Abstract
Formaldehyde in precipitation and in surface seawater has been measured at Woods Hole, Massachusetts (U.S.A.) a mid-latitude coastal site. From these measurements and a calculation of the diffusion-controlled air-to-sea transfer rate of the compound we estimate the wet and dry flux of H2CO from the troposphere to nearby coastal waters to be 6.3 µg cm-2 yr-1 for precipitation and 5.7 µg cm-2 yr-1 for gaseous diffusion. A comparison of these values with a simple photochemical model shows that these transfers may represent a significant removal mechanism for tropospheric formaldehyde.
The total flux of H2CO is equivalent to an input of 4.8 µg cm-2 yr-1 organic carbon, ≥1% of estimated total organic carbon air-to-sea transfer. The absence of a detectable amount of formaldehyde in surface seawater suggests that its fate might be biological uptake. This view is supported by the finding that seawater enriched with formaldehyde shows a gradual loss of the compound, whereas the level remains unchanged in sterile seawater under light and dark conditions.