Researchers from the University of California, Irvine have discovered hundreds of methane-emitting hotspots throughout Los Angeles, Orange and Riverside counties, according to a new study published this week in the Journal of Geophysical Research: Atmospheres.
Lead author Francesca Hopkins and a team of atmospheric scientists conducted a mobile survey along the Los Angeles Basin to identify the highest emitters of the greenhouse gas, which is the second-biggest contributor to climate change behind carbon dioxide, they explained.
The survey “identified numerous methane hot spots that could be targets for these mitigation activities,” Hopkins, a former student at UCI who is now an environmental scientist at the Jet Propulsion Laboratory (JPL) in Pasadena, said in a statement.
She and her colleagues used a cargo van equipped with special instruments they used to measure various greenhouse gases, including methane and CO2, along a several-hundred mile stretch of the Los Angeles Basin. They found a total of 213 methane hotspots, including a so-called “clean port” refueling center in Long Beach, power plants and water treatment centers.
Greenhouse gas sources include cattle, landfills, fueling stations
Furthermore, Hopkins’ team recorded elevated methane levels throughout the basin. Two-thirds of that methane came from fossil fuel-related sources, they said, and other known sources of the gas included “cattle, geologic seeps, landfills and compressed natural gas fueling stations.”
The survey was conducted prior to a gas well leak at Aliso Canyon that temporarily forced more than a thousand Porter Ranch residents from their homes, the study authors said, and suggest that there is a persistent cloud of methane lingering over the region. A sampling mast attached to the van’s roof and spectrometers allowed them to continuously collect and analyze air samples.
“Mobile measurements are really important because you can examine the fine-scale structure of variations in methane within neighborhoods and begin to identify the origins,” lead investigator Jim Randerson, UCI Chancellor’s Professor of Earth System Science, said in a study. “It’s often not possible to pinpoint individual sources with aircraft observations.”
Randerson added that the findings indicate that “natural gas leaks are ubiquitous throughout the Los Angeles Basin,” and that there is a need to “develop a regional partnership with stakeholders to identify the source of these leaks and make a plan for fixing them.” Riley Duren from the JPL Megacities Carbon Project added that it will help experts “gain a much clearer understanding of the problem” of methane sources in municipal areas.
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