{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,4]],"date-time":"2026-03-04T03:07:20Z","timestamp":1772593640905,"version":"3.50.1"},"reference-count":54,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2019,4,3]],"date-time":"2019-04-03T00:00:00Z","timestamp":1554249600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Atmosphere"],"abstract":"<jats:p>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 &lt; 1 km from the power plant, show a distinct diel pattern in TGM, with peak concentrations occurring during the night (1.7 \u00b1 0.3 ng m\u22123) and minimum concentrations mid-day (1.5 \u00b1 0.2 ng m\u22123). 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\u2019s 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.<\/jats:p>","DOI":"10.3390\/atmos10040176","type":"journal-article","created":{"date-parts":[[2019,4,4]],"date-time":"2019-04-04T03:13:42Z","timestamp":1554347622000},"page":"176","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Ambient Mercury Observations near a Coal-Fired Power Plant in a Western U.S. Urban Area"],"prefix":"10.3390","volume":"10","author":[{"given":"Lynne E.","family":"Gratz","sequence":"first","affiliation":[{"name":"Colorado College, Environmental Studies Program, Colorado Springs, CO 80903, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6986-4451","authenticated-orcid":false,"given":"Chris S.","family":"Eckley","sequence":"additional","affiliation":[{"name":"U.S. Environmental Protection Agency, Region 10, Seattle, WA 98101, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Story J.","family":"Schwantes","sequence":"additional","affiliation":[{"name":"Colorado College, Environmental Studies Program, Colorado Springs, CO 80903, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Erick","family":"Mattson","sequence":"additional","affiliation":[{"name":"Colorado Department of Public Health and Environment, Air Pollution Control Division, Glendale, CO 80246, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,4,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1579\/0044-7447(2007)36[3:MEAHEI]2.0.CO;2","article-title":"Methylmercury exposure and health effects in humans: A worldwide concern","volume":"36","author":"Mergler","year":"2007","journal-title":"Ambio"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4967","DOI":"10.1021\/es305071v","article-title":"Mercury as a Global Pollutant: Sources, Pathways, and Effects","volume":"47","author":"Driscoll","year":"2013","journal-title":"Environ. Sci. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1146\/annurev.environ.051308.084314","article-title":"Global Biogeochemical Cycling of Mercury: A Review","volume":"34","author":"Selin","year":"2009","journal-title":"Ann. Rev. Environ. Resour."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2983","DOI":"10.1021\/es802474j","article-title":"Projections of Global Mercury in 2050","volume":"43","author":"Streets","year":"2009","journal-title":"Environ. Sci. Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"5951","DOI":"10.5194\/acp-10-5951-2010","article-title":"Global mercury emissions to the atmosphere from anthropogenic and natural sources","volume":"10","author":"Pirrone","year":"2010","journal-title":"Atmos. Chem. Phys."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Mason, R., and Pirron, N. (2009). Mercury emissions from natural processes and their importance in the global mercury cycle. Mercury Fate and Transport in the Global Atmosphere, Springer.","DOI":"10.1007\/978-0-387-93958-2"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"373","DOI":"10.1016\/j.scitotenv.2009.10.006","article-title":"Ambient air total gaseous mercury concentrations in the vicinity of coal-fired power plants in Alberta, Canada","volume":"408","author":"Mazur","year":"2009","journal-title":"Sci. Total Environ."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"4946","DOI":"10.1021\/es803214h","article-title":"Spatial Variability of Mercury Wet Deposition in Eastern Ohio: Summertime Meteorological Case Study Analysis of Local Source Influences","volume":"43","author":"White","year":"2009","journal-title":"Environ. Sci. Technol."