Atmosphere-biosphere exchange of CH sub 4 , CO sub 2 , and O sub 3
The atmosphere-biosphere exchange was measured for CO{sub 2} and O{sub 3} in a tropical rain forest in the wet season of 1987, and for CO{sub 2}, CH{sub 4}, and O{sub 3} in a subarctic tundra in summer 1988. Photosynthesis and respiration were found to be in approximate balance in the rain forest. Net ecosystem uptake of CO{sub 2} in the forest increased with intensity of light in the range of measurements. It is suggested that photosynthesis of a well-watered forest is primarily controlled by photosynthetically active radiation. Changes in the distribution of cloud cover, associated for example with El Nino, might induce globally significant changes in primary productivity and carbon storage. Soil moisture controls in tundra the distribution and association of vegetation types and the atmosphere-biosphere exchange Of CO{sub 2}, although light intensity also influences the daily and seasonal net exchange of CO{sub 2}. Methane fluxes from the subarctic tundra averaged 25 {plus minus} 1 (SE) mgCH{sub 4}/M{sup 2}/d, representing 6 percent the net uptake of carbon for the 30 days of measurement. Ozone deposition fluxes averaged {approximately}1.0 {times} 10{sup 11} molecules cm{sup {minus}2}s{sup {minus}1} in the tropical forest and in the arctic tundra, similar in magnitude to the estimated mean stratospheric input. Ozone deposition fluxes were proportional to O{sub 3} concentrations in the surface layer and regulated by turbulent transport and stomatal activity. Day-time ozone concentrations and deposition velocities measured at {approximately}10 m above canopy averaged {approximately}5 ppb and 1.8 cm s{sup {minus}1} over the tropical forest and {approximately}25 ppb and 0.25 cm s{sup {minus}1} over the subarctic tundra, respectively. These results imply that widespread deforestation in the tropics may impact on the ozone budget and the photochemistry of the troposphere in the region.
- Research Organization:
- Harvard Univ., Cambridge, MA (United States)
- OSTI ID:
- 5094144
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
01 COAL, LIGNITE, AND PEAT
CARBON DIOXIDE
AIR-BIOSPHERE INTERACTIONS
METHANE
OZONE
TROPICAL REGIONS
AIR POLLUTION
TUNDRA
AIR POLLUTION MONITORING
CLOUDS
DEFORESTATION
ECOLOGICAL CONCENTRATION
PHOTOSYNTHESIS
RESPIRATION
SEASONAL VARIATIONS
ALKANES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
HYDROCARBONS
MONITORING
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
POLLUTION
SYNTHESIS
VARIATIONS
540120* - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)
010900 - Coal
Lignite
& Peat- Environmental Aspects