CHARACTERIZATION OF TECHNOGENIC MAGNETIC PARTICLES (TMPS) WITHIN THE CONTEXT OF URBAN POLLUTION IN GARY, INDIANA

Technogenic magnetic particles (TMPs) are residual particles with magnetic properties originating from anthropogenic sources (e.g., fuel combustion, steel production) and are commonly deposited in soils and road sediments. TMPs are also often correlated with heavy metal pollution in urban and industrialized areas. The close association of TMPs in and near urban areas makes this topic one of environmental impact and concern. TMPs and metal-rich particles containing harmful metals less than or equal to 10 μm can be respirated or invade the deep lung and potentially enter the bloodstream. Physical and cognitive damage to both adults and children who are exposed may result. The objective of this study is to characterize the nature and elemental chemistry of TMPs separated from selected road sediment samples collected from Gary, Indiana by utilizing scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The variability in size, chemical composition, shape, and textural appearances of TMPs amongst different samples is poorly constrained in road sediment and placing new constraints on these properties will aid in sourcing materials and assessment of potential health implications.

A preliminary SEM-EDS analysis of sample material showed a variety of metal-rich particles. These particles varied in diameter from approximately 100 μm to 10 μm. Textural appearances of these particles indicate derivation consistent with steel manufacturing. Major elements identified in each particle include Fe, Si, Al, and Mn while minor elements include Ti, Cr, V, and K. SEM work provides constraints for the first application of electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to these materials.

Although initial SEM work shows complexity in TMPs, future work will aim to integrate the textural, mineralogical, and elemental characteristics of TMPs in order to trace their source(s) and assess potential health risks. The initial observations from initial microscopy efforts raise concerns about the presence and extent of heavy metal pollution in the Gary, Indiana area, and further investigation is warranted.