Frequency Dependent Magnetic Susceptibility in Topsoil of Bandung City, Indonesia

Soil contains lithogenic components as well as anthropogenic components including combustion residues from traffic activities. The high traffic activities in major cities such as Bandung have caused the air pollution level to increase significantly. These activities might also produce significant combustion residues that accumulate, among others, in the topsoils. Compared with lithogenic components in topsoil, the anthropogenic combustion residues might have different magnetic signatures that could be detected by magnetic measurements. In this study, 38 topsoil samples from 19 roadside sampling points in Bandung City were collected and magnetically analysed to map the magnetic signatures due to traffic activities. The samples were measured for magnetic susceptibility using Bartington MS2B Susceptibility Meter and hysteresis parameter analysed from Vibrating Sample Magnetometer (VSM). The results show that the values of mass-specific magnetic susceptibility (χLF) vary from 391.20 to 1835.20×10-8 m3/kg with the average value of 1012.16 × 10-8 m3/kg while the values of frequency dependent susceptibility (χFD%) vary from 0.54% to 4.48% with the average value of 1.9%. The relatively high value of magnetic susceptibility indicates higher concentration of magnetic minerals compared to that of pristine topsoil around Bandung. This is in agreement with similar studies on roadside topsoil elsewhere. The poor correlation between mass-specific magnetic susceptibility and frequency dependent magnetic susceptibility infers that the magnetic minerals are predominantly non superparamagnetic. This finding is supported by magnetic hysteresis parameters showing that the predominant grains are likely to be pseudo-single domain (PSD) if magnetite is assumed to be the predominant magnetic mineral. Similar studies in German and China reported that the predominant magnetic mineral is mixture of single domain to multi domain magnetite.

Mercury in Sediment Core Samples From Deep Siberian Ice-Rich Permafrost

We determine Hg concentrations of various deposits in Siberia’s deep permafrost and link sediment properties and Hg enrichment to establish a first Hg inventory of late Pleistocene permafrost down to a depth of 36 m below surface. As Arctic warming is transforming the ice-rich permafrost of Siberia, sediment is released and increases the flux of particulates to the Arctic shelf seas through thawing coasts, lakeshores, and river floodplains. Heavy metals within soils and sediments are also released and may increasingly enter Arctic waters and the biological food chain. High levels of mercury (Hg) have been reported from shallow soils across the Arctic. Rapid thawing is now mobilizing sediment from deeper strata, but so far little is known about Hg concentrations in deep permafrost. Here, forty-one samples from sediment successions at seven sites and of different states of permafrost degradation on Bykovsky Peninsula (northern Yakutian coast) and in the Yukechi Alas region (Central Yakutia) were analyzed for Hg, total carbon, total nitrogen, and total organic carbon as well as grain-size distribution, bulk density, and mass specific magnetic susceptibility. We show average Hg concentrations of 9.72 ± 9.28 μg kg−1 in the deep sediments, an amount comparable to the few previous Arctic studies existing, and a significant correlation of Hg content with total organic carbon, total nitrogen, grain-size distribution, and mass specific magnetic susceptibility. Hg concentrations are higher in the generally sandier sediments of the Bykovsky Peninsula than in the siltier sediments of the Yukechi Alas. The ratio of Hg to total organic carbon in this study is 2.57 g kg−1, including samples with very low carbon content. We conclude that many deep permafrost sediments, some of which have been frozen for millennia, contain elevated concentrations of Hg and the stock of Hg ready to be released by erosion is of significance for the Arctic ecosystem. The Hg mobilized may accumulate on the way to or in the shallow sea, and where it enters into active biogeochemical cycles of aquatic systems it may concentrate in food webs. Our study highlights the need for better understanding Hg stocks and Hg release from permafrost.

Assessment of ecological and geochemical state of alluvial soils of floodplains of small rivers of Perm

In the conditions of the city of Perm - a multidisciplinary industrial center of Russia, the regularities and quantitative characteristics of the redox and ecological-geochemical state of the soils of the floodplains of small rivers-tributaries of the Kama River within the Votkinsk reservoir are revealed. The regularities of the content, distribution and interrelation of potentially toxic chemical elements are established, the priority elements-pollutants, and their mobility in floodplain soils are determined. It was found that under the influence of heterogeneity of redox conditions, sorption, gley, and hydrogen sulfide geochemical barriers are formed in the soil profile. It was found that when hydrogenic pollution of urban alluvial soils occurs, natural-technogenic associations of chemical elements are formed in their profile, which differ from natural associations in the background soil. Elemental geochemical associations are characterized at different levels of technogenic load on the floodplains of small rivers. The relationship between the concentration of chemical elements and the value of the specific magnetic susceptibility in floodplain soils is determined. Keywords: REDOX STATE, HEAVY METALS, GEOCHEMICAL COEFFICIENTS, URBO-ALLUVIAL SOILS, CHEMOSEMS ON URBO-ALLUVIAL SOILS

