Surface Wetness as an Unexpected Control on Forest Exchange of Volatile Organic Acids

S. R. Fulgham, D. B. Millet, H. D. Alwe, A. H. Goldstein, S. Schobesberger, D. K. Farmer

Research output: Contribution to journalArticle


We report bidirectional exchange of volatile acids, including isocyanic and alkanoic acids, over a pine forest across multiple seasons. The exchange velocity of these acids is well correlated with dew point depression, suggesting an equilibrium-driven continuum of flux. Wetness on forest surfaces impacts the vertical exchange of gases, and we suggest that water films and droplets drive equilibrium partitioning, with acids being solvated in surface wetness and released through evaporation. Despite their volatility, these acids partition into neutral-to-alkaline aqueous films, consistent with reported dew pH. This relationship between exchange velocity and dew point depression holds for a wetter mixed forest, but not a very dry orchard. Dew point depression is an excellent indicator of acid fluxes so long as the canopy is occasionally wetted.

Original languageEnglish (US)
Article numbere2020GL088745
JournalGeophysical Research Letters
Issue number15
StatePublished - Aug 16 2020


  • biosphere-atmosphere exchange
  • isocyanic acid
  • organic acids
  • surface wetness

Fingerprint Dive into the research topics of 'Surface Wetness as an Unexpected Control on Forest Exchange of Volatile Organic Acids'. Together they form a unique fingerprint.

  • Cite this