Abstract
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−3) and minimum concentrations mid-day (1.5 ± 0.2 ng m−3). The TGM concentrations were not correlated with wind originating from the direction of the plant or with sulfur dioxide (SO2) 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.
Highlights
Mercury is a neurotoxin that can severely impact cognitive abilities, in a developing nervous system or at high levels of exposure [1]
= GEM + GOM), carbon dioxide (CO2), SO2, carbon monoxide (CO), and meteorological parameters that were collected from June 15 to October 20, 2016 at a site approximately 0.9 km northwest of the Martin Drake power plant (Figure 1)
+ GOM), carbon dioxide (CO2 ), SO2, carbon monoxide (CO), and meteorological parameters that were collected from June 15 to October 20, 2016 at a site approximately 0.9 km northwest of the Martin
Summary
Mercury is a neurotoxin that can severely impact cognitive abilities, in a developing nervous system or at high levels of exposure [1]. Elevated levels of methylmercury, which is the organic and more toxic/bioaccumulative form of Hg, have been reported in numerous bird, fish, and mammal species [2], and the primary pathway for human exposure is through the consumption of contaminated fish [1]. Mercury is present in much lower concentrations in an oxidized form, either in the gas phase (gaseous oxidized Hg; GOM) or bound to particles (particle-bound Hg; PBM), which is readily removed by wet and dry deposition [2,3]. The spatial impacts of Hg emissions on ecosystems and human health range from local to global in scale
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