USING MAGNETISM TO ASSESS COMBUSTION PARTICLES IN THE TOPSOIL OF THE AKRON, OHIO REGION

Anthropogenic combustion activities, including vehicle traffic, produce ultrafine particles that can reduce air quality and pose health concerns to people inhaling these particles. Combustion particles have magnetic and morphologic characteristics that are readily distinguishable from naturally formed soil particles. This study measured the magnetic properties of urban, sub-urban and rural topsoil in the Akron, Ohio area in order to examine the role of road density and population on the amount of combustion products present in the environment. All topsoil samples were obtained from well-drained, level areas at least 12m away from the nearest road in an attempt to minimize local soil differences and obtain each site’s atmospheric fallout signature. As the distance from the city center of Akron increases, the concentration of the magnetic material in the topsoil decreases. In addition, the type of magnetic particles present in the soil is different for the urban samples compared to the sub-urban and rural samples. Urban topsoil has large amounts of magnetically coarse-grained particles. Remanence-bearing particles were extracted from the soil with a rare-earth magnet, examined using a scanning electron microscope, and found to contain spherules characteristic of combustion processes. Sub-urban and rural topsoil contains low amounts of magnetically fine-grained particles including superparamagnetic sizes. These magnetic characteristics are indicative of natural soil forming processes. The elevated magnetic concentration and combustion products in the urban setting correspond to increased population and road density. As population and road density decrease in the sub-urban and rural settings, the magnetic combustion products in the topsoil also decrease. Studies by others have shown that the amount of combustion products is often directly correlated to heavy metal content in soils. My study shows that mapping the magnetic properties of topsoil is an efficient way to determine the spatial distribution of combustion products in an area and thus better understand regional pollution related issues.