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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) 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. [ABSTRACT FROM AUTHOR]

We present a study on the environmental magnetic response to urbanization processes from nine sediment cores from East Lake in Wuhan, China. The concentration of magnetic particles, heavy metals and organic matter in the upper 2–18 cm of the sediment cores have been significantly elevated due to the input of coarse magnetite grains from industrial (e.g. power generation and steelmaking) and other anthropogenic activities (e.g. vehicle emissions). Concentration-related magnetic parameters, such as magnetic susceptibility (χ), saturation isothermal remanent magnetization and anhysteretic remanent magnetization, are significantly correlated with concentration of heavy metals and organic matter, for example, Pearson's correlation coefficients are 0.921 for χ-Cu, 0.660 for χ-Pb and 0.848 for χ-loss-on-ignition, respectively. The magnetic properties of the lake sediments document the pollution history caused by human impact on the lake catchment during urbanization. The environmental quality of the lake was fairly good before the 1960s. Magnetic, heavy metal and organic matter contents of the sediments were low and relatively constant, which indicates relatively stable natural inputs from the lake catchment. Pollution trends since the 1960s are reflected in downcore magnetic property variations of the lake sediment. The concentration of magnetic particles in the lake sediments started to increase since 1957, when the Wuhan Iron and Steel Company and the Qingshan Thermal Power Plant, which are located upwind of the lake, were built and put into production. Lake pollution was further aggravated since the acceleration of industrialization and urbanization in East Lake area in the 1980s, which is verified by the elevated concentration of heavy metals and organic matter in the sediments. The magnetic mineral concentration in the lake sediment increased continuously until it peaked in the 1990s and has remained a high level since then. These results suggest that magnetic properties respond sensitively to environmental status, and that the magnetic properties of sediments can provide an excellent record of the industrial and anthropogenic history in an urban lake catchment. [ABSTRACT FROM AUTHOR]

Magnetic measurements and heavy metal analyses were performed on 133 samples from the urban soils around the East Lake in Wuhan, China. Samples were collected from four areas with different environmental settings: a heavy industrial area well known for thermal power generation and steel works; villages located in the downwind area of the industrial area; a main road with heavy traffic and roads around the East Lake. Results show that concentrations of magnetic particle and heavy metals in urban topsoils are significantly elevated due to the input of coarser-grained magnetite from industrial (e.g. power generation and steel production) and other anthropogenic activities (e.g. vehicle emissions). Concentration-related magnetic parameters, for example, magnetic susceptibility, saturation isothermal remanent magnetization and anhysteretic remanent magnetization, significantly correlate with the concentration of heavy metals. Moreover, in terms of grain sizes, the magnetic particles of different origins can be efficiently discriminated at the studied region. Therefore, magnetic measurements provide a basis for discrimination and identification of different contamination sources, and can be used as an economic alternative to chemical analysis when mapping heavy metal contamination in urban soil around the East Lake region, Wuhan, China. [ABSTRACT FROM AUTHOR]