Abstract View
Ambient Chlorine Chemistry in an Oil and Gas Production Region: Evidence from a FIGAERO-CIMS
CATHERINE MASOUD, Nirvan Bhattacharyya, Kristi McPherson, Leif Jahn, Pearl Abue, Kanan Patel, Daniel C. Blomdahl, Pawel K. Misztal, Lea Hildebrandt Ruiz, University of Texas at Austin
Abstract Number: 667
Working Group: Aerosol Chemistry
Abstract
Unconventional oil and gas development (UOGD) has increased dramatically in the United States. As chlorinated compounds are added to hydraulic fracturing water, UOGD may be a source of chlorine, contributing to atmospheric chemistry and the formation of secondary organic aerosol in these regions. In the spring of 2021, we deployed a suite of instrumentation to Karnes City, Texas, a rural area in the middle of the Eagle Ford Shale, to investigate the impact of UOGD on air quality. We measured airborne pollutants including halogenated and oxygenated species (Cl2, ClNO2, N2O5 and OVOCs) using a High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer operated in iodide mode (I- HR-ToF-CIMS) and equipped with a Filter Inlet for Gases and Aerosols (FIGAERO). Measurements show several episodes of substantially elevated Cl2 and ClNO2 levels, consistent with the presence of a local chlorine source. We also find evidence of organic chlorides in the gas and particle phases indicating the contribution of chlorine chemistry in formation of secondary pollutants in the area. We deployed an oxidative flow reactor which conducted Cl-initiated oxidative aging of ambient air and provides markers for Cl-initiated reactions in the ambient air.
The measurement campaign included other instrumentation such as a Vocus-PTR-ToF-MS (with a VIA inlet), aerosol chemical speciation monitor, scanning electrical mobility spectrometer, a photometric ozone monitor, a chemiluminescence NOx monitor, and a CAPS NO2 monitor. We utilize data from these instruments to supplement the FIGAERO-I-CIMS data and investigate chlorine chemistry and its role in secondary organic aerosol formation in this inland oil and gas production region.