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.

On the rock magnetic properties and petrofabric (AMS) analyses of trachytic, phonolitic, basaltic dikes and conesheets emplaced on the Miocene Tejeda caldera complex, on Gran Canary Island, Spain.

<p>The Miocene Tejeda Complex on Gran Canaria (Canary Islands) is characterized by more than 500 trachytic and phonolitic conesheets, dikes, hypabyssal syenite stocks and subordinate radial dikes from a 20-km diameter intrusive complex in the volcaniclastic fill of the Miocene Tejeda caldera (20 x 35 km) on Gran Canaria, Canary Islands. The dikes intruded concentrically around a central axis or radial symmetry and dip uniformly an average of~41 degrees toward the center.We have conducted a pilot study of magnetic properties as well as Anisotropy of Magnetic Susceptibility (AMS) on a variety of dikes (trachytic and phonolitic and basaltic in composition) to investigate the possibility of obtaining petrofabrics results that would allow us to test the origin of the formation of the Tejeda conesheets that most likely resulted from deformation processes due to resurgent doming initiated by recurrent replenishment of a flat  laccolith-like magma chamber. The current ideas indicate that the formation of the cone-shaped fractures were originated by a magma supply exceeding the volume that could be compensated for by up-doming of the overlying caldera fill. Thus far, our AMS results indicate that all the ten intrusives studied despite their different lithologies are susceptible of carrying a measurable magnetic signal. Low-field magnetic susceptibility vs temperature (k-T 28-700<sup>o</sup>C) experiments have identified mainly one primary magnetic mineral phase namely stoichiometric magnetite, Curie temperature of 585<sup>o</sup>C,  SIRM, hysteresis loops and back-field were performed and yielded a series of secondary magnetic mineral present as well and corroborated by FORC’s results. The petrofabric in the intrusive bodies results show coherent flow azimuths regardless of their time of emplacement. Three main types of magnetic fabrics, (i.e. A to C) were found. Fabric type A (plane Kmax-Kint parallel to the dike plane) represents magma flow direction within the intrusives and is the dominant fabric (~60% of all the intrusives) studied thus far. The Kmax axis inclinations show that about 70% of the intrusives were fed by inclined vertical magma fluxes (inclinations greater than 30<sup>o</sup>), and the rest of them (~30%) by horizontal to sub-horizontal magma fluxes. Vertical magma flow means inclined magma injection inside fractures, and become more probable as the source is therefore located very close to the origin of the caldera</p>

Linking cave sediments and soil magnetism in the Urșilor cave (Romania)

<p>Cyclical changes in the magnetic mineral assemblages have been observed in numerous sedimentary records confirming the relationship between rock magnetism and past global change. Several studies have shown that the magnetic susceptibility data of cave sediments reflect both long- and short-term climatic oscillations. These magnetic susceptibility variations are attributed to changes in climate-controlled pedogenesis which influence the production of low coercivity magnetic mineral phases, magnetite, and maghemite outside the cave. These soils with climate-dependent magnetic properties are then washed, blown, or tracked into the cave where they accumulate, creating the changes observed in rock magnetic data. We present a rockmagnetism study of the sediments from the Urșilor cave and the soils above the cave. Our focus is the detailed characterization of the ferromagnetic mineralogy preserved in the cave sediments and its links with potential soil sources. In the cave, we sampled four sections (2-3 m high) consisting mainly of silts and clays, with some sand layers. The age of the sediments is older than 40 ka. At the surface, we sampled various types of soils from 9 sites. For all samples, we measured: variation of magnetic susceptibility with frequency (976 and 15616 Hz), the anisotropy of magnetic susceptibility, isothermal remanent magnetization, and anhysteretic remanent magnetization. Because soils are characterized by the presence of superparamagnetic magnetite produced by pedogenesis which can be detected by the frequency dependence of magnetic susceptibility, we also measured the frequency dependence of soils and selected cave sediment samples at 13 frequencies (between 128 and 512000 Hz). Multi-frequencies measurements of the magnetic susceptibility of recent soils show that all the sampled soils have a strong frequency dependence indicating the presence of superparamagnetic particles produced by pedogenesis. Most of the sediment samples have an important frequency dependence similar to the one observed in the recent soils. As a preliminary conclusion, we can state that most of the fine cave sediments contain superparamagnetic particles, which can be probably attributed to soils transported into the cave by erosion. These results suggest that during the deposition of high magnetic susceptibility sediments it was a climate favorable for intense pedogenesis. The interpretation of the intervals with lower values of magnetic susceptibility is still under investigation to decide if represents a climatic signal or a change in the dynamics of sediment transport. <strong>Acknowledgment:</strong> The research leading to these results has received funding from the EEA Grants 2014-2021, under Project contract no. EEA-RO-NO-2018-0126.</p>

Highly-magnetic mineral protein-tannin vehicles with anti-breast cancer activity

Anticancer hybrid mineral highly-magnetic protein-tannin vehicles are tunable and controllable external triggers for drug delivery systems. The saturation level of submicron particles of calcium carbonate with magnetic nanoparticles was achieved....