Technogenic magnetic particles from steel metallurgy and iron mining in topsoil: Indicative characteristic by magnetic parameters and Mössbauer spectra.

Technogenic magnetic particles (TMPs), produced during various industrial processes, are released into the atmosphere as dust and get deposited on the surrounding topsoil. The mineralogical and structural differences of TMPs produced in different technological processes should be reflected in their magnetic properties and therefore should be indicative for industrial pollution sources. The goal of this study was to characterize the TMPs by novel methodological approach, based on combination of magnetic methods and Mössbauer spectroscopy to indicate parameters that are discriminative enough to be used as environmental indicators for iron metallurgy, steel production, and iron mining. We collected the topsoil samples in the vicinity of 4 European iron- and steelworks, located in three different countries (Poland, Norway, and Czech Republic) and operating for minimum 40 years. We sampled also topsoil close to the opencast iron mine, iron ore dressing plant, and over strongly magnetic natural background. Analysis of the hyperfine parameters of the Mössbauer spectra revealed that TMPs are "magnetite-like" minerals with low stoichiometry. It is indicated by ratio of iron ions contributions in B sites (octahedral) and A sites (tetrahedral) in magnetite spinel structure, which is much lower than 2.0 (theoretical value for stoichiometric magnetite). The characteristic feature of TMPs collected from the vicinity of old metallurgical plants (>180 years) was the high contribution of surface components probably related to the surface oxidation/maghemitization. We found that, TMPs can be easily differentiated from geogenic magnetite based on their magnetic parameters. The TMP produced by the iron and steel metallurgy had relatively narrow ranges of magnetic parameters (saturation ratio Mrs/Ms, <0.15, coercivity ratio Bcr/Bc 2.5-6.0 and saturation to susceptibility ratio Mrs/χ 3.5-15). These magnetic parameters may be indicative for TMPs emitted by these pollution sources and helpful in the study of historical pollution sources in topsoil in urban and post-industrial areas.

Geochemical characteristics of solid particles deposited on experimental plots established for traffic pollution monitoring in different countries.

The main aim of this research was to identify the mineralogical, morphological, and chemical characteristics of solid particles emitted by vehicular traffic and deposited on special monitoring plots located on the roadside of five countries with different climatic conditions and traffic structure. Within 24 months of exposure, the composition of the matrix used at the monitoring plots changed. Percentage quartz content decreased in all locations, and due to the input from local sources, the share of other mineral phases increased. In some locations, an increase in the share of mineral phases associated with local parent rock and soil erosion was noted (e.g. Helsinki, Böblingen). In other places, material associated with abrasion of the road surface was characteristic (e.g. Gliwice, Opole). The composition of pollutants accumulated at all the monitoring plots was varied, however the common feature was the presence of technogenic magnetic particles in the matrix after exposure. Analyses showed that numerous irregular, angular particles of iron oxides with porous surface, which are carriers for a number of metals and metalloids were present in the samples. Angular iron oxides containing zinc, chromium, and copper are usually considered as non-exhaust traffic emissions. Another type of iron oxides particles found in the samples were magnetic spherules related to exhaust emissions (smaller spherules, < 20 µm). Study of results confirmed the effectiveness of the testing method for roadside pollution monitoring related to currently emitted solid particles accumulated on matrix of known mineral composition.

Assessment of elements mobility in anthropogenic layer of historical wastes related to glass production in Izera Mountains (SW Poland).

A geophysical survey conducted in the remote forest glade, located in the Izery Mountains (SW Poland), revealed the existence of an anthropogenic layer of historical glass wastes dumped in this area during the activity of a glass factory in the 18th and 19th centuries and domestic wastes dumped during the second part of the 20th century. The aim of the study was assessment of potential ecological risk related to the release of potentially toxic elements to the soil, groundwater and surface waters. The assessment was done on the base of classical geochemical analysis supported by calculation of environmental indices as well as on mobility of elements (leaching test and BCR sequential extraction). As an innovative aspect in the geostatistical interpretation of the data, some magnetic parameters (magnetic susceptibility-χ, χ/Fe ratio) were also used. It allowed for a better understanding of the relationship of PTEs with various forms of iron. The BCR sequential extraction found that among the PTEs, only Zn (up to 43%) was in a potentially mobile fraction probably occurring in ionic form, associated with iron oxides only by surface adsorption forces. The leaching has shown a slight increase in Zn and Cu content in the surface waters; however, it was not considered to be a real ecological threat because the pH of the waste material and soil cover is >6.0 and the scenario of a radical decrease in pH is rather unrealistic. The other PTEs were associated with more stable E2, E3 and E4 fractions. Zinc, similar to Ni, Co and Cu in waste samples, was highly correlated with magnetic parameters (χ and χ/Fe). It means that a considerable part of these metals was associated with ferrimagnetic iron oxides, although they can also occur in the form of inclusions in aluminosilicates and enclosed in glassy phases.

