INVESTIGATIONS OF HEAVY METAL POLLUTION IN STREET SEDIMENTS FROM AN URBAN COMMUNITY: A CASE STUDY FROM TERRE HAUTE, INDIANA

Urbanization combined with an increase in vehicle usage has led to elevated levels of pollution along roadways worldwide. Terre Haute, Indiana is an ideal location to explore road pollution because of its long history of coal-fired power plants, steel manufacturing, high-traffic volumes, and older homes containing lead-based paint that may contribute to roadway pollution. To better understand this problem, this study examines pollution contained within street sediments found along Wabash Ave., which is a busy roadway in Terre Haute.

Heavy metal concentrations for six bulk street sediment samples were determined by pXRF at DePauw University. All six samples showed elevated concentrations of Pb (37 - 109 ppm), Zn (233 - 424 ppm), As (6 - 16 ppm), and Cu (42 - 99 ppm). The highest concentrations were found in close proximity to automotive shops and in the western portion of the study area, which is closer to downtown Terre Haute. Stereomicroscope observations reveal a variety of particle types that include geogenic sediment, organic matter, iron-rich particles, glassy spheres, paint particles, plastic material, and other debris. Detailed scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) confirm the presence of technogenic Fe-rich spheres (~10 - 50µm), lead chromate (PbCrO₄) paint (~1-10µm), glass micro-beads (<10 to >100µm), and other minor heavy metal particles (e.g., Mn, W, and Ti).

Although heavy metal concentrations did not exceed EPA risk screening levels, all six samples contained concentrations that exceed natural values found within soils in the Wabash Valley. Due to the proximity of the samples collected to residential neighborhoods, these particles may pose a public health concern for nearby communities.