The R/V Atlantis and HOV Alvin (left) - Photo by L. Lamar. Aromatic molecules surrounding a hydrothermal vent field (right) - Illustration by E. Pae.
Oceanic dissolved organic carbon (DOC) is one of the largest reservoirs of reduced carbon on Earth. Condensed aromatic (graphitic, soot-like) molecules are known to be the least reactive and most long-lived component of oceanic DOC. Therefore, it is important to understand where condensed aromatic DOC is formed and how it is cycled in marine environments. Sasha Wagner and researchers at the University of Delaware (Andrew Wozniak, Suni Shah Walter, and George Luther) have teamed up to answer the question: Are hydrothermal vents the source of this long-lived, soot-like carbon that persists in the deep ocean?
A few years ago, Wozniak and Luther discovered small bits of graphite in hydrothermal fluids at the East Pacific Rise 9°N vent field. Around the same time, Wagner used isotopic measurements to determine that soot-like molecules in the deep Pacific Ocean have a marine origin, and do not come from wildfires on land as previously thought. Radiocarbon dating also supports a deep sea, probably hydrothermal, source of this graphitic, soot-like carbon. With multiple studies now pointing towards hydrothermal vents as a likely source of ancient aromatic DOC, there was only one thing left to do - Go straight to the source and find out!
To answer their question, Wagner and her team will sample vent fluids directly, along with ocean water and marine sediments, and use a suite of geochemical techniques to determine whether mid-ocean ridge hydrothermal vents are a source of this long-lived, condensed aromatic DOC. The project involves a field campaign at the East Pacific Rise 9°N hydrothermal vent site located off the western coast of Central America. Project findings will reveal the role of hydrothermal vents in producing and sequestering carbon in the deep ocean.
Additional details about this project entitled “Collaborative Research: Hydrothermal vent systems mediate the formation and fate of refractory aromatic carbon in the deep ocean” are publicly available on the National Science Foundation website.
