Magnetic Susceptibility and XRF Analysis of Soils from Baton Rouge, Louisiana: Correlation and Implications for Heavy Metal Pollution

Magnetic properties such as magnetic susceptibility (MS) and saturation isothermal remanent magnetization (SIRM) have been used in numerous studies to detect and monitor anthropogenic pollution because of its high sensitivity, easy obtainability, and cost efficiency. Recently, the combination with XRF analyses has been used to identify and quantify heavy element concentrations. Results will be presented from a study that has been conducted over the past nine years, focused in and around Baton Rouge, Louisiana covering an area approximately 260 km2. Samples have been collected at 327 sites, including 6,540 magnetic susceptibility measurements in the field taken with a hand-held susceptibility probe, as well as 654 samples taken from the topsoil and the subsurface for lab analysis of SIRM, magnetic susceptibility, and XRF analysis. We selected Baton Rouge because of the presence of rural, industrial, metropolitan, and suburban sites in close proximity, allowing for the comparison of both magnetic properties and element concentrations in these settings, without the influence of other factors, such as climate, soil type, or bedrock. In addition to the magnetic properties, we measured the Mo, Zr, Sr, Ba, U, Rb, Th, Pb, Au, Se, As, Hg, Zn, W, Cu, Cr, Ni, Co, Fe, and Mn concentrations with an XRF scanner. The results revealed that the peak magnetic susceptibility was generally detected in the western part of the map area, near the industrial area. The magnetic susceptibility decreased as the distance increased from the industrial area, indicating that the source is anthropogenic. The geochemical analysis showed that magnetic susceptibility and the elemental concentrations of barium, nickel, lead, thorium, and zinc are statically significant. For future studies, a larger map area would be beneficial, especially extending westward, across the Mississippi River. This would allow for further comparison of the magnetic susceptibility distribution and the wind patterns in Baton Rouge