Featured Research

from universities, journals, and other organizations

Nighttime Chemistry Affects Ozone Formation

Date:
April 13, 2004
Source:
American Geophysical Union
Summary:
When it comes to air pollution, what goes on at night can be just as important as what happens during the day, say National Oceanic and Atmospheric Administration (NOAA) scientists and their colleagues in a study published 10 April in Geophysical Research Letters.

WASHINGTON - When it comes to air pollution, what goes on at night can be just as important as what happens during the day, say National Oceanic and Atmospheric Administration (NOAA) scientists and their colleagues in a study published 10 April in Geophysical Research Letters.

The scientists found that nighttime chemical processes remove nitrogen oxides (NOx) from the atmosphere in the marine boundary layer off the coast of New England. These gases are one of the two basic ingredients for making ozone pollution. With less nitrogen oxides in the atmosphere, ozone production the next day will almost always be reduced in New England. Ozone is a strong oxidant and can lead to respiratory problems in humans, as well as affect plant life.

Lead author Steven S. Brown and many of his co-authors are at NOAA's Aeronomy Laboratory and NOAA's Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder, Colorado. Scientists at the NOAA Pacific Marine Environmental Laboratory, the University of New Hampshire, and the University of Colorado also participated in the study.

Ozone forms in the presence of sunlight from chemical reactions between hydrocarbons (also known as volatile organic compounds, or VOCs) and nitrogen oxides, both of which are emitted by human activities such as fossil-fuel burning, as well as by natural sources. Most studies have focused on the daytime processes associated with ozone pollution.

But, Brown notes, "Atmospheric chemistry never sleeps" and more information is needed about nighttime chemistry. After sunset, nitrogen oxide compounds undergo reactions that make two new nitrogen-containing gases that exist mainly at night. These "nocturnal nitrogen oxides" have the potential to either remove nitrogen from the atmosphere or to store it and re-release it when daylight returns--two possibilities that have vastly different consequences for subsequent ozone formation.

The authors studied the two nocturnal gases, known chemically as nitrate radical (NO3) and dinitrogen pentoxide (N2O5). The gases had been previously either impossible to measure (dinitrogen pentoxide) or measurable only over a large volume of air (nitrate radical). A new capability recently applied by Brown and his colleagues has made it possible to measure each gas in a small volume of sampled air. The scientists got their first look at the nighttime chemistry during the summer of 2002, when the new instrument was deployed off the coast of New England on the NOAA Research Vessel Ronald H. Brown, as part of an air quality study of the region.

They found that the nocturnal gases effectively removed nitrogen oxides from the atmosphere by forming nitric acid, a gas that rapidly deposits to the surface in the marine environment that the scientists investigated. The net result is that the nitrogen oxides that are thus removed can no longer participate in ozone-forming chemistry the next day. Scientists at the University of New Hampshire provided key measurements of the nitric acid during the study.

"This nighttime process takes out about as much as daytime processes. Under nearly all polluted conditions, this will short-circuit some of the ozone production that would have occurred the next day in New England," Brown says.

The result is important to include in air quality models of the region, because it affects the amount of ozone that is expected to form per unit of nitrogen oxide pollution. New nighttime processes are a "must-have" for air quality forecasts and simulations in New England, and perhaps other areas, the researchers say.

"The nighttime chemistry is a new piece of the air quality puzzle. We need to find out more about when and where it is important, so that we will be able to provide more accurate predictions of ozone pollution for the public," said A.R. Ravishankara, a co-author of the study at NOAA's Aeronomy Laboratory.

The research was funded by the New England Air Quality Study and NOAA.


Story Source:

The above story is based on materials provided by American Geophysical Union. Note: Materials may be edited for content and length.


Cite This Page:

American Geophysical Union. "Nighttime Chemistry Affects Ozone Formation." ScienceDaily. ScienceDaily, 13 April 2004. <www.sciencedaily.com/releases/2004/04/040413002358.htm>.
American Geophysical Union. (2004, April 13). Nighttime Chemistry Affects Ozone Formation. ScienceDaily. Retrieved August 29, 2014 from www.sciencedaily.com/releases/2004/04/040413002358.htm
American Geophysical Union. "Nighttime Chemistry Affects Ozone Formation." ScienceDaily. www.sciencedaily.com/releases/2004/04/040413002358.htm (accessed August 29, 2014).

Share This




More Earth & Climate News

Friday, August 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Scientists Have Figured Out Why Rocks Move In Death Valley

Scientists Have Figured Out Why Rocks Move In Death Valley

Newsy (Aug. 28, 2014) The mystery of the moving rocks in Death Valley, California, has finally been solved. Scientists are pointing to a combo of water, ice and wind. Video provided by Newsy
Powered by NewsLook.com
Big Waves, Minor Flooding from Hurricane

Big Waves, Minor Flooding from Hurricane

AP (Aug. 27, 2014) Thundering surf spawned by Hurricane Marie pounded the Southern California coast Wednesday, causing minor flooding in a low-lying beach town. High surf warnings were posted for Los Angeles County south through Orange County. (Aug. 27) Video provided by AP
Powered by NewsLook.com
Calif. Quake Underscores Need for Early Warning

Calif. Quake Underscores Need for Early Warning

AP (Aug. 26, 2014) Researchers at UC Berkeley are testing a prototype of an earthquake early warning system that California is pursuing years after places like Mexico and Japan already have them up and running. (August 26) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins