AN INVESTIGATION OF MINERALOGY AND METAL POLLUTION FROM PARKING LOT SEDIMENT AT MIAMI UNIVERSITY HAMILTON: IMPLICATIONS FOR STORMWATER MANAGEMENT

The city of Hamilton, Ohio has a legacy of manufacturing and is representative of several mid-size postindustrial cities in the Midwest. Urban pollution in such settings is complex and discerning vehicular components from other components can be challenging. Parking lots are urban environments which can provide insight into details of sources of urban pollution because of their area and use. Sediment from parking lots at the Miami University Hamilton Campus were taken from three sites surrounding the campus, only one of which has storm water mitigation basins. The parking lots are on a gentle slope and samples were collected at the base of the slope. Common minerals found in all of the parking lot sediment samples include plagioclase feldspar, iron oxides, quartz, and dolomite. Coal spherules are also present in the samples as are small clusters of iron sulfide crystals. Coal spherules show a range of preservation from nearly glassy smooth surfaces to rough corroded surfaces. Iron sulfide particles exhibit some dissolution textures. Scanning electron microscopy (SEM) revealed several particles of iron-chromium steel and these particles had the dimensions of approximately 100 micrometers, and appear to have a fractured surface. SEM also showed zinc particles are common and are approximately 100 to 200 micrometers in dimension. Zinc particles commonly are oval in shape, and have a fine texture, with apparent corrosion present. The storm water basins in the one parking lot are aggregate beds of rocks, which appear to trap sediment as water flows into them. Limited bulk chemical data indicate average concentrations for elements of concern are Cr = 38 ppm, Cu = 52 ppm, Pb = 24 ppm, Zn = 489 ppm. Elemental ratios of Cu and Zn in parking lot sediment suggest a link between the former coal plant in the northern part of the city. Parking lot investigations may prove valuable for pollution source identification and may prove viability of stormwater mitigation basin approaches.