Atmospheric implications of light alkane emissions from the U.S. oil and gas sector

New efficient drilling techniques triggered a massive growth of unconventional oil and natural gas production in North America starting in 2005. Emissions of a variety of volatile organic compounds (VOCs) from the oil and gas sector occur during well development and production phases, and emissions to the atmosphere also continue when wells are abandoned. Determining VOC emission fluxes in the context of rapid growth of the oil and natural gas industry presents a big challenge for emission inventories. In the U.S., the latest version of the 2011 National Emission Inventory (NEI2011v6.3) includes updates over important oil and natural gas basins and speciation profiles based on the Western Regional Air Partnership. We incorporated the NEI2011v6.3 into the GEOS-Chem chemical transport model to simulate the atmospheric abundances of C2-C5 alkanes over the U.S. attributed to emissions from the oil and gas sector. We present results from a nested high-resolution (0.5 degree x 0.667 degree) simulation over North America. C2-C5 alkane emissions from NEI 2011v6.3 increase across the U.S. compared to the previous NEI 2011 v2 incorporated as default in GEOS-Chem. Ethane (C2H6) and propane (C3H8) emission fluxes increased over important oil and natural gas basins. We compare our simulation to a suite of surface observations, column measurements, and aircraft profiles. Finally, we estimate the contribution that C2-C5 alkanes make to the abundance and production of important secondary species including ozone, peroxy acetyl nitrate, and several ketones.