A PRELIMINARY URBAN GEOCHEMICAL EXPLORATION OF STREET SEDIMENTS OF GARY, INDIANA INDICATES MAJOR CONCERNS ARE WARRANTED

Gary, Indiana is one of the most heavily industrialized and distressed cities in the rust belt (Forbes, 2013). A significant, but yet uninvestigated, component of pollution in Gary is street sediment. This environmental media is important due to primary and secondary exposure to the population including airborne reworking, tracking into homes and workplaces, redistribution into freshwater ecosystems and introduction into soil environments such a yards and playgrounds. Street sediment may pose a direct risk to human health. Concentrations and forms (e.g., oxides, glassy spherules) of pollutants in street sediment in Gary are unknown and potential exists for high metal contamination. An initial set of 27 unknowns were collected along Broadway, 11th Avenue and Central Avenue. Preliminary inductively coupled plasma – optical emission spectroscopy (ICP-OES) and scanning electron microscopy (SEM) investigations were conducted to assess the nature and distribution of metal pollutants in street sediments. Concentrations of some metals (e.g., Zn, V, Pb) in a number of sediment samples were too high to produce reliable numbers during the initial analysis, and are being reanalyzed. ICP-OES results show elevated (>1,500 mg/kg) concentrations of manganese present in all samples, and there is a spatial trend of decreasing concentration from the main steel manufacturing site to 3.8 km toward the south in the study area. SEM-EDS measurements revealed that Mn is present in numerous technogenic spherule particles; Mn is a metal known to have to connections to brain and neurological disease (e.g., Dobson et al. 2004; Pal et al. 1997). Other metals that are well recognized as having either neurological (e.g., Zn, Pb) or carcinogenic (e.g., Cr, Ni) properties are also common in technogenic particles at concentrations of several weight percent, both as spherules and in discrete phases. The preliminary results of this urban geochemistry study thus demonstrates that there is great need for a detailed systematic investigation of spatial trends of metal concentrations, the form and source of metals, and the particle size distribution of metals. Human health likely is impacted by the pollutants observed and this study opens new questions regarding public health and steel manufacturing activities in Gary, Indiana.