Air Quality at a Ranch Site in the Western Part of the Eagle Ford shale

The booming unconventional oil and gas industry in the Eagle Ford shale in southern Texas continues to grow. Modeling studies of the air quality impacts of the Eagle Ford rely on emission inventories that may underestimate emissions from such operations, and air quality monitoring in the area remains limited. We conducted an air quality study on a ranch in Dimmit County, Texas, which was ranked 6th in Texas for natural gas production and 10th in Texas for oil production as of April 2015. An automated GC-FID was used to measure the concentration of hydrocarbons (C3 - C14), with concurrent measurements of CO, CO2, H2O, O3, NO/NOx. In addition, the concentration and sizing of aerosols ranging from 0.6 to 20 µm aerodynamic diameter were measured with a GRIMM aerosol spectrometer (GRIMM 1.108), and meteorological variables including wind speed, direction, temperature, relative humidity, precipitation, and insolation were recorded. We report on local air quality and changes during the process as observed during the measurement campaign. Local drilling on the ranch began in May 2015 and production started in June 2015, at a site approximately 5 km southeast of the air quality trailer. Local air quality showed typically low, near background abundances of CO and NOx early during the campaign, and more frequent local NOx plumes during the drilling and production phases. Aerosol mass measurements were also relatively low and well within attainment of NAAQS particulate matter standards. We assess OH radical reactivity of individual and/or groups of VOCs using observed concentrations and their reaction rate coefficient with OH, the dominant VOC sink in the troposphere.