Magnetic screening of a pollution hotspot in the Lausitz area, Eastern Germany: correlation analysis between magnetic proxies and heavy metal contamination in soils

Assessment of Potentially Toxic Elements’ Contamination in the Soil of Greater Cairo, Egypt Using Geochemical and Magnetic Attributes

Enhanced soil’s magnetic susceptibility reflects particles of anthropogenic/natural origin; therefore, it can be utilized as an indication of soil contamination. A total of 51 different land-use soil samples collected from Greater Cairo, Egypt, were assessed integrally using potentially toxic elements content (PTEs), magnetic susceptibility, and statistical and spatial analysis. PTE concentrations were compared to the world average, threshold, and screening values set by literature. Various environmental indices were estimated to assess soil contamination with these elements. Spatial distribution maps of PTEs and environmental indices were constructed to provide decision makers with a certain identification of riskier areas. In general, the concentrations of the analyzed PTEs showed variation with land-use types and follows a pattern of: Industrial > Agricultural > Urban. The distribution of PTEs in Greater Cairo was influenced by several anthropogenic sources, including traffic emission, industrial activity, and agricultural practices. The measured magnetic susceptibility values indicate magnetically enhanced soil signals dominated by multi-domain or pseudo-single-domain superparamagnetic particles of anthropogenic origin. A significant association was observed between magnetic susceptibility values and Co, Cr, Cu, Ni, and V, and the calculated environmental indices. It can be concluded that magnetic susceptibility is of proven effectivity in the assessment of soil contamination.

Tracking Airborne Pollution with Environmental Magnetism in A Medium-Sized African City

As in other parts of the world, air pollution over West and Central Africa has major health and meteorological impacts. Air quality assessment and its possible sanitary impact have become essential even in medium-sized towns, therefore amplifying the need for easy-to-implement monitoring methods with low environmental impact. We present here the potential of magnetic methods to monitor air quality at street level in the medium-sized city of Maroua (northern Cameroon) affected by dust-laden desert winds. More than five hundred (544) samples of bark and leaves taken from Neem trees in Maroua were analyzed. Magnetic susceptibility, saturation remanence, and S-ratio were found to determine the concentration and nature of magnetic particles. They are dominated by magnetite-like particle signals as a part of particulate emissions due to urban activities, including both traffic, composed of a substantial proportion of motorcycles, and wood burning for food preparation. We show that both bark and leaves from Neem trees are adequate passive bio-recorders. The use of both enables different times and heights to be sampled, allowing for the high-resolution monitoring, in terms of spatialization, of various urban environments. Particle emissions require assessment and screening that could be carried out rapidly and efficiently by magnetic methods on bio-recorders, even in cities impacted by dust-laden wind.

An environmental magnetic record of heavy metal pollution in Vembanad lagoon, southwest coast of India

Magnetic signature of the iron-bearing minerals archived in sediments is sensitive to change in environment and therefore, studied to reconstruct the signals linked with environmental processes. In the present work, we have analyzed 11 sediment cores from Vembanad lagoon, southwest coast of India, to estimate the magnetic fluctuations associated with environmental processes. Down-core variation in magnetic susceptibility and anhysteretic, isothermal and saturation isothermal remnant magnetization and S and H-ratios have been interpreted to map the degree and spatial distribution of anthropogenic pollution in and around the lagoon. Downcore variation of magnetic susceptibility of Vembanad lagoon sediments varies from 10 to 100 × 10^-8 m³/ kg. The top layers of sediment samples from river mouth regions (Periyar and Muvattupuzha rivers) show higher susceptibility values and incidentally these samples are of coarse sized. The subtle variations in SIRM/χ_lf ratios suggest that there are magnetic grain size differences in the samples. The SIRM and χ_lf relation suggests that dominant magnetic grain size in sediments. The low ARM/χ_lf ratios suggest a relatively higher ferrimagnetic contribution and coarser magnetite grain size. Rock magnetism data reveal that the coarse magnetic grain size is affecting the pollution of Vembanad lagoon. We also analyzed downcore variability of metal concentrations such as Fe, Mn, Cu, Zn, Ni and Cr, and all these metals exhibit higher concentrations in the top layers of the cores. Our study suggests that higher values of magnetic parameters and metal concentrations are due to various anthropogenic sources.

Complementary Use of Magnetometric Measurements for Geochemical Investigation of Light REE Concentration in Anthropogenically Polluted Soils

The purpose of this study was to use fast geophysical measurements of soil magnetic susceptibility (κ) as supplementary data for chemical measurements of selected light rare earth elements (REEs) in soil. In order to ensure diversity in soil conditions, anthropogenic conditions and types of land use, seven areas were selected, all located in regions subjected to past or present industrial pollution. Magnetometric parameters were measured using a selected magnetic sensor that was specially designed for measurements of soil cores and were used to classify collected soil cores into six distinctive types. The analysis of REEs concentrations in soil was carried out taking into account the grouping of collected soil samples based on the type of study area (open, forested and mountain), and additionally on the measured magnetometric parameters of collected soil cores. A use of magnetometric measurements provided different, but complementary to chemical measurements information, which allowed to obtain deeper insight on REEs concentrations in soils in studied areas.

