showed also secondary, strong peak in subsoil. Thus, the results reveal that magnetometric measurements in soil profile might be useful as supplementary method for analyzing of concentrations of rare-earth elements. Contrary, magnetometric measurements performed on the soil surface were poorly correlated with a concentration of La and Ce in soil, because they have weaker magnetic properties than typical fly ashes emitted by industry.

Spatial variability of soil magnetic susceptibility under different scales: a case study of Xiangtan

The characteristics of soil magnetic parameters can reflect the natural environment evolution and the human activities influence. By systematically sampling and measuring the sediments and onshore soils in representative water of Xiangtan City, spatial estimation was carried out by Kriging Spatial Interpolation with the help of SPSS, ArcGIS, Surfer, and other statistical and spatial analysis software. The results showed that: (1) Under the city scale, the spatial variation of soil magnetic susceptibility was large and ranged from 1.167×10−8 m3 kg−1 to 165.93×10−8 m3 kg−1; (2) the soil magnetic susceptibility varies greatly under different land-use patterns, which may be related to the accumulation and absorption of magnetic substances in the soil environments. On the functional area scale, human activities on soil magnetic susceptibility were relatively large, which might be closely related to agricultural activities and domestic waste discharge; (3) the distribution of soil magnetic susceptibility was mainly affected by various factors; (4) the spatial autocorrelation distance decreased from the city scale to the functional area scale. Structural elements, such as sedimentation, topographic gradient, animals and plants, have a more significant influence on the spatial distribution of soil magnetic susceptibility.

ІНФОРМАТИВНІСТЬ МАГНІТНИХ МЕТОДІВ ПРИ МОНІТОРИНГУ ПРИРОДНО-ТЕХНОГЕННИХ ПРОЦЕСІВ, ЯКІ ПОВ'ЯЗАНІ З ОБ'ЄКТАМИ КРИТИЧНОЇ ІНФРАСТРУКТУРИ

Presented are the results of research studies with the attracting of the GIS and geophysical methods for solving the problems of monitoring of dangerous natural and man-made processes at the areas of the critical infrastructure objects location. The possible ways of the magnetic methods applied for the critical infrastructure objects monitoring were considered. The natural and man-made processes associated with the critical infrastructure were defined. Among them are the objects that can influence the changes in soils, atmospheric air composition, as well as near-surface geological horizons. The most important objects are the energy enterprises, chemical industry, transport network, and landslide areas. The "Rzhyshchev" section and the "Grebeni" site were used as testing objects of the landslide critical infrastructure. According to the results of processing of cosmoimages and measurements of lateral and vertical distributions of magnetic susceptibility of soils and near-surface geological horizons, the classification of territory risks has been carried out. The territory of the cliff on the slopes of the Dnieper is the most potentially dangerous. Anthropogenically impacted natural and man-made territory of the field road and private economy has received an average category of risks. The most risky part of the site are the elements of the landscape, which are located on the land with a minimum slope, the absence of anthropogenic loading, agricultural land and virgin land. Magnetic methods proved to be rapid, effective and low-cost technology for the study of natural and man-made processes associated with objects of critical infrastructure. The integration with other geophysical, soil science methods, and GIS technologies are required.

土壤磁化率的研究与应用综述

土壤磁化率的研究与应用综述

МАГНІТНА СПРИЙНЯТЛИВІСТЬ ҐРУНТІВ У СКЛАДІ ЕРОЗІЄЗНАВЧИХ ДОСЛІДЖЕНЬ

Water erosion of the soil is a major factor in the degradation of agricultural land in Ukraine. About 13 million hectares of arable land need additional protection. The study of the influence of the mentioned hazard processes is important both for the scientists and land endusers. The purpose of the paper is to demonstrate the possibilities of soil magnetic susceptibility mapping in erosion studies. The comparison with traditional methods is implemented. The studies were carried out at the territory of Farm Enterprise "Phoenix" of the Bliznyukovsky district of the Kharkiv region at the distance of 6 km to the southeast of the Lozova. The study site is used for crop production. The relief of the site is complicated by the developed ravine network. The soil is ordinary chernozems (Haplic Chernozems in WRB classification). We have registered high correlation between magnetic susceptibility (MS) of the studied chernozems and humus content (organic matter). The Spearman correlation coefficient slightly depends on the frequency magnetic susceptibility coefficient. The results give the opportunity to recommend soil MS studies as the additional tool in soil erosion mapping. The magnetic measurements are expensive and fast for the humus (organic matter) identification of eroded soil. The relation of the values of soil MS and the value of potential soil loss at the studied area was low. The study of the magnetic mineralogy confirmed the absence of the anthropogenic soil pollution. We confirmed this by the values of the frequency dependence of magnetic susceptibility which were above 6. The domination of the superparamagnetic (SP) grains with the size less than 20 nm was confirmed by the values of the frequency dependence of magnetic too. The majority of the MS values are 10-20. The magnetic minerals of the studied soil have been formed in real time under the pedogenic (natural soil formation) process.

