Any of you who have been watching for a while know that we like hydrothermal vents. They make it possible for sea life to exist without sunlight, they add all sorts of nutrients to seawater, they add material to the ocean floor that records flips in the Earth’s magnetic field, and they do a lot of good things while just looking cool. Now we are learning that they are spouting ancient dissolved organic carbon into the ocean.
In general, the organic carbon in the ocean comes from organisms doing photosynthesis at the ocean surface. Some of that carbon – Carbon-14 – is radioactive and over time will decay, and the ratio of the resulting elements allows the age of the material to be determined.
In looking at the ratios of carbon in seawater from a variety of sites, researchers led by Ellen Druffel discovered that the water near hydrothermal vents appears to be ancient, implying that dissolved organics from the deep past are somehow released in or near hydrothermal vents. It’s unclear if the vents themselves are responsible, or if microbes at the vents eat dissolved inorganic carbon and process it into dissolved organic carbon that is old in nature. More research is needed, and it’s awesome that these vents have more mysteries for us to explore.
“Dissolved Organic Radiocarbon in the Eastern Pacific and Southern Oceans,” Ellen R. M. Druffel et al., 2021 May 24, Geophysical Research Letters