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

doi:10.1029/2020GL088745

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

Soil, Water, and Climate

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

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 language	English (US)
Article number	e2020GL088745
Journal	Geophysical Research Letters
Volume	47
Issue number	15
DOIs	https://doi.org/10.1029/2020GL088745
State	Published - Aug 16 2020

Bibliographical note

Funding Information:
We thank William Massman (U.S. Forest Service) and Frank Wania (University of Toronto) for assistance, and NOAA (NA14OAR4310141), the Academy of Finland (310682), and NSF (AGS‐1932771, AGS‐1428257) for funding.

Publisher Copyright:
©2020. The Authors.

Keywords

biosphere-atmosphere exchange
isocyanic acid
organic acids
surface wetness

Access

10.1029/2020GL088745

OpenUrl availability

Full text

Cite this

@article{919cfc3fe1164958b81b97a69ee93c92,

title = "Surface Wetness as an Unexpected Control on Forest Exchange of Volatile Organic Acids",

abstract = "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.",

keywords = "biosphere-atmosphere exchange, isocyanic acid, organic acids, surface wetness",

author = "Fulgham, {S. R.} and Millet, {D. B.} and Alwe, {H. D.} and Goldstein, {A. H.} and S. Schobesberger and Farmer, {D. K.}",

note = "Funding Information: We thank William Massman (U.S. Forest Service) and Frank Wania (University of Toronto) for assistance, and NOAA (NA14OAR4310141), the Academy of Finland (310682), and NSF (AGS‐1932771, AGS‐1428257) for funding. Publisher Copyright: {\textcopyright}2020. The Authors.",

year = "2020",

month = aug,

day = "16",

doi = "10.1029/2020GL088745",

language = "English (US)",

volume = "47",

journal = "Geophysical Research Letters",

issn = "0094-8276",

publisher = "American Geophysical Union",

number = "15",

}

TY - JOUR

T1 - Surface Wetness as an Unexpected Control on Forest Exchange of Volatile Organic Acids

AU - Fulgham, S. R.

AU - Millet, D. B.

AU - Alwe, H. D.

AU - Goldstein, A. H.

AU - Schobesberger, S.

AU - Farmer, D. K.

N1 - Funding Information: We thank William Massman (U.S. Forest Service) and Frank Wania (University of Toronto) for assistance, and NOAA (NA14OAR4310141), the Academy of Finland (310682), and NSF (AGS‐1932771, AGS‐1428257) for funding. Publisher Copyright: ©2020. The Authors.

PY - 2020/8/16

Y1 - 2020/8/16

N2 - 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.

AB - 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.

KW - biosphere-atmosphere exchange

KW - isocyanic acid

KW - organic acids

KW - surface wetness

UR - http://www.scopus.com/inward/record.url?scp=85089362761&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85089362761&partnerID=8YFLogxK

U2 - 10.1029/2020GL088745

DO - 10.1029/2020GL088745

M3 - Article

AN - SCOPUS:85089362761

SN - 0094-8276

VL - 47

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 15

M1 - e2020GL088745

ER -

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

Abstract

Bibliographical note

Keywords

Access

OpenUrl availability

Other files and links

Fingerprint

Cite this