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Purpose: Iron-bearing magnetic minerals in the sediments of the water-level fluctuation zone (WLFZ) in large reservoirs play critical roles in the burial and release of organic carbon and pollutants. This study aims to reveal the spatial distribution of magnetic minerals across different elevations and reaches within the WLFZ of the Three Gorges Reservoir (TGR), the largest reservoir in the world, and their links to sediment provenance and hydrodynamic conditions. This study will provide a fundamental basis for future investigations in the roles of magnetic minerals in the circulation processes of pollutants and organic carbon within the WLFZ of fluvial-reservoir systems. Materials and methods: ~ 300 sediment samples and nearby side-slope soils were collected from various altitudes within the WLFZ at ten different sites of the TGR. The magnetic properties of these sediments and soils were examined using environmental magnetism. Additionally, previously reported data on magnetic properties of suspended sediments from upstream rivers flowing into the TGR were assembled. Nearby side-slope soils and suspended samples were used to represent magnetic properties of potential sources for the sediments within the WLFZ. Results and discussion: Our findings reveal that magnetite/maghemite and hematite particles dominate the sediments within the WLFZ of the TGR. Relatively higher concentration of hematite particles in the upper part (> 165 m) of WLFZ mainly originates from or are nearby side-slope soils, whereas higher concentration of magnetite/maghemite particles in the lower part of WLFZ is primarily due to sediment supply from upstream of the Yangtze River. The dominance of coarser magnetite/maghemite within the WLFZ of the upper reach of the TGR, from Jiangjin district to Fuling district, is due to strong water flow velocity. An increase in the concentration of nanosized fine-grained magnetic particles within the WLFZ of the middle and lower reaches of the TGR can be attributed to a combination of reduced water dynamics and intense regional soil erosion of nearby side slopes. Conclusions: Our findings indicate that the concentration and grain size of magnetic minerals exhibit spatial variations within the WLFZ of reservoirs under the influences of sediment provenance and hydrodynamics. These findings provide fundamental insights on future exploration into the crucial roles of iron-bearing magnetic minerals in the accumulation, migration, and transformation of pollutants and organic carbon within the WLFZ of reservoirs and their response to changes in sediment sources and water dynamics. [ABSTRACT FROM AUTHOR]

An urgent environmental problem in the Perm region is the increased concentration of some heavy metals in soils. This paper presents the results of studying the ecological and geochemical role of the magnetic fraction of soils in the Middle Cis-Urals. The study used magnetometry, geostatistical and geochemistry methods. It has been established that the magnetic fraction is a geochemical barrier in soils and accumulates potentially toxic elements (Mn, Ni, Cu, Co, and Pb). The total content of Mn, Zn, Ni, Cu, Co, and Pb in the soils of the agricultural landscapes of the taiga-forest zone of the Middle Cis-Urals exceeds the clarke of world soils. The ecological-magnetic subprofile of the studied soils is subdivided into ecological-magnetic layers: accumulation, destruction, and stable state of magnetic particles. The environmental organizations of the Perm region are recommended to use methods of ecological magnetism for carrying out soil-ecological monitoring and identifying land contaminated with heavy metals. The obtained information about the elemental chemical composition of soils of the Middle Cis-Urals can be used in the management of land resources and the development of the concept of land policy in the region. [ABSTRACT FROM AUTHOR]

Purpose: This 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 methods: Bottom 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 discussion: The 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). Conclusion: PTE 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. [ABSTRACT FROM AUTHOR]

While there is a general sense that reservoirs can act as sentinels of climate change, their efficacy has not been thoroughly analyzed. Here multiple-proxy analyses including 210Pb, grain size, heavy metals, magnetic parameters, and spheroidal carbonaceous particles (SCPs) were conducted for a sediment core from a typical subtropical reservoir in South China (Huangkeng Reservoir). 210Pb dating revealed that the core spans from ~ 1964 to 2019, with the sedimentary rate increasing during recent years. The sedimentary environment was mainly influenced by natural process (especially precipitation), along with the accumulation of Cr, Ni, Cu, V, As, Sb, and Co and most magnetic particles. However, four heave metals (Cd, Pb, Tl, and Zn) were found mainly from atmospheric deposition from industrial/agricultural activities in Huizhou City, which was also indicated by SCPs, S-ratio, and χARM/SIRM. According to temporal variation of SCPs, the atmospheric pollution history of nearby city (Huizhou City as the most close one) from 1964 was reconstructed. The study shows that reservoir sediments, especially in areas with few or no natural lakes, are high-efficacy and high-resolution achieves for research on environmental evolution in the Anthropocene related to global change and intensifying human activities. [ABSTRACT FROM AUTHOR]

We present millennial to centennial-scale monsoon variability during the Late-Pleistocene to Holocene using multi-proxy data from 100 cm thick peat deposit in the Baspa Valley, northwest Himalaya. Based on high-resolution mineral magnetism, carbon isotope, and total organic carbon data supported by radiocarbon dating, four climatic phases of alternating strengthened and weakened Indian summer monsoon (ISM) are identified for the last 20 kyr in the higher central Himalaya. Periods of strengthened ISM are dated to ~15 to ~14 ka, ~10 to ~7 ka, ~2.4 to ~1.3 ka, and 243 yr BP to present, which is ascribed to the post-Older Dryas associated with an increase in solar insolation. The phases of weakened ISM are bracketed between ~20 and ~15 ka, ~14 to ~10 ka, ~7 to ~2.4 ka, and ~1300 to ~243 yr BP. These phases are attributed to global cooling events, i.e., the Last Glacial Maximum (LGM), Younger Dryas (YD), and the Middle to Late Holocene. They govern by changes in the solar insolation. [ABSTRACT FROM AUTHOR]

This study is close to an earlier urban soil survey carried out for a rapidly growing city with a high traffic density in Aurangabad city, India. Consequently, it aims to use the environmental magnetism approach to assess roadside emissions at a known polluted site. Magnetic measurements have been successfully implemented in soil studies and seem to be a suitable approach for pollution assessment in industrial and roadside areas of the study area. The present study was accomplished for magnetic susceptibility, isothermal remanent magnetization, coercivity, hysteresis measurements, thermomagnetic curves, scanning electron microscopy, and energy-dispersive spectroscopy analysis to evaluate the absolute fraction of magnetic minerals in bulk soil samples. The soils displayed variation in magnetic susceptibility values, which was influenced by concentration, domain states, and morphological characteristics of magnetic minerals. Substantial variation in the mineralogical composition of soils deriving from different industrial activities was noticed. The results indicate that industrial and roadside soil samples with mostly coarser and irregular-shaped show ferrimagnetic minerals. The presence of iron–titanium combination in most of the samples is due to titanomagnetite accompanying the titanium-bearing grains. In soils, a higher amount of ferrimagnetic minerals (magnetite, titanomagnetite, maghemite) with a minor content of antiferromagnetic minerals (hematite/goethite) was noticed. These studies reveal that magnetic and morphological characterization of soils can be used as an appropriate tracer for industrial and roadside soil pollution, which leads to new avenues for more detailed chemical mapping. [ABSTRACT FROM AUTHOR]

Characterization of magnetic, morphological, chemical properties and source apportionment of environmental transporters (dust and soil) around Mejia Thermal Power Station (MTPS), West Bengal, India were performed. Rock magnetic measurements combined with scanning electron microscopy (SEM) and X-ray fluorescence (XRF) study distinguish the mineral magnetic phases and identify their environmental implications concerning anthropogenic and natural factors. Findings of this study strengthen detection of anthropogenic magnetite, contributed by traffic and MTPS emission in dust and soil, respectively. However, presence of antiferromagnetic minerals in residential areas confirms their lithogenic and/or pedogenic origin. Existence of a low amount of anthropogenic magnetite in residential areas indicates their onset from fly ash emission due to prevailing north-easterly wind direction. Both soil and dust samples are categorized into three types of ferrimagnetic particles (spherules, irregular, and aggregate) with diverse morphologies and enriched iron concentration. Soil and dust were influenced by quartz, while the average concentrations of potentially toxic elements (PTEs) occurred in decreasing order of Ba>Zr>Cr>V>Sr>Zn>Y>Nb>Pb>Co>Sc>Ga>Ni. Sampling sites near ash pond with higher concentrations of PTEs than those situated at distance suggest that PTEs association with fly ash happened during coal combustion. This explains the observed correlation between magnetite particles and proxies for multiple pollution sources (like MTPS and traffic). It also reveals the necessity for attention when detecting abundance of anthropogenic magnetite using environmental magnetic methods. Thus, the identification of magnetite using environmental magnetic measurements can be used as a tracer for natural loading within anthropogenic background. [ABSTRACT FROM AUTHOR]