Investigation of Concentration and Distribution of Elements in Three Environmental Compartments in the Region of Mitrovica, Kosovo: Soil, Honey and Bee Pollen

The abundances of selected elements in different environmental compartments, namely soil, honey, and bee pollen, was determined in this study. For that purpose, sixteen soil and honey samples, and nine pollen samples were taken in the region of Mitrovica, Kosovo. The concentration of elements was measured by ICP-AES and ICP-MS. Pollution level concentrations of Pb, Zn, As, and Cd were observed in soil. The level of soil pollution was estimated by calculating pollution indices. Pb was also observed at high concentrations in honey, as was Cd and Pb in pollen. Pearson’s correlation coefficients revealed mostly weak and moderate correlations of the concentrations of the eight selected elements among the soil, honey, and pollen samples. Several groups of elements with geogenic and anthropogenic origin were identified by hierarchical cluster analysis. The concentrations of selected heavy metals for soil and honey were compared to those in neighboring countries, and those for pollen with samples from Turkey, Serbia, and Jordan.

A multi-proxy magnetic approach for monitoring large-scale airborne pollution impact

The interpretive utility of environmental magnetic proxies for investigating airborne particulate matter (PM) pollution impact is restricted by differences in soil composition, land cover and land use. For soil magnetic applications, land use strongly influences magnetic particle distribution down the soil profile, even in homogeneous soil environments. Here, an adaptive approach is engineered to provide accurate magnetic proxy information for pollution monitoring across different land use types. In an 81-km² area between two industrial harbours, the irregular distribution of forests, arable lands, pasture and residential areas prevented robustly relating topsoil magnetic susceptibility data to known pollution impacts. Although normalized topsoil susceptibility values showed improved potential for deriving airborne pollution impacts, optimal results were obtained by depth-integrating magnetic susceptibility logs, revealing long-term impacts of both active and decommissioned industrial facilities. Complementing soil magnetic observations, active and passive (bio)magnetic monitoring allowed discriminating short-term pollution patterns and evaluating changes in PM impact across the study area. Hereby, active PM receptors (strawberry leaves and plastic coated cardboards (PCCs)) provided promising results, yet passive receptors allowed estimating pollution impacts more efficiently. For the latter, species-independent grass leaf sampling reflected airborne PM depositional patterns most accurately, whereas wiped anthropogenic surfaces proved too sensitive to wash-off.

Carbon fractionation and stable carbon isotopic fingerprint of road dusts near coal power plant with emphases on coal-related source apportionment

Road dust from coal utilization is a significant source contributing to the generation of pollutants that can affect the health of people residing within close proximity to roadways. In this study, road dust samples were collected from different directions centered around a coal-fired power plant in Huainan. Black carbon (BC), soot, char, organic carbon (OC) and total carbon (TC), as well as the δ¹³C of samples, were determined. Compared to the reference locations which were distant from the power plant, the research areas surrounding the power plant were featured by significantly higher OC/BC ratio and TC concentration. The OC/BC showed significant difference in urban vs. rural areas, and at different distances from the central power plant, which implied that the source and spread of carbonaceous species was dominantly affected by wind direction and urban/rural area differences. Surface morphology analysis showed that the road dust was mixed with spherical particles similar to fly ash. High-resolution XPS C1s spectrum revealed the existence of metal carbide, metal carbonate, and CF₃ in the road dust samples. The speciation of carbon in road dusts was found correlated with sampling directions and urban functional areas. Based on the δ¹³C and OC/BC, it could be inferred that coal-related substances might be important sources of road dusts.

Elemental and magnetic analyses, source identification, and oxidative potential of airborne, passive, and street dust particles in Asaluyeh County, Iran

One of the most important environmental issues in arid and semi-arid regions is deposition of dust particles. In this study, airborne, passive, and street dust samples were collected in Asaluyeh County, in August 2017, September 2017, and February 2018. The PM_2.5 and PM₁₀ concentrations for the sampling period ranged between 19.7 and 76.0 μg/m³ and 47.16-348 μg/m³ with an average of 46.4 μg/m³ and 143 μg/m³, respectively. Monthly dust deposition rates ranged from 5.2 to 26.1 g/m² with an average of 17.85 g/m². Positive Matrix Factorization (PMF) applied to the dust compositional data indicated that Sb, Zn, Pb, Mo, Cu, and As come from anthropogenic sources while Al, Fe, Ti, Mn, Ni, Cr, and Co originate mostly from geogenic sources. The PMF results indicated that the geogenic material was the major source of passive and airborne dust samples. Elemental compositions were similar for passive dust and local surface soil. Frequency-dependent magnetic susceptibility (χ_If and χ_fd%) showed that the local soil is entisol. Isothermal remanent magnetization (IRM_-100mT/IRM_1T) versus saturation IRM (SIRM) demonstrated that the background sample contains ferrimagnetic minerals, but with increasing SIRM, the concentration of soft magnetic magnetite-like phases increases and the magnetic particles are larger. Mrs./Ms. versus Bcr/Bc indicated that the magnetic particles sizes were probably between 120 and 1000 nm. Eu values and the mean Eu/Eu* and La/Al values clearly show that the airborne dust is most affected by oil industries, while passive dust samples primarily originated from local surface soils. These assumptions were confirmed by Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model results. The samples display a moderate level of oxidation towards ascorbic acid (OP_AA) and glutathione (OP_GSH). Regarding the passive and airborne dust samples, backward Generalized Estimating Equations (GEE) modeling results display a significant positive relationship between geogenic material and oxidative potential (OP). It includes many redox-active transition metals. Alternatively, the street dust OP is strongly related to geogenic and industrial sources and OP_AA is marginally related to urban sources. It was shown that measured magnetic parameters can be used for OP estimation.

