Isoprene and monoterpene fluxes measured above Amazonian rainforest and their dependence on light and temperature

Canopy scale emissions of isoprene and monoterpenes from Amazonian rainforest were measured by eddy covariance and eddy accumulation techniques. The peak mixing ratios at about 10 m above the canopy occurred in the afternoon and were typically about 90 ppt v of α-pinene and 4–5 ppb v of isoprene. α-...

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Bibliographic Details
Published in:	Atmospheric environment (1994) Vol. 36; no. 14; pp. 2421 - 2426
Main Authors:	Rinne, H.J.I., Guenther, A.B., Greenberg, J.P., Harley, P.C.
Format:	Journal Article
Language:	English
Published:	Oxford Elsevier Ltd 01-05-2002 Elsevier Science
Subjects:	Applied sciences Atmospheric pollution Chemical composition and interactions. Ionic interactions and processes Dispersed sources and other Earth, ocean, space Exact sciences and technology External geophysics isoprene light effects Meteorology monoterpenes Pollution Pollution sources. Measurement results rain forests South America Brazil Amazon Basin America South America, Amazonia Natural origin pollution Light effect Rain forest Emission content Temperature effect Volatile organic compound Tropical forest Pollutant emission Time variation Biogenic factor Flux density Air biosphere interaction Micrometeorology Monoterpene Air pollution Mixing ratio Isoprene
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Summary:	Canopy scale emissions of isoprene and monoterpenes from Amazonian rainforest were measured by eddy covariance and eddy accumulation techniques. The peak mixing ratios at about 10 m above the canopy occurred in the afternoon and were typically about 90 ppt v of α-pinene and 4–5 ppb v of isoprene. α-pinene was the most abundant monoterpene in the air above the canopy comprising ≈50% of the total monoterpene mixing ratio. Measured isoprene fluxes were almost 10 times higher than α-pinene fluxes. Normalized conditions of 30°C and 1000 μmol m −2 s −1 were associated with an isoprene flux of 2.4 mg m −2 h −1 and a β-pinene flux of 0.26 mg m −2 h −1. Both fluxes were lower than values that have been specified for Amazon rainforests in global emission models. Isoprene flux correlated with a light- and temperature-dependent emission activity factor, and even better with measured sensible heat flux. The variation in the measured α-pinene fluxes, as well as the diurnal cycle of mixing ratio, suggest emissions that are dependent on both light and temperature. The light and temperature dependence can have a significant effect on the modeled diurnal cycle of monoterpene emission as well as on the total monoterpene emission.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	1352-2310 1873-2844
DOI:	10.1016/S1352-2310(01)00523-4