scholarly journals Integrated Magnetic Analyses for the Discrimination of Urban and Industrial Dusts

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1056
Author(s):  
Beata Górka-Kostrubiec ◽  
Tadeusz Magiera ◽  
Katarzyna Dudzisz ◽  
Sylwia Dytłow ◽  
Małgorzata Wawer ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Particles ◽  
Steel Production ◽  
Hysteresis Loops ◽  
Street Dust ◽  
Single Domain ◽  
Magnetic Fraction ◽  
Magnetic Methods ◽  
Urban Dusts ◽  
Traffic Related Pollution

Industrial and urban dusts were characterized by investigating their magnetic properties. Topsoil composed of technogenic magnetic particles (TMP) originating from areas affected by three ironworks, street dust mainly composed of traffic-related pollution, and particulate matter (PM) from urban agglomeration in Warsaw, Poland were investigated. Several magnetic methods, namely magnetic susceptibility, thermomagnetic curves, hysteresis loops, decomposition of isothermal remanent magnetization acquisition curves, and first-order reversal curves, were performed to evaluate the magnetic fraction of dust. Magnetite was the main magnetic phase in all types of samples, with a small amount of high-coercive hematite within ironworks and street dust samples. Significant differences were observed in the domain structure (grain size) of industrial and traffic-related magnetic particles. The grain size of TMP obtained from steel production was in the range of 5–20 µm and was predominated by a mixture of single-domain (SD) and multidomain (MD) grains, with the prevalence of SD grains in the topsoil affected by Třinec ironwork. The traffic-related dust contained finer grains with a size of about 0.1 µm, which is characteristic of the pseudo-single-domain (PSD)/SD threshold. Street dusts were composed of a slightly higher proportion of MD grains, while PM also revealed the typical behavior of superparamagnetic particles.

Multi-proxy study of the Cretaceous-Paleogene (K-Pg) boundary in deep-sea turbiditic sediments in the Uzgruň section (Outer Flysch Carpathians, Czech Republic)

2021 ◽  
Author(s):  
Šimon Kdýr ◽  
Tiiu Elbra ◽  
Miroslav Bubík ◽  
Petr Schnabl ◽  
Lilian Švábenická
Keyword(s):  
Magnetic Susceptibility ◽  
Czech Republic ◽  
Detection Limit ◽  
Remanent Magnetization ◽  
Magnetic Particles ◽  
Principal Component ◽  
Natural Remanent Magnetization ◽  
Ongoing Research ◽  
Small Stream ◽  
Magnetic Methods

<p>The composite profile, with 4 studied sections, is located near the Uzgruň village (Czech Republic) next to a small stream. The profile is composed of Late Maastrichtian to Palaeocene flysch sediments and the K-Pg boundary is set in claystones within this turbiditic setting. Ongoing research of local paleoenvironment and stratigraphy is based on paleo- and rock-magnetic methods, micropaleontology and geochemistry to obtain more detailed view of the local situation during the K-Pg extinction event. Based on biostratigraphy, two dinocyst zones (Bubík et al., 2002): Palynodium grallator and Carpatella cornuta (first occurrence in the Danian), two calcareous nannofossil zones in the Upper Maastrichtian, and the agglutinated foraminifer zone Rzehakina fissistomata in the Paleogene were distinguished. Biostratigraphic data support the K-Pg boundary interval. The uppermost Maastrichtian is indicated by nannofossil species Micula prinsii, UC26d<sup>TP</sup> zone. Basal Paleogene non-calcareous strata contain dinocyst Carpatella cornuta and agglutinated foraminifers of Rzehakina fissistomata zone. The presence of low-latitude nannofossil taxa M. prinsii and Ceratolithoides kamptneri show input of warm waters during the uppermost Maastrichtian. Several rock-magnetic methods, such as acquisition of Isothermal remanent magnetization (IRM), acquisition of Anhysteretic remanent magnetization (ARM), Anisotropy of magnetic susceptibility (AMS), Field dependence of magnetic susceptibility (HD) and Frequency dependence of magnetic susceptibility (FD), were applied to estimate behaviour and origin of magnetic particles. Natural remanent magnetization (NRM) values of samples range from 0.09 to 2.48 mA/m. Volume normalized magnetic susceptibility (MS) show values from 130 up to 1197 SI*10-6. There is no increase observed in MS across stratigraphic boundary due to turbiditic evolution of sediment. Due to character of sediments, we applied alternating field (AF) demagnetization and used principal component analysis (PCA; Kirschvink, 1980) for estimation of characteristic remanent component. Most of the K/Pg sections worldwide have well documented Iridium anomaly. In Uzgruň, the preliminary results show that although the values are not as pronounced, the Ir at K-Pg boundary is still higher than in surrounding sediments. For tracing of Deccan traps effect we plan to apply mercury (Hg)/total organic carbon (TOC) stratigraphy. TOC content of 20 pilot samples is low, but not under detection limit of the instrumentation (mean value 0.92 wt%). One sample reached value 4.41 wt% of TOC. Sulphur contents are reaching 1 wt%, but several samples were under detection limit of the instrumentation. Sulphur concentrations suggest more reduction conditions of burial.</p><p>Current research is supported by Czech Science Foundation project no. 19-07516S and is in accordance with research plan no. RVO67985831.</p><p>Bubík, M., Adamová, M., Bąk, M., Franců, J., Gedl, P., Mikuláš, R., Švábenická, L., & Uchman, A. (2002). Výsledky výzkumu hranice křída/terciér v magurském flyši u Uzgruně. Geologické výzkumy na Moravě a ve Slezsku, 9, 18–22</p><p>L. Kirschvink (1980), The least-squares line and plane and the analysis of palaeomagnetic data, Geophysical Journal International, 62(3), 699–718, https://doi.org/10.1111/j.1365-246X.1980.tb02601.x</p>