Evaluating the potential of topsoil magnetic pollution mapping across different land use classes

Soil magnetic measurements are used increasingly to estimate the impact of airborne, combustion-related particulate matter (PM) pollution in dense measurement grids. Although many studies have proven the potential of topsoil magnetic measurements in environmental monitoring, their application is not straightforward when factors such as parent material or land use have to be accounted for. Often, the influence of land use on the soil magnetic signal is circumvented by targeting forest soils, where deposited magnetic particles are best preserved in the topsoil. However, when large forests are absent, e.g. in densely populated areas or environments with more heterogeneous land use, this approach often impedes reliable and comprehensive spatial sampling. We evaluated if topsoil magnetic pollution mapping across different land use classes, against a homogeneous geological environment of sandy soils, could help increase the spatial reliability of results in regional scale surveys. Although detailed magnetic property analysis and evaluation of trace metal concentrations in soils on arable land, forest and pasture showed the impact of atmospheric pollution, topsoil susceptibility measurements did not allow delineating the magnetic footprint of PM pollution. Land use strongly influenced the distribution of magnetic particles through soil, and the evaluation of anomalous magnetic topsoil enhancement required the integration of downhole susceptibility soundings. We conclude that topsoil susceptibility mapping remains a useful tool to evaluate PM pollution impact, yet its application potential across land use classes is limited.

Using Geostatistical Gaussian Simulation for Designing and Interpreting Soil Surface Magnetic Susceptibility Measurements

This paper presents a new approach to the assessment of the uncertainty of using geostatistical Gaussian simulation in soil magnetometry. In the study area, numerous measurements of soil magnetic susceptibility were made, and spatial distributions of soil magnetic susceptibility were simulated. The parameters of variograms of soil magnetic susceptibility measured in the study area were determined and compared with those of simulated soil magnetic susceptibility. Regardless of the measurement scheme used, reproducibility of the original semivariograms of soil magnetic susceptibility was satisfactorily achieved when applying simulated values. A nugget effect, a sill, and a range of correlations of variograms of simulated values of soil magnetic susceptibility were similar to those of measured values. When the input data for the geostatistical simulation were averaged, the measured values of soil magnetic susceptibility and simulated spatial distributions were characterized by slightly lower standard deviations in comparison with the result of simulations based on the non-averaged, measured ones. At the same time, however, local variability of soil magnetic susceptibility was reproduced less. The accuracy of the calculations of point parameters and spatial distributions—based on the averaged values of soil magnetic susceptibility—were satisfactory, but when using geostatistical methods, it is recommended to use non-averaged magnetic susceptibility measurements.

Magnetic, geochemical characterization and health risk assessment of road dust in Xuanwei and Fuyuan, China

As an accumulation of solid organic and inorganic pollutant particles on outdoor ground surfaces, road dust is an important carrier of heavy metal contaminants and can be a valuable medium for characterizing urban environmental quality. Because the dusts can be an important source of atmospheric particles and take impact on human health, the aim of this study described in detail the mineralogical characteristics, morphology, and heavy metal content of road dust from Xuanwei and Fuyuan, locations with high lung cancer incidence. Our results show that the average concentrations of heavy metals in road dust were higher than their background values. Higher concentrations of heavy metals were found in the magnetic fractions (MFs) than in the non-magnetic fractions (NMFs). Magnetic measurements revealed high magnetic susceptibility values in the road dust samples, and the dominant magnetic carrier was magnetite. The magnetic grains were predominantly pseudo-single domain, multi-domain, and coarse-grained stable single domains (coarse SSD) in size. SEM/XRD analysis identified two groups of magnetic particles: spherules and angular/aggregate particles. Hazard index (HI) values for adults exposure to road dust samples, including MF, Bulk, and NMF, in both areas were lower or close to safe levels, while HI values for childhood exposure to magnetic fractions in both areas were very close or higher than safe levels. Cancer risks from road dust exposure in both areas were in the acceptable value range.