The changing pattern of magnetic characteristics in eastern European loess deposits is the most similar across the world to that of the Chinese Loess Plateau, both of which are dominated by the strength of pedogenesis. Hence a systematical study to the rock magnetism of eastern European loess is not only helpful for understanding the paleoclimatic information preserved by themselves, but also beneficial for promoting the cognition of the pedogenic mechanism in loess records. In this study, a detailed rock-magnetic analysis of seventy loess/paleosol samples, taken from the Titel Loess Plateau in northern Serbia, is carried out for a better understanding of the magnetic records since late Middle Pleistocene. The results provide us some implications. First, the magnetic susceptibility values of the paleosols in the Titel loess-paleosol sequence are generally less than 100×10−8 m3 kg−1, significantly lower than those of the loess sections in the Chinese Loess Plateau, even though they are under similar climatic conditions. However, the behaviors of the parameters related to the distributions of magnetic particles in these two regions are similar. The difference in the contents of ferrimagnetic minerals is the leading reason that caused the difference in their magnetic characteristics, but the mechanism is still open to study. Second, based on the analysis of thermomagnetic curves, a gradually increasing trend of the relative contents of maghemite over the last four glacial-interglacial cycles is identified. The realization of thermally unstable maghemite from Chinese loess leads us to speculate that the long-term increasing trend of the relative contents of maghemite in Titel loess-paleosol sequence likely is a mineralogical response to the progressive enhancement of continental climate in the Pannonian Basin since the Middle Pleistocene. [ABSTRACT FROM AUTHOR]

The present study was designed to characterize the magnetic proxy for sewage-related pollution from river sediments. A suite of mineral magnetic analyses including low-field magnetic susceptibility, isothermal remanent magnetization (IRM) acquisition and demagnetization, back-field IRM treatment, and thermal demagnetization of composite IRMs are carried out for topsoil samples collected from river sediments in Daejeon, South Korea. A 350-m long in situ profile of magnetic susceptibility shows a background mean magnetic susceptibility of 22.4 ± 5.6 × 10−5 SI. The coercivity spectra display dual peaks of lower- and higher-coercivity fractions. The predominance of magnetic signal with maximum unblocking temperatures of 580 °C points to magnetite as the sole magnetic mineral. Hence the lower- and higher-coercivity fractions correspond to coarse-grained and fine-grained magnetite, respectively. Extraordinarily high magnetic susceptibility was observed from BTC02, near to the sewage discharge point. However, its mineral magnetic properties and particle morphologies are not different to those of other soil samples. Then, it is apparent that a high magnetic susceptibility simply reflects the high concentration of magnetites in BTC02. It is likely that a continuous discharge of heavy metal enriched water at the discharging point concentrated significant amount of magnetic particles. It is fortunate that anomalously high magnetic susceptibility (by implication heavy metal concentrations) diminished only several meters away from the discharge point. Perhaps, influences of anthropogenic magnetite were diluted as the high magnetic phases were washed away from the water cycles along the river. In practice, it can be proposed that a periodic replacement of soils near the sewage discharge point is efficient to reduce the heavy metal concentrations. [ABSTRACT FROM AUTHOR]

The employment of magnetic characterization of anthropogenically produced magnetic particles (APMs) as a proxy for discriminating the pollution sources around Kolaghat thermal power station, West Bengal, India, is complemented by microscopic analysis and elemental composition in the present study. The magnetic measurements such as magnetic susceptibility (χlf), isothermal remanent magnetization, coercivity spectra, hysteresis measurements, and thermomagnetic curves (κ − T) were implemented to evaluate the magnetic gestures of APMs, which are accompanied by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analysis to explore the morphological characteristics. The studied samples illustrated a wide variety of χlf values, which were determined by the concentration of APMs. The magnetic measurements revealed that the studied samples comprised pseudo-single-domain magnetite with minor titanomagnetite (s), maghemite, and hematite/goethite. SEM analysis portrayed varied morphological properties of APMs like spherules (viz. smooth, hollow, and meld-like spherules), which are usually coupled with fossil fuel combustion, and irregular-shaped APMs, which are generated from traffic emission and natural background input. Elemental composition as interpreted by EDS analysis displays varied composition of APMs, which indicates the influence of industrial and traffic emissions in the study area. This study exhibited that magnetic and microscopic characterization of APMs can be used as an appropriate tracer for soil and dust pollution, which provides significant perspectives for further detailed chemical mapping. [ABSTRACT FROM AUTHOR]

Speleothems are ideal archives of environmental magnetism and paleomagnetism, since they retain continuous magnetic signals in stable conditions and can be used for reliable radiometric dating using U-series and radiocarbon methods. However, their weak magnetic signals hinder the widespread use of this archive in the field of geoscience. While previous studies successfully reconstructed paleomagnetic signatures and paleoenvironmental changes, the time resolutions presented were insufficient. Recently emerging scanning SQUID microscopy (SSM) in this field can image very weak magnetic fields while maintaining high spatial resolution that could likely overcome this obstacle. In this study, we employed SSM for high spatial resolution magnetic mapping on a stalagmite collected at Anahulu cave in Tongatapu Island, the Kingdom of Tonga. The average measured magnetic field after 5 mT alternating field demagnetization is ca. 0.27 nT with a sensor-to-sample distance of ~ 200 µm. A stronger magnetic field (average: ca. 0.62 nT) was observed above the grayish surface layer compared to that of the white inner part (average: ca. 0.09 nT) associated with the laminated structures of the speleothem at the submillimeter scale, which scanning resolution of the SSM in this study is comparable to the annual growth rates of the speleothem. The magnetization of the speleothem sample calculated from an inversion of isothermal remanent magnetization (IRM) also suggests that the magnetic mineral content in the surface layer is higher than the inner part. This feature was further investigated by low-temperature magnetometry. Our results show that the main magnetic carriers of the speleothem under study are magnetite and maghemite and it can contain hematite or ε-Fe2O3. The first-order reversal curve (FORC) measurements and the decomposition of IRM curves show that this speleothem contains a mixture of magnetic minerals with different coercivities and domain states. The contribution from maghemite to the total magnetization of the grayish surface layer was much higher than the white inner part. Such differences in magnetic mineralogy of the grayish surface layer from that of the inner part suggest that the depositional environment shifted and was likely changed due to the oxidative environment. [ABSTRACT FROM AUTHOR]

Soil formation is influenced mainly by lithology, climate, organic matter, vegetation, topography, and time. Soil-forming processes have been well studied in temperate regions. However, there is little data on such processes in the tropics. In this work, we have studied the environmental magnetic properties of lateritic soils developed on gneiss and charnockite. We sampled surficial soils from different environmental settings (urban, agricultural, pristine, and gleyed) to determine the processes involved in their formation. A range of environmental magnetic parameters and inter-parametric ratios were investigated to determine the magnetic concentration, grain-size and mineralogy of the soil samples. Redness rating (RR) index was also calculated to estimate the reddening of tropical soils and to examine its relationship with magnetic properties. The pristine soils exhibit the highest average value for χlf and a higher value of χfd%, indicating a greater amount of ultra-fine magnetic minerals. The gleyed and agricultural soils are weakly magnetic, probably be due to waterlogging, and are characterized by a coarser magnetic grain size. A high proportion of "soft" ferrimagnetic minerals like magnetite and titanomagnetite is present in the samples (average S-ratio ~ 0.90). Hematite content is the highest in unburnt soils and the least in gleyed soils (unburnt > burnt > pristine > urban > agricultural > gleyed). The high concentration of hematite in these soils could be due to transformation of maghemite, resulting from low-temperature oxidation of magnetite. We documented a distinction between the magnetic properties of burnt and unburnt soil types as fire can significantly enhance the magnetic values of unburnt soils. The concentration of hematite (indicated by HIRM) and redness rating (RR) index are fairly well correlated for all the sample types with the exception of urban (r = 0.51; p = 0.11; n = 11) and unburnt soils (r = 0.60; p = 0.28; n = 5), which show a strong correlation. Therefore, RR index can be effectively used as an indicator of reddening of tropical soils due to pedogenesis. This study demonstrates that environmental magnetism can aid in differentiating the diverse environments of soils even though they developed on a similar rock type and under similar climatic conditions. [ABSTRACT FROM AUTHOR]

