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
7 Publications
Applied Filters: First Letter Of Title: M Reset
Marine biogenic source of atmospheric organic nitrogen in the subtropical North Atlantic
K.E. Altieri, S.E. Fawcett, A.J. Peters, D.M. Sigman, M.G. Hastings
Global models estimate that the anthropogenic component of atmospheric nitrogen (N) deposition to the ocean accounts for up to a third of the ocean s external N supply and 10% of anthropogenic CO2 uptake. However, there are few observational constraints from the marine atmospheric environment to validate these findings. Due to the paucity of…
Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method
K.L. Casciotti, D.M. Sigman, M.G. Hastings, J.K. Böhlke, A. Hilkert
We report a novel method for measurement of the oxygen isotopic composition (18O/16O) of nitrate (NO3-) from both seawater and freshwater. The denitrifier method, based on the isotope ratio analysis of nitrous oxide generated from sample nitrate by cultured denitrifying bacteria, has been described elsewhere for its use in nitrogen isotope ratio …
Measuring 15N-NH4/+ in marine, estuarine and fresh waters: An adaptation of the ammonia diffusion method for samples with low ammonium concentrations
R.M. Holmes, J.W. McClelland, D.M. Sigman, B. Fry, B.J. Peterson
We present a method for measuring 15N-NH4+ in marine, estuarine and fresh waters. The advantage of this method is that it is broadly applicable to all types of water and it allows measurements in samples with lower ammonium concentrations than has previously been possible. The procedure is a modification of the ammonia diffusion method and uses…
The mechanism of isotope fractionation during algal nitrate assimilation as illuminated by the 15N/14N of intracellular nitrate
J.A. Needoba, D.M. Sigman, P.J. Harrison
The 15N/14N of nitrate in the external medium and intracellular pool of the cultured marine diatom Thalassiosira weissflogii (Grun.) Fryxell et Hasle was measured during nitrate assimilation under low light, a 12:12-h light:dark cycle, low temperature, or low iron conditions. The 15N/14N of the nitrate in the medium and the particulate matter both…
Megacity development and the demise of coastal coral communities: Evidence from coral skeleton δ15N records in the Pearl River estuary
N.N. Duprey, T.X. Wang, T. Kim, J.D. Cybulski, H.B. Vonhof, P.J. Crutzen, G.H. Haug, D.M. Sigman, A. Martínez-García, D.M. Baker
Historical coral skeleton (CS) δ18O and δ15N records were produced from samples recovered from sedimentary deposits, held in natural history museum collections, and cored into modern coral heads. These records were used to assess the influence of global warming and regional eutrophication, respectively, on the decline of coastal coral communities…
A method for nitrite removal in nitrate N and O isotope analyses
J. Granger, D.M. Sigman, M.G. Prokopenko, M.F. Lehmann, P.D. Tortell
We describe a method to remove nitrite from seawater and freshwater samples to determine the nitrogen (N) and oxygen (O) isotopic composition of nitrate in aqueous samples (15N/14N and 18O/16O, respectively). This method is simple, inexpensive, and effective in the removal of nitrite without compromising the natural N and O isotopic composition of…
Molecular characterization of water soluble organic nitrogen in marine rainwater by ultra-high resolution electrospray ionization mass spectrometry
K.E. Altieri, M.G. Hastings, A.J. Peters, D.M. Sigman
Atmospheric water soluble organic nitrogen (WSON) is a subset of the complex organic matter in aerosols and rainwater, which impacts cloud condensation processes and aerosol chemical and optical properties and may play a significant role in the biogeochemical cycle of N. However, its sources, composition, connections to inorganic N, and…