Archive for bottom water

The Ross Sea deep microbial community’s role in sequestering CO2

Posted by mmaheigan 
· Thursday, November 9th, 2017 

Antarctic shelf systems generate the densest waters in the world. These shelf waters are the building blocks of Antarctic Bottom Water, the ocean’s abyssal water mass. These bottom waters have the potential to sequester carbon out of the atmosphere for millennia. One such form of marine carbon is dissolved organic carbon (DOC). DOC is produced in the surface ocean via primary production and is the global ocean’s largest standing stock of reduced carbon.

In a recent study, Bercovici et al (2017) used hydrographic and biogeochemical measurements to assess the mechanism that brings DOC into the shelf waters of the Ross Sea, the shelf system in the Pacific sector of Antarctica. These mechanisms include sinking particles, brine rejection caused by katabatic winds in the Terra Nova Bay polynya, and vertical mixing. This study revealed that DOC is primarily introduced into the deeper shelf waters via convective overturning and deep vertical mixing upon the onset of austral winter. Substantial DOC enrichment of shelf waters suggests that this carbon is exported off the shelf into Antarctic Bottom Water. However, this study finds much of the excess Ross Sea shelf DOC is actually consumed and remineralized to CO2 by deep microbial communities at the slope of the Ross Sea shelf, ultimately sequestering this carbon into the ocean’s interior.

Physical and biological processes have the potential to introduce carbon into the dense shelf waters (blue) in the Ross Sea. Incoming waters (yellow) are modified from the Southern Ocean’s circumpolar waters. At the onset of winter, cooler temperatures and katabatic winds cause brine rejection. The rejection of brine, sinking particles and vertical mixing are all potential mechanisms for bringing DOC to the dense shelf waters. At the shelf slope, outflowing shelf waters ultimately contribute to Antarctic Bottom Water formation. This research furthers our understanding of global carbon cycling through demonstrating that Antarctic shelf systems have the potential to sequester organic carbon into the abyssal ocean.

Authors:
Sarah K. Bercovici (Rosenstiel School of Marine and Atmospheric Science, University of Miami)
Bruce A. Huber (Lamont Doherty Earth Observatory, Columbia University)
Hans B. Dejong (Stanford University)
Robert B. Dunbar (Stanford University)
Dennis A. Hansell (Rosenstiel School of Marine and Atmospheric Science, University of Miami)

Filter by Keyword

acidification air-sea interactions allometry AMOC Antarctica anthropogenic carbon aragonite saturation arctic argo Atlantic Atlantic modeling atmospheric CO2 atmospheric nitrogen deposition autonomous observing autonomous platforms BATS bcg-argo biogeochemical cycles biogeochemical models biological pump biological uptake bloom blooms blue carbon bottom water calcification calcite carbon-climate feedback carbon cycle Caribbean CCS changing marine ecosystems changing ocean chemistry chl a chlorophyll circulation climate change CO2 coastal and estuarine coastal carbon fluxes coastal ocean cobalt community composition conservation cooling effect copepod coral reefs DCM deep convection deep ocean deep sea coral diatoms dimethylsulfide DOC domoic acid dust earth system models eddy Education Ekman transport emissions ENSO enzyme equatorial regions estuarine and coastal carbon fluxes estuary EXPORTS filter feeders filtration rates fish fisheries floats fluid dynamics fluorescence food webs forams geochemistry geoengineering GEOTRACES glaciers gliders global carbon budget global warming greenhouse gas Greenland Gulf of Maine Gulf of Mexico Gulf Stream gyre harmful algal bloom human impact hydrothermal hypoxia ice age ice ages ice cover iron iron fertilization isotopes katabatic winds kelvin waves kuroshio larvaceans lateral transport lidar ligands mangroves marine boundary layer marine snowfall marshes meltwater mesopelagic mesoscale metagenome metals methane microbes microlayer microorganisms microscale microzooplankton midwater mixed layer mixotrophy modeling mode water formation molecular diffusion MPT NASA net community production new technology nitrogen nitrogen fixation nitrous oxide north atlantic north pacific nutricline nutrient budget nutrient cycling nutrient flux nutrient limitation nutrients ocean-atmosphere ocean carbon uptake and storage ocean color ocean observatories ODZ oligotrophic OMZ open ocean organic particles overturning circulation oxygen paleoceanography particle flux particulate organic carbon pCO2 PDO pH phosphorus photosynthesis physical processes physiology phytoplankton plankton polar regions pollutants primary productivity pteropods radioisotopes remineralization remote sensing residence time respiration rivers Rossby waves Ross Sea ROV salinity salt marsh satellite scale seagrass sea ice sea level rise seasonal patterns sediments sensors shelf system ship-based observations sinking particles SOCCOM southern ocean south pacific speciation species oscillations subduction submesoscale subpolar subtropical subtropical gyres subtropical mode water surface ocean teleconnections temperature thermohaline thorium time-series top predators trace element trace elements trace metals trait-based transfer efficiency transient features trophic transfer tropical turbulence twilight zone upper ocean upper water column upwelling US CLIVAR velocity gradient ventilation vertical flux vertical migration vertical transport western boundary currents wetlands winter mixing zooplankton

Copyright © 2019 - OCB Project Office, Woods Hole Oceanographic Institution, 266 Woods Hole Rd, MS #25, Woods Hole, MA 02543 USA Phone: 508-289-2838  •  Fax: 508-457-2193  •  Email: ocb_news@us-ocb.org

link to nsflink to noaalink to WHOI

Funding for the Ocean Carbon & Biogeochemistry Project Office is provided by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA). The OCB Project Office is housed at the Woods Hole Oceanographic Institution.