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

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

Statistical assessment to magnetic susceptibility and heavy metal data for characterizing the coastal sediment of East coast of Tamilnadu, India

A rapid urbanization and industrialization enhances the significant heavy metal pollution in the sediments of coastal area and introduced a serious threat to the human health. In the present study, concentration of heavy metals such as Al, Ti, Fe, V, Cr, Mn, Co, Zn, La, Pb, Mg, Ca, Ni, Cd and Ba are determined in sediments along Periyakalapet to Parangaipettai coastal area, Tamilnadu using energy dispersive X-ray fluorescence spectrometer (EDXRF).These metals have more affinity to establish metallic bond with ferrous material leading to enhancement of sediment magnetic susceptibility. Hence, a magnetic susceptibility (χLF, χHF, χFD) measurement was carried for sediments by using MS2B dual frequency susceptibility meter. Multivariate statistical analysis (Pearson correlation, factor and cluster analysis) was carried out between heavy metals and magnetic susceptibility to assess the anthropogenic impact in the sediments. The study revealed that a magnetic susceptibility measurement is an inexpensive, fast, non-destructive and suitable method to identify the heavy metal pollution sources.

Magnetic signature, geochemistry, and oral bioaccessibility of "technogenic" metals in contaminated industrial soils from Sindos Industrial Area, Northern Greece

The objective of this study was to assess the contamination level of potentially harmful elements (PHEs) in industrial soils and how this relates to environmental magnetism. Moreover, emphasis was given to the determination of the potential mobile fractions of typically "technogenic" metals. Therefore, magnetic and geochemical parameters were determined in topsoils (0-20 cm) collected around a chemical industry in Sindos Industrial Area, Thessaloniki, Greece. Soil samples were presented significantly enriched in "technogenic" metals such Cd, Pb, and Zn, while cases of severe soil contamination were observed in sampling sites north-west of the industrial unit. Contents of Cd, Cr, Cu, Ni, Pb, Mo, Sb, Sn, and Zn in soils and pollution load index (PLI) were highly correlated with mass specific magnetic susceptibility (χ _lf). Similarly, enrichment factor (EF) and geoaccumulation index (I _geo) for "technogenic" Pb and Zn exhibited high positive correlation factors with χ _lf. Principal component analysis (PCA) classified PHEs along with the magnetic variable (χ _lf) into a common group indicating anthropogenic influence. The water extractable concentrations were substantially low, while the descending order of UBM (Unified BARGE Method) extractable concentrations in the gastric phase was Zn > Pb > As > Cd, yet Cd showed the highest bioaccessibility (almost 95%).

Geostatistical discrimination between different sources of soil pollutants using a magneto-geochemical data set

The primary goal of this work was to distinguish between soil pollution from long-range and local transport of atmospheric pollutants using soil magnetometry supported by geochemical analyses. The study area was located in the Izery region of Poland (within the "Black Triangle" region, which is the nickname for one of Europe's most polluted areas, where Germany, Poland and the Czech Republic meet). One site of the study area was situated in the Forest Glade and was exposed to anthropogenic pollution from a former glasswork. The second site of the study area was located on a neighboring hill (Granicznik) of which the western, northwestern and southwestern parts of the slope were exposed to the long-range transport of atmospheric pollutants from the Czech Republic, Germany and Poland. Magnetic susceptibility was measured on the soil surface and in the soil samples using a MS2 Bartington meter equipped with MS2D and MS2C sensors, respectively. Using soil magnetometry, it was possible to discriminate between long-range transport of atmospheric pollutants and anthropogenic pollution related to the former glasswork located in the Forest Glade. Additionally, using MS2C measurements and geochemical analyses of sixteen trace elements, it was possible to discriminate between natural and anthropogenic origins of a soil magnetic susceptibility signal. Our results indicate that the Forest Glade site is characterized by relatively significant anthropogenic translocation of topsoil horizons, presence of artefacts, more hot spots, very high spatial variability, and higher nugget effect than on the Granicznik Hill.

Technogenic magnetic particles in soils as evidence of historical mining and smelting activity: A case of the Brynica River Valley, Poland

In the area of Brynica River basin (Upper Silesia, southern Poland) the exploitation and smelting of iron, silver and lead ores was historically documented since early Middle Ages. First investigations showed that metallurgy industry had a large impact from 9th century (AD) until the Second World War. The aim of the study was to use magnetic prospection to detect traces of past mining and ore smelting in Brynica River Valley located in Upper Silesia (southern Poland). The field screening was performed by measurement magnetic susceptibility (κ) on surface and in vertical profiles and was supported locally by gradiometric measurements. Vertical distribution of magnetic susceptibility values was closely associated with the type of soil use. Historical technogenic magnetic particles resulting from exploitation, processing, and smelting of iron, silver, and lead ores were accumulated in the soil layer at the depth 10 to 25cm. They were represented by sharp-edged particles of slag, coke, as well as various mineralogical forms of iron minerals and aggregates composed of carbon particles, aluminosilicate glass, and single particles of metallic iron. The additional geochemical study in adjacent peat bog supported by radiocarbon dating was also performed. The application of integrated geochemical-magnetic methods to reconstruct the historical accumulation of pollutants in the studied peat bog was effective. The magnetic peak, which was pointed out by magnetic analyses, is consistent with the presence of charcoal and pollution from heavy metals, such as Ag, Cd, Cu, Fe, Pb, or Sn. The results of this work will be helpful for the further study of human's impact on the environment related to the historical and even pre-historical ore exploitation and smelting and also used for better targeting the archeological excavations on such areas.

