| Title: | Oxidation of Volatile Organic Compounds as the Major Source of Formic Acid in a Mixed Forest Canopy |
| Author(s): | Alwe HD; Millet DB; Chen X; Raff JD; Payne ZC; Fledderman K; |
| Address: | "Department of Soil, Water, and Climate University of Minnesota, Twin Cities Saint Paul MN USA. School of Public and Environmental Affairs Indiana University Bloomington IN USA. Department of Chemistry Indiana University Bloomington IN USA" |
| ISSN/ISBN: | 0094-8276 (Print) 1944-8007 (Electronic) 0094-8276 (Linking) |
| Abstract: | "Formic acid (HCOOH) is among the most abundant carboxylic acids in the atmosphere, but its budget is poorly understood. We present eddy flux, vertical gradient, and soil chamber measurements from a mixed forest and apply the data to better constrain HCOOH source/sink pathways. While the cumulative above-canopy flux was downward, HCOOH exchange was bidirectional, with extended periods of net upward and downward flux. Net above-canopy fluxes were mostly upward during warmer/drier periods. The implied gross canopy HCOOH source corresponds to 3% and 38% of observed isoprene and monoterpene carbon emissions and is 15x underestimated in a state-of-science atmospheric model (GEOS-Chem). Gradient and soil chamber measurements identify the canopy layer as the controlling source of HCOOH or its precursors to the forest environment; below-canopy sources were minor. A correlation analysis using an ensemble of marker volatile organic compounds suggests that secondary formation, not direct emission, is the major source driving ambient HCOOH" |
| Keywords: | Eddy co-variance fluxes Formic acid; |
| Notes: | "PubMed-not-MEDLINEAlwe, Hariprasad D Millet, Dylan B Chen, Xin Raff, Jonathan D Payne, Zachary C Fledderman, Kathryn eng NNX14AP89G/NASA/NASA/ 2019/05/10 Geophys Res Lett. 2019 Mar 16; 46(5):2940-2948. doi: 10.1029/2018GL081526. Epub 2019 Mar 12" |