},{"key":"ref_9","first-page":"10339","article-title":"Impact of Closing Canada\u2019s Largest Point-Source of Mercury Emissions on Local Atmospheric Mercury Concentrations","volume":"47","author":"Eckley","year":"2013","journal-title":"Environ. Sci. Technol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1007\/s13280-017-1004-9","article-title":"A review of global environmental mercury processes in response to human and natural perturbations: Changes of emissions, climate, and land use","volume":"47","author":"Obrist","year":"2018","journal-title":"Ambio"},{"key":"ref_11","unstructured":"U.S. Environmental Protection Agency (2018, October 08). Mercury Study Report to Congress, Volume II: An Inventory of Anthropogenic Mercury Emissions in the United States, Available online: https:\/\/19january2017snapshot.epa.gov\/sites\/production\/files\/2015-09\/documents\/volume2.pdf."},{"key":"ref_12","unstructured":"U.S. Environmental Protection Agency (2018, October 08). 2015 TRI National Analysis, Mercury Air Releases Trend, Available online: https:\/\/19january2017snapshot.epa.gov\/trinationalanalysis\/mercury-air-releases-trend-2015-tri-national-analysis_.html."},{"key":"ref_13","unstructured":"U.S. Environmental Protection Agency (2018, October 08). Federal Register Vol. 77, No. 32, Rules and Regulations. National Emission Standards for Hazardous Air Pollutants from Coal- and Oil-Fired Electric Utility Steam Generating Units and Standards of Performance for Fossil-Fuel-Fired Electric Utility, Industrial-Commercial-Institutional, and Small Industrial-Commercial-Institutional Steam Generating Units, Available online: https:\/\/www3.epa.gov\/airtoxics\/utility\/fr16fe12.pdf."},{"key":"ref_14","unstructured":"U.S. Census Bureau, Population Division (2019, March 19). 2017 population estimates for cities and towns, Available online: https:\/\/www.census.gov\/data\/tables\/2017\/demo\/popest\/total-cities-and-towns.html#tables."},{"key":"ref_15","unstructured":"U.S. Environmental Protection Agency (2016, September 23). 2014 National Emissions Inventory version 2 Technical Support Document. Office of Air Quality Planning and Standards, Available online: https:\/\/www.epa.gov\/air-emissions-inventories\/2014-national-emissions-inventory-nei-data."},{"key":"ref_16","unstructured":"(2018, October 08). Colorado Springs Utilities, Martin Drake Power Plant Decommissioning. Available online: https:\/\/www.csu.org\/Pages\/martin-drake-r.aspx."},{"key":"ref_17","unstructured":"U.S. Environmental Protection Agency (2019, February 01). 2011 National Emissions Inventory Technical Support Document. Office of Air Quality Planning and Standards, Available online: https:\/\/www.epa.gov\/air-emissions-inventories\/2011-national-emissions-inventory-nei-data."},{"key":"ref_18","unstructured":"U.S. Environmental Protection Agency (2019, February 01). 2008 National Emissions Inventory Technical Support Document. Office of Air Quality Planning and Standards, Available online: https:\/\/www.epa.gov\/air-emissions-inventories\/2008-national-emissions-inventory-nei-data."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"10389","DOI":"10.1021\/acs.est.5b01755","article-title":"Mercury Emission Ratios from Coal-Fired Power Plants in the Southeastern United States during NOMADSS","volume":"49","author":"Ambrose","year":"2015","journal-title":"Environ. Sci. Technol."},{"key":"ref_20","unstructured":"U.S. Environmental Protection Agency (2019, March 14). Air Markets Program Data (AMPD), Available online: http:\/\/ampd.epa.gov\/ampd\/."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"635","DOI":"10.3390\/atmos5030635","article-title":"A Survey of Mercury in Air and Precipitation across Canada: Patterns and Trends","volume":"5","author":"Cole","year":"2014","journal-title":"Atmosphere"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Godish, T. (2004). Air Quality, CRC Press. [4th ed.].","DOI":"10.1201\/b13168"},{"key":"ref_23","unstructured":"Lindsey, R. (2018, October 08). Climate Change: Atmospheric Carbon Dioxide. National Oceanographic and Atmospheric Administration, News & Features. Available online: https:\/\/www.climate.gov\/news-features\/understanding-climate\/climate-change-atmospheric-carbon-dioxide."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"4464","DOI":"10.1029\/2002JD003031","article-title":"Reanalysis of tropospheric CO trends: Effects of the 1997-1998 wildfires","volume":"108","author":"Novelli","year":"2003","journal-title":"J. Geophys. Res."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1016\/j.atmosenv.2014.05.076","article-title":"Causes of increasing ozone and decreasing carbon monoxide in springtime at the Mt. Bachelor Observatory from 2004 to 2013","volume":"109","author":"Gratz","year":"2015","journal-title":"Atmos. Environ."