Formaldehyde in Remote Marine Air and Rain:
Flux Measurements and Estimates

O. C. Zafiriou, J. Alford, M. Herrera, E. T. Peltzer and R. B. Gagosian
Woods Hole Oceanographic Institution
Woods Hole, MA 02543, USA.

S. C. Liu
NOAA Aeronomy Laboratory
Boulder, CO 80303, USA.

Geophysical Research Letters (1980) 7: 341-344.

Received: 7 January 1980.
Accepted: 12 February 1980.


The tropospheric trace constituent formaldehyde, HCHO, was measured in rain and in the gas phase during the wet season at Enewetak Atoll, a remote marine site in the central equatorial Pacific. Rainwater averaged 8 ± 2 µg/kg; the gas phase averaged 0.4 ± 0.2 ppbv (0.5 µg/m³). These values, especially the rain, are among the lowest reported to date. The formaldehyde flux to the sea by rainout and washout extrapolates to 0.010 g/m²/y, The gaseous flux to the sea into the sea surface is estimated to be 0.05 g/m²/y by an air-sea exchange calculation that takes into account enhanced uptake by hydroxide-catalyzed formaldehyde hydration. The measured mixing ratio is close to the 0.18 ppbv prediction of a tropospheric chemistry model calculation. The methane oxidation chain probably is the sole formaldehyde source in the Enewetak area. The total formaldehyde flux as carbon into the ocean is ~2% of the estimated total organic carbon from rainout and washout. About 2-4% of the calculated column formaldehyde production is removed from the atmosphere by these processes.


This work was supported by National Science Foundation Grant OCE 77-12914 (SEAREX). M. Herrera acknowledges a Summer Student fellowship at WHOI. We thank the SEAREX logistics group and the Wet Season Chief Scientist, Dr. E. Atlas, for on-site cooperation, and Dr. A. M. Thompson for analytical hints and critical manuscript review. This is Woods Hole Oceanographic Institution Contribution Number 4506.

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