Application of receptor modeling to atmospheric constituents at Potsdam and Stockton, New York

Over a period of two summers, PM_2.5 mass, its composition, total PAHs, and vapor phase mercury concentrations were determined at Potsdam and Stockton, NY. Daily PM_2.5 concentrations ranged from 0.47 to 53.7 μgm−3 at the Potsdam site, and from 0.82 to 47.23 μgm −3 at the Stockton site with large differences between the two sites. Potsdam consistently had lower average mass than Stockton. The average PM_2.5 mass concentration during summer, 2000 was 8.92 and 15.59 μgm −3 in Potsdam and Stockton, respectively while the average PM _2.5 mass concentration of summer 2001 was 10.97 and 15.60 μgm −3 at the Potsdam and Stockton sites, respectively. On average, sulfate was the most abundant species, ranging from 41% to 44% of the total mass at the Stockton and Potsdam sites, respectively. The percentage of black carbon showed a big difference between the two sites. The black carbon at the Potsdam site represented 4% of the total mass while at the Stockton, 2.8%. Nitrate comprised 2% of the mass at both sites while the average concentrations at the Stockton site were higher than that at the Potsdam site. Si, Al, Mg, Ca, and Fe are characteristic elements of soil. Their concentrations were higher at the Stockton than at the Potsdam site indicating that the Stockton site might be more influenced by soil dust than the Potsdam site. The total PAH concentration was in the range of 1.0–7.6 ngm−3 at the Potsdam site and 1.0–7.0 ngm−3 at the Stockton site. The total alkyl-PAHs concentrations were in the range of 0.1–8.1 ngm−3 at the Potsdam site and 0.1–13.9 ngm −3 at the Stockton site. The average daily total PAH concentration was 3.2 ngm−3 at the Potsdam site and 2.9 ngm −3 at the Stockton site. The average daily total alkyl-PAH concentrations were much higher at the Potsdam site than at Stockton (2.8 ngm−3 versus 1 ngm−3). The dominant PAH at both sites was phenanthrene, which comprised 43% and 52% of the total PAHs at Stockton and Potsdam, respectively. The mean vapor phase mercury concentration at the Potsdam site (2.43 ± 1.23 ngm−3, n = 93) was higher than that at the Stockton site (1.23 ± 1.00 ng−3, n = 61) in 2000. However, in 2001, the opposite was true (1.14 ± 0.80 ngm−3, n = 92 at Potsdam, 1.62 ± 1.47 ngm −3, n = 93 at Stockton).; A factor analysis method, PMF (Positive Matrix Factorization) utilizing error estimates of the data to provide optimum data point scaling , was applied to obtain information about possible sources of PM_2.5 composition, PAHs and vapor phase mercury. Seven and six factors were resolved from Potsdam and Stockton sites, respectively. Six sources are common between these two sites. They are secondary sulfate with a high concentration of S; nitrate source which is dominated by NO₃−; soil represented by Al, Si, Ca, Fe; wood smoke characterized by K; Cu smelter with high concentration of Cu; Zn smelter source mixed with Zn and Pb. At the Potsdam site, a nickel smelter source was also resolved. PSCF (Potential Source Contribution Function) was used to identify the potential source regions and preferred transport pathways for those possible air pollutant sources.