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"8711","DOI":"10.1016\/j.atmosenv.2007.07.028","article-title":"McHenry tunnel study: Source profiles and mercury emissions from diesel and gasoline powered vehicles","volume":"41","author":"Landis","year":"2007","journal-title":"Atmos. Environ."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"7547","DOI":"10.1016\/j.atmosenv.2007.05.043","article-title":"Mercury emissions from automobiles using gasoline, diesel, and LPG","volume":"41","author":"Won","year":"2007","journal-title":"Atmos. Environ."},{"key":"ref_28","first-page":"295","article-title":"An overview of the HYSPLIT_4 modeling system for trajectories, dispersion and deposition","volume":"47","author":"Draxler","year":"1998","journal-title":"Aust. Meteorol. Mag."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1003","DOI":"10.1016\/S1352-2310(02)00917-2","article-title":"Temporal and spatial variability of total gaseous mercury in Canada: Results from the Canadian Atmospheric Mercury Measurement Network (CAMNet)","volume":"37","author":"Kellerhals","year":"2003","journal-title":"Atmos. Environ."},{"key":"ref_30","first-page":"D14302","article-title":"Observations of speciated atmospheric mercury at three sites in Nevada: Evidence for a free tropospheric source of reactive gaseous mercury","volume":"114","author":"Gustin","year":"2009","journal-title":"J. Geophys. Res."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"499","DOI":"10.1016\/j.atmosenv.2011.09.056","article-title":"Diurnal and seasonal variation of mercury species at coastal-suburban, urban, and rural sites in the southeastern United States","volume":"47","author":"Nair","year":"2012","journal-title":"Atmos. Environ."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1016\/j.scitotenv.2012.08.076","article-title":"Atmospheric transport of speciated mercury across southern Lake Michigan: Influence from emission sources in the Chicago\/Gary urban area","volume":"448","author":"Gratz","year":"2013","journal-title":"Sci. Total Environ."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1029\/2003JD004159","article-title":"Temporal variation of total gaseous mercury in the air of Guiyang, China","volume":"109","author":"Feng","year":"2004","journal-title":"J. Geophys. Res.-Atmos."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"612","DOI":"10.1016\/j.chemosphere.2012.03.041","article-title":"Spatial trend and pollution assessment of total mercury and methylmercury pollution in the Pearl River Delta soil, South China","volume":"88","author":"Chen","year":"2012","journal-title":"Chemosphere"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"4269","DOI":"10.1016\/j.atmosenv.2006.04.004","article-title":"Diurnal and seasonal trends in total gaseous mercury flux from three urban ground surfaces","volume":"40","author":"Gabriel","year":"2006","journal-title":"Atmos. Environ."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"8617","DOI":"10.5194\/acp-10-8617-2010","article-title":"Assessing the trends and effects of environmental parameters on the behavior of mercury in the lower atmosphere over cropped land over four seasons","volume":"10","author":"Baya","year":"2010","journal-title":"Atmos. Chem. Phys."},{"key":"ref_37","unstructured":"U.S. Geological Survey (2018, October 08). Mineral Resource Data System (MRDS), Available online: https:\/\/mrdata.usgs.gov\/mrds\/show-mrds.php?dep_id=10311068."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/j.chemosphere.2015.03.014","article-title":"Gas-exchange chamber analysis of elemental mercury deposition\/emission to alluvium, ore, and mine tailings","volume":"131","author":"Miller","year":"2015","journal-title":"Chemosphere"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"369","DOI":"10.1016\/j.apgeochem.2007.12.008","article-title":"Gaseous mercury emissions from urban surfaces: Controls and spatiotemporal trends","volume":"23","author":"Eckley","year":"2008","journal-title":"Appl. Geochem."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"2003","DOI":"10.1016\/j.envpol.2010.12.006","article-title":"Source, concentration, and distribution of elemental mercury in the atmosphere in Toronto, Canada","volume":"159","author":"Cairns","year":"2011","journal-title":"Environ. Pollut."