Regional sources of particulate sulfate, SO2, PM2.5, HCl, and HNO3, in New York, NY

Simultaneous measurements of gaseous HONO, HNO3, HCl, SO2, and NH3 from July 1999 to June 2000 and fine-fraction particulate (<2.5 μm) sulfate and PM2.5 mass from January 1999 to November 2000 were made at Bronx and Manhattan in New York City. Air trajectories were used to study the impact of upwind emissions on the observed concentrations in New York City. Episodes of high concentrations of the chemical species were observed at both Bronx and Manhattan throughout the year, although, they were more prominent during summer. The highest concentrations were invariably associated with the air flow from southwest to west of New York City. Three-hour HYSPLIT4 air trajectories were used to apportion the daily measured concentrations as a function of direction. On an annual basis 43% of sulfate, 14% of the sulfur dioxide, 30% of the PM2.5 mass, 27% of HCl, and 24% of HNO3 were attributed to upwind emissions, with the remaining amounts due to emissions in the metropolitan New York.