But the new findings -- which have implications for petrochemical-producing cities around the world -- come with a catch, says a team of scientists from the Cooperative Institute for Research in Environmental Sciences, or CIRES, a joint institute of the University of Colorado at Boulder and the National Oceanic and Atmospheric Administration.
The problem is that industry still significantly underestimates the amounts of reactive chemicals being released into the air, according to airplane measurements made by the research team as part of the study. Inaccuracies in the reporting of emissions pose big challenges for the reduction and regulation of emissions coming from petrochemical plants. The emissions are important to monitor, because some chemicals released from the plants react to form ground-level ozone that can be harmful to human health and agricultural crops.
"Emissions may have decreased some, but there's still a long way to go," said study author Joost de Gouw, a CIRES atmospheric scientist. "And the emission inventories by industry were not any better in 2006 than they were in 2000."
States that regularly suffer from ozone problems like Texas are required by the federal government to scientifically model what happens during air pollution episodes and develop plans for mitigation. For that to happen effectively, modelers need good inventories, says the research team.
"Initial inventories are not based on measurements. They're based on estimates," said de Gouw. "When you go back to verify those estimates, we find they're not very accurate."
To check on those estimates, lead study author Rebecca Washenfelder of NOAA's Earth System Research Laboratory and CIRES, along with de Gouw, took to the plumes in an aircraft, the NOAA WP-3D, outfitted with an array of air quality measuring instruments. The plane flew through emissions over Houston as part of the second Texas Air Quality Study in 2006, sampling air for signs of ingredients of the chemical reaction that makes ozone, including nitrogen oxides and reactive hydrocarbons.
Washenfelder, de Gouw and their study colleagues compared these measurements with data taken during similar flyovers from the first Texas Air Quality Study in 2000 and another flight in 2002. They then compared those measurements against emissions inventories for each year. In all cases, the industry-reported inventories -- which are supplied to the U.S. Environmental Protection Agency -- didn't agree with the measured amounts of pollutants.
The conflicting data is likely a problem of estimation and general industry practice. "There are tens of thousands of valves and fittings installed throughout the plants in most cases with an assumed -- not measured -- leak rate for each," Washenfelder said.
But industry is taking steps to lessen ozone-causing emissions, and repairs to petrochemical plants may have contributed to recent emission declines. Washenfelder and de Gouw found that the concentrations of ethene and propene -- which both contribute to ozone formation -- dropped by 52 percent and 48 percent respectively between 2000 and 2006.
The two scientists see the study as a wake-up call for emissions monitoring.
"There are a lot of discussions with the petrochemical industry on how to measure these things instead of relying on estimates," said de Gouw. "I think the No. 1 issue here is awareness. As soon as industry is aware that there could be emissions problems down the road, they can figure out how to fix them at lower cost."
The study been accepted for publication in the Journal of Geophysical Research – Atmospheres, a publication of the American Geophysical Union. Funding for the project came from NOAA Air Quality, NOAA Climate Research and Modeling Program, the Texas Commission on Environmental Quality and a National Research Council Postdoctoral Fellowship.
A podcast on the study can be heard at http://colorado.edu/news/podcasts/.
Rebecca Washenfelder | EurekAlert!
Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen
Shallow soils promote savannas in South America
20.10.2017 | Senckenberg Forschungsinstitut und Naturmuseen
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research