Study of road dust magnetic phases as the main carrier of potentially harmful trace elements

Mineralogical and morphological characteristics and heavy metal content of different fractions (bulk, non-magnetic fraction-NMF and magnetic fraction-MF) of road dusts from the city of Thessaloniki (Northern Greece) were investigated. Main emphasis was given on the magnetic phases extracted from these dusts. High magnetic susceptibility values were presented, whereas the MFs content of road dust samples ranged in 2.2-14.7 wt.%. Thermomagnetic analyses indicated that the dominating magnetic carrier in all road dust samples was magnetite, while the presence of hematite and iron sulphides in the investigated samples cannot be excluded. SEM/EDX analyses identified two groups of ferrimagnetic particles: spherules with various surface morphologies and textures and angular/aggregate particles with elevated heavy metal contents, especially Cr. The road dusts (bulk samples) were dominated by calcium, while the mean concentrations of trace elements decreased in the order Zn > Mn > Cu > Pb > Cr > Ni > V > Sn > As > Sb > Co > Mo > W > Cd. MFs exhibited significantly higher concentrations of trace elements compared to NMFs indicating that these potentially harmful elements (PHEs) are preferentially enriched in the MFs and highly associated with the ferrimagnetic particles. Hazard Index (HI) obtained for both adults and children through exposure to bulk dust samples were lower or close to the safe level (=1). On the contrary, the HIs for the magnetic phases indicated that both children and adults are experiencing potential health risk since HI for Cr was significantly higher than safe level. Cancer risk due to road dust exposure is low.

Atmospheric pollution history at Linfen (China) uncovered by magnetic and chemical parameters of sediments from a water reservoir

We studied magnetic and chemical parameters of sediments from sediments of a water reservoir at Linfen (China) in order to quantitatively reconstruct the atmospheric pollution history in this region. The results show that the main magnetic phases are magnetite and maghemite originating from the surrounding catchment and from anthropogenic activities, and there is a significant positive relationship between magnetic concentration parameters and heavy metals concentrations, indicating that magnetic proxies can be used to monitor the anthropogenic pollution. In order to uncover the atmospheric pollution history, we combined the known events of environmental improvement with variations of magnetic susceptibility (χ) and heavy metals along the cores to obtain a detailed chronological framework. In addition, air comprehensive pollution index (ACPI) was reconstructed from regression equation among magnetic and chemical parameters as well as atmospheric monitoring data. Based on these results, the atmospheric pollution history was successfully reconstructed.

Geostatistical Microscale Study of Magnetic Susceptibility in Soil Profile and Magnetic Indicators of Potential Soil Pollution

Directional variograms, along the soil profile, can be useful and precise tool that can be used to increase the precision of the assessment of soil pollution. The detail analysis of spatial variability in the soil profile can be also an important part of the standardization of soil magnetometry as a screening method for an assessment of soil pollution related to the dust deposition. The goal of this study was to investigate the correlation between basic parameters of spatial correlations of magnetic susceptibility in the soil profile, such as a range of correlation and a sill, and selected magnetometric indicators of soil pollution. Magnetic indicators were an area under the curve of magnetic susceptibility versus a depth in the soil profile, values of magnetic susceptibility at depths ranging from 1 to 10 cm, and maximum and background values of magnetic susceptibility in the soil profile. These indicators were previously analyzed in the literature. The results showed that a range of correlation of magnetic susceptibility was significantly correlated with magnetic susceptibility measured at depths 1, 2, and 3 cm. It suggests that a range of correlation is a good measure of pollutants' dispersion in the soil profile. The sill of the variogram of magnetic susceptibility was found to be significantly correlated with the area under the curve of plot of magnetic susceptibility that is related to the soil pollution. In consequence, the parameters of microscale spatial variability of magnetic susceptibility in s soil profile are important measures that take into consideration the spatial aspect of s soil pollution.

Response of magnetic properties to heavy metal pollution in dust from three industrial cities in China

Magnetic method is a reliable and powerful technique for identification of the relative contribution of industrial pollutants. However, it has not been fully applied in urban area impacted by non-ferrous metal (NFM) smelting/processing activities. The aim of this study is to explore the applicability of magnetic methods for detecting heavy metal contamination in dust from three NFM smelting/processing industrial cities (Ezhou, Zhuzhou, and Hezhang) in China. The enhancements of magnetic susceptibility (MS) and saturation isothermal remanent magnetization (SIRM) together with heavy metals were significant in the studied areas in comparison with the background values. Scanning electron microscope (SEM) analysis revealed that magnetic particles in dust from Ezhou were dominated by spherules, while those from Zhuzhou and Hezhang were mainly consisted of irregular-shaped particles. κ-T curves and X-ray diffraction (XRD) analyses indicated that the magnetic particles from Ezhou were dominated by magnetite and metallic iron, whereas those from Zhuzhou and Hezhang were consisted of magnetite and hematite. Our study indicates that magnetic properties of the dust are sensitive to the NFM smelting/processing related heavy metal pollutants. However, the relationship between magnetic parameters and heavy metals was influenced by the presence of metallic iron particles and multi-sources of metal pollutants.

