Use of oxygen isotopy in the study of SO/sub 2/ to sulfates in the atmosphere
Previous experimental results have indicated that the /sup 18/O//sup 16/O ratios in water vapor, precipitation water, and sulfate contained in precipitation water vary seasonally (higher in summer, lower in winter), while the /sup 18/0//sup 16/0 ratio in atmospheric particulate sulfate appears to vary randomly with season. The samples were arbitrarily intermittent and therefore did not necessarily represent continuous, temporal variations of the oxygen isotopes, except during the three-day sampling period within each month. It was postulated on the basis of the data obtained, that since the two-year averages of /sup 18/0 content in particulate sulfate and precipitation sulfate were about equal, both were probably formed by the same aqueous oxidation mechanism in clouds. In recent studies, sequential seven-day samples of water vapor, particulate sulfate and sulfur dioxide were continuously collected throughout the four seasons. Samples of rain and snow were also collected for most of the precipitation events during this period. The results obtained from this more intensive sampling program give an alternative and possibly more accurate interpretation of the apparent lack of agreement between the isotopic qualities of precipitation and particulate sulfates. Results indicate that SO/sub 2/ in the atmosphere is converted to sulfate in the late fall, winter, and early spring predominantly by an aqueous oxidation mechanism that yields sulfates isotopically similar, if not identical, to sulfates found in precipitation water: while in the late spring, summer, and early fall, SO/sub 2/ is converted predominantly by a sun-induced mechanism that yields sulfates more depleted in /sup 18/0. The predominating summer mechanism(s) may involve reactions of SO/sub 2/ with 0H radicals or other free radicals, or reactions with photochemically produced aqueous-phase oxidants, such as H/sub 2/0/sub 2/. (JGB)
- Research Organization:
- Argonne National Lab., IL (USA)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5769930
- Report Number(s):
- CONF-791065--2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Atmospheric-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
AEROSOLS
AIR POLLUTION
ATMOSPHERIC PRECIPITATIONS
CHALCOGENIDES
CHEMICAL REACTIONS
CLOUDS
COLLOIDS
DAILY VARIATIONS
DISPERSIONS
EVEN-EVEN NUCLEI
FLUIDS
GASES
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
HYDROXYL RADICALS
ISOTOPE APPLICATIONS
ISOTOPE EFFECTS
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MONITORING
NUCLEI
OXIDATION
OXIDES
OXYGEN 16
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PEROXIDES
PHOTOCHEMICAL REACTIONS
POLLUTION
RADICALS
RAIN
SAMPLING
SEASONAL VARIATIONS
SOLS
STABLE ISOTOPES
SULFATES
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
TRACER TECHNIQUES
VAPORS
VARIATIONS
WATER VAPOR