Studies in the Modern Ocean

CTD/hydrocast package descending into the Southern Ocean. Photo Kenemy

The CTD/hydrocast package descending into the Southern Ocean water column from the deck of the South African research icebreaker S.A. Agulhas II, sailing from Cape Town to the Antarctic winter ice edge. Photo: Preston Cosslett Kemeny ’15

 

References

AuthorTitleTypeYear
11 Publications
Applied Filters: First Letter Of Title: G Reset
The GEOTRACES Intermediate Data Product 2014
E. Mawji, R. Schlitzer, E.M. Dodas, C. Abadie, W. Abouchami, R.F. Anderson, O. Baars, et al

The GEOTRACES Intermediate Data Product 2014 (IDP2014) is the first publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2013. It consists of two parts: (1) a compilation of digital data for more than 200 trace elements and isotopes (TEIs) as well as…

The GEOTRACES Intermediate Data Product 2017
R. Schlitzer, R.F. Anderson, E.M. Dodas, M. Lohan, W. Geibert, A. Tagliabue, A. Bowie, et al

The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the…

Glacial-to-interglacial changes in nitrate supply and consumption in the subarctic North Pacific from microfossil-bound N isotopes at two trophic levels
H. Ren, A.S. Studer, S. Serno, D.M. Sigman, G. Winckler, R.F. Anderson, S. Oleynik, R. Gersonde, G.H. Haug
Reduced nitrate supply to the subarctic North Pacific (SNP) surface during the last ice age has been inferred from coupled changes in diatom-bound δ15N (DB-δ15N), bulk sedimentary δ15N, and biogenic fluxes. However, the reliability of bulk sedimentary and DB-δ15N has been questioned, and a previously reported δ15N minimum during Heinrich Stadial 1…
Glacial/interglacial changes in nutrient supply and stratification in the western subarctic North Pacific since the penultimate glacial maximum
B.G. Brunelle, D.M. Sigman, S.L. Jaccard, L.D. Keigwin, B. Plessen, G. Schettler, M.S. Cook, G.H. Haug
In piston cores from the open subarctic Pacific and the Okhotsk Sea, diatom-bound δ15N (δ15Ndb), biogenic opal, calcium carbonate, and barium were measured from coretop to the previous glacial maximum (MIS 6). Glacial intervals are generally characterized by high δ15Ndb (∼8‰) and low productivity, whereas interglacial intervals have a lower δ15Ndb…
Glacial/interglacial changes in subarctic north pacific stratification
S.L. Jaccard, G.H. Haug, D.M. Sigman, T.F. Pedersen, H.R. Thierstein, U. Röhl
Since the first evidence of low algal productivity during ice ages in the Antarctic Zone of the Southern Ocean was discovered, there has been debate as to whether it was associated with increased polar ocean stratification or with sea-ice cover, shortening the productive season. The sediment concentration of biogenic barium at Ocean Drilling…
Glacial/interglacial changes in the isotopes of nitrate from the Greenland Ice Sheet Project 2 (GISP2) ice core
M.G. Hastings, D.M. Sigman, E.J. Steig
The 15N/14N and 18O/16O ratios of nitrate in the Greenland Ice Sheet Project 2 (GISP2) (Summit, Greenland) ice core are much higher in ice from the last glacial period than in the pre-industrial Holocene, despite the lack of a significant glacial/interglacial change in nitrate concentration. While both the 15N/14N and 18O/16O records are…
Glacial/interglacial variations in atmospheric carbon dioxide
D.M. Sigman, E.A. Boyle
Twenty years ago, measurements on ice cores showed that the concentration of carbon dioxide in the atmosphere was lower during the ice ages than it is today. As yet, there is no broadly accepted explanation for this difference. Current investigations focus on the ocean s biological pump , the sequestration of carbon in the ocean interior by the…
Glacial/interglacial variations in production and nitrogen fixation in the Cariaco Basin during the last 580 kyr
G.H. Haug, T.F. Pedersen, D.M. Sigman, S.E. Calvert, B. Nielsen, L.C. Peterson
The effect of sea level change on nutrient supply to the anoxic Cariaco demonstrates the fundamental importance of nitrogen (N2) fixation and phosphate to oceanic production. As N2 fixation produces biomass of low δ15N and has been reported to be an important component of the nitrogen cycle in the modern Cariaco Basin, we propose that it…
Global Nitrogen Cycle: Critical Enzymes, Organisms, and Processes for Nitrogen Budgets and Dynamics
X. Zhang, B.B. Ward, D.M. Sigman
Nitrogen (N) is used in many of life s fundamental biomolecules, and it is also a participant in environmental redox chemistry. Biogeochemical processes control the amount and form of N available to organisms ("fixed"N). These interacting processes result in N acting as the proximate limiting nutrient in most surface environments. Here, we review…
Ground-truthing the planktic foraminifer-bound nitrogen isotope paleo-proxy in the Sargasso Sea
S.M. Smart, H. Ren, S.E. Fawcett, R. Schiebel, M. Conte, P.A. Rafter, K.K. Ellis, M.A. Weigand, S. Oleynik, G.H. Haug, D.M. Sigman
We report the nitrogen (N) isotope ratios (δ15N) of planktic foraminifera collected from upper-ocean net tows (surface to 200 m), moored sediment traps, and core-top sediments at the Bermuda Time-series Site in the northern Sargasso Sea between 2009 and 2013. Consistent with previous measurements from low-latitude core-top sediments, the annually…
Gulf Stream intensification after the early Pliocene shoaling of the Central American Seaway
A. Auderset, A. Martínez-García, R. Tiedemann, A.P. Hasenfratz, T.I. Eglinton, R. Schiebel, D.M. Sigman, G.H. Haug
The shoaling of the Central American Seaway (CAS) around 4.6 Ma (million years ago) is thought to have enhanced the Gulf Stream, strengthening the Atlantic Meridional Overturning Circulation and potentially influencing the evolution of Pliocene climate. Paleoclimate records indicate a buildup of heat and salt in the Caribbean and changes in the…