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
5 Publications
Applied Filters: First Letter Of Title: L Reset
Laboratory Assessment of the Impact of Chemical Oxidation, Mineral Dissolution, and Heating on the Nitrogen Isotopic Composition of Fossil-Bound Organic Matter
A. Martínez-García, J. Jung, X.E. Ai, D.M. Sigman, A. Auderset, N.N. Duprey, A.D. Foreman, F. Fripiat, J.N. Leichliter, T. Lüdecke, S. Moretti, T. Wald

Fossil-bound organic material holds great potential for the reconstruction of past changes in nitrogen (N) cycling. Here, with a series of laboratory experiments, we assess the potential effect of oxidative degradation, fossil dissolution, and thermal alteration on the fossil-bound N isotopic composition of different fossil types, including…

Life and death of a sewage treatment plant recorded in a coral skeleton Δ15N record
N.N. Duprey, X.T. Wang, P.D. Thompson, J.E. Pleadwell, L.J. Raymundo, K. Kim, D.M. Sigman, D.M. Baker
We investigated the potential of coral skeleton δ15N (CS-δ15N) records for tracking anthropogenic-N sources in coral reef ecosystems. We produced a 56 yr-long CS-δ15N record (1958–2014) from a reef flat in Guam that has been exposed to varying 1) levels of sewage treatment 2) population density, and 3) land use. Increasing population density (from…
Linking diversity and stable isotope fractionation in ammonia-oxidizing bacteria
K.L. Casciotti, D.M. Sigman, B.B. Ward

The link between similarity in amino acid sequence,for ammonia monooxygenase (AMO) and isotopic discrimination for ammonia oxidation (εAMO) was investigated in β-subdivision ammonia-oxidizing bacteria. The isotope effects for ammonia oxidation in pure cultures of the nitrifying strains. Nitrosomonas marina, Nitrosomonas C-113a, Nitrosospira…

Links between tropical rainfall and North Atlantic climate during the last glacial period
G. Deplazes, A. Lückge, L.C. Peterson, A. Timmermann, Y. Hamann, K.A. Hughen, U. Röhl, C. Laj, M.A. Cane, D.M. Sigman, G.H. Haug
During the last glacial period, the North Atlantic regionexperienced pronounced, millennial-scale alternations between cold, stadial conditions and milder interstadial conditions - commonly referred to as Dansgaard-Oeschger oscillations - as well as periods of massive iceberg discharge known as Heinrich events1. Changes in Northern Hemisphere…
Low-nutrient organic matter in the Sargasso Sea thermocline: A hypothesis for its role, identity, and carbon cycle implications
S.E. Fawcett, K.S. Johnson, S.C. Riser, N. Van Oostende, D.M. Sigman
Despite slow nutrient supply to the subtropical surface ocean, its rates of annual inorganic carbon drawdown and net oxygen production are similar to those of nutrient-rich high latitude waters. This surprisingly rapid carbon drawdown, if due to the production and export of marine biomass, cannot be explained in terms of known nutrient supply…