Paper No. 11
Presentation Time: 11:30 AM
A PRELIMINARY STUDY ON DUST COLLECTION METHODOLOGY IN NPU-V, ATLANTA, GEORGIA FOR THE PURPOSE OF ACURATELY ASSESSING TRACE METAL COMPOSITION IN THE URBAN ENVIROMENT
The aerosolization of particulate matter (PM), dependent upon debris dimensions and turbulence force, is an important factor to consider when conducting field research involving the collection of samples with a dust component. While it is widely accepted that PM2.2 (2.2 um in diameter) and finer are easily if not indefinitely suspended, PM100 and smaller are susceptible to aerosolization. PM50 is usually the maximum size for continued airborne transport once turbulence has ceased.
Review of literature involving dust component analysis from the urban environment reveals that collection methodology largely consists of sweeping a designated area. This study was conducted for the purpose of identifying potential sample loss due to the turbulence introduced by such methodology. To assess this, a vacuum system fitted with a series of filters designed to retain PM2.2 and larger, was constructed to compare sample composition with the widely used sweeping method. The methodologies were applied simultaneously and adjacent to one another at 40 locations within Neighborhood Planning Unit V (NPU-V), a southern region of Atlanta, GA. Sample compositions were estimated using energy-dispersive X-ray fluorescence (XRF), and the relationship between the two methodologies’ sample compositions was examined using linear regression and covariance analysis. Lead (Pb) in particular was used as an aerosolized PM loss proxy as findings indicate Pb is most concentrated in the smallest (<50um) size fraction of road dust samples and because the health implications of this trace metal in the smaller size fractions make knowledge of the element’s presence valuable to urban communities. Significant covariance exists between the two methodologies’ sample compositions, suggesting that our sweeping methods were roughly equivalent to our vacuuming methods. An alternative explanation is that material observed adhering to the interior of the vacuum tubes roughly approximates material lost during sweeping. Acid digestion and AA analyses are underway to improve the analytical precision and test for any finer-scale particulate losses. The study provided insight into future design improvements, which in conjunction with further analysis of samples’ size fraction components, may expose a viable relationship between methods' results.