Photo above: Sediments being discharged from the Mississippi River. Credit: NOAA.
Sediments released from major rivers may influence how carbon dioxide emerges from
organic matter in deep, offshore waters, says a new study in Marine Chemistry.
(January 19, 2016) A new scientific journal article reports that carbon dioxide can emerge from the deep ocean in a surprising way — a new piece of the global carbon “puzzle” that researchers must solve to fully understand major issues like climate change.
The article, published recently in the peer-reviewed journal Marine Chemistry, was authored by a Mote Marine Laboratory scientist who performed the research with Georgia Institute of Technology and the Laboratoire des Sciences du Climat et de l'Environnement in France. The study was funded in part by the U.S.-based National Science Foundation and France’s Agence Nationale de la Recherche.
The study looks at organic matter — carbon-rich muck — deposited as deep as 16,400-feet (5,000-meters) in the ocean, far offshore of coastlines with big river systems. Bacteria feed on this muck and release the greenhouse gas carbon dioxide, using certain chemical “ingredients” from their environment in the process. The new study used state-of-the-art, electrochemical techniques to investigate how bacteria do this at two deep-water carbon deposits offshore of Africa’s Congo River and the U.S. Mississippi River mouths. Results suggest these deep-dwelling bacteria are releasing carbon dioxide by using unexpected ingredients — metal ions that were once believed to be rare or absent at such depths. This new finding calls into question how much carbon dioxide is really emerging from some deep deposits, while offering new clues toward finding out.
The study’s focus — the life and times of ocean muck — might sound less than thrilling at first. However, sediments in the sea are an important part of the global carbon cycle, which is full of questions that must be answered to understand some of the most significant processes on Earth.