April 2010

Rock Magnetic Properties of Soils in Baton Rouge, Louisiana: Implications for Potential Anthropogenic Impact on the Environment

By Hannah Vedrines, University of Louisiana at Lafayette

Abstract Summary

Magnetic susceptibility is a property that is easily, rapidly, and inexpensively determined and provides a highly sensitive measurement of the compositional changes of mineral materials in soil. The objective of this study is to detect the presence of magnetic anthropogenic particles related to environmental pollution by measuring the magnetic signature of soil samples. Magnetic susceptibility is influenced both anthropogenically by industrial processes and naturally by lithological, and pedological heavy metal content. In this study I sampled 260 km2 (110 mi2) in Baton Rouge, Louisiana, in 2.6 km2 (1 mi2) subsets and covered a variety of environmental settings, from rural city outskirts to industrialized parts of the inner city. At each site a statistically significant number (20) of susceptibility measurements were obtained with a field probe and discrete surface and subsurface samples were taken for detailed laboratory studies. Contour maps and histograms of magnetic susceptibility values indicate a strong correlation between the magnetic susceptibility and the environmental setting, with the mode of the susceptibility shifting from 0.006x10-3SI in rural areas to 0.273x10-3SI in the urbanized/industrialized parts of the city. Susceptibility enhancements in the industrialized area of Baton Rouge are consistently detected in all susceptibility and saturation isothermal magnetization (SIRM) maps. Field susceptibility measurements were statistically analyzed and appear to show a better correlation of magnetic susceptibility values to anthropogenic atmospheric settling than discrete measurements, which are only based on one sample per site. Enhanced susceptibility measurements do not appear to be dominated by lithology or soil in this particular area with the exception of the Udarent soils. IRM acquisition curves indicate the presence of both, high- and low coercivity minerals, probably magnetite with a small amount of a high-coercivity mineral, such as hematite or goethite.

Biographical Sketch

Hannah Lynn Vedrines was born to Christopher and Cheryl Vedrines in New Iberia, Louisiana, on September 16, 1986. She graduated from Catholic High School in New Iberia, Louisiana, in May of 2004. After high school graduation, Hannah attended the University of Louisiana at Lafayette where she studied Geology. In May 2008, she received a Bachelor of Science in Geology. In the Fall of 2008, Hannah began graduate school at the University of Louisiana at Lafayette. In June of 2009, she gave birth to her son, Jude, and continued her graduate education. While working towards a Master of Science degree, she worked part-time for a local oil and gas company and was a graduate assistant at the University of Louisiana at Lafayette. She received the first place Gordon I. Atwater award for best poster at the 2009 Gulf Coast Association of Geological Societies convention. Upon completion of her Master of Science degree, Hannah hopes to secure employment as an environmental or petroleum geologist in the Acadiana area of Louisiana.