Analysis of the trends in ambient ethane and methane in the Baltimore-Washington region
Abstract
There has been an unprecedented rise in natural gas production and usage in the continental United States. The increase in natural gas activity can have implications for air quality and greenhouse gas footprint. Trends of methane, the primary component of natural gas, and ethane, second major component, can be used to understand the sources of natural gas emissions. The Baltimore-Washington region has two principal sources of methane - local emissions from leaks in the natural gas delivery station and regional emissions via transport from upwind fracking regions (Vinciguerra et al., 2015, Ren et al., 2019). Estimates of methane emissions from both these sources remain uncertain. Ambient ethane mixing ratios measured at Photochemical Assessment Monitoring Station (PAMS) site in Essex, MD, displayed a steady increase until 2015, followed by a gradual decline after 2015. Methane mixing ratios measured at three towers near Baltimore City, showed a slight increase between 2017 and 2018. A pronounced diurnal cycle of methane at the three towers but not at an upwind (west of Baltimore) site was observed, suggesting local emissions. Ambient methane mixing ratios measured at the upwind site, northwest of Baltimore city were significantly lower than the methane mixing ratios at the Baltimore City towers and show little diurnal cycle. The upwind site also showed similar enhancements over background both during daytime and nighttime as compared to the Baltimore city towers, which had higher enhancements during nighttime. The average upwind methane in southwestern Pennsylvania was 1981 ppbv, based on three research flights in the region (Ren et al., 2019), which to close average methane observed at the upwind site. These data suggest that the local emissions from the natural gas delivery system, are the dominant source of methane for the years 2017-2018. Our goal here is to understand what sources dictate the trends in the ambient ethane and methane mixing ratio. Such studies will help to quantify the emissions from each source and help in reducing emissions from these sectors.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A51J2706S
- Keywords:
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- 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0330 Geochemical cycles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0493 Urban systems;
- BIOGEOSCIENCES