The relationship between magnetic parameters and heavy metal contents of indoor dust in e-waste recycling impacted area, Southeast China

Environmental contamination due to uncontrolled e-waste recycling is an emerging global problem. The aim of this study is to test the applicability of magnetic methods for detecting the metal pollutants emitted from e-waste recycling activities. Dust samples collected from a typical e-waste recycling region in Guiyu, Guangdong Province, China, were investigated using magnetic, geochemical, micro-morphological and mineralogical analysis. The values of mass-specific susceptibility (χ) and saturation isothermal remanent magnetization (SIRM) in dusts from e-waste recycling impacted areas ranged from 101 to 636×10(-8) m(3) kg(-1) and from 10.5 to 85.2×10(-3) Am(2) kg(-1), respectively. There was a significant correlation between SIRM and χ (r(2)=0.747, p<0.001), indicating that ferrimagnetic minerals were dominating χ in the dust samples. The values of χ(fd)% varied from 2.6 to 4.6% with a mean of 3.4%, which suggested that magnetic carriers in the dusts are predominately coarse-grained particles. Two shapes of magnetic particles, spherule (10-150 μm) and angular-shaped particles (30-300 μm), were identified by scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDX) analyses. κ-T curves, magnetic hysteresis loops and X-ray diffraction (XRD) analysis indicated that these magnetic particles were magnetite and goethite. There were significant correlations between SIRM and heavy metals (especially Cd, Co, Fe, Ni and Zn) as well as the Tomlinson pollution load index (PLI) of the dust, indicating that SIRM can be used as an efficient proxy for metal pollution in the e-waste recycling impacted area.

Enrichment and solubility of trace metals associated with magnetic extracts in industrially derived contaminated soils

Magnetic fractions (MFs) in industrially derived contaminated soils were extracted with a magnetic separation procedure. Total, soluble, and bioaccessible Cr, Cu, Pb and Zn in the MFs and non-magnetic fractions (NMFs) were analyzed using aqua regia and extraction tests, such as deionized water, toxicity characteristic leaching procedure (TCLP), and gastric juice simulation (GJST) test. Compared with the non-magnetic fractions, soil MFs were enriched with Fe, Mn, Pb, Cd, Cr, Cu, and Ni. Extraction tests indicated that soil MFs contained higher water, TCLP, and GJST-extractable Cr, Cu, Pb, and Zn concentrations than the soil NMFs. The TCLP-extractable Pb concentration in the MFs exceeded the USEPA hazardous waste criteria, suggesting that soil MFs have a potentially environmental pollution risk. Solubility of trace metals was variable in the different extraction tests, which has the order of GJST > TCLP > water. TCLP test showed Cu and Zn were more mobile than Cr and Pb while bioaccessibility of trace metal defined by GJST test showed the order of Cu ≈ Cr ≈ Zn > Pb. These findings suggested that the MFs in the industrially derived contaminated soils had higher possibility of polluting water bodies, and careful environmental impact assessment was necessary.

Geostatistical 3-dimensional integration of measurements of soil magnetic susceptibility

In soil magnetometry, two types of measurements are usually performed. The first type is measurements performed on the soil surface, frequently using an MS2D sensor. The second type includes measurements of magnetic susceptibility carried out in the soil profile, usually to a depth of about 30 cm. Up to now, such measurement results were analyzed separately. However, it is possible and advantageous to integrate these two types of measurements. The goal of the study was to integrate measurements of magnetic susceptibility performed on the soil surface and in the soil profile. More specifically, the goal was to obtain 3-dimensional spatial distributions of magnetic susceptibility of the topsoil horizon. Results show that it is possible to effectively integrate measurements of magnetic susceptibility performed on the soil surface and in the soil profile. Moreover, the 3-dimensional spatial distribution that is obtained shows the magnetic susceptibility of the top 20 cm of soil, which includes the soil horizons where most of the heavy metals are accumulated. The analysis of such a spatial distribution can be very helpful in delineating areas where the heightened magnetic susceptibility is a result of the influence of anthropogenic pollution from those areas where it results from lithogenic origin. It is possible to investigate where the volumes of soil with heightened magnetic susceptibility are located in the soil profile and in this way investigate which characteristic type of soil profile it is.

