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Active Atmosphere-Ecosystem Exchange of the Vast Majority of Detected Volatile Organic Compounds

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Science  09 Aug 2013:
Vol. 341, Issue 6146, pp. 643-647
DOI: 10.1126/science.1235053

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Two-Way Street

Most studies of volatile organic compounds (VOCs) found in the atmosphere, which play important roles in atmospheric chemistry, have concentrated on dominant species such as isoprene. There are thousands of other classes of VOCs, and how they are exchanged between the biosphere and the atmosphere is unclear. Park et al. (p. 643) measured the fluxes of more than 500 types of VOCs using a highly sensitive type of mass spectrometry and an absolute value eddy covariance method. The majority of these species were actively exchanged between the atmosphere and the biosphere, with more than a quarter showing net deposition. These results should help to improve air quality and global climate models, and strengthen our understanding of atmospheric VOC chemistry.

Abstract

Numerous volatile organic compounds (VOCs) exist in Earth’s atmosphere, most of which originate from biogenic emissions. Despite VOCs’ critical role in tropospheric chemistry, studies for evaluating their atmosphere-ecosystem exchange (emission and deposition) have been limited to a few dominant compounds owing to a lack of appropriate measurement techniques. Using a high–mass resolution proton transfer reaction–time of flight–mass spectrometer and an absolute value eddy-covariance method, we directly measured 186 organic ions with net deposition, and 494 that have bidirectional flux. This observation of active atmosphere-ecosystem exchange of the vast majority of detected VOCs poses a challenge to current emission, air quality, and global climate models, which do not account for this extremely large range of compounds. This observation also provides new insight for understanding the atmospheric VOC budget.

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