0 1995, by the American Society of Limnology and Oceanography, Inc. Biological production of formaldehyde in the marine environment

We investigated biological production of low-molecular-weight (LMW) carbonyl compounds (e.g. form-aldehyde, acetaldehyde, propanal, and glyoxal) in axenic unialgal phytoplankton cultures of Skeletonema costatum and Heterocapsa pygmaea and in several natural plankton assemblages collected at a coastal location in southeastern North Carolina. Of the compounds studied, formaldehyde was the only LMW carbonyl produced by the biota with the exception of a single natural assemblage which also produced propanal. Similar patterns of biological production and utilization of formaldehyde were observed during these culture experiments. Concentrations in filtrates increased while chlorophyll a concentrations remained relatively low, then declined as the organisms began their exponential growth phase. These oscillations in formaldehyde concentration suggest biota are both generating and using formaldehyde concurrently. In situ depth profiles provided additional information regarding the turnover of formaldehyde. Concentrations were relatively high at the surface and decreased to a minimum near the chlorophyll maximum, below which no consistent trends in formaldehyde concentration were observed. This study is the first known report of biological production of a LMW aldehyde in the marine environment. About 15-20 % of the total organic C (TOC) in th