Assessment of heavy metal pollution from a Fe-smelting plant in urban river sediments using environmental magnetic and geochemical methods

Environmental magnetic proxies provide a rapid means of assessing the degree of industrial heavy metal pollution in soils and sediments. To test the efficiency of magnetic methods for detecting contaminates from a Fe-smelting plant in Loudi City, Hunan Province (China) we investigated river sediments from Lianshui River. Both magnetic and non-magnetic (microscopic, chemical and statistical) methods were used to characterize these sediments. Anthropogenic heavy metals coexist with coarse-grained magnetic spherules. It can be demonstrated that the Pollution Load Index of industrial heavy metals (Fe, V, Cr, Mo, Zn, Pb, Cd, Cu) and the logarithm of saturation isothermal remanent magnetization, a proxy for magnetic concentration, are significantly correlated. The distribution heavy metal pollution in the Lianshui River is controlled by surface water transport and deposition. Our findings demonstrate that magnetic methods have a useful and practical application for detecting and mapping pollution in and around modern industrial cities.

Evaluation of environmental magnetic pollution screening in soils of basaltic origin: results from Nashik Thermal Power Station, Maharashtra, India

BACKGROUND, AIM, AND SCOPE

Soils of basaltic origin cause difficulties in environmental magnetic screening for heavy metal pollution due to their natural high background values. Magnetic parameters and heavy metal content of highly magnetic topsoils from the Deccan Trap basalts are investigated to assess their potential for use in environmental magnetic pollution screening. This work extends the fast and cost-effective magnetic pollution screening techniques into soils with high natural magnetic signals.

MATERIALS AND METHODS

Fifty-five topsoil samples from N-S and W-E transects were collected and subdivided according to grain size using wet sieving technique. Magnetic susceptibility, soft isothermal remanent magnetization (Soft IRM), thermomagnetic analysis, scanning electron microscopy (SEM), and heavy metal analysis were performed on the samples.

RESULTS

Magnetic analyses reveal a significant input of anthropogenic magnetic particulate matter within 6 km of the power plant and the adjacent ash pond. Results depend strongly on the stage of soil development and vary spatially. While results in the W, E, and S directions are easily interpretable, in the N direction, the contribution of the anthropogenic magnetic matter is difficult to assess due to high magnetic background values, less developed soils, and a more limited contribution from the fly ash sources. Prevailing winds towards directions with more enhanced values seem to have a certain effect on particulate matter accumulation in the topsoil. Thermomagnetic measurements show Verwey transition and Hopkinson peak, thus proving the presence of ferrimagnetic mineral phases close to the pollution source. A quantitative decrease of the anthropogenic ferrimagnetic mineral concentration with increased distance is evident in Soft IRM measurements. SEM investigations of quantitatively extracted magnetic particles confirm the fly ash distribution pattern obtained from the magnetic and heavy metal analyses. Evaluation of magnetic and chemical data in concert with the Pollution Load IndiceS (PLIS) of Pb, Zn, and Cu reveals a good relationship between magnetic susceptibility and the metal content.

CONCLUSIONS

Integrated approaches in data acquisition of magnetic and chemical parameters enable the application of magnetic screening methods in highly magnetic soils. Combined data evaluation allows identification of sampling sites that are affected by human activity, through the deviation of the magnetic and chemical data from the general trend. It is shown that integrative analysis of magnetic parameters and a limited metal concentration dataset can enhance the quality of the output of environmental magnetic pollution screening significantly.

Magnetic properties of the road dusts from two parks in Wuhan city, China: implications for mapping urban environment

Magnetic parameters and heavy metal concentrations of road dusts collected from two parks with distance about 16 km in Wuhan city, China, were measured. The Guishan Park is circled by main roads with heavy traffic, and the Moshan Park is located on the downwind hills of steelworks and a power plant. Mean values of magnetic susceptibility (χ) and saturation magnetization (M (s)) of the dusts from the Moshan Park are 1.31 and 1.57 times those from the Guishan Park, respectively. Their magnetic mineralogy is dominated by pseudo-single domain magnetite; however, minor hematite was also identified in those from the Guishan Park. The dominant sources of non-natural magnetic particles and heavy metals were inferred as windblown emissions from the steelworks and the power plant for the Moshan Park, and road/railway traffics for the Guishan Park, respectively. Spatial variation in magnetic properties of road dust in the two parks and their different magnetic behavior propose that the magnetic measurements are sensitive to the different pollutant origins, as well as the urban environment, and that magnetic techniques have a high efficiency in mapping urban environment. Correlation between magnetic parameters and heavy metal concentrations is strongly site-specific: strong correlations were observed in the Moshan Park with correlation coefficients generally higher than 0.800, whereas correlations are poor in the Guishan Park. Therefore, it is strongly recommended that these relationships should be examined thoroughly before magnetic mapping.

Change of magnetic properties due to fluctuations of hydrocarbon contaminated groundwater in unconsolidated sediments

Sediments affected by fluctuations of hydrocarbon contaminated groundwater were studied at a former military site. Due to remediation, groundwater table fluctuation (GWTF) extends over approximately one meter. Three cores were collected, penetrating through the GWTF zone. Magnetic parameters, sediment properties and hydrocarbon content were measured. We discovered that magnetic concentration parameters increased towards the top of the GWTF zone. Magnetite is responsible for this enhancement; rock magnetic parameters indicate that the newly formed magnetite is in a single domain rather than a superparamagnetic state. The presence of hydrocarbons is apparently essential for magnetite to form, as there is clearly less magnetic enhancement in the core, which is outside of the strongly contaminated area. From our results we conclude that the top of the fluctuation zone has the most intensive geomicrobiological activity probably responsible for magnetite formation. This finding could be relevant for developing methods for simply and quickly detecting oil spills.

