An investigation of road sediment in Gary, Indiana revealed high levels of various trace metals such as Zn, Mn, and Cr, often exceeding those of background reference concentrations as shown through geoaccumulation indices and contamination factors. The hazard index (HI) value for Mn in children was >1 (1.7), suggesting possible long-term non-carcinogenic health risk. Mn HI for children is even higher for the five samples closest to a US Steel facility, with an HI of 2.8. Through SEM-EDS analysis, the prevalence of small particulates (PM2.5 and PM2.5-10) containing potentially harmful elements such as Mn and Pb illustrate a health risk through direct inhalation or ingestion. The small nature of particulates in general may also pose an increased health risk for respiratory diseases such as asthma. Mn concentrations in the road sediment were particularly high, with 30 out of 32 samples exceeding 1800 ppm. Mn and V concentrations show a strong spatial trend of decreasing concentration away from a US Steel facility. These spatial trends along with correlation plots of the bulk chemistry suggest that industrial steel manufacturing, particularly US Steel in Gary, is a major contributing source of Mn and V. Fe and Cr show a moderate decrease in concentrations away from the US Steel facility, which suggests some sourcing from the steel facility when coupled with bulk chemistry plots. Zn and Cu do not show much evidence of sourcing from the US Steel facility, likely due to increased mixing from other sources. Further work constraining anthropogenic sources, the bioaccessible fraction of metals, and analysis of direct atmospheric particulates can help with remedial activity and risk assessment.
Keywords: Environmental justice; Heavy metals; Particulate matter; Road sediment; Steel pollution.
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