Diurnal cycle of O[sub 3] and monoterpenes in a coniferous forest: Importance of atmospheric stability, surface exchange, and chemistry

Journal Article · Sat Mar 20 00:00:00 EST 1993 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JD02829· OSTI ID:6600163

Johansson, C; Janson, R W ^[1]

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1. Stockholm Univ. (Sweden)

A one-dimensional model of turbulent diffusion and chemistry has been applied to evaluate measurements of the diurnal variation of O[sub 3] and monoterpenes in a coniferous forest in Sweden. The role of photochemical, meteorological, and surface exchange processes was investigated by studying days characteristic of neutral and stable/unstable conditions, respectively. The atmospheric concentrations and surface exchange rates of O[sub 3], monoterpenes and NO[sub x] were taken from measurements at the site, using chamber techniques for the flux measurements. The model calculations showed the predominant role of turbulent mixing in the observed diurnal variation of O[sub 3] and monoterpenes. The reaction with OH accounted for 50-60% of the terpene loss over a 24-hour period with a well-mixed boundary layer and about 40% when nighttime conditions were stable. Increasing the background O[sub 3] concentration to 80-90 ppbv increased the relative importance of the terpene + O[sub 3] reaction to equal that of the OH reaction. The terpene chemical lifetime was found to be shortest, less than 1 hour, under neutral nighttime conditions when NO[sub 3] concentrations were high. Under stable nighttime conditions, the lower boundary layer became chemically less active due to the depletion of O[sub 3] and NO[sub 3]. Terpene reactions were found to be significant nighttime sinks for O[sub 3] and NO[sub 3] under stable conditions and during periods or at sites of nocturnal terpene emission rates greater than 150 [mu]g/m[sup 2] h. An increase in NO[sub x] concentrations from 0.5 ppbv to 1 and then 5 ppbv, changed O[sub 3] concentrations first up and then down, by not more than 1 ppbv. At terpene emission rates of 50-100 [mu]g (m[sup 2] h)[sup [minus]1], the terpene + OH reaction caused less than 5% of the OH loss near the surface, while at a rate of 1,500 [mu]g (m[sup 2] h)[sup [minus]1], it accounted for up to 30-40% of OH loss. 54 refs., 8 figs., 2 tabs.

• OSTI ID: 6600163
• Journal Information: Journal of Geophysical Research; (United States), Vol. 98:D3; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CONIFERS
ATMOSPHERIC CHEMISTRY
MATHEMATICAL MODELS
FORESTS
OZONE
ECOLOGICAL CONCENTRATION
TERPENES
AIR
CHEMISTRY
DAILY VARIATIONS
DIFFUSION
EMISSION
HEIGHT
HYDROXYL RADICALS
INTERFERENCE
LIFETIME
METEOROLOGY
MIXING
NITROGEN OXIDES
PHOTOCHEMICAL REACTIONS
SINKS
STABILITY
SWEDEN
TURBULENCE
CHALCOGENIDES
CHEMICAL REACTIONS
DEVELOPED COUNTRIES
DIMENSIONS
EUROPE
FLUIDS
GASES
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PINOPHYTA
PLANTS
RADICALS
SCANDINAVIA
VARIATIONS
540120* - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)
540110
540210 - Environment
Terrestrial- Basic Studies- (1990-)
560300 - Chemicals Metabolism & Toxicology