Environmental and rock magnetic investigations into provenance and processes of west Iberian margin sediments

2020 ◽  
Author(s):  
Matthew Nichols ◽  
Chuang Xuan ◽  
David A. Hodell ◽  
Carl Richter ◽  
Gary D. Acton ◽  
...  
Keyword(s):  
Magnetic Material ◽  
Grain Size ◽  
Rock Magnetism ◽  
Sediment Cores ◽  
Hysteresis Loops ◽  
Ice Cores ◽  
Sediment Provenance ◽  
The West ◽  
Significant Difference ◽  
Iberian Margin

<p>Ocean sediment records from the West Iberian margin can be correlated to both Antarctic and Greenland ice cores as well as to European terrestrial pollen data. Previous studies have focussed on comparatively short sediment cores collected from relatively deep-water sites (i.e. >~2500mbsl). Here we present magnetic mineralogy and grain size from Integrated Ocean Drilling Programme Sites U1385 (2585mbsl) and U1391 (1085mbsl) to further understand magnetic sediment provenance and palaeocurrent evolution on the west Iberian margin dating back to ~416 ka. The gradient of IRM acquisition curves, shape of hysteresis loops, and marked decrease in magnetic susceptibility at ~580°C indicate that magnetite is the dominant magnetic phase at Site U1391. At depth, increased contributions of a higher coercivity component are seen at intervals where the concentration of magnetic material is low. FORC diagrams indicate the presence of a narrow ridge elongated along the Bc axis consistent with a higher coercivity component observed in IRM acquisition data. Magnetic grain size proxy (k<sub>ARM</sub>/k) records from Site U1391 also show a significant difference in pattern of variability at depth. After ~130 ka k<sub>ARM</sub>/k closely follows relative sea level, however prior to ~130 ka there is higher frequency variability with apparent coarser magnetic grain size, suggesting the higher coercivity component could have resulted from diagenetic processes. This is particularly apparent during warm intervals where magnetic material concentration is low (MIS 7, 9 and 11). This behaviour differs from that observed at either Site U1385, or in the younger portion of the record at Site U1391. We infer that the intervals of diagenetically effected sediments at U1391 could have resulted from increased productivity, vertical migration of the Mediterranean outflow water and associated changes in bottom water ventilation. Further understanding of sediment composition, redox conditions, transport and provenance through the last few glacial cycles underpins much of the other palaeoclimatic investigation at these sites. Results from our analysis of rock magnetism will be used to guide the reconstruction of reliable relative palaeointensity records from the Iberian Margin sediments to assess past geomagnetic changes in the region.</p>

Deducing the role of eolian dust sedimentation during soil forming periods on mineral magnetic records and its implications for paleoclimate reconstructions

2020 ◽  
Author(s):  
Diana Jordanova ◽  
Neli Jordanova
Keyword(s):  
Grain Size ◽  
Conceptual Model ◽  
Climate Models ◽  
Soil Depth ◽  
Soil Formation ◽  
Magnetic Characteristics ◽  
Magnetic Fraction ◽  
Maximum Enhancement ◽  
The Past ◽  
Terrestrial Environments

<p>Obtaining reliable global and regional records of the past climatic changes during the glacial Pleistocene is of prime importance for building up consistent climate models of the near and far future. Magnetic signature along sequences of alternating loess and (paleo)soil units from the terrestrial environments is considered as semi-continuous record of climate change in the geological past. However, soil formation in aeolian landscapes may occur under different and changing conditions of dust sedimentation. Viewing from this standpoint the depth variations of several rock magnetic characteristics along profiles of Holocene soils from low Danube area allowed us to establish a set of criteria for identification of the past regimes of aeolian sedimentation persisted during the soil forming periods. A conceptual model for the time evolution of the grain size of the pedogenic magnetic fraction  with soil depth is proposed,  which is build upon  the mechanism of soil formation – accretional or  stable land surfaces,  or a combination of the two. According to the proposed conceptual model, discrimination between accretional soils and soils developed without dust additions during soil forming period can be done. Accretional soils are characterized by parallel changes in grain size sensitive magnetic proxies. Soils, developed at stable landscape conditions show gradation of the depths at which maximum enhancement of various proxies occurs with deepest occurrence of the maximum in frequency dependent magnetic susceptibility, followed by depth of maximum anhysteretic susceptibility and the normalized anhysteretic to isothermal remanence acquired at 100mT field. It is shown that the mean coercivity of the pedogenic component of accretional soils is higher than that of soils developed without eolian input at equal temperature conditions because of the soils’ thermal gradient and different depths, at which pedogenic minerals form in the two settings.</p>

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