Purpose: We investigated the magnetic properties (abundance, grain size, and mineralogy) of iron oxides present in Lake L-55 sediments, Schirmacher Oasis, East Antarctica, with an aim to understand their spatial distribution and the underlying mechanisms that control their formation and distribution. Methods: Twenty-five surficial sediments retrieved from different parts of Lake L-55 were subjected to the entire range of environmental magnetic (magnetic susceptibility, anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM)) measurements (at different field strengths). Inter-parametric ratios (χARM/SIRM, χARM/χlf, χARM/χfd, IRM20 mT/SIRM, IRM20 mT/ARM, S-ratio, L-ratio) provided insights into the magnetic properties (abundance, grain size, and mineralogy of iron oxides). Scanning electron microscopic-energy dispersive X-ray spectroscopic (SEM-EDS) analysis was performed on magnetic extracts from a few sediments. Besides, organic matter (%) was also calculated for the sediment samples. Principal component analysis was performed to gain information on the presence of different components and their relative dominance. Results: The iron oxides are strongly magnetic (high values of concentration-dependent parameters). The principal iron oxide is magnetite (S-ratio > 0.90) which is coarse-grained (multi-domain (MD) and stable single-domain (SSD) grains), and there is no influence of authigenic greigite, bacterial magnetite, and anthropogenic magnetite. The mineralogy is confirmed by SEM-EDS data. The iron oxides are of different grain sizes, and their contribution is in the order of MD > SSD > SP as shown by the principal component analysis. Pedogenic iron oxide minerals seem to be present in the samples whose formation is due to the oxidation of magnetite into hematite. However, they are of SSD size and not SP, suggesting that the intensity of pedogenesis is not sufficient to form SP grains. Conclusion: The iron oxide minerals are mainly terrigenous, and the biogenic activity within the lake is not sufficient to modify the ferrimagnetic minerals. Spatial distribution patterns suggest the non-uniform distribution of magnetite/titanomagnetite of varying sizes in the lake basin which is transported by both melt water streams and winds. [ABSTRACT FROM AUTHOR]

Urban street dust constitutes important intermediate products for the transmission of solid organic and inorganic pollutants in the urban environment. In this study, 133 street dust samples were collected from Xinyang to explore their magnetic characteristics, spatial distribution, and environmental implications using magnetic measurements. The results are as follows. (1) There were ferrimagnetic, antiferrimagnetic, and paramagnetic (e.g., lepidocrocite) minerals in the dust. Among these, the dominant magnetic carriers were ferrimagnetic minerals. Furthermore, magnetite was a first-order ferrimagnetic carrier. (2) The magnetic domains of the dust were pseudo single-domain to multi-domain. (3) The magnetic concentration (χ and SIRM) of dust were 2.6 and 4.1 times higher than those of background samples that were not polluted by urban and anthropogenic activities, respectively. Therefore, we conclude that the dust consisted of high concentration of ferrimagnetic minerals and coarse magnetic particles. (4) The magnetic distribution was spatially different. The industrial area, which was the most polluted sampling area, had the highest magnetic concentration and the coarsest magnetic particles. This was attributable to industrial emissions, fossil fuel combustion, and exhaust emissions from heavy-laden trucks. Residential and commercial areas, which were the second most polluted areas, had higher concentration and coarser particles. This was primarily due to the high population density and traffic activities of mini-cars (i.e., high flux and exhaust emissions). Hence, the conclusion is that the magnetic characteristics, spatial distribution, and the sources of dust are dictated by anthropogenic activities. Our results indicate that the magnetic method is a highly effective tool to monitor urban environmental pollution. [ABSTRACT FROM AUTHOR]

Heavy metals, one of the most toxic classes of pollutants, are resistant to degradation and harmful to the biological environment. The lakes that have developed on the Tibetan Plateau are ideal regions to investigate historic heavy metal pollution, particularly through the use of the reliable 210Pb dating technique. Environmental magnetism has been successfully applied to estimate heavy metal pollution in different environmental systems due to its characteristics of simple processing steps, good sensitivity, and non-destructibility. However, it has not yet been applied to assess heavy metal pollution in lake sediments on the Tibetan Plateau. A series of environmental magnetic investigations of Qiangyong Co Lake sediments (southern Tibetan Plateau) was therefore conducted to explore the relationship between magnetic minerals and mercury (Hg) concentrations. The results showed that the magnetic mineral species in lake sediments remained stable, with similar levels of four different components from 1899 to 2011. However, the proportion of component 1 (C1, hematite) increased continuously with the corresponding decrease in the proportion of C2 (goethite), while the proportions of C3 and C4 (magnetite) did not change significantly. As a result, the bulk magnetic signals (e.g., SIRM and χlf) were unsuitable for the evaluation of the Hg concentration; however, the proportion of hematite had a strong positive correlation with the Hg concentration. It is possible that the Qiangyong Glacier (the main water supply for Qiangyong Co Lake) has experienced faster melting with global and local warming, and the Hg trapped in cryoconite and ice was released. Hematite, with a large specific surface area, has a strong capacity for absorbing Hg, and both materials are ultimately transported to Qiangyong Co Lake. The proportion of hematite in a sample is therefore a suitable semi-quantitative proxy that can be used to evaluate the Hg concentration in Qiangyong Co Lake sediments. This study confirmed that the variation of magnetic minerals can provide a new method to estimate the variation of Hg concentrations and to study the process of Hg deposition in lakes in the southern Tibetan Plateau on the basis of a detailed environmental magnetic analysis. [ABSTRACT FROM AUTHOR]

A 95-cm subalpine peat core from the Daping Swamp, located in the transition zone between the middle and southern subtropical regions of China, provides an environmental mineral magnetism record over the past ~ 3000 years. Magnetic concentration-dependent parameters [i.e. magnetic susceptibility (χlf), anhysteretic susceptibility (χARM), and saturation isothermal remanent magnetization (SIRM)] and grain size-dependent parameters [i.e. percentage frequency-dependent susceptibility (χfd%), SIRM/χlf, and χARM/χlf] of core and catchment sediments were measured to characterize provenance and catchment processes. Multi-magnetic parameters revealed that the primary magnetic minerals in the peat samples were mainly detrital magnetic minerals, which originated from catchment surface soil erosion. Changes in vegetation coverage as well as pedogenesis induced by rainfall variation play an important role in controlling the input of magnetic materials. Therefore, we infer that variations of magnetic features in the core bear potential to elucidate the history of environmental changes in the past ~ 3000 years, which are closely related to Asian summer monsoon evolution. Multiple parameters revealed that in three periods (i.e. 2700–2500, 1600–1000, and 500–300 cal year BP), decreased pedogenesis intensity and increased erosion induced by decline in vegetation coverage under dry conditions led to increased input of magnetic minerals, especially the coarser minerals in peat samples. However, in the two periods (i.e. 2500–1600, and 1000–500 cal year BP), multi-magnetic proxies indicate increased pedogenesis and decreased input of magnetic minerals dominated by fine-grained magnetic minerals caused by increased vegetation coverage under relatively wet and warm conditions. These climatic periods are of broad regional consistence across the world. The general trend of the late Holocene climate revealed by magnetic parameters confirms the sensitivity of environmental magnetism in this peat succession from the subalpine western Nanling Mountains to the climatic/environmental variability in the Asian summer monsoon region. [ABSTRACT FROM AUTHOR]

The Holocene environmental evolution in coastal area, including deltas and estuaries, is vital to the Neolithic colonization in the eastern China. A 29-m long sediment core XL was obtained from the region between the Taihu Lake and Qiantang Estuary, and multiple analyses on the core sediments have been done to investigate the evolution history of the inner coastal zone of Hangzhou Bay during the Holocene. Six sedimentary facies are identified since the late Pleistocene, including the paleosol at the bottom, overlain by tidal-flat-channel complex (TFC), tidal-distributary-channel (TDC), inner estuarine basin (IEB), subtidal-to-intertidal-flat, and fluvial-plain facies. The TFC and TDC facies are dated to be formed before 8500 cal yr BP, featured by relatively coarse sediments, high magnetic properties and less abundant foraminifera, denoting the tide-influenced setting with large terrestrial inputs. The IEB facies characterized by the most abundant foraminifera fossils and the lowest sediment magnetic properties, is inferred to be deposited during the maximum flooding period between 8500 and 7900 cal yr BP. The branch estuary was then infilled by local sediments with a shallowing-upward subtidal-to-intertidal sequence during 7900-4300 cal yr BP. At last the fluvial plain system developed since no later than 4300 cal yr BP, favouring the rapid development of Neolithic cultures in the region. [ABSTRACT FROM AUTHOR]

