| Ambient vapor phase mercury concentrations including elemental mercury (Hg0) and reactive gaseous mercury (RGM; Hg2+) were measured at the Potsdam, Stockton, and Sterling sites in NY. The contribution of RGM (4.2 ± 6.4, 5.7 ± 9.2, 6.0 ± 10.8 pg m −3 at the Potsdam, Stockton, and Sterling sites, respectively) was about 0.2∼3% of the total vapor phase mercury concentration measured (TVM: 1.84 ± 1.24, 1.83 ± 1.32, 3.02 ± 2.14 ng m−3, respectively) at the three receptor sites. The relationship between ozone and mercury concentrations was not distinct. However, there was a significant positive correlation between water vapor mixing ratio and elemental mercury concentrations, indicating that reduction of Hg 2+ to Hg0 occurred in liquid water contained in clouds and fogs. Total vapor phase mercury (TVM) concentrations had a generally negative correlation with temperature, whereas RGM concentrations had a positive relationship. However, these temporal variations of mercury were not statistically significant.; Hybrid receptor modeling incorporating backward trajectories including potential source contribution function (PSCF), residence time weighted concentration (RTWC), and simplified quantitative transport bias analysis (SQTBA) was performed to identify source areas of TVM. Using PSCF, southern New York, North Carolina, and eastern Massachusetts were identified as important source areas in the United States, while the copper smelters and waste incinerators located in eastern Quebec and Ontario were determined to be significant sources in Canada. RTWC indicated that metal industrial facilities in eastern Quebec, coal-fired power plants in western PA, southwestern NY, and Wisconsin and waste incinerators located in eastern Indiana, Michigan, and Ohio were significant sources. Southeastern NY, Massachusetts, and western Pennsylvania were identified to be significant by SQTBA. The Atlantic Ocean was suggested to be a possible mercury source by all three receptor models.; PSCF incorporating back-dispersion and deposition was applied for RGM, as well as PSCF based on back-trajectories. Two different approaches yielded considerably different results, primarily due to the consideration of dispersion rather than deposition. Identified source are coal-fired power plants located in western Pennsylvania and southwestern NY, and mining facilities around Lake Superior for RGM. |
