PB IN URBAN ROAD DUST OF ATLANTA, GEORGIA: DISTRIBUTION AND GEOSTATISTICAL ANALYSES
Persistence of Pb in urban soils is an enduring health issue in cities worldwide. Despite concerted efforts of municipal, state, and federal governments to restrict emissions and remediate contaminated soils, thousands of cases of lead poisoning in children continue across the country. The study of concentrations and distribution of Pb(II) in urban and metropolitan areas can help to identify possible sources of of Pb(II) and potential remediation approaches.
This study is the first broad scale look at Pb and other heavy metals in heavily populated areas of Atlanta, Georgia, a metropolitan area of ~5.5 million people, sampled at spatially high resolution. One hundred and two road dust samples were taken from road surfaces in Atlanta Neighborhood Planning Units V and M, an area of about 4 km2. Samples were sieved at 250µm, digested by 4-acids, and analyzed for 33 elements by inductively coupled plasma atomic emission spectrometry. Supplementary data are available from spot analyses made by hand-held energy-dispersive X-ray fluorescence spectrometer. Preliminary results show high concentration in several areas, in some cases exceeding 1000 mg/kg Pb.
Geostatistical analyses were done to predict values at locations where we do not have samples. Prediction maps generated from these analyses show the lead concentrations and distribution for optimum interpolation or "kriging". Kriging uses the weighted average of the available data. In our function we do not assume that the weightings are a simple function of distance alone (as is the case of inverse-distance weighting); rather, we determine the weightings based on the data. This is done by using spatial stationarity, using a semivariogram function for quantification. The prediction of distribution of Pb(II) and the Kriging methods used aid in the estimation of unsafe Pb(II) concentrations and aid the decision makers of the greater Atlanta area in their ability to not only remediate the areas of high concentration but also help them to take a proactive stance in the prevention of lead further poisoning Atlanta’s citizens, especially children.