Gratz Lynne E, Eckley Chris S, Schwantes Story J, Mattson Erick
Colorado College, Environmental Studies Program, Colorado Springs, CO 80903, USA.
U.S. Environmental Protection Agency, Region 10, Seattle, WA 98101, USA.
Atmosphere (Basel). 2019;10(4):176. doi: 10.3390/atmos10040176.
We report on the continuous ambient measurements of total gaseous mercury (TGM) and several ancillary air quality parameters that were collected in Colorado Springs, CO. This urban area, which is located adjacent to the Front Range of the Rocky Mountains, is the second largest metropolitan area in Colorado and has a centrally located coal-fired power plant that installed mercury (Hg) emission controls the year prior to our study. There are few other Hg point sources within the city. Our results, which were obtained from a measurement site < 1 km from the power plant, show a distinct diel pattern in TGM, with peak concentrations occurring during the night (1.7 ± 0.3 ng m) and minimum concentrations mid-day (1.5 ± 0.2 ng m). The TGM concentrations were not correlated with wind originating from the direction of the plant or with sulfur dioxide (SO) mixing ratios, and they were not elevated when the atmospheric mixing height was above the effective stack height. These findings suggest that the current Hg emissions from the CFPP did not significantly influence local TGM, and they are consistent with the facility's relatively low reported annual emissions of 0.20 kg Hg per year. Instead, variability in the regional signal, diurnal meteorological conditions, and/or near-surface emission sources appears to more greatly influence TGM at this urban site.
我们报告了在科罗拉多州科罗拉多斯普林斯市进行的总气态汞（TGM）及若干辅助空气质量参数的连续环境测量结果。该市区位于落基山脉前缘附近，是科罗拉多州第二大大都市地区，且有一座位于市中心的燃煤发电厂，在我们开展研究的前一年安装了汞（Hg）排放控制装置。市内几乎没有其他汞排放点源。我们从距离发电厂不到1公里的测量点获得的结果显示，TGM呈现出明显的日变化模式，夜间浓度达到峰值（1.7±0.3纳克/立方米），中午浓度最低（1.5±0.2纳克/立方米）。TGM浓度与来自电厂方向的风或二氧化硫（SO）混合比均无相关性，并且当大气混合高度高于有效烟囱高度时，TGM浓度并未升高。这些发现表明，当前CFPP的汞排放对当地TGM没有显著影响，这与该设施报告的相对较低的年排放量（每年0.20千克汞）相一致。相反，区域信号的变化、昼夜气象条件和/或近地表排放源似乎对该城市地区的TGM影响更大。