The use of mineral magnetic techniques as pollution proxy for road deposited sediment was explored using various statistical approaches. Standard techniques were adopted for measurement of mineral magnetic and geochemical parameters. The analyses of magnetic parameters revealed that the samples were dominated by ferrimagnetic minerals and multidomain grains. This implied that the magnetic fractions in the samples might be of anthropogenic origin. Results also indicate that the samples were dominated by low coercive, magnetically soft minerals. Thermomagnetic curves confirmed magnetite as the remanence bearing magnetic mineral having a Curie point temperature of ~580 °C. The strong association observed between magnetic susceptibility, susceptibility of anhysteric remanent magnetization and saturation isothermal remanent magnetization and aluminum, titanium, manganese, iron, chromium and lead demonstrated that these metals occurred as ferrimagnetic particles of technogenic origin resulting from vehicular sources. Assessment of pollution status of the road deposited sediment identified silicon and lead as the priority pollutants of concern. Generally, pollution load index was <1 (mean, 0.66 ± 0.14), indicating that the samples were not polluted in the overall, but the metals were in the buildup stage requiring constant monitoring. The sources of pollutants from principal component and cluster analyses identified the sources of pollution to be mainly from vehicular emissions such as brake linings, exhaust materials, tire wear, corroded metal parts, abrasion of lubricating oil and road construction materials. This study found that mineral magnetic techniques offer great potential as pollution proxy for soil pollution studies. [ABSTRACT FROM AUTHOR]

A study of near surface sediments from the Dan River (southeastern USA) was conducted to assess the use of magnetic properties as proxies of coal ash after a recent spill. The watershed geology is diverse and potentially contributes magnetic minerals to riverbed sediment from diabase dikes in the Dan River Triassic Basin and from granitic gneiss outside the basin. Coal ash is heterogeneous, including aluminosilicate spheres, amorphous particles and carbonaceous rods and lacy particles. The magnetic fraction of ash from the failed storage pond is up to 17 wt% and is mostly composed of black spheres with maghemite and magnetite. Ash was detected in riverbed sediment from quiet water settings such as inside of meander bends, the confluence of tributary streams and near islands between the spill site and 20 miles downstream in the Schoolfield Reservoir, Danville, VA. The strong magnetic signal is detected above background in riverbed samples and is strongly positively correlated with total ash; elevated low field magnetic susceptibility ( χ ) is evident in samples with ≥ 12% ash content. Anhysteretic remanent magnetization and hysteresis parameters delineate native sediment, ash-bearing sediment, and diabase dikes. Between 20 and 70 miles downstream of the spill site, ash concentrations were either buried or too low due to dilution with native sediment to be detected with χ in riverbed samples. [ABSTRACT FROM AUTHOR]

A study of surface sediments from the Anllóns riverbed (northwestern Spain) was conducted to assess the use of their magnetic properties as proxies of recent trace element contamination (i.e., As, Zn, Pb, Cr, Ni and Cu). Thermomagnetic curves, hysteresis parameters, specific magnetic susceptibility χ, frequency-dependent magnetic susceptibility κ %, magnetic remanence and saturation isothermal remanent magnetization ratios (i.e., S and SIRM/ χ) reveal the presence of mostly fine-grained magnetite and maghemite in these samples. The Tomlinson Pollution Load Index (PLI), as well as the magnetic parameters χ, κ %, SIRM/ χ and S-ratios, vary more or less in agreement to each other when they are sequentially arranged throughout a 30-km-long transect that goes from the town of Carballo to the river mouth in Ponteceso. From that profile, it is possible to identify an anomaly of χ that lies between two small peaks of the PLI and seems to define a contaminated area probably linked to a diffuse low-impact source of pollution. There is also a conspicuous peak of the PLI that is likely associated to a nearby gold mine. The variations of the κ %'s along the transect are the ones that best reflect the changes in the PLI values, regardless of the level of contamination. This result suggests that adsorption is the main mechanism of trace elements removal by Fe oxides in these samples. Direct signal analyses, used to decompose the isothermal remanent magnetization curves, reveal the presence of four magnetic fractions, with varying relative concentrations all over the profile, namely single-domain magnetite, close to the superparamagnetic threshold (SD/SP) and/or maghemite ( $$\log B_{1/2}$$ ca 1.2), single-domain magnetite ( $$\log B_{1/2}$$ ca 2), hematite ( $$\log B_{1/2}$$ ca 2.5) and goethite ( $$\log B_{1/2}$$ ca 3.5). Integrating all the available information, it was sketched out a likely sequence of events that included magnetic minerals neoformation in parent soils, their subsequent chemical transformations and the contamination episodes that affected the region. [ABSTRACT FROM AUTHOR]

The content of selected elements (Al, As, Ca, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, S, Ti, V and Zn) was measured in samples of the lichen Evernia prunastri exposed for 30, 90 and 180 days around a cement mill, limestone and basalt quarries and urban and agricultural areas in SW Slovakia. Lichens transplanted around the investigated quarries and the cement mill rapidly (30 days) reflected the deposition of dust-associated elements, namely Ca (at the cement mill and the limestone quarry) and Fe, Ti and V (around the cement mill and the basalt quarry), and their content remained significantly higher throughout the whole period (30-180 days) with respect to the surrounding environment. Airborne pollutants (such as S) progressively increased in the study area from 30 to 180 days. The magnetic properties of lichen transplants exposed for 180 days have been characterized and compared with those of native lichens ( Xanthoria parietina) and neighbouring bark, soil and rock samples, in order to test the suitability of native and transplanted samples as air pollution magnetic biomonitors. The magnetic mineralogy was homogeneous in all samples, with the exception of the samples from the basalt quarry. The transplants showed excellent correlations between the saturation remanent magnetization (Mrs) and the content of Fe. Native samples had a similar magnetic signature, but the values of the concentration-dependent magnetic parameters were up to two orders of magnitude higher, reflecting higher concentrations of magnetic particles. The concentrations of As, Ca and Cr in lichens correlated with Mrs values after neglecting the samples from the basalt quarry, which showed distinct magnetic properties, suggesting the cement mill as a likely source. Conversely, Ti and Mn were mostly (but not exclusively) associated with dust from the basalt quarry. It is suggested that the natural geological characteristics of the substrate may strongly affect the magnetic properties of lichen thalli. Taking this into account, the results of this study point out the suitability of lichens as air pollution magnetic biomonitors. [ABSTRACT FROM AUTHOR]

Magnetic biomonitoring techniques and in situ topsoil magnetic susceptibility measurements have been shown to be rapid, cost-effective, and useful methods for investigating roadside pollution. However, combustible vegetation in samples makes it very difficult to use them in high-temperature magnetic experiments although the thermal alteration of spontaneous magnetization is a fundamental magnetic property and can be used to identify reliably the magnetic minerals. Here, we report the first magnetic biomonitoring results of dust deposited on plant leaves along the Tateyama-Kurobe Alpine route at the highly protected Midagahara wetland areas of Mt. Tateyama in Toyama, Japan. In-field magnetic susceptibility from 15 sites (161 points) shows higher susceptibilities near the roadside. Dust deposited on the leaves of Sasa kurilensis, or dwarf bamboo, has been wiped off at 12 sites (64 samples) with a commercial ethanol wipe sheet or silica wool damped in ethanol and subjected to rock magnetic analyses. Thermomagnetic remanence curves and low-temperature behaviors for samples collected near the roadside using silica wool show clearly that the main magnetic mineral in the dust is partially oxidized magnetite. Further, detailed rock magnetic analyses and elemental analyses of leaves in the study area indicate that (a) the magnetic mineralogy on leaves' surface is consistent throughout the study area and (b) higher saturation isothermal remanent magnetization intensities as well as higher concentrations of Pb, Fe, Cr, and Y are observed near the roadside, i.e., the closer to the roadside, the more anthropogenic materials, including partially oxidized magnetite, are present. Also, microscopic observations show the lack of spherical grains, indicating that dust on the roadside leaves is derived from passing vehicle rather than industrial process. Both rock magnetic and geochemical results show that S. kurilensis would be an excellent candidate for investigating air pollution. Also, the proposed wiping-off method of collecting dust from plant surfaces is an effective non-destructive method that can be applied even in highly restricted collection areas, because detailed magnetic mineralogy, including superparamagnetic minerals, could be determined with the use of silica wool for use in both high- and low-temperature experiments. [ABSTRACT FROM AUTHOR]

This contribution comprises geological and magnetic results obtained in loess and paleosols profiles outcropped in the Pampean plain (Argentina). The sedimentary sequence exposed in Córdoba province is represented by four profiles Corralito I, Corralito II, Monte Ral815o and Lozada, 32°S 64°14'W (Argentina). These profiles were mineralogically described and magnetically analyzed. The sediments that compound the profiles contain volcanic glass between 20 and 90%. The results of two paleosols with different percentage of volcanic glass in the parent material (correlated to Marine Isotope Stage 5, MIS 5) exposed at Corralito I and Lozada, were compared; an important relationship between environmental magnetism signal and volcanic glass content was observed. All the results suggest that there are variations between different paleosols of the same area and age; such variations are attributed to content of volcanic glass in parent material; time of exposure of the parent material to pedogenic processes; and geomorphological place of each profile. At present, it is not possible to quantify certainly the paleo-precipitation index. Only qualitative interpretation can be done taking into account many variables of the geological system. [ABSTRACT FROM AUTHOR]

