CORRELATION BETWEEN MAGNETIC PROPERTIES AND HEAVY METAL CONTAMINATION FROM URBAN SOILS: A CASE STUDY FROM LAKE CHARLES, LOUISIANA

Large petroleum and chemical industries have been conducting business in Lake Charles, Louisiana and surrounding areas for the past 100 years. Industrial resource processing and collection methods can result in serious pollution and damage to soils and land, including the discharge of heavy metal compounds into the environment. These processes are predominantly accompanied by the release of fine-grained magnetic particles, enhancing the magnetic susceptibility of soils and making measurements of magnetic susceptibility a fast and easy-to-use screening tool for detecting heavy metals in the environment. Enhanced magnetic susceptibility in soils can be linked to higher concentrations of heavy metals. It can therefore be used as a mapping tool to detect potential contaminants for more detailed chemical analysis. This study aims to understand the correlation between magnetic susceptibility and heavy metal concentrations and map their distribution to determine the extent of anthropogenic pollution in urban areas. We will present preliminary results from 50 sampling sites in Lake Charles, Louisiana, collecting 20 surface magnetic susceptibility measurements with a hand-held susceptibility probe at each site and samples for subsequent lab analysis from the topsoil and the subsurface. Magnetic properties will be characterized by several methods, including isothermal remanent acquisition curves, hysteresis properties and low-temperature magnetic behavior. Elemental concentrations will be determined by X-ray fluorescence. Statistical analysis together with GIS analysis and contour maps will be applied to reveal the influence of contaminants on the magnetic susceptibility. Based on the results of previous studies we expect a positive correlation between magnetic susceptibility and heavy metal concentrations in urban soils and anticipate the use of magnetic susceptibility screening in significantly larger parts of the city as a fast, low-cost and highly efficient approach to detect contaminated urban areas.