Effects of Contour Plowing by Rotary Cultivator on Vertical Redistribution of Soil Organic Carbon

Simulated tillage and magnetic tracing techniques were applied to study the effects of contour plowing by rotary cultivator on vertical migration of soil organic carbon (SOC) on a steep hillslope in purple soil, revealing the relationship between SOC vertical and downslope movements. Contour plowing by rotary cultivator played an important role on downslope transfers of the soil, resulting in an obvious transformation of soil profiles with tillage depth at the summit position. The depth distribution of soil magnetic susceptibility showed that tillage brought about the vertical downward migration of the soil magnetic tracer. The intense tillage led to the vertically downward transfer of SOC, but vertical redistribution patterns differed from one another at different slope positions. Due to upward migration of parent rock debris and downslope transport of soil, SOC concentrations in the surface soil layer (0-10 cm) was reduced significantly at the summit position. For the backslope and footslope positions, SOC concentrations at 0-20 cm was reduced remarkably due to mixture effects of tillage and tillage erosion. SOC in the surface layer (0-5 cm) was decreased slightly at the toeslope position, but that at 5-20 cm increased significantly. This study indicated that the vertical movement of soil interacted with the downslope movement, which resulted in significant variation of SOC from the summit to toeslope positions.

Soil magnetism and climatic variation across the Shanxi Loess Plateau, China

Soil magnetic parameters are increasingly being linked to climatic and environmental variation, and thus provide an useful information for tracking perturbations in terrestrial environments. Climate data and the magnetic properties of modern topsoil samples were examined across a 680 km transect of the Shanxi Loess Plateau and compared to regional climate data – including temperature and precipitation. The results revealed median values of magnetic susceptibility (79.49 × 10−8 m3kg−1), saturation isothermal remanent magnetization (SIRM 1058.37 × 10−5Am2kg−1), and anhysteretic remanence magnetization (ARM 14.29 × 10−5Am2kg−1), respectively. Soils were also shown to contain a high prevalence of super paramagnetic (SP) grains, as indicated by frequency dependent susceptibility above 5%. Soil magnetic susceptibility, SIRM, and ARM showed a significant correlation with the mean annual precipitation (MAP), while a weak association was observed between ARM and mean annual temperature (MAT). The spatial distribution of topsoil magnetism in the region suggests a strong gradient from north to south, which is consistent with a moderate rainfall gradient of 350– 700 mm.yr−1. Overall, these data showed that soil magnetic properties across the Shanxi Loess Plateau are similar to other loess-derived soils in China and reflect the influence of climatic parameters in their genesis, especially rainfall.

Quantitative relationships between climate and magnetic susceptibility of soils on the Bačka Loess Plateau (Vojvodina, Serbia)

Magnetic properties of soils formed in and on loess substrate and their relation to climate are of general interest in paleoclimate and pedological research. The loess-paleosol sequences (LPS) in the Vojvodina region (Serbia) have been the subject of intensive study. On the Bačka loess plateau (BLP), covering approximately 2500 km2, six different soil types are observed. While the stratigraphy of the LPS has been investigated the relation between climatic factors and magnetic properties of surface soil have not yet been examined. In this study we analyze 50 samples of chernozem soils, which have been dominated by climatic factors during their formation. Previous studies have confirmed that the formation of magnetic properties in soils is related to climate, and especially rainfall, because of the response of hematite and goethite to different, climatically-driven regimes. The sensitivity of certain iron-bearing minerals to climate has also been documented in the literature. Climatic variables for the BLP were derived from six-decade national meteorological datasets. Low frequency magnetic susceptibility (χ) and frequency dependent magnetic susceptibility (χfd) were determined for each site and compared to the mean annual precipitation (MAP), mean annual temperature (MAT) and the De Martonne aridity index (IDM). The meteorological variables were interpolated to sampling points by Kriging method in ArcMap 10.1. Our results suggest that values of χ and χfd both decrease from south to north and so does the precipitation. Thus, our work provides new evidence for the relationship between precipitation, temperature, aridity and magnetic properties of modern top soils. The obtained and analyzed data may help in the future to improve transfer functions of the relationship between magnetic susceptibility and climatic data.

