LEAD (PB) IN URBAN SOIL

Lead (Pb), a versatile metal, is commonly found in urban soils because of its wide range of industrial uses and its resistance to degradation. Pb has been used over the past few centuries, primarily in gasoline and paint in the 20th century, and can have long-lasting negative health effects following exposure, particularly for children. This caused the USEPA to set a standard of 400 parts per million for bare soils to limit human exposure. The risk of Pb exposure is based on its speciation (chemical form) in soils. This project aims to identify the speciation and total concentration of Pb in soils as a function of distance from a home and roadways to determine the relative contribution of paint- versus gasoline-derived Pb at a given home property, and as a function of depth in the soil. Soils were collected from three homes in Northeast, Ohio which were known to have been painted with Pb paint. Soil samples were collected from lateral transects at 1 m increments from the front of each house toward the street and from the back of the house, and from a soil core collected in 10 cm increments near the front foundation of each house. The soils will be analyzed by the following suite of methods: (1) X-ray fluorescence to determine the bulk concentration of Pb and other trace metals; (2) Scanning Electron Microscopy with Electron Dispersive Spectroscopy to identify the physical speciation of Pb-bearing phases; and (3) X-ray Diffraction to determine the bulk mineralogy of the soils . Preliminary XRF results show a concentration gradient at the front of a home; with high concentration near the home and a decrease in concentration near the road, and with high concentration near the surface and a decrease as depth increases. Results from this study will aid in refining potential reclamation needs across the wider urban area.