Search Results - "Sigman, D. M"

Two Modes of Change in Southern Ocean Productivity Over the Past Million Years by Jaccard, S. L., Hayes, C. T., Martínez-García, A., Hodell, D. A., Anderson, R. F., Sigman, D. M., Haug, G. H.

“…Export of organic carbon from surface waters of the Antarctic Zone of the Southern Ocean decreased during the last ice age, coinciding with declining…”
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Measurement of the Oxygen Isotopic Composition of Nitrate in Seawater and Freshwater Using the Denitrifier Method by Casciotti, K. L, Sigman, D. M, Hastings, M. Galanter, Böhlke, J. K, Hilkert, A

“…We report a novel method for measurement of the oxygen isotopic composition (18O/16O) of nitrate (NO3 -) from both seawater and freshwater. The denitrifier…”
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A Bacterial Method for the Nitrogen Isotopic Analysis of Nitrate in Seawater and Freshwater by Sigman, D. M, Casciotti, K. L, Andreani, M, Barford, C, Galanter, M, Böhlke, J. K

“…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…”
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No iron fertilization in the equatorial Pacific Ocean during the last ice age by Costa, K. M., McManus, J. F., Anderson, R. F., Ren, H., Sigman, D. M., Winckler, G., Fleisher, M. Q., Marcantonio, F., Ravelo, A. C.

“…Core isotope measurements in the equatorial Pacific Ocean reveal that although atmospheric dust deposition during the last ice age was higher than today’s, the…”
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Coupled nitrification-denitrification in sediment of the eastern Bering Sea shelf leads to 15N enrichment of fixed N in shelf waters by Granger, J., Prokopenko, M. G., Sigman, D. M., Mordy, C. W., Morse, Z. M., Morales, L. V., Sambrotto, R. N., Plessen, B.

“…We studied the nitrogen biogeochemistry of the ice‐covered eastern Bering Sea shelf using the isotope ratios (15N/14N and 18O/16O) of NO3− and other N species…”
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Foraminiferal Isotope Evidence of Reduced Nitrogen Fixation in the Ice Age Atlantic Ocean by Ren, H, Sigman, D.M, Meckler, A.N, Plessen, B, Robinson, R.S, Rosenthal, Y, Haug, G.H

“…Fixed nitrogen (N) is a limiting nutrient for algae in the low-latitude ocean, and its oceanic inventory may have been higher during ice ages, thus helping to…”
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Isotopic evidence for a marine ammonium source in rainwater at Bermuda by Altieri, K. E., Hastings, M. G., Peters, A. J., Oleynik, S., Sigman, D. M.

“…Emissions of anthropogenic nitrogen (N) to the atmosphere have increased tenfold since preindustrial times, resulting in increased N deposition to terrestrial…”
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Tracking Agulhas Leakage in the South Atlantic Using Modern Planktic Foraminifera Nitrogen Isotopes by Granger, R., Smart, S. M., Foreman, A., Auderset, A., Campbell, E. C., Marshall, T. A., Haug, G. H., Sigman, D. M., Martínez‐García, A., Fawcett, S. E.

“…Seawater transported into the South Atlantic from the Indian Ocean via “Agulhas leakage” modulates global ocean circulation and has been linked to…”
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Molecular characterization of water soluble organic nitrogen in marine rainwater by ultra-high resolution electrospray ionization mass spectrometry by Altieri, K. E, Hastings, M. G, Peters, A. J, Sigman, D. M

“…Atmospheric water soluble organic nitrogen (WSON) is a subset of the complex organic matter in aerosols and rainwater, which impacts cloud condensation…”
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Distinct nitrogen isotopic compositions of healthy and cancerous tissue in mice brain and head&neck micro-biopsies by Straub, M, Sigman, D M, Auderset, A, Ollivier, J, Petit, B, Hinnenberg, B, Rubach, F, Oleynik, S, Vozenin, M-C, Martínez-García, A

“…Cancerous cells can recycle metabolic ammonium for their growth. As this ammonium has a low nitrogen isotope ratio ( N/ N), its recycling may cause cancer…”
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Nitrogen and oxygen isotopic constraints on the origin of atmospheric nitrate in coastal Antarctica by Savarino, J., Kaiser, J., Morin, S., Sigman, D. M., Thiemens, M. H.

