Executive Summary- Project 10-024
Surface Measurements and One-Dimensional Modeling Related to Ozone Formation in the Suburban Dallas-Fort Worth Area
Ozone (O3) in the part of the atmosphere closest to the Earth's surface is an air pollutant that is a respiratory irritant and that causes damage to plant leaves and human-made structures. It is important to note that O3 is not emitted directly from pollution sources but rather forms in the atmosphere when oxides of nitrogen (NOx) and volatile organic compounds (VOCs) mix in the presence of sunlight. While some amount of O3 in the lower atmosphere is formed naturally, the amount of O3 in the atmosphere of the Dallas-Fort Worth (DFW) region exceeds that which is allowable by the National Ambient Air Quality Standards (NAAQS) established by the Environmental Protection Agency.
In the DFW area, the most prevalent local emission sources of NOx and VOCs are automobiles and other motor vehicles and a number of large point sources, specifically electric power plants and cement kilns. However, O3 levels have not decreased significantly in recent years despite gradual decreases in NOx and VOC emissions from automobiles. It is theorized that the dramatic increase in both the number of natural gas wells and the production of natural gas in the DFW region are contributing to additional VOC and NOx sources, leading to the hypothesis that there is a relationship between O3 levels and natural gas activities. A team from Rice University, the University of Houston (UH), and the University of New Hampshire (UNH) will investigate this hypothesis by performing an air quality sampling campaign that is described below.
The Rice, UH, and UNH team will install several additional pieces of air quality monitoring equipment at the Eagle Mountain Lake Texas Commission on Environmental Quality monitoring site for a one-month period from May 15 to June 15, 2011. Eagle Mountain Lake is located approximately 30 kilometers to the northwest of downtown Forth Worth. This location was chosen for several reasons. First, there is a wealth of natural gas activity in this region. Second, wind in the DFW area often blows toward the northwest, indicating that the site will be subject to the emissions from Forth Worth. Lastly, other monitoring has noted the high levels of O3 in the northwest corner of the DFW region. The timing of the campaign was selected to optimize likely O3 formation (due to favorable meteorological conditions), staff availability, and duration of the project.
Relevant measurements will include not only the concentrations of O3, NOx, and VOCs but also values for other relevant chemical and physical variables, including meteorological parameters. In addition, a group from the University of Michigan will conduct computational modeling that will be used in conjunction with the data generated from these measurements to determine the VOC emissions, atmospheric reactions, and meteorological conditions that lead to O3 formation in the DFW region.