INTEGRATING OF GEOPHYSICAL AND AGROCHEMICAL METHODS FOR SLOPE LANDS STUDYING

The increasing of the soil degradation of agricultural lands in Ukraine requires the improvement of their survey system. First of all, it is related to the increase of the accuracy of determinations and the density of the measurement grid. To perform these tasks, new methods are involved, primarily the geophysics ones. There are certain advantages of the integration of the studies as well as development of the substantiated rational combination of methods. Recently, promising results of the application of the magnetic susceptibility of soil to characterize the agronomic properties have been obtained. This study shows the results of the integrated application of a number of agrochemical methods and determinations of mass-specific magnetic susceptibility (MS) on the example of podzolized chernozems of Kharkiv district of Kharkiv region. We identified the possibilities of culling of values of soil characteristics from the proceeding of the results of definition of MS. The nature of the correlation between MS and humus content allows us to recommend the replacement of more expensive determination of humus content with cheaper MS. Soil magnetic susceptibility correctly reflects the spatial distribution of the main indicators of eroded lands: the humus content, and physical clay. We propose the study of sloping lands with more optimal techniques of the MS measurement of the soil as the most accessible tool.

Magnetic Susceptibility of Permafrost Meadow-Chernozem Soils of Central Yakutia

Magnetic susceptibility was studied for the first time, as well as geographical and genetic features of the formation of properties and composition of permafrost meadowchernozem soils in Central Yakutia, depending on the conditions of soil formation and anthropogenic impact. A total of 11 soil sections were studied, with 6 soils developing under natural vegetation, and 5 under various agricultural lands. Various soil research methods, such as comparative geographical, profile-genetic, and comparative-analytical, were used in the course of this work, and the composition and properties of soils were determined using generally accepted methods. The volume magnetic susceptibility (VMS) was determined using a smallsized magnetic susceptibility meter KM-7, which is an improved version of the kt- 6 kappameter. The value of the specific magnetic susceptibility (SMS) was obtained by dividing the VMS value by the soil density p (expressed in kg/m3), χ = χ/p. It is shown that the properties of the studied soils differed significantly depending on the conditions of soil formation, as well as on the nature and level of anthropogenic impact. Also, the values of VMS and SMS of these soils of natural landscapes of Central Yakutia changed significantly, making up 31.4-138.9 Si units, respectively. 31.4-102.3ꞏ10-8 m3/kg. Even more variable values of VMS and SMS were observed in anthropogenic-modified analogs of the studied soils, where the values of VMS were 31.5-267.8 Si units, and those of SMS– 30.6-199.8ꞏ10-8 m3/kg. The magnetic profiles of the studied soils, which are characterized by the ratio χ/χc in the soils of natural landscapes corresponded to a more or less uniform type of distribution, where the values of the ratio χ/χc were 0.7-1.3, while in the studied soils of anthropogenic landscapes the values of these relations significantly narrow down and expanded to 0.2-2.0. This cardinally distinguishes the magnetic profiles of the studied permafrost meadow-chernozem soils from the corresponding chernozem soils of other non-permafrost regions of Russia, where accumulative types of magnetic profiles are usually formed, and the ratio χ/χc in the surface humus horizons is about 1,5 or even more.

Features of the physicochemical properties of narrow fractions of aggregates of diamond nanopowders modified with iron ions

The paper presents the results of a study of the physical and chemical properties of narrow fractions of diamond nanopowders with a low content of non-diamond carbon grade ASUD-99. Six fractions with different average diameters of diamond particle aggregates from 28.785 to 3.891 μm were obtained by separating a 0.2 % aqueous suspension of the initial powders by the sedimentation method. It has been found that the smallest aggregates consist of larger particles with a smaller specific surface area and a lower interaction energy between them. This conclusion is confirmed by a decrease in the porosity of the obtained aggregates. So, if the pore volume in the largest aggregates of diamond particles is 0.859 ml/g, then in the smallest 0.550 ml/g, while the pore radius of diamond aggregates in different fractions changes insignificantly. Separation in a magnetic field at different currents of diamond nanopowders with a specific magnetic susceptibility of 0.52×10-8 m3 kg, treated with a solution of 5 % iron chloride, made it possible to obtain five fractions that differ from each other in specific magnetic susceptibility (c) – from magnetic fractions with c = 4.30×10-8 m3/kg to diamagnetic – with c = –0.11×10-8 m3/kg. It is shown that the modification of diamond nanopowders with iron ions increases the separation selectivity and makes it possible to isolate diamagnetic powders.

Magnetic Susceptibility of Spider Webs and Dust: Preliminary Study in Wrocław, Poland

Previous studies have proven that spider webs can be a reliable tool for magnetic biomonitoring. This study aims to present the magnetic susceptibility values of urban road dust (URD) settled indoors and outdoors, and compare these values with spider webs exposed to indoor and outdoor pollutants, and therefore to discuss their potential environmental implications. The webs of Eratigena atrica, Tegenaria ferruginea, and Agelena labyrinthica (Agelenidae) spiders from outdoor and indoor study sites were investigated, along with dust deposited on filters (indoors) and dust collected from the surrounding neighborhood (outdoors). Magnetic measurements revealed elevated levels of magnetic pollutants at all investigated sites in the city of Wrocław. The indoor/outdoor ratios of mass-specific magnetic susceptibility for the studied samples suggested a prevalence of indoor pollution sources at two of the sites (prosthetic laboratory and environmental science laboratory), whereas the third site (tenement house neighborhood) was dominated by material that presumably originated from predominantly outdoor sources. The indoor/outdoor ratios of magnetic susceptibility for the investigated matrices at the examined sites were highly comparable, which is promising for the utilization of spider webs in magnetic monitoring.

