AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Trends in Concentrations of Atmospheric Gaseous and Particulate Species at Look Rock as Related to Primary Emissions Reductions
STEPHANIE SHAW, Roger Tanner, Solomon Bairai, Stephen Mueller, Tennessee Valley Authority
Abstract Number: 286 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Air quality measurements at Look Rock, TN, (LR) begun in 1980, were later expanded to an NPS-operated IMPROVE network station, and expanded again by TVA (1999-2007) to examine the effects of EGU emissions reductions of SO2 and NOx on air quality at the station. LR was designated a non-urban NCORE site in 2010, and continuous monitoring of aerosol mass, sulfate, black carbon and primary and secondary gases, supplemented by enhanced measurements during a series of intensive research studies, have produced a uniquely comprehensive air quality database on background levels of species relevant to NAAQS for ozone and particulate matter for a high-altitude site in the southeastern USA. Analysis of temporal trends (1999-2013) has been conducted at the site in collaboration with SAS activities at LR and other southeastern U.S. locations.
Key findings from these trend studies include the observation that primary pollutant levels have consistently tracked emissions reductions from EGUs and other primary sources in the region, but reductions in secondary pollutants such as particulate sulfate and, specifically, ozone have been less than proportional. Organic carbonaceous material (OM) remains a major contributor to fine particulate mass at the site, as confirmed by ACMS measurements at the site in 2013. A large portion (65-85%) of OM derives from modern carbon, based on 14C measurements. Important parameters affecting ozone levels, fine mass, and visibility also include the specific diurnal meteorology at this ridge-top site, its location in a largely mixed-deciduous forest, and the presence of primary sources of precursors at distances of 50-500 km from the site in all directions.