Copper ore mining and processing are among the most harmful anthropogenic influences for the environment and they are a subject of international and national law regulations. Recultivation of areas influenced by mining and processing industry is commonly applied and monitored in order to restore as much as possible the natural environment. In this study, environmental magnetic methods are applied in order to assess the degree of soil restoration in terms of soil development, after remediation of waste dump from Cu-processing plant. Soils developed under birch forest stands of different age (5, 15, and 25 years) as well as raw waste material were sampled along depth down to 20-30 cm. Variations in magnetic parameters and ratios obtained (magnetic susceptibility, frequency-dependent magnetic susceptibility, anhysteretic remanence (ARM), isothermal remanence (IRM), ARM/IRM) suggest the presence of magnetic enhancement in the upper 0-15 cm, the thickness of this layer varying depending on the age of the forest stand. Magnetic mineral responsible for this enhancement is of magnetite type, while waste material contains a large amount of hematite, as evidenced by coercivity analysis of IRM acquisition curves and thermal demagnetization of composite IRM. Magnetic grain-sized proxy parameters suggest that magnetite particles are coarser, magnetically stable, while no or minor amount of superparamagnetic grains were detected at room temperature. A well-defined linear regression between the topsoil magnetic susceptibility and the approximate age of the forest stand provides an indication that the magnetic enhancement is of pedogenic origin. It is concluded that the observed magnetic enhancement of recultivated soils studied is linked to a combined effect of pedogenic contribution and possible additions of industrial ashes as a liming agent for soil restoration. [ABSTRACT FROM AUTHOR]

Environmental magnetic and grain size measurements were carried out on sand samples collected from nine sand pits along a 20-km coastal stretch of Arnala Beach, North Maharashtra, India. This study sets out to identify the potential heavy (magnetite) mineral-rich sites in a dynamic coastal system and decipher their enrichment processes. Combination of rock-magnetic and grain size data of the sand pits mirrors the differential heavy mineral fluxes along the coast. Two distinct and well-separated bands of magnetite enrichments were identified. The upper magnetite band (UMB) is more pronounced and shows uniform magnetite enrichment representing the present-day beach erosional state. A well-separated lower magnetite band (LMB) had highest magnetite concentration at Vaitarna River mouth and depicts a strong decrease in magnetite content and clastic (mean) grain size away from the river mouth. This suggests that the NW-SE-directed coast-parallel sediment transport in the past played a major role in the formation of magnetite-rich layers of LMB. A non-enriched zone (NEZ) between UMB and LMB is magnetically weak and showed large variations in clastic grain sizes and possibly represents a period of sediment accretion. A strong correlation between magnetite concentration and magnetic grain size was found for all the sand pit samples, with highest magnetic susceptibility values being dominated by coarser magnetic grains. This relationship needs to be further exploited as a potential fingerprint to identify the heavy mineral lag deposits in coastal environments. Our study explores the potential of using environmental magnetism and sedimentological methods to identify the potential areas enriched in heavy (magnetic) minerals and explains the mechanism of their formation. [ABSTRACT FROM AUTHOR]

Aeolian loess deposits contain abundant information about the evolution of the paleoenvironment. For example, paleoclimate changes recorded in Chinese loess area obtained significant achievement in the past few decades. Compared to Chinese loess, research on Indian loess is lacking. Currently, most studies focus on the Kashmir area located in the southern Himalayas, and studies on other areas are rare. However, field observations demonstrate that the sediments around the New Delhi-Agra-Jaipur Plain are similar to Chinese loess-paleosol sequences. For example, the boundary between two strata is transitional and without horizontal bedding. Moreover, obvious pedogenic horizons developed among sediment sequences, probably indicating unrecognised aeolian deposits in the Indo-Gangetic Plain (IGP). To confirm this, pilot samples were obtained from the IGP and detailed indoor measurements conducted. The results indicate that the distribution patterns of particle size and rare earth elements (REE) of the pilot samples are similar to Chinese loess. Furthermore, the scanning electronic microscopy (SEM) images of pilot samples show obvious conchoidal fractures, dash-shaped concavities, and abundant small pits that usually form through mechanical impact. These are typical characteristics of aeolian particles. In addition, environmental and rock magnetic measurements indicate that the dominant magnetic minerals in the pilot samples are magnetite and maghemite, and that they likely contain small amounts of hematite. Furthermore, conventional magnetic parameters are comparable with Chinese loess. Based on this, aeolian loess deposits are widely distributed in the IGP, which may have promoted the development of Indian farming and contributed towards the prosperity of ancient Indian civilisation. This study also provides a new and valuable record for the research on paleoclimate changes in the study area in the future. [ABSTRACT FROM AUTHOR]

Dispersion of pollutants from mining areas can result in risks to human health. The dynamic interaction of geological processes can generate complex situations that favor enrichment in toxic elements by sedimentary and diagenetic mechanisms. In order to explore the distribution of iron-rich minerals in coastal and river sediments, a geophysical campaign was performed along the outlet of the Piscinas and Naracauli Rivers that drain two abandoned mining areas in SW Sardinia. Both rivers flow into the Mediterranean Sea, a bay where fluvial, marine, and eolian processes interact. The geophysical campaign comprised magnetometry and ground-penetrating radar surveys. Magnetic properties were controlled by means of magnetic susceptibility measurements along the beach and dune areas, through sampling of surface sediments, natural outcrops and trenches, and considering different grain size intervals. Results indicate enrichment in ferromagnetic minerals at the leeside of dunes and berms. Sedimentological interpretation is supported by means of ground-penetrating radar. Due to both sedimentary and diagenetic processes, the 100- to 300-μm fraction of fine sands exhibits high susceptibility. Implied tenors of toxic elements in the magnetite may represent a serious hazard to environmental and health security. The results inferred from magnetic anomalies support the applicability of the geophysical approach in order to locate high concentrations of iron-rich particles both at surface and below ground and the usefulness of joint evaluation of magnetic susceptibility and ground-penetrating radar in order to characterize the sedimentary and geomorphology-controlled magnetite distribution. [ABSTRACT FROM AUTHOR]

Magnetite in mixture with metallic iron in indoor dust samples was examined using several magnetic analyses, thermomagnetic curves of the magnetic susceptibility and the induced magnetization vs. temperature, hysteresis loops, and first-order reversal curves. The study of the magnetic properties was supplemented by the analysis of chemical elements and electron microscopic observation. The metallic iron in the mixture affects the values of hysteresis parameters, decreasing coercivity ( B ) and increasing saturation magnetization ( M ), and it is responsible for the magnetic enhancement of magnetic susceptibility. The thermomagnetic curves show several distinct features: the first Curie temperature of magnetite, the second one (∼764 °C) of iron, and the rapid decrease on the heating curves (between 600 and 750 °C) caused by the oxidation of iron to magnetite. Two magnetochemical processes appear during the thermal treatment of indoor dust: the oxidation of iron to magnetite and the neo-formation of magnetite as a result of chemical transformation of non-magnetic minerals. The shift of the hysteresis parameter ratios from the multi-domain (MD) region towards the single-domain (SD) region on the Day-Dunlop plot is controlled by the oxidation of iron in the thermally induced process and the grain size of the new formed magnetite. The magnetic properties of indoor dust are a potential indicator of indoor air pollution. Elemental iron plays an important role in the development of inflammation in humans via oxidative stress, so that the presence of metallic Fe in indoor dust can affect human health. [ABSTRACT FROM AUTHOR]

Magnetic properties of deposits around the shipwrecks ('Munin' and 'Abille') in the Gulf of Gdańsk were investigated. Values of magnetic susceptibility ( χ) are relatively low; however, they reveal significant differences between investigated sites. The values of χ around 'Abille' wreck were 5-8×10-8 m3/kg. Around 'Munin' wreck results were more diversified reaching value of χ between 3.07×10-8m3/kg and 12.92×10-8 m3/kg. The spatial variability of χ coincided with near-bottom water currents distribution in the Gulf of Gdańsk. Magnetic minerals were identified by thermomagnetic analysis. Around 'Abille' wreck we have found magnetite with small amount of maghemite or hematite. The 'Munin' sediments include only one magnetic phase; in several samples it is magnetite, in the others - maghemite. Day-Dunlop plot shows that 'Abille' set is shifted towards lower magnetization ratio and higher coercivity ratio. The correlation between the distribution of χ and hydrodynamic condition around shipwrecks allows to determine the direction of contaminant transport. [ABSTRACT FROM AUTHOR]