MAGNETIC STUDIES OF NATURAL AND MAN-MADE PROCESSES OF CRITICAL INFRASTRUCTURE OBJECTS AT THE AREA "GLINKA"

The results of magnetic soil and underlying rocks studies at the area near Lake Glinka are considered. This study was performed as a part of the landslide investigation of the urban environment of the Kyiv agglomeration. The aim was to detect the natural and man-made processes affecting critical infrastructure. Under field condition we measured the volume magnetic susceptibility of soil κ (10-3 SI), and sampling was performed. Under laboratory conditions we measured and then calculated the mass-specific magnetic susceptibility χ (10-8 m3/kg), and its frequency dependence χFD (%). The soil of the study area is gray forest (Greyic Phaeozems Albic in WRB) with signs of urban soil. Magnetic studies were conducted at two points on the high landslide bank of the Lake Glinka, as well as on the opposite low bank. On the low bank, we organised measurements and sampling along the micro-catena and at the vertical soil section to study the soil genetic horizons. Magnetic polygons were constructed based on cosmography downloaded by ArcGIS. The classification of the polygons is made by the attracting the magnetic susceptibility and its frequency dependence. We identified the polygon with the highest values of magnetic susceptibility (χ = 54 × 10-8 m3/kg) and the lowest value of frequency dependence (χFD = 3.6 %). This is the soil with man-made pollution. Two polygons with similar values of magnetic parameters were identified: χ = 25-35 × 10-8 m3/kg, χFD = 8-10 %. Such values are related to the natural soils. Three polygons (two on the the low bank and one on the high landslide bank of Glinka) have average intensity values of magnetic parameters: χ=35-40 × 10-8 m3/kg, χFD = 6-7 %. The vertical distribution of soil magnetic parameters in genetic horizons was observed and the redistribution of magnetic matherial was detected. Such kind of the redistribution indicates the erosion processes. The magnetic properties of soils are important for the joint interpretation with electric tomography, GPR measurements, and GIS analysis of the national landslide database of Ukraine. The results are useful for the development of the algorithm for the environmental monitoring of the critical infrastructure at the urban area.

Magnetic Behavior of Carbon Materials Made from Biomass by Fe-Assisted Hydrothermal Carbonization

Biomass magnetic materials were synthesized by several hydrothermal carbonization methods, by which iron was provided in different ways: as FeCl3 prior to or during hydrothermal carbonization, as pure Fe particles, or as magnetic ferrofluid, followed or not by pyrolysis processes. The materials were thoughtfully characterized in terms of elemental composition, thermal degradation, porosity (N2 adsorption, SEM micrography), surface chemistry (FTIR spectroscopy, XRD diffraction), and magnetization curves on a self-made installation. The results indicated that the process design can significantly improve the structure and chemistry of the material, as well as the magnetization effect induced on the adsorbent. Fe as FeCl3 was more interesting in regards to the development of porosity, mainly creating micropores, although it did not provide magnetism to the material unless a further pyrolysis was applied. Thermal treatment at 600 °C did not only increase the BET-specific surface (SBET) (262 m2 g−1) of the hydrochar, but also involved the transformation of Fe into magnetite, providing magnetic behavior of the hydrochar. Increasing pyrolyisis temperature to 800 °C even enhanced a better development of porosity (SBET of 424 m2 g−1) and also increased the specific magnetic susceptibility of the hydrochar as a result of the further transition of Fe into wustite and hydroxi-ferrite.

Study of a possibility of enrichment of fine-crushed magnetite ore by dry magnetic separation

Dry magnetic separation (DMS) enables to separate the non-magnetic fraction of iron ores at the initial stage of their concentration and therefore to decrease cost of their further processing. However, a considerable amount of metal is lost in DMS tails at that. The efficiency of DMS considerably depends on difference between the upper and lower limits of the ore coarseness) ore coarseness range), delivered for concentration. At the Magnitogorsk steel-works crushing and concentration plant No. 5 this range is from 50 mm up to 15 mm. To determine the optimal ore size, delivered to DMS, studies accomplished to determine the specific magnetic susceptibility of the magnetite and the burden for the magnetite ore of Maly Kuibas deposit. After the study of different size iron ore separation, a reasonability of the DMS feed size decreasing down to 30–7 mm shown. A possibility to obtain additional product of 7–0 mm size determined, suitable for sintering. It will enable to decrease the amount of material, delivered for crushing and wet magnetic separation, as well as to decrease expenses for transporting and storage of wet separation tails. Peculiarities of fine magnetite ore processing by DMS in a suspended state considered, optimal parameters of the separator determined and its high efficiency for magnetite ore of 7–0 mm size concentration shown.