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1088\/1748-9326\/aac8e6","article-title":"Identifying and evaluating urban mercury emission sources through passive sampler-based mapping of atmospheric concentration","volume":"13","author":"McLagan","year":"2018","journal-title":"Environ. Res. Lett."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"8049","DOI":"10.5194\/acp-9-8049-2009","article-title":"High levels of reactive gaseous mercury observed at a high elevation research laboratory in the Rocky Mountains","volume":"9","author":"Obrist","year":"2009","journal-title":"Atmos. Chem. Phys"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"10494","DOI":"10.1002\/2015GL066645","article-title":"Oxidation of mercury by bromine in the subtropical free troposphere","volume":"42","author":"Gratz","year":"2015","journal-title":"Geophys. Res. Lett."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1511","DOI":"10.5194\/acp-16-1511-2016","article-title":"Origin of Oxidized Mercury in the Summertime Free Troposphere over the Southeastern United States","volume":"16","author":"Shah","year":"2016","journal-title":"Atmos. Chem. Phys."},{"key":"ref_45","first-page":"D00V22","article-title":"Springtime high surface ozone events over the western United States: Quantifying the role of stratospheric intrusions","volume":"117","author":"Lin","year":"2012","journal-title":"J. Geophys. Res."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"3648","DOI":"10.1016\/j.atmosenv.2009.02.063","article-title":"Improved fluorescence peak integration in the Tekran 2537 for applications with sub-optimal sample loadings","volume":"43","author":"Swartzendruber","year":"2009","journal-title":"Atmos. Environ."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"7204","DOI":"10.1021\/es5026432","article-title":"Progress on Understanding Atmospheric Mercury Hampered by Uncertain Measurements","volume":"48","author":"Jaffe","year":"2014","journal-title":"Environ. Sci. Technol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1970","DOI":"10.1021\/es062323m","article-title":"Estimation of dry deposition of atmospheric mercury in Nevada by direct and indirect methods","volume":"41","author":"Lyman","year":"2007","journal-title":"Environ. Sci. Technol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"11864","DOI":"10.1002\/2014JD022336","article-title":"Regression modeling of gas-particle partitioning of atmospheric oxidized mercury from temperature data","volume":"119","author":"Cheng","year":"2014","journal-title":"J. Geophys. Res."},{"key":"ref_50","unstructured":"U.S. Environmental Protection Agency (2019, March 12). 2017 Air Quality Statistics by City, Released March 2018, Available online: https:\/\/www.epa.gov\/air-trends\/air-quality-cities-and-counties."},{"key":"ref_51","unstructured":"Colorado Department of Public Health and Environment (2019, March 11). Air Pollution Control Division Technical Services Program Quality Assurance Project Plan, Available online: https:\/\/www.colorado.gov\/airquality\/tech_doc_repository.aspx?action=open&file=APCD_QAPP_07302015.pdf."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"1275","DOI":"10.1016\/j.atmosenv.2004.11.007","article-title":"A year of continuous measurements of three atmospheric mercury species (GEM, RGM, and Hgp) in southern Quebec, Canada","volume":"39","author":"Poissant","year":"2005","journal-title":"Atmos. Environ."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"1911","DOI":"10.1016\/j.atmosenv.2006.10.063","article-title":"Temporal variability of mercury speciation in urban air","volume":"41","author":"Liu","year":"2007","journal-title":"Atmos. Environ."},{"key":"ref_54","unstructured":"U.S. Environmental Protection Agency (2017, December 14). Pollutant Emission Summary Files for Earlier NEIs (2005 NEI), Available online: https:\/\/www.epa.gov\/air-emissions-inventories\/pollutant-emissions-summary-files-earlier-neis."}],"container-title":["Atmosphere"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4433\/10\/4\/176\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:42:37Z","timestamp":1760186557000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4433\/10\/4\/176"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,4,3]]},"references-count":54,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2019,4]]}},"alternative-id":["atmos10040176"],"URL":"https:\/\/doi.org\/10.3390\/atmos10040176","relation":{},"ISSN":["2073-4433"],"issn-type":[{"value":"2073-4433","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,4,3]]}}}