This study investigates the seasonal and spatial variation of traffic-induced particle matter in order to evaluate the pollutant distribution and the representativeness of the single air quality monitoring station in the city centre of Turku, southwest Finland. Study focused on parks, kindergarten and school yards as well as heavily trafficked sites. Sampling was done using active magnetic biomonitoring, which is highly applicable in polluted areas lacking native species. Sphagnum papillosum moss bags were exposed separately in road dust period, which is experienced after snow melt and the resuspension of sanding material in spring, and summer season for about 60 days in 2013. Moss bags are magnetically and elementally (e.g. Al, Cr, Fe, Na, Ni, Pb) more enriched in road dust period and near heavily trafficked sites than in summer season and in the courtyard or park sites. Magnetic properties indicate that particle matter is composed of fine-grained pseudo-single-domain magnetite towards superparamagnetic-single-domain grain sizes. Intensive road dust period overrides the variation of prevailing conditions as indicated by three paired samples showing finer grain sizes and higher element levels in courtyard/park sites than in traffic sites in summer. The results emphasise the effectiveness of active magnetic biomonitoring for the assessment of spatially representative air quality monitoring stations and related modelling approaches. [ABSTRACT FROM AUTHOR]

The agricultural soils near the city of Coimbra (central Portugal) have high levels of potentially toxic trace elements (PTEs). This is a pioneering study that allows the characterization of agricultural soils in central Portugal, using the environmental magnetism techniques and further to establish the main sources of pollution. On completion of magnetic analyses, a scanning electron microscope observation was carried out on magnetic extracts to provide information on the possible origin of particles in general. Chemical studies show a high concentration of some of PTEs in the topsoil. Statistical studies were used for examination of the relationships between the magnetic properties of soil samples and the concentrations of chemical elements. A positive and significant correlation was observed between magnetic measurements and PTEs concentrations. Principal component analysis allowed us to conclude that the main sources of the analysed elements are mostly related to the burning of fossil fuels. The results confirm that (1) simple, rapid and non-destructive magnetic measurements can provide useful information about PTEs enrichment in agricultural soils near the urban centre, (2) the environmental magnetism techniques can be used as a proxy for spatial distribution of pollution in this area and (3) the combination of magnetic methods with chemical and statistical analysis is an efficient tool for the identification of the main pollution sources in poorly industrialized areas and to assess environmental implications. [ABSTRACT FROM AUTHOR]

This study reports a detailed examination of the magnetic mineralogy of street dust samples collected in Xuzhou, a heavily industrial city in China. Several different approaches have been utilized in the characterization, from standard mineral magnetic techniques such as magnetic hysteresis and microscopy to non-standard techniques such as Mössbauer spectroscopy. Magnetic properties and the concentrations of four metals including Cu, Zn, Ba and Pb were reported for each sample. The primary magnetic mineral was found to be multidomain magnetite-like material. Scanning electron microscope analyses of street dust revealed: spherule-shaped iron oxides and angular particles with complex chemical composition. The concentrations of Cu, Zn, Pb and Ba were 3, 4.8, 2.8 and 1.3 times higher, respectively, than the soil background values of this study area. Both Cu and Ba showed significant correlations with the magnetic concentration parameters χ ARM (susceptibility of anhysteretic remanent magnetization) and saturation isothermal remanent magnetization. The combination of the various methods offers a powerful analytical technique in the study of magnetic properties of street dust. [ABSTRACT FROM AUTHOR]

Longer-term environmental studies are increasingly used to better understand contemporary ecosystems conditions and for forecasting their future trajectories. Here, we use radiometric measurements and the characterisation of sediment properties from six mountain and a lowland lake in Central Eastern Europe with the aim to assess temporal and spatial variability in sediment accumulation rates (SARs) in relation to three socio-economic regimes: traditional (1840-1948), socialist (1948-1989) and post-socialist (post-1990). We also set out to determine reference conditions for these lakes i.e. conditions before significant human impact. Our results show a trend of increasing SARs from basal sediments (pre 1840) towards the present at only two sites. This contrasts with findings from Western and Central European lakes where SARs have predominantly increased from 1850 towards the top of cores. We highlight the differential impacts of the traditional, socialist and post-socialist periods on the SARs at these lakes. Lowland and mid-elevations lakes ( n = 2) were most markedly impacted by the socialist period of land use regime; lakes from the southern Carpathians ( n = 2) were more impacted in the traditional period (transhumance pastoral activities), whereas those from the north ( n = 3) in the socialist and post-socialist periods (summer pastoralism). Results from our study show a continuous anthropogenic impact during the entire period considered, even in remote mountain areas. This suggests that a temporal frame of 100-150 years is too short to meaningfully register the reference conditions of these lakes. Furthermore, a predominantly natural state may not have existed for centuries in this region. [ABSTRACT FROM AUTHOR]

This paper demonstrates the efficiency of magnetic techniques to provide identification and differentiation of contaminating emission sources. Three areas from different emission sources were selected for this study: roadside soils (27 samples), soils near a power plant (37 samples), and soils near a cement plant (32 samples). Self-organizing map (SOM) has become a largely used methodology to classify large amounts of data. From the U-matrix it is easy to see that the bottom three rows of the SOM formed a very clear cluster. The soils near the power plant exhibited high values of χfd and χ/SIRM ratio. The separating factor between roadside soils and soils near the cement plant is that the former had higher value of χ. Discriminant analysis of the four magnetic variables indicated that the magnetic parameter χ/SIRM was the most powerful in discriminating among soil samples from the three areas. Biplots combining magnetic parameters allow the identification and differentiation of different pollutant emission sources. These results lead to the conclusion that the χ/SIRM ratio is a good indicator in discriminating different contamination sources, which is consistent with the previous result. Soil samples from roadside and near the power plant were dominated by ferrimagnetic materials while soil samples near the cement plant had low χ/SIRM and relatively high SIRM/ χ values, indicative of being contaminated by hematite. [ABSTRACT FROM AUTHOR]

We report mineral magnetic measurements (magnetic susceptibility, anhysteretic and isothermal remanence, magnetic hysteresis and thermomagnetic properties) from a 2.46-m-long sediment core taken in Xingyun Lake, Yunnan, China. Results demonstrate that magnetic minerals in the lake sediment are dominated by stable single-domain (SSD) ferrimagnetic minerals derived mainly from in-washed catchment soil. Magnetic susceptibility increases sharply during the period AD ~500-1050, and the grain size of magnetic minerals decreases. These changes are accompanied by increases in the concentrations of Fe, Ti, Zr and Si, and by decreased tree pollen percentages. δO measures in speleothems from South China demonstrate that climate was relatively uniform during this interval. Documentary evidence, however, indicates a large increase in the human population of Yunnan Province at that time. We conclude that the late Holocene sediment record from Xingyun Lake reflects a dramatic increase in soil erosion that was caused by a growing human population, which in turn was responsible for increased deforestation and agricultural activity. Our results from Xingyun Lake are consistent with sediment magnetic records from Erhai Lake, located near our study site. We therefore conclude that the interval AD ~500-1050 corresponded to a regional-scale increase in the intensity of human activity on the Yunnan-Guizhou Plateau. [ABSTRACT FROM AUTHOR]

The combination of magnetic and geochemical methods was used to determine the mineralogy, grain size and domain structure of magnetic particles in indoor dust collected in 195 sites in Warsaw, Poland. Data show an asymmetric distribution of magnetic susceptibility ( χ) in the wide range of 20-1514 × 10 m kg. Comparison of magnetic parameters shows that the internal dust contains outside pollution characteristic for air and soil. More than 90% of indoor dust samples were characterized by roughly uniform magnetic mineralogy, typical for fine grained magnetite (diameter of 0.2-5 μm), and grain size between pseudo-single-domain and small multi-domain with small contribution of superpara-magnetic particles (∼10%). Samples with χ larger than 220 × 10 m kg contain mainly magnetite and an anthropogenic metallic Fe with T > 700°C. The indoor dust contains, characteristic for the urban areas, spherical magnetic particles originated from fossil fuel combustion processes and mixture of irregular angular iron-oxides grains containing other elements, including Na, Ca, Al, Si, K, S, Mn, Cl, and Mg. [ABSTRACT FROM AUTHOR]

