Near-real time infrared observations of acidic sulfates in /open quotes/clean/close quotes/ air at Mauna Loa, Hawaii

Conference · Fri Jan 01 00:00:00 EST 1988

OSTI ID:5120615

Johnson, S A; Kumar, R

Sulfuric acid and its partially or completely neutralized salts with ammonia are believed to result from the oxidation of sulfur dioxide in cloud water and in other heterogeneous media present in the atmosphere. Due to the natural abundance of ammonia and the ubiquitous presence of sulfur in the atmosphere, (NH/sub 4/)/sub 2/SO/sub 4/ is commonly the dominant chemical species in the ambient aerosol. The amounts of ammonium sulfates are expected to be very low in areas far removed from anthropogenic emissions of sulfur dioxide. The chemical composition of submicrometer aerosol particles was determined at the Mauna Loa Observatory (MLO) on Mauna Loa in Hawaii during an eight-day period in August 1986. The MLO site was selected for this measurement because it is the only ground-based aerosol observatory in the remote Pacific Ocean that allows extended sampling of aerosols in the free troposphere. Measurements were made using an attenuated total internal reflection (ATR) impactor system. The impactor collects size-fractionated submicrometer particles for analysis by ATR infrared spectroscopy. The collected samples were analyzed using an on-site Perkin Elmer dispersive infrared spectrophotometer. Infrared absorption spectra (4000 to 250 cm/sup /minus/1/) of the samples were obtained within minutes after the ATR substrates were removed from the impactor. Absorbances were measured for sulfate, nitrate, and ammonium. Acidic sulfate showed infrared absorbances at 600 cm/sup /minus/1/ and 1210 cm/sup /minus/1/ in addition. Results showed that ammonium sulfate was the dominant chemical species in the submicrometer particles. Over half of the nearly 40 samples collected showed an acidic sulfate component. Consecutive samples were found to change from completely neutralized ammonium sulfate to acidic ammonium sulfates in a two-hour time interval. 5 refs., 1 tab.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5120615
• Report Number(s): CONF-8806123-1; ON: DE88010047
• Resource Relation: Conference: Symposium on the chemistry of acid rain: effect and abatement, Toronto, Canada, 5 Jun 1988
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AEROSOLS
SAMPLING
SULFATES
ABSORPTION
AIR
AMMONIA
CLOUDS
DAILY VARIATIONS
HAWAII
INFRARED SPECTRA
MEASURING INSTRUMENTS
NITRATES
OXIDATION
SULFUR DIOXIDE
WATER
CHALCOGENIDES
CHEMICAL REACTIONS
COLLOIDS
DISPERSIONS
FEDERAL REGION IX
FLUIDS
GASES
HYDRIDES
HYDROGEN COMPOUNDS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NORTH AMERICA
OXIDES
OXYGEN COMPOUNDS
SOLS
SPECTRA
SULFUR COMPOUNDS
SULFUR OXIDES
USA
VARIATIONS
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)
500500 - Environment
Atmospheric- Site Resource & Use Studies- (-1989)