Outdoor air pollution in China is an emerging issue that has been linked to a high number of premature deaths in the past decade. Shanghai is a mega city with an area of 6340 km2 and a population of more than 24 million. Considering its rapid population growth, motorization, urbanization, and industrial activities, Shanghai is under serious stress from airborne contaminants, including airborne particulate matter (PM). The objective of this work was to characterize potentially aerosolized road dusts from Shanghai. To achieve this objective, road dust samples were taken from 66 sampling sites throughout Shanghai. Dust samples were characterized by ICP-MS and by scanning and transmission electron microscopy coupled with energy-dispersive X-ray spectrometry and selected area electron diffraction. GIS spatial analysis was performed to yield a geographical distribution of heavy metal contaminants in road dusts. Dust samples were aerosolized in the laboratory to identify the PM2.5 and ultrafine (or nanoscale) components of dust that may be resuspended by wind or city activities. Results show that the PM2.5 component of dusts contained a &gt;5 times higher concentration of certain metals (V, Cr, Ni, Cu, As, Mo, Ag, and Sn) than bulk samples, which indicates that they were more likely to be present in particles smaller than 2.5 μm. Lead was found in elevated concentrations in many samples (42 – 9626 mg kg-1), particularly in a sampling site located near an e-waste facility, in the form of PbS and PbSO4 particles, often associated with SnSO4. GIS maps also show high concentrations of Cu, Co, and Ni present in the region where Pb was found. The aerosolization of the street dust in the laboratory resulted in aerosol emission factors ranging from 3.3×106 to 4.7×107 particles per mg of dust, with an average of (1.9±0.4)×107 PM2.5 particles per mg of dust. We estimate an average of 3.2 ± 0.7 μg per mg of dust to become resuspended in the form of PM2.5 in the city of Shanghai. Street dust may act as a sink for various NPs from many different origins. This information can be used to inform air quality models and policy makers interested in the contribution of road dust in to environmental pollution in large cities.

Identification of potentially aerosolized nanoparticles in road dust from Shanghai

251st National Meeting (2016)

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