Deep-sea black carbon comes from hydrothermal vents

Date:
February 10, 2023
Source:
Hokkaido University
Summary:
Hydrothermal vents have been identified as a previously undiscovered
source of dissolved black carbon in the oceans, furthering the
understanding of the role of oceans as a carbon sink.


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FULL STORY ========================================================================== Hydrothermal vents have been identified as a previously undiscovered
source of dissolved black carbon in the oceans, furthering the
understanding of the role of oceans as a carbon sink.


==========================================================================
The ocean is one of the largest dynamic carbon sinks in the world, and is susceptible to increased carbon emissions from human activities. There
are even proposals to use the ocean to sequester carbon in an effort
to reduce the carbon emissions. However, much of the processes by which
the ocean functions as a carbon sink are not fully understood.

Associate Professor Youhei Yamashita and grad student Yutaro Mori at
Hokkaido University, along with Professor Hiroshi Ogawa at AORI, The
University of Tokyo, have revealed conclusive evidence that hydrothermal
vents are a previously unknown source of dissolved black carbon in the
deep ocean. Their discoveries were published in the journal Science
Advances.

"One of the largest carbon pools on the Earth's surface is the dissolved organic carbon in the ocean," explains Ogawa. "We were interested in
a portion of this pool, known as dissolved black carbon (DBC), which
cannot be utilized by organisms. The source of DBC in the deep sea was
unknown, although hydrothermal vents were suspected to be involved."
The researchers analyzed the distribution of DBC in the ocean basins of
the North Pacific Ocean and Eastern South Pacific Ocean, and compared
the data with previously reported concentrations of a helium isotope
that is associated with hydrothermal vent emissions, as well as oxygen utilization in these areas.

Their findings showed that hydrothermal vents were an important source
of DBC in the Pacific Ocean. This hydrothermal DBC is most likely formed
due to the mixing of the hot fluids from hydrothermal vents with cold
seawater, and is transported over long distances -- up to thousands of kilometers away.

"Most importantly, our research indicates that the DBC from hydrothermal
vents is an important source of dissolved organic carbon in the deep
ocean. In terms of DBC inputs to the ocean, hydrothermal vents may
contribute up to half as much DBC as that which is formed by biomass
burning or fossil fuel combustion and subsequently transported via rivers
or atmospheric deposition," concluded Yamashita. Further research is
required to understand exactly how DBC is formed from hydrothermal vents.

* RELATED_TOPICS
o Earth_&_Climate
# Oceanography # Global_Warming # Geology # Air_Quality #
Geography # Forest # Earth_Science # Geochemistry
* RELATED_TERMS
o Carbon_dioxide_sink o Carbon_cycle o Ocean_acidification o
Forest o Carbon_dioxide o Carbon_monoxide o Sea_water o Plankton

========================================================================== Story Source: Materials provided by Hokkaido_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Youhei Yamashita, Yutaro Mori, and Hiroshi
Ogawa. Hydrothermal-derived
black carbon as a source of recalcitrant dissolved organic carbon
in the ocean. Science Advances, 2023 DOI: 10.1126/sciadv.ade3807 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230210145821.htm

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