Visakhapatnam is one of the major port cities, and it is developed into a hub of many large- and medium-scale industries. Due to growing industrialization and urbanization, coast is vulnerable to both organic and inorganic micro-pollutants. Twenty-five surface sediments were collected along the Visakhapatnam coast for the measurement of texture size, petroleum hydrocarbons, trace metals and environmental magnetic parameters. The percentage of coarser particles was more in the northern region, whereas the percentage of fine particles was increased toward south. Elevated levels of petroleum hydrocarbons and trace metals were attributed due to marine and land-based sources, in particular, those were due to shipping activities, treated and partially treated sewage and industrial wastes. The concentrations of trace metals, petroleum hydrocarbons and magnetic minerals were decreased from nearshore to seaward. Our results revealed that the magnetic mineralogy is dominated by magnetite with a small proportion of hematite, and the grain size of magnetic minerals was in the range of pseudo-single domain to multidomain nature with detrital origin. From the principal component analysis, the magnetic concentration and mineralogy-dependent parameters co-vary with the heavy metal and PHC concentrations, suggesting that the inputs of magnetic minerals, petroleum hydrocarbons and heavy metals in the Visakhapatnam shelf sediments were derived from the same anthropogenic sources. Thus, the large magnetic dataset can be used to reduce the number of chemical analysis; hence, environmental magnetic parameters were used as a proxy for both organic and inorganic micro-pollutants. [ABSTRACT FROM AUTHOR]

We investigate magnetic phase (trans)formation in the presence of petroleum hydrocarbons and its relation to bacterial activity, in particular in the zone of remediation driven fluctuating water levels at a former military air base in the Czech Republic. In a previous study an increase of magnetite concentration from the groundwater table towards the top of the groundwater fluctuation zone (GWFZ) was reported, however with limited reliability as there was no control on small-scale effects. To recognize statistically significant magnetic signatures versus depth, we obtained multiple sediment cores from three locations in January 2011 and April 2012, penetrating the unsaturated zone, the GWFZ and the uppermost one meter below the groundwater level (∼2.3 m depth at the time of sampling). Magnetic concentration variation versus depth was determined by measuring magnetic susceptibility (MS) and remanence parameters. Small-scale features were identified and eliminated by statistical processing of multiple cores. A trend of increasing MS values from the lowermost position of the groundwater table upward was verified and highest magnetic concentration was found at the top of the GWFZ. Magnetic mineralogy indicates that newly formed fine-grained magnetite in the single domain to small pseudo-single domain range is responsible for the MS enhancement confirming previous results. There is no correlation with the depth variation of hydrocarbon (HC) concentrations; however, total organic carbon is linked to MS and may represent a degradation product of HC that is bioavailable for microorganisms. Bacterial activity is likely responsible for magnetite formation as indicated by most probable number (MPN) results of iron-metabolizing bacteria. The comparison of our results with an earlier study conducted at the same site revealed that magnetic concentration clearly decreased since remediation was terminated in 2008, possibly due to dissolution of magnetite. [ABSTRACT FROM AUTHOR]

The concentrations of metals (Pb, Cu, Zn, Co, Ni, Fe and Mn) in the <2.5 μm fraction of surface soils (0-5 cm) from highly industrialized areas in Xuzhou (China) were determined. All analyzed metals with the exception of Mn and Co in the present study showed elevated concentrations in the <2.5 μm fraction of soils compared to background concentrations, particularly for Zn. Metal enrichment was positively correlated with carbonate complexation constants (but not bulk solubility products) as well as the first stability constants of metal-citrate, likely suggesting that both metal-organic complexation and/or precipitation of carbonate surfaces that subsequently adsorb metals are likely responsible for these metal enrichment on these samples. Sequential extraction analysis shows the metals Pb, Cu, Zn, Co and Mn were largely associated with the reducible fraction, whereas Ni was largely associated with the oxidisable fraction. Manganese is the only metal showing significant association with the exchangeable fraction (up to 33 %), suggesting that it may be the most susceptible metal to mobilization. Mineral magnetic analysis indicates that ferrimagnetic SSD + SP (stable single domain + superparamagnetic) minerals dominated the <2.5 μm fraction of Xuzhou surface soils. Lead, Cu and Zn were found to show significant correlations with χlf ( p < 0.01), suggesting that magnetic technique might be beneficially used as a rapid and inexpensive method to estimate these metal contaminations in the <2.5 μm fraction of surface soils. [ABSTRACT FROM AUTHOR]

The southeastern Chinese Loess Plateau is the terminal deposition area of dusts transported by the East Asian winter monsoon and the frontal area penetrated by the East Asian summer monsoon, and thus a climate sensitive region. This paper reports a rock magnetic study of a Quaternary loess-paleosol section in such a region. We tried to reconstruct the paleoclimate evolution history in the region during 1.95-0.40 Ma with magnetic parameters. The results show a general up-section decreasing trend of the ratio of HIRM/(SIRM-IRM), indicating a long-term decreasing trend of hematite coercivities in the deposits, which can be mainly related to the cooling and aridification trend of the environment in interglacial depositional area and glacial dust source region. The ratio, χ/ χ, widely used to reflect the variations of magnetic mineral grain size, manifests a long-term increasing trend of the magnetic mineral grain size and tends to indicate an overall weakening trend of the East Asian summer monsoon that controlled the pedogenic intensity. Although the regional multi-segmented paleoclimatic records revealed by several magnetic parameters in our study, the long-term Asian cooling and aridification trend inferred here is of global correlation significance. [ABSTRACT FROM AUTHOR]

Rock-magnetic investigations of environmental samples, such as soils, dust and leaves, can provide useful information on environmental stress. Aim of this paper is to report on the first magnetic survey carried out on environmental samples from Bogotá, Colombia, which is the fifth most populated city of Latin America. We studied three kinds of samples in order to evaluate their potential as pollution markers: soils, urban dust and leaves of the Sauco (Sambucus nigra) tree. Standard magnetic methods were used to analyze the three groups of samples, with special emphasis on leaves investigated here for the first time for environmental purposes. Samples were collected along two perpendicular transects in an area of the city presumably unpolluted, with two different systems of public transportation. Thermomagnetic curves obtained from soils and atmospheric dust show clearly defined ferrimagnetic phase (probably magnetite) as the main magnetic carrier. Curves of acquisition of isothermal remanent magnetization confirm the ferrimagnetic character of magnetic particles. Frequency-dependent magnetic susceptibility was found between 0 and 10%, suggesting less-important contribution of ultrafine super-paramagnetic magnetite. The apparent contradictory results between soils and the rest of samples may reflect different accumulation period for magnetic particles, being shorter for leaves and urban dust than for soils. [ABSTRACT FROM AUTHOR]

As the largest industrial city locating in the Northwestern China, Lanzhou has become one of the most seriously polluted cities in the world. In this study, investigations were performed on the magnetic properties, heavy metals and organic matter contents of a total of 23 sediment samples collected from eight selected rivers in the Lanzhou urban area. The results of the study indicate that the magnetic properties of the sediment samples are predominated by low-coercivity magnetite. The river sediments are classified into three types, i.e., downstream polluted, upstream polluted, and less affected, based on the contribution from anthropogenic activities in different segments of the river as indicated by the variation of magnetic mineral concentration parameters. Moreover, a strong linear positive correlation exists among some of the magnetic parameters and organic matter content, heavy metals (Cr, Ni, Pb, Zn, Fe) and total enrichment factor ( R) of the bulk deposit samples, which indicates that environmental magnetic technology may be an effective method for distinguishing source apportionment and monitoring river sediment pollution in urban areas. [ABSTRACT FROM AUTHOR]

The Ponnaiyar River is one of the largest rivers of the Tamil Nadu state (India), flowing a distance of 430 km from its point of origin to the sea. This work contributes with new data of magnetic and elemental composition of river sediments, and improves the knowledge obtained by preliminary and previous studies of rivers from Southeastern India. Magnetic susceptibility, anhysteretic and isothermal remanent magnetization and chemical determinations (major and trace metals) were measured. Magnetic results reveal the predominance of magnetite-like mineral with magnetic grain size variations along the river and in depth. Most of the uppermost samples have the major presence of trace metals and higher values of magnetic concentration. Magnetic and chemical variables were also analysed as potential pollution indicators using multivariate statistical techniques: canonical correlation and fuzzy c-means clustering analyses, which confirmed the existence of relationships, but not in a simple way, between magnetic and chemical variables. Furthermore, fuzzy analysis allows classifying the data in different well-differentiated groups regarding the trace metal load, concentration and feature-dependent parameters. The most polluted samples show high concentration of trace elements and magnetic carriers, softer and coarser magnetic minerals; on the contrary, the unpolluted samples (from the deepest sediments) have the opposite characteristics. [ABSTRACT FROM AUTHOR]

