Abiotic and biotic control of methanol exchanges in a temperate mixed forest

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Authors
Laffineur, Q.
Aubinet, M.
Schoon, N.
Amelynck, C.
Muller, J.-F.
Dewulf, J.
Van Langenhove, H.
Steppe, K.
Heinesch, B.
Discipline
Earth and related Environmental sciences
Subject
adsorption
biogenic emission
biotic factor
degradation
deposition
desorption
diurnal variation
flux measurement
forest ecosystem
methanol
mixed forest
net ecosystem exchange
seasonal variation
temperate forest
Ardennes [Western Europe]
Audience
Scientific
Date
2012Metadata
Show full item recordDescription
Methanol exchanges over a mixed temperate forest in the Belgian Ardennes were measured for more than one vegetation season using disjunct eddy-covariance by a mass scanning technique and Proton Transfer Reaction Mass Spectrometry (PTR-MS). Half-hourly methanol fluxes were measured in the range of −0.6 μg m−2 s−1 to 0.6 μg m−2 s−1, and net daily methanol fluxes were generally negative in summer and autumn and positive in spring. On average, the negative fluxes dominated (i.e. the site behaved as a net sink), in contrast to what had been found in previous studies. An original model describing the adsorption/desorption of methanol in water films present in the forest ecosystem and the methanol degradation process was developed. Its calibration, based on field measurements, predicted a mean methanol degradation rate of −0.0074 μg m−2 s−1 and a half lifetime for methanol in water films of 57.4 h. Biogenic emissions dominated the exchange only in spring, with a standard emission factor of 0.76 μg m−2 s−1. The great ability of the model to reproduce the long-term evolution, as well as the diurnal variation of the fluxes, suggests that the adsorption/desorption and degradation processes play an important role in the global methanol budget. This result underlines the need to conduct long-term measurements in order to accurately capture these processes and to better estimate methanol fluxes at the ecosystem scale.
Citation
Laffineur, Q.; Aubinet, M.; Schoon, N.; Amelynck, C.; Muller, J.-F.; Dewulf, J.; Van Langenhove, H.; Steppe, K.; Heinesch, B. (2012). Abiotic and biotic control of methanol exchanges in a temperate mixed forest. , Atmospheric Chemistry and Physics, Vol. 12, Issue 1, 577-590, DOI: 10.5194/acp-12-577-2012.Identifiers
scopus: 2-s2.0-84855959627
Type
Article
Peer-Review
Yes
Language
eng