Environmental magnetism and application in the continental shelf sediments of India

Mineral magnetic and geochemical analyses were carried out on surface sediments from the continental shelf of India. The purpose of this study is to examine the environmental assessment of heavy metal concentrations and its impact in the coastal environment using magnetic techniques and to gain an understanding on the factors controlling metal concentrations and distributions in the east and west coast of India. The strong relationships between Anhysteretic Remanent Magnetization (chi(ARM)) and heavy metals can be explained by the role of iron oxides controlling metal concentrations, though the link is also reinforced by the strong tendency of chi(ARM) to be associated with the finer particle sizes. Higher values of magnetic susceptibility, IRM(20 mT) and SIRM are associated with the east coast shelf sediments suggest the presence of high ferrimagnetic content, which can be derived from the weathering products of the Deccan Basalts. chi(ARM) can be used as a normalizer for particle size effects in the way that Aluminium (Al) is often used. The relationship between magnetic parameters and heavy metal concentrations (Fe, Cu, Cr and Ni) showed a strong positive correlation in the east coast sediments, much less so in the case of the west coast. This finding suggests that the simple, rapid and non-destructive magnetic measurement can be used as an indicator for the heavy metal contamination and proxies for the measurement of heavy metals content in the coastal environment.

Heavy metal contents and magnetic susceptibility of soils along an urban-rural gradient in rapidly growing city of Eastern China

The accumulation of heavy metals (Cd, Cr, Cu, Pb and Zn) and magnetic minerals in soils along an urban-rural gradient in the rapidly growing Hangzhou City, Eastern China, was measured. The analytical results indicated that heavy metal concentrations, magnetic susceptibility (chilf) and saturation isothermal remnant magnetization (SIRM) in soils decreased with increasing distance from the urban center. The significant relationships existed between heavy metal concentrations, chilf and SIRM and distance from the urban center. The soils in the urban areas were enriched with Cd, Cu, Pb and Zn. Elevated concentrations of heavy metals (especially Cd and Zn) in urban areas indicated the evidence for the accumulation of heavy metal contaminants from anthropogenic activities. Enhanced heavy metal concentrations and magnetic susceptibility were located in the uppermost soil horizons (0-10 cm), decreasing downwards to background values. The significant positive correlations between the Tomlinson Pollution Load Index (PLI) and magnetic susceptibility and SIRM were observed in polluted soil samples. Strong positive correlation indicated that magnetic screening/monitoring provided a fast and non-destructive tool, which can be effectively used as a proxy to detect environmental pollution in rapidly growing urbanization regions affected by anthropogenic activities.

Magnetic susceptibility as an indicator of heavy metal contamination in compost

One of the main restrictions to the agronomic use of compost is the excess of heavy metals, which are often present due to inadequate separation of biodegradable fractions from non-degradable or inert materials. Magnetic susceptibility (MS) measurements are a simple technique that has been reported as a useful tool for assessing anthropogenic pollution, especially heavy metal pollution on soil and sediment samples. The close relationship of MS with heavy metal contamination has been proved by combined analyses of chemical and magnetic data. In this study, the MS and total heavy metal concentrations of eight composts from different origins were determined; all composts were passed under a magnet to remove the magnetic material, and total heavy metals were determined again. In our work, high correlations were found between magnetic susceptibility and total Cd, Zn, Pb, Cr and Ni, thus confirming the applicability of MS measurement as a proxy for heavy metal contamination in compost quality assessments. The application of a magnet over the composts reduced the MS as well as the heavy metal content, the reduction of Fe and MS being the most significantly correlated. Thus, the inclusion of an additional magnetic separation step in the post-process compost finishing could be envisaged.

Determination of anthropogenic boundary depth in industrially polluted soil and semi-quantification of heavy metal loads using magnetic susceptibility

This study focuses on magnetic susceptibility processing and analysis towards fast and cost-efficient discrimination and semi-quantification of anthropogenic heavy metal loads in soil. Spatial variability of magnetic susceptibility was investigated on sets of soil cores from both "polluted" and "less polluted" forest soil close to a steel mill near Leoben, Austria. Test sites of approximately 10 m(2) represent "site scale" dimensions. Statistical analysis of magnetic data provides a boundary depth indicating the transition from the "polluted" to the deeper, "unpolluted" zone in contaminated natural soil. Introduction of a block master curve simplifies the complex variations of individual curves, and represents magnetic susceptibility at "site scale". For linking the block master curve to heavy metals we only require magnetic susceptibility data from one soil core and heavy metal data from two sub-samples from the same core. Our optimized magnetic susceptibility data processing scheme provides an applicable tool to semi-quantify anthropogenic heavy metal loads in soil.