ANALYSIS OF SURFACE SOIL LEAD CONTAMINATION IN URBAN NEIGHBORHOODS OF DAVENPORT, IOWA

Davenport, IA, is a typical Midwestern city with a population of ~102,600 residents and is characterized by aging infrastructure and housing stock. Consequently, alarmingly high rates of child lead poisoning—as a result of deteriorating lead paint—constitute a major public health concern in some urban neighborhoods. Augustana College’s Upper Mississippi Center is an organization that helps urban and rural communities solve sustainability challenges by mobilizing the college’s resources. In conjunction with their Sustainable Working Landscapes Initiative (SWLI), a research team conducted free home lead screenings in vulnerable Davenport neighborhoods to better understand the severity of the problem. Via appointment, 27 homes were tested for lead in their paint, dust, soil, and water. Many of the highest-risk homes were found in low-income neighborhoods. The purpose of this study was to assess the extent of soil lead contamination and lead bioavailability in this urban setting. A total of 56 composite soil samples were collected: 26 Drip Zone (DZ), 18 Center of Yard (CY), and 12 Play Area (PA). These designations correspond to, respectively: soil within 1 m of the home’s foundation, soil elsewhere in the yard, and soil elsewhere in the yard but deemed a high-traffic area for children. Samples were taken from a depth of 1.5 cm, oven-dried, milled, and pressed into pellets for XRF analyses. The maximum concentrations of lead measured were 5190 ppm (DZ), 1335 ppm (CY), and 1091 ppm (PA). Minimum values measured were 24 ppm (DZ), 36 ppm (CY), and 176 ppm (PA). Average values included 1509 ppm (DZ), 373 ppm (CY), and 343 ppm (PA). A significant relationship between soil lead content and age of the home was found (R² = 0.57). Soil lead mobility and retention—and hence bioavailability—is determined by soil characteristics. Total P, Pb, and pH of the soil were measured and used to construct leaching experiments for 8 select composite samples, using the USGS Field Leach Test (FLT). Of these samples, an average of 4.1% Pb was leached from the soil into water. The ubiquitous contamination of this well-documented neurotoxin threatens the livelihood of Davenport residents and especially poses irreversible health issues for children under the age of 6.