Browsing Natural Sciences and Mathematics by Subject "lead"
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USING THE SPATIAL VARIABILITY OF LEAD IN URBAN SOILS AND DEMOGRAPHIC VARIABLES TO PREDICT EXPOSURE RISKS: AN ENVIRONMENTAL JUSTICE ANALYSIS IN TERRE HAUTE, INDIANATerre Haute, Indiana, is similar to many older cities throughout the United States with a history of manufacturing and industry that relied on extensive road and rail networks. This industrial history has resulted in the presence of over 20 brownfields and even a Superfund Site within the city today. Historic neighborhoods and abundance of pre-1950’s homes is another characteristic of the city. Unfortunately, improper removal and deterioration of lead (Pb) paints, as well as high Pb solder used in gutters, appear to be significant sources of soil Pb in Terre Haute. Despite the fact that most new environmental sources of Pb pollution have been eradicated, many areas of the city still have elevated soil Pb concentrations and the city continues to have children with elevated blood Pb levels. With the Center for Disease Control’s recent reduction in screening levels for blood Pb from 10 μg/dL to 5 μg/dL, the occurrence of children with childhood Pb poisoning could be greater than previously recognized. The goal of this study was to better understand the modern-day spatial distribution of Pb in surface soils across the city of Terre Haute. To achieve this goal, surface soil samples were collected across the city. New data were collected from city-owned properties (i.e. parks, cemeteries, and abandoned lots), Indiana State University land holdings within the city, residential properties, and community gardens. Data collected from residential areas included samples near the road, from beneath the gutter dripline of the house, in the backyard, in the garden, and other areas of importance to the homeowner. Samples were analyzed via handheld X-ray fluorescence (XRF) analyzer on site to provide homeowner with immediate feedback with the ultimate goal of increasing the use of safer urban gardening practices. Samples were then dried and crushed to re-analyze with the portable XRF, and samples with values >200 ppm Pb were processed and analyzed with the ICP-OES to verify the results. Results produced a wide range of Pb concentrations, from <5 ppm to >30,000 ppm for the residential areas. The spatial distribution of Pb was determined using a simple ordinary kriging method and Empirical Bayesian Kriging method by analyzing the total sample set, samples collected near the road, samples from yards and gardens, and under the gutter driplines of homes were also kriged. Samples collected near the gutter dripline had the highest Pb concentrations, while overall spatial trends depict higher Pb concentrations in the historic portion of the city, with concentrations decreasing with distance from the older part of the city. The predicted Pb concentrations generated from the total sample set was then compared to demographic, environmental, and infrastructure characteristics for Terre Haute. OLS regressions using both maximum and average Pb concentrations indicate a statistically significant (p=0.000) positive correlation between high Pb concentrations and percentage of vacant homes. Maximum and average Pb concentrations were then linked to individual U.S. Census block groups with associated demographic attributes. Bivariate local indicator of spatial association (Bi-LISA) analysis indicates populations of low socio-economic status are regularly being exposed to higher Pb concentrations in their neighborhoods, while populations with higher socio-economic status are exposed to lower Pb concentrations. The higher Pb concentrations and populations with lower socio-economic status both occur in the central portion of the city where historic development occurred representing environmental injustice.