Lead Distribution Is Correlated with Urbanization in the Chicagoland Area.

High lead concentrations in soil are a major concern for children living in urban areas. As populations rise, more people are living in urbanized environments. Understanding the spatial distribution of soil lead is extremely important to keep the public safe. The city of Chicago is one such city where urbanization has reached as far as seven counties forming what is known as Chicagoland. Soil samples were taken from 189 randomly located sites, stratified by land use across the Chicagoland area to study the distribution of soil lead. Statistical analysis was used to examine soil lead concentrations and urban factors including: land use, distance to a road, distance to a highway, distance to a building, distance from the urban center (Navy Pier). We found significant correlations between soil lead concentrations and urban factors. There was a negative log relationship between concentrations of lead and the sample distance from the urban center. Our analyses showed that industrial, commercial, and other highly urban land uses had the highest concentrations of lead while more natural areas like forests and parks, had the lowest concentrations. Industrial areas, roads, and highways have been known to have high levels of soil lead contamination due to use of leaded gasoline and paint. Areas near old buildings have been known to have high soil lead concentrations from lead-based paints. Lead is relatively immobile in soil, so the initial contamination may have occurred many years ago. This information will improve our land use planning and help us identify potential hot spots of soil lead contamination.