“…Throughout the year 2001, aerosol samples were collected continuously for 10 to 15 days at the French Antarctic Station Dumont d'Urville (DDU) (66°40' S,…”
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Enzyme‐level interconversion of nitrate and nitrite in the fall mixed layer of the Antarctic Ocean by Kemeny, P. C., Weigand, M. A., Zhang, R., Carter, B. R., Karsh, K. L., Fawcett, S. E., Sigman, D. M.

“…In the Southern Ocean, the nitrogen (N) isotopes of organic matter and the N and oxygen (O) isotopes of nitrate (NO3−) have been used to investigate NO3−…”
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Nitrogen losses in anoxic marine sediments driven by Thioploca–anammox bacterial consortia by Prokopenko, M. G., Hirst, M. B., De Brabandere, L., Lawrence, D. J. P., Berelson, W. M., Granger, J., Chang, B. X., Dawson, S., Crane III, E. J., Chong, L., Thamdrup, B., Townsend-Small, A., Sigman, D. M.

“…A novel symbiotic consortium is described between two chemolithotrophic bacteria — anaerobic ammonium-oxidizing (anammox) bacteria and the nitrate-sequestering…”
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Deglacial pulses of deep-ocean silicate into the subtropical North Atlantic Ocean by Meckler, A. N., Sigman, D. M., Gibson, K. A., François, R., Martínez-García, A., Jaccard, S. L., Röhl, U., Peterson, L. C., Tiedemann, R., Haug, G. H.

“…Records of biogenic opal export in the North Atlantic Ocean show pronounced maxima during each glacial termination over the past 550,000 years, consistent with…”
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Glacial/Interglacial Changes in Subarctic North Pacific Stratification by Jaccard, S. L, Haug, G. H, Sigman, D. M, Pedersen, T. F, Thierstein, H. R, Röhl, U

“…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…”
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Seasonal variations in N and O isotopes of nitrate in snow at Summit, Greenland: Implications for the study of nitrate in snow and ice cores by Hastings, Meredith G., Steig, E. J., Sigman, D. M.

“…Nitrogen and oxygen isotopes of NO3− have been measured in snow and firn from Summit, Greenland. The 15N/14N and 18O/16O ratios of NO3− in recently fallen snow…”
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Time-transgressive North Atlantic productivity changes upon Northern Hemisphere glaciation by Lawrence, K. T., Sigman, D. M., Herbert, T. D., Riihimaki, C. A., Bolton, C. T., Martinez-Garcia, A., Rosell-Mele, A., Haug, G. H.

“…Marine biological export productivity declined in high‐latitude regions in the North Pacific and Southern Ocean 2.7 million years ago, in parallel with the…”
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Isotopic composition of rainwater nitrate at Bermuda: The influence of air mass source and chemistry in the marine boundary layer by Altieri, K. E., Hastings, M. G., Gobel, A. R., Peters, A. J., Sigman, D. M.

“…Emissions of anthropogenic nitrogen (N) to the atmosphere have increased tenfold since preindustrial times, resulting in increased N deposition to terrestrial…”
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Southward Migration of the Intertropical Convergence Zone through the Holocene by Haug, Gerald H., Hughen, Konrad A., Sigman, Daniel M., Peterson, Larry C., Röhl, Ursula

“…Titanium and iron concentration data from the anoxic Cariaco Basin, off the Venezuelan coast, can be used to infer variations in the hydrological cycle over…”
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A Seasonal Model of Nitrogen Isotopes in the Ice Age Antarctic Zone: Support for Weakening of the Southern Ocean Upper Overturning Cell by Kemeny, P. C., Kast, E. R., Hain, M. P., Fawcett, S. E., Fripiat, F., Studer, A. S., Martínez‐García, A., Haug, G. H., Sigman, D. M.

“…In the Antarctic Zone of the Southern Ocean, the coupled observations of elevated diatom‐bound 15N/14N (δ15Ndb) and reduced export production during the ice…”
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