A total of 115 urban soil samples collected on grid bases from Al-Karak, South Jordan, were investigated for their field and dual-frequency magnetic susceptibility ( χ, χ) and heavy metal content using Bartington susceptibility meters and ICP-MS. The upper soils have higher magnetic susceptibility values than lower soils, and large particles contain more heavy metals and higher magnetic susceptibility than smaller particles. This might be attributed to the lack of pedogenesis due to arid climate influence. Within the upper soil all heavy metal showed positive significant correlation with upper soil low-frequency χ. This was evident from the distribution maps produced by Surfer 9.0 for χ and heavy metals. The results showed that higher χ is associated with traffic-dominated sites more than other areas. The frequency-dependent susceptibility ( χfd %) falls between 2 and 10 %, which indicate the presence of admixture of fine supermagnetic particles. Mildly correlation exists between χfd % and χ, which implies that soils contain anthropogenic multi-domain grains. Selected samples have been analyzed for their mineral constituents; the results indicate the presence of magnetite as the main magnetic mineral. This confirms the anthropogenic source of pollution mainly from the vehicle-related materials. The results indicate the applicability of magnetic susceptibility for pollution detection. [ABSTRACT FROM AUTHOR]

Geophysical methods are widely applied to soils for resolving different tasks in precision agriculture, pollution evaluation, erosion estimation, etc. Environmental magnetic methods were applied in our study on a collection of soil samples from area near Rosslau (Germany), which was gathered on the basis of a field electromagnetic induction study. Magnetic laboratory analyses include magnetic susceptibility, isothermal remanent magnetization (IRM), anhysteretic remanent magnetization (ARM), thermomagnetic analyses for determination of the kind of magnetic minerals present in soils. The results reveal the presence of statistically significant inverse correlations between magnetic susceptibility, as well as remanent magnetizations ARM and IRM, and conductivity values. This maybe ascribed to influence of topography and water regime on the iron oxide forms in soil and the influence of soil moisture on soil conductivity. Magnetic measurements on soil cores showed close correspondence between soil horizons outlined in 1 m-long cores, and depth changes in mass-specific magnetic susceptibility. Existing relationships between magnetic characteristics, soil reaction pH, and nutrients' content (total nitrogen, carbon and sulphur) have been explored by cluster analysis and general regression model statistics. The results reveal the presence of significant correlations between nutrients' content, magnetic susceptibility and the grain size sensitive ratio ARM/χ. These are expressed by numerical equations, representing pedotransfer functions, which predict the content of Nitrogen, Carbon and Sulphur through combination of magnetic parameters and soil pH. The obtained pedotransfer functions for the particular case of Gley soils and Fluvisols studied could be used for application of magnetic methods in agricultural practice as a fast and inexpensive proxy evaluation of the content of these nutrition elements. [ABSTRACT FROM AUTHOR]

The paper presents a personal summary of the role of magnetic measurements in lake sediment studies. Examples are used to illustrate the main variations in lake sediment magnetic properties and the processes controlling their variations. These are considered in terms of sediment sequences: (1) that are virtually devoid of magnetic minerals; (2) the magnetic properties of which are dominated by input of magnetic minerals from 'primary', unweathered catchment sources (3) with magnetic properties indicative of erosion of weathered material, mainly magnetically enhanced topsoil; (4) that have received minimal input of terrigenous ferrimagnetic minerals but are rich in biogenic magnetite (5) parts of which have experienced dissolution diagenesis (6) in which signals from erosion, biogenic magnetite and dissolution can all be detected and (7) that are dominated by the presence of authigenic greigite. Additional issues, including the importance of particle size variations as a control of magnetic properties, the under-representation of haematite and goethite in the magnetic record and the significance of atmospheric deposition are also considered. A concluding section briefly outlines the present status of environmental magnetism and its role in palaeoenvironmental research based on lake sediment studies. [ABSTRACT FROM AUTHOR]

Fifty-one tree leaves were sampled in the industrial area, residential area, and Fenhe River ecological zone, for the purpose of a magnetic study on atmospheric pollution in Linfen City, Shanxi Province, China. Measurements of mass-specific magnetic susceptibility (γ) show a significant variation range (from 11.6 × 10 m/kg to 129.7 × 10 m/kg). Overall values of magnetic susceptibility decline in the following sequence: industrial area > residential area > Fenhe River ecological zone. The relatively elevated concentration-related magnetic parameters (saturation isothermal remanent magnetization, anhysteretic remanent magnetization and magnetic susceptibility) appear in the industrial area, with their highest values in the vicinity of Linfen Steel Mill. Magnetic particles are dominated by multidomain, magnetite-like minerals. Magnetic particle concentration and grain size both decrease with the increasing distance from industrial area, indicating the industrial area, especially Linfen Steel Mill, is the main source of atmospheric particle pollution. Residential area and Fenhe River ecological zone are also affected by industrial emission to a certain extent. The results of this study indicate that magnetic measurements of tree leaves are practicable for monitoring and determination of atmospheric pollution in Linfen City. [ABSTRACT FROM AUTHOR]

This study is a systematic analysis of the magnetic characteristics and heavy metal elements in soil samples collected from Lanzhou City, China. The 117 surface soil samples were measured to study the feasibility and effectiveness of environmental magnetism for evaluating heavy metal pollution in urban soils. Results of the study indicate that low-coercivity magnetite dominates the magnetic properties in the samples. The high values of the soil magnetic mineral concentration parameters and low values of magnetic particle size parameters are distributed throughout the northern area of Xigu District, the industrial zones of the eastern section of Chengguan District and the districts of the narrow sections connecting Chengguan District and the other three districts; these parameters are fundamentally consistent with the distribution of the high values of the Pollution Load Index and Nemerow Pollution Index. Semi-quantitative studies which use the environmental magnetic method to monitor pollution of heavy metals (such as As, Cr, Cu, Ni, Pb, Zn, and Fe) have shown that when χ⩽35×10 m kg, it is unpolluted; when 35 ⩽ χ<150×10 m kg, it is moderately polluted to unpolluted; when 150 ⩽ χ<365×10 m kg, it is moderately polluted; when 365 ⩽ χ<750×10 m kg, χ%<2.7 and χ/SIRM<0.2×10 m A, it is moderately to highly polluted; when χ⩾750×10 m kg, χ%<2.7 and χ/SIRM<0.2×10 m A, it is highly polluted. The region of moderately to highly polluted distribution is caused by industry and vehicles, showing that the change of pollution in Lanzhou City bears the trend of 'vehicle emission + industrial'. [ABSTRACT FROM AUTHOR]

Spatial variations in lake sediments are a product of their depositional heterogeneities. To better correlate synchronous strata in Huangqihai Lake, two sections were excavated from the lake-center and the lake-shore. The study involved detailed lithology, mineralogy, and rock magnetic analysis. The results show that the frequency-dependent susceptibility, which is related to the content of super-paramagnetic minerals, is relatively easy to contrast between the two sections. However, mass susceptibility and saturation isothermal remanence, which are related to the content of total magnetic minerals, are difficult to contrast. A possible reason for this difference is that small-particle super-paramagnetic minerals are formed mainly during pedogenic processes, which correlates well with climate change and avoids the effects of local factors when corrections are made at the whole-lake scale. Both sections can be divided into three stages, which appear to be well correlated with previous results obtained through other environmental proxies. [ABSTRACT FROM AUTHOR]

The magnetic susceptibility of loess from the Ily Basin, northwestern China shows maximum values in S0 paleosols but minimum values in other paleosols, the mechanism of which has been well debated. In this work, systematic magnetic measurements were made on a representative section from Neleke county. The results show that the loess horizons (L1, L2 and L3) have multi-domain magnetite grains of aeolian origin, S0 is characterized by production of pedogenetic ultrafine-grained ferrimagnetic minerals, and the other paleosols (S1, S2, and S3) are characterized by the formation of nonferrimagnetic minerals associated with waterlogging. The correlation between the low concentration of ferrimagnets, high paramagnetic content, high magnetic coercivity remanence, fine ferrimagnetic grain size and intensified pedogenesis suggest two competing processes of pedogenetic enhancement and pedogenetic depletion in the lower paleosols. Pedogenetic depletion dominates and is responsible for the low susceptibility. Changes in magnetic grain size distribution occur during pedogenetic depletion. The susceptibility variations are of multiple origins in the loess of the Ily Basin. Pedogenetic enhancement, pedogenetic depletion, and allochthonous input of magnetic minerals should all be taken into account to explain the variations of magnetic parameters. [ABSTRACT FROM AUTHOR]