Integration of soil magnetometry and geochemistry for assessment of human health risk from metallurgical slag dumps.

The main objective of the study was an assessment of the pollution level of agricultural land located close to dumps of industrial waste remaining after former Zn and Pb ore processing in Poland. The integrated geophysical-geochemical methods were applied for assessment of soil quality with respect to trace element pollution. Additionally, human health risk induced by the contaminated arable soil and dusting slag heap was estimated. The investigations pointed out that soils in the vicinity of the metallurgical slag dump in Piekary were heavily polluted. Spatial distribution of magnetic susceptibility corresponding well with distribution of the content of potentially toxic elements indicated the local "pollution hotspots." Proper geophysical and geochemical data interpretation supported by statistical factor analysis enabled identification of three different sources of pollution including metallurgical slug dump as a main source, but also traffic pollution influencing the area located along the busy road and relatively strong influence of the geochemical background. Computed health hazard index revealed no adverse health effect to the farmers cultivating arable soil, but in the direct vicinity of dusting, slag dump health risk occurred, caused mostly by very toxic elements as As and Tl. In the future, investigation should be focused on contribution of different sources to the heavy metal pollution in soil-crop system in this area. It should be highlighted that a site-specific approach should be taken in order to redevelop this kind of area in order to reduce ecological and human health threat. The study proved the integrated two-stage geophysical-geochemical method to be a feasible, reliable, and cost-effective tool for identification of the extent of soil pollution and areas at risk.

Coke industry and steel metallurgy as the source of soil contamination by technogenic magnetic particles, heavy metals and polycyclic aromatic hydrocarbons.

Application of integrated magnetic, geochemical and mineralogical methods for qualitative and quantitative assessment of forest topsoils exposed to the industrial emissions was the objective of this manuscript. Volume magnetic susceptibility (κ) in three areas of southern Poland close to the coke and metallurgical plants was measured directly in the field. Representative topsoil samples were collected for further chemical and mineralogical analyses. Topsoil magnetic susceptibility in the studied areas depended mainly on the content of technogenic magnetic particles (TMPs) and decreased downwind at increasing distance from the emitters. In the vicinity of coking plants a high amount of polycyclic aromatic hydrocarbons (PAHs) was observed, especially the most carcinogenic ones with four- and five-member rings. No significant concentration of TMPs (estimated on the base of κ values) and heavy metals (HM) was observed in area where the coke plant was the only pollution source. In areas with both coke and metallurgical industry, higher amounts of TMPs, PAHs and HM were detected. Morphological and mineralogical analyses of TMPs separated from contaminated soil samples revealed their high heterogeneity in respect of morphology, grain size, mineral and chemical constitution. Pollution load index and toxicity equivalent concentration of PAHs used for soil quality assessment indicated its high level of pollution.

Characteristics of current roadside pollution using test-monitoring plots.

The aim of the study was the qualitative recognition of the existing roadside pollutants deposited in topsoils located close to roads with high traffic volume. So far, the studies have helped to determine the content of pollutants that accumulated over a long period of time. Traditionally, it has been difficult to distinguish between roadside pollution and pollution from other industrial sources. In order to avoid such problems and to accurately recognize present threats originating from road traffic, test-monitoring plots were installed in Poland (Gliwice and Opole), Germany (Tübingen, Ulm and Böblingen), Finland (Helsinki), Tajikistan (Dushanbe) and China (Lanzhou). To install the monitoring plots, the upper 7 cm of topsoil was removed and replaced with boxes filled with clean quartz sand. The sand, with a known chemical composition and neutral magnetic (diamagnetic) properties, was considered as a neutral matrix for the accumulation of traffic pollutants. Within 24 months of exposure, both the magnetic susceptibility values and heavy metal content increased, but with highly diverse differences. The highest values were observed in Germany, Tajikistan and China. Correlation coefficients between the magnetic susceptibility values and investigated elements, as well as PAHs indicate that magnetic susceptibility is a geophysical parameter that can be used, under defined conditions, as an indicator of soil pollution caused by traffic emissions.