Date of Award

1-1-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemical Engineering

First Advisor

Frank M. Bowman

Abstract

Oil and gas production in the Bakken region increased dramatically more than a decade ago. In my first analysis, a WRF-Chem modeling study of the Northern Great Plains was conducted for a July 2010 baseline scenario prior to the largest of these production increases. Simulations using the RACM-MADE/SORGAM, CBMZ-MOSAIC, and MOZART-MOSAIC chemistry-aerosol mechanisms were compared to each other and against ground level observations. All three gas-aerosol modules produced similar prediction results for O3 and NO2, with moderate correlation to hourly measurements and monthly average values overpredicted by 20% for O3 and underpredicted by 5% for NO2. Monthly average PM2.5 concentrations were relatively accurate, but correlation to hourly measurements was very low and predictions of PM2.5 subspecies exhibited high variability with a mix of over and underpredictions depending on the mechanism. Pollutant concentrations were relatively low across the mostly rural study domain, especially in the Bakken region. Results from this work can be used as a basis of comparison for studies of more recent time periods that include increased oil and gas-related emissions.In the second modeling study baseline and high production scenarios corresponding to July 2010 and July 2014, respectively, were simulated with WRF-Chem and the MOZART-MOSAIC chemistry-aerosol mechanisms to investigate changes in main atmospheric pollutant concentrations due to increased oil and gas production activities in the region. Emission fluxes of main gaseous pollutants showed a general decreasing trend from baseline levels. Similarly, considerable decreases were observed in predicted mean average monthly concentrations for NO2 and PM2.5 of -38% for NO2, and -34% for PM2.5. Predictions of mean monthly averages of particulate subspecies showed a decrease of -25% for EC, -48% for NO3 and -11% for NH4 with an increase of 8% for OC. Monthly mean concentrations of NO2 revealed a slight increase between 2 and 3 ppb for the high production scenario over the Bakken Shale region, which could be correlated with increased oil production activities. Future work could analyze the ongoing sustained high oil production activity environment over the Bakken Shale by comparing main pollutant emissions and model output concentrations between the NEI-2017 and NEI-2014 emissions inventories to assess what localized changes of main air quality pollutants are predicted at or near areas of known oil production activities.

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