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
6 Publications
Applied Filters: First Letter Of Title: B Reset
A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater
D.M. Sigman, K.L. Casciotti, M. Andreani, C. Barford, M. Galanter, J.K. Böhlke

We report a new method for measurement of the isotopic composition of nitrate (NO3-) at the natural-abundance level in both seawater and freshwater. The method is based on the isotopic analysis of nitrous oxide (N2O) generated from nitrate by denitrifying bacteria that lack N2O-reductase activity. The isotopic composition of both nitrogen and…

The Bering Strait was flooded 10,000 years before the Last Glacial Maximum
J.R. Farmer, T. Pico, O.M. Underwood, R. Stout, J. Granger, T.M. Cronin, François Fripiat, A. Martínez-García, G.H. Haug, D.M. Sigman

The cyclic growth and decay of continental ice sheets can be reconstructed from the history of global sea level. Sea level is relatively well constrained for the Last Glacial Maximum (LGM, 26,500 to 19,000 y ago, 26.5 to 19 ka) and the ensuing deglaciation. However, sea-level estimates for the period of ice-sheet growth before the LGM vary by …

Biogenic-to-lithogenic handoff of particulate Zn affects the Zn cycle in the Southern Ocean
J. Duan, R. Cloete, J.C. Loock, A. Lanzirotti, M. Newville, A. Martínez-García, D.M. Sigman, P.J. Lam, A.N. Roychoudhury, S.C.B. Myneni
Zinc (Zn) is vital to marine organisms. Its active uptake by phytoplankton results in a substantial depletion of dissolved Zn, and Zn bound to particulate organic matter replenishes dissolved Zn in the ocean through remineralization. However, we found that particulate Zn changes from Zn bound to phosphoryls in cells to recalcitrant inorganic pools…
The bioinorganic chemistry of the ancient ocean: The co-evolution of cyanobacterial metal requirements and biogeochemical cycles at the Archean-Proterozoic boundary?
M.A. Saito, D.M. Sigman, F.M.M. Morel
Recent evidence from the sulfur isotopic record indicates a transition ∼2.5 billion years ago from an ocean chemistry first dominated by iron and then by sulfide. It has been hypothesized that the selection of metal centers in metalloenzymes has been influenced by the availability of metals through geological time, in particular as a result of…
The Biological Pump in the Past
D.M. Sigman, G.H. Haug

It is easy to imagine that the terrestrial biosphere sequesters atmospheric carbon dioxide; the form and quantity of the sequestered carbon, living or dead organic matter, are striking. In the ocean, there are no aggregations of biomass comparable to the forests on land. Yet biological productivity in the ocean plays a central role in the…

The Biological Pump in the Past
M.P. Hain, D.M. Sigman, G.H. Haug
The ocean s biological pump refers to the coupled biological, chemical, and physical processes that work to concentrate carbon and other biologically active elements in the voluminous ocean interior, sequestering them from the surface ocean and the atmosphere. Current research seeks to understand the relationship of the ocean s biological pump…