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.