A MULTI-ANALYTICAL APPROACH TO IDENTIFYING POTENTIAL POLLUTANTS IN STREET SEDIMENT USING GEOACCUMULATION, GIS, ELECTRON MICROSCOPY, AND XRF

Road sediment is an important environmental media that can be used to monitor a variety of pollutants in a community. One contaminant type of high concern is heavy metals which may have multiple sources and may persist in the environment. Road sediment can be a sink but also a source for redistribution of heavy metals and thus understanding patterns of these pollutants in road sediment may provide constraints on community environmental issues and constrain actions and concerns. Ten road sediment samples were collected from Boulder City, Nevada; a suburban area southeast of Las Vegas with an arid to semi-arid climate. Few studies on road sediment have been complete in this climate therefore multiple analytical approaches were taken. Road sediment is a publicly available and accessible medium which harbors geological, biological, and anthropogenic material. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and X-ray fluorescence (XRF) were used to analyze the samples. Data was then used to create IDW (inverse distanced weighted) maps highlighting areas of concern with concentrations of potentially high heavy metals. Geoaccumulation indices were calculated and IDW maps were created to compare to the maps using the raw XRF data. Electron microscopy data places constraints on the form of metals observed in the maps. Bulk XRF data repeatedly shows appreciable concentrations of Cr, Zn, and Mn which are interpreted to be sourced from industry and vehicular activity. This study provides a foundation for future research in metal distribution in road sediment in the southwestern US.