Characterization of the Plumes Passing over Lower Manhattan after the World Trade Center Disaster

摘要

During the three-month period from October 1, 2001 to December 15, 2001 impactor measurements were carried out on the roof of the Environmental Measurements Laboratory (EML), approximately 45 m above the street level in New York City, to characterize plumes passing over the laboratory. Depending on the wind direction it was hoped to intercept aerosols originating from the disaster of the World Trade Center. More than 25 plumes were detected in our samples. With southwest winds on October 3, an aerosol plume, transported from the WTC, was observed over EML. The total particulates collected on all stages reached a peak mass concentration of 267 μg/m~3 at 08:15 with more than 39% of the mass in the 0.56 to 0.34 μm stage. The October 3rd sample showed that almost 75% of the total mass at the peak seen at EML was below 1.15 μm. The observed size distribution was bimodal and showed a strong temporal variation as the modes shifted from a dominant coarse to a fine mode. The detected plume lasted for more than 9 hours. It is this fine particulate mode that is of concern to human health exposure.