Particle fluxes associated with mesoscale eddies in the Sargasso Sea
Buesseler, Ken O.
Lamborg, Carl H.
Johnson, Rodney J.
Pike, Steven M.
McGillicuddy, Dennis J.
MetadataShow full item record
We examined the impact of a cyclonic eddy and mode-water eddy on particle flux in the Sargasso Sea. The primary method used to quantify flux was based upon measurements of the natural radionuclide, 234Th, and these flux estimates were compared to results from sediment traps in both eddies, and a 210Po/210Pb flux method in the mode-water eddy. Particulate organic carbon (POC) fluxes at 150m ranged from 1 to 4 mmol C m-2 d-1 and were comparable between methods, especially considering differences in integration times scales of each approach. Our main conclusion is that relative to summer mean conditions at the Bermuda Atlantic Time-series Study (BATS) site, eddy-driven changes in biogeochemistry did not enhance local POC fluxes during this later, more mature stage of the eddy life cycle (>6 months old). The absence of an enhancement in POC flux puts a constraint on the timing of higher POC flux events, which are thought to have caused the local O2 minima below each eddy, and must have taken place >2 months prior to our arrival. The mode-water eddy did enhance preferentially diatom biomass in its center where we estimated a factor of 3 times higher biogenic Si flux than the BATS summer average. An unexpected finding in the highly depth resolved 234Th data sets are narrow layers of particle export and remineralization within the eddy. In particular, a strong excess 234Th signal is seen below the deep chlorophyll maxima which we attribute to remineralization of 234Th bearing particles. At this depth below the euphotic zone, de novo particle production in the euphotic zone has stopped, yet particle remineralization continues via consumption of labile sinking material by bacteria and/or zooplankton. These data suggest that further study of processes in ocean layers is warranted not only within, but below the euphotic zone.
Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 55 (2008): 1426-1444, doi:10.1016/j.dsr2.2008.02.007.
Showing items related by title, author, creator and subject.
A new method for the estimation of sinking particle fluxes from measurements of the particle size distribution, average sinking velocity, and carbon content McDonnell, Andrew M. P.; Buesseler, Ken O. (Association for the Sciences of Limnology and Oceanography, 2012-05)We describe a new method for estimating sinking particulate carbon fluxes at high spatial and temporal resolutions from measurements of the particle concentration size distribution taken with an in situ camera system, in ...
What can paired measurements of Th isotope activity and particle concentration tell us about particle cycling in the ocean? Marchal, Olivier; Lam, Phoebe J. (2012-04-17)The ability of paired measurements of thorium isotope activity and particle concentration to constrain rate constants of sorption reactions and particle dynamics in the ocean is examined. This study is motivated by GEOTRACES ...
Richardson, Mary Josephine (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1980-05)This study of particulate matter in the water column and the underlying surface sediments verifies the occurrence of local, present-day resuspension in the deep sea. The location of the major portion of this work was the ...