Researchers at the Woods Hole Oceanographic Institution (WHOI) have discovered a massive, previously unaccounted for, source of methanol in the ocean: phytoplankton.
The study found that these microscopic organisms, which form the base of the marine food web, have an ability to biologically produce methanol in the ocean in quantities that could rival or exceed that which is produced on land.
“Methanol can be considered a ‘baby sugar’ molecule and is rapidly consumed in the ocean by abundant bacteria – called methylotrophs – which specialize in this type of food,” said Dr. Tracy Mincer, WHOI associate scientist. “However, up until now, the thought was that methanol in the ocean came from an overflow of terrestrial methanol in the atmosphere. So, this discovery reveals a huge source of methanol that has gone completely unaccounted for in global methanol estimates.”
Mincer and his lab team discovered that, instead of producing methanol steadily over time, phytoplankton release it in quick episodic pulses, and only during certain stages of growth.
One of the most noteworthy aspects of the study, according to Mincer, was the amount of methanol plankton were able to produce. Based on lab measurements, he estimates that at least a million tons of the compound is produced in the world’s oceans each year – which could exceed the amount found in the atmosphere.
“In our cultures, we were surprised to see so much methanol being produced,” said Mincer. “The fact that the quantities in the ocean could rival or exceed levels on land indicates that the abundance of methylotrophic microbes – and the overall metabolic demand for methanol – is higher than previously thought.”
According to Dr. Brian Heikes, a professor and atmospheric chemist at the University of Rhode Island’s Graduate School of Oceanography, the findings help shore up previously hypothesized – but unquantified – oceanic sources of methanol.
“Up until now, in situ oceanic methanol sources have been speculative. This study is significant because it shows there is a system that can make and consume methanol biologically in the ocean in large quantities. That wasn’t fully appreciated before,” said Heikes.
While the findings fill a number of important knowledge gaps, Mincer feels the study has opened up a new set of research questions that need to be addressed.
The work was supported by the National Science Foundation, WHOI noted.