Sources of fine particulate sulfate in New York

Daily PM2.5 sulfate measurements are reported for July 2001 through June 2002 from three New York State sites that were a part of the New York Supersite Program. The sampling sites were located at Queens, Pinnacle State Park, and Whiteface Mountain. Quarterly mean sulfate concentrations at these sites were respectively; 5.05, 5.08, and 3.14 μg/m3 during July–September (QIII); 2.84, 2.26, and 1.40 μg/m3 during October–December (QIV); 2.71, 2.39, and 1.55 μg/m3 during January–March (QI); and 4.17, 4.52, and 2.15 μg/m3 during April–June (QII). Although the sites are separated by several hundred kilometers and surrounded by highly varied population densities, their sulfate concentrations have very similar patterns. These data show that sulfate concentrations over broad regions of the Northeast are correlated. Backward air trajectories were used to evaluate the regional sources of sulfate impacting these sites. The highest sulfate concentrations at all three sites were associated with air masses that pass through the Ohio River Valley and the area around the Great Lakes Basin. Moderately high concentrations at Pinnacle and Queens were also associated with air flow through the Mid-Atlantic states. In addition, we used air trajectories to estimate local versus transported components. On an annual basis, 44–55% of the sulfate at Queens and 60% at Whiteface and Pinnacle was transported.