SOIL AND ATMOSPHERIC CHEMISTRY IN URBAN ATLANTA: FINDINGS FROM THE CSAW (COMMUNITY, SOIL, AIR, AND WATER) NSF RESEARCH EXPERIENCES FOR UNDERGRADUATES SITE

During summer 2012 Georgia State University hosted an NSF REU site in urban Atlanta. One of the three teams focused on Neighborhood Planning Unit-V (NPU-V) of southeastern Atlanta. The team partnered with a local grassroots environmental group to learn about residents' concerns and guide the research. NPU-V consists of six neighborhoods south of downtown, bisected by the I-75/I-85 connector and bordered to the north by I-20. These highways built in the 1950’s both divided the community and established long-term sources for both lead (Pb) and nitrogen dioxide (NO₂).

Urban soils surrounding highways are well known reservoirs of Pb from historic emissions from leaded gasoline. The first part of this study characterized Pb concentrations in 300 soil and road dust samples, and then examined whether the concentrations, composition, and spatial distribution of this Pb were related to negative health effects in NPU-V. Dust samples were sieved and the < 250 µm fraction was retested. Lead was detected at levels ranging from 11 mg/kg to 969 mg/kg, with a median of 64 mg/kg. The samples containing the highest lead content were then analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD and SEM results were inconclusive, but XRF data showed that soil and dust samples were not correlated, suggesting different sources for the different sample types.

The second part of this study measured NO₂ levels across NPU-V as an indicator of air pollution to test whether NO₂ levels vary spatially and examine how NO₂ contributes to the air quality and health of the community. Twenty-six samples were collected across NPU-V using passive OGAWA NO₂ badges mounted to telephone poles. The average NO₂ concentration for each sample was determined by nitrite extraction and UV-vis absorbance spectroscopy. Concentrations ranged from 7 ppb to 21 ppb. Geospatial analysis showed a direct relationship between proximity to the highway and higher NO₂levels.

This preliminary assessment of Pb and NO₂ levels in NPU-V demonstrates how geochemical studies can be used to support local grassroots environmental efforts to identify and characterized real or perceived environmental hazards. Local stakeholders and decision makers need quantitative geochemical data to understand hazards in their communities and design appropriate responses.