Geochemical characterization of the loess-paleosol sequence in northeast China

Long-term weathering patterns in northeastern China are not well known due to few well-preserved terrestrial paleo-environmental archives in this area. The Chaoyang section is a typical well-preserved loess-paleosol sequence in northeast China with continuous deposition since 423 ka BP; the deposit thus represents an archive of climate change for this region. The sequence was geochemically characterized by major elemental compositions, elemental ratios, a ternary diagram of Al2O3-(CaO* + Na2O)-K2O, improved quantitative reconstruction and elemental distributions with respect to the average for the upper continental crust (AUCC). Another typical loess-paleosol sequence of Lingtai section from the central Chinese Loess Plateau was used for comparison with the loess-paleosol one. The similar AUCC-normalized major elemental distributions and strong correlation of the major elemental compositions between the loess-paleosol sequences indicate that they may have originated predominantly from a similar loess source. Based on the variability in chemical indices corresponding to soil magnetic susceptibility (SUS) and field observations, the loess-paleosol formation period of 423–77 ka BP was separated into eight sub-periods including four periods with greater chemical weathering intensity (paleosols) and four periods characterized by the relative lesser chemical weathering intensity (loess). Relatively intense desilication and fersiallitization primarily occurred in the loess-paleosol sequence from northeast China with greater losses of SiO2 (3.54% in average) and gains of Fe2O3 (0.77%) and Al2O3 (0.33%). Such processes also were reflected in an increase in the amount of K2O (0.41%). Ca and Na leaching was still predominant in the loess-paleosol sequence from the central Chinese Loess Plateau with greater losses of CaO (28.03%) and Na2O (14.03%). The sequence from northeast China records chemical weathering during 423–77 ka BP, which is comparable to the weathering cycles in the sequence from the central Chinese Loess Plateau.

Satellite data and soil magnetic susceptibility measurements for heavy metals monitoring: findings from Agri Valley (Southern Italy)

Heavy metals pollution is a widespread problem in urbanized and industrial areas and there is a need of optimized and effective strategies for identifying and monitoring polluted areas. This study proposes an improved methodology based on Landsat satellite data and magnetic susceptibility measurements carried out in situ and in laboratory. Findings suggest that expeditious field surveys of soil magnetic susceptibility within stressed vegetated areas are a reliable indicator of soil contamination. Moreover, this procedure could provide a method for assessing heavy metals impacts and could be used to examine the effectiveness of emission control strategies.

Impact of an iron mine and a nickel smelter at the Norwegian/Russian border close to the Barents Sea on surface soil magnetic susceptibility and content of potentially toxic elements

An important problem in soil magnetometry is unraveling the soil contamination signal in areas with multiple emitters. Here, geophysical and geochemical measurements were performed at four sites on a north - south transect along the Pasvik River in the Barents Region (northern Norway). These sites are influenced by depositions from the Bjørnevatn iron mine and a Ni-Cu smelter in Nikel, Russia. To relate the degree and type of pollution from these sources to the corresponding magnetic signal, the topsoil concentrations of 12 Potentially Toxic Elements (PTEs) (As, Cd, Co, Cr, Cu, Fe, Mo, Ni, Pb, Se, Ti, Zn), were determined, magnetic hysteresis parameters and thermomagnetic properties were measured. In situ magnetic low-field susceptibility decreases from north to south with increasing distance from the iron mine. Relatively large magnetic multidomain grains of magnetite and/or titanomagnetite are responsible for the strong magnetic signal from the topsoil close to Bjørnevatn. These particles are related to increased enrichment factors of As, Mo and Cu, yielding high positive correlation coefficients with susceptibility values. At a site furthest away from the iron mine and located 7 km from the Ni-Cu smelter magnetic susceptibility values are much lower but significant positive correlations on the level of p < .1 with 8 PTEs (Ni, Cu, Co, Se, As, Zn, Cd, Cr) have been observed. The magnetic signal in this area is due to fine-grained primary sulphides and secondary fine-grained magnetite and/or maghemite.