Kast, E.R., M.L. Griffiths, S.L. Kim, Z.C. Rao, K. Shimada, M.A. Becker, H.M. Maisch, R.A. Eagle, C.A. Clarke, A.N. Neumann, M.E. Karnes, T. Lüdecke, J.N. Leichliter, A. Martínez-García, A.A. Akhtar, X.T. Wang, G.H. Haug, and D.M. Sigman. (2022) 2022. “Cenozoic Megatooth Sharks Occupied Extremely High Trophic Positions”. Science Advances 8 (25). doi:10.1126/sciadv.abl6529.

François, R., M.A. Altabett, E.-F. Yu, D.M. Sigman, M.P. Bacon, M. Frank, G. Bohrmann, G. Bareille, and L.D. Labeyrie. 1997. “Contribution of Southern Ocean Surface-Water Stratification to Low Atmospheric CO2 Concentrations During the Last Glacial Period”. Nature 389. Nature Publishing Group: 929-35. doi:10.1038/40073.

Difiore, P.J., D.M. Sigman, T.W. Trull, M.J. Lourey, K. Karsh, G. Cane, and R. Ho. 2006. “Nitrogen Isotope Constraints on Subantarctic Biogeochemistry”. Journal of Geophysical Research: Oceans 111. Blackwell Publishing Ltd. doi:10.1029/2005JC003216.

Sigman, D.M., S.L. Jaccard, and G.H. Haug. 2004. “Polar Ocean Stratification in a Cold Climate”. Nature 428: 59-63. doi:10.1038/nature02357.

Carrillo, J.H., M.G. Hastings, D.M. Sigman, and B.J. Huebert. 2002. “Atmospheric Deposition of Inorganic and Organic Nitrogen and Base Cations in Hawaii”. Global Biogeochemical Cycles 16. American Geophysical Union: 24-1. doi:10.1029/2002gb001892.

Granger, J., D.M. Sigman, M.G. Prokopenko, M.F. Lehmann, and P.D. Tortell. 2006. “A Method for Nitrite Removal in Nitrate N and O Isotope Analyses”. Limnology and Oceanography: Methods 4. American Society of Limnology and Oceanography Inc.: 205-12. doi:10.4319/lom.2006.4.205.

Granger, J., D.M. Sigman, J.A. Needoba, and P.J. Harrison. 2004. “Coupled Nitrogen and Oxygen Isotope Fractionation of Nitrate During Assimilation by Cultures of Marine Phytoplankton”. Limnology and Oceanography 49. American Society of Limnology and Oceanography Inc.: 1763-73. doi:10.4319/lo.2004.49.5.1763.

Sigman, D.M., K.L. Casciotti, M. Andreani, C. Barford, M. Galanter, and J.K. Böhlke. 2001. “A Bacterial Method for the Nitrogen Isotopic Analysis of Nitrate in Seawater and Freshwater”. Analytical Chemistry 73: 4145-53. doi:10.1021/ac010088e.

Houlton, B.Z., D.M. Sigman, and L.O. Hedin. 2006. “Isotopic Evidence for Large Gaseous Nitrogen Losses from Tropical Rainforests”. Proceedings of the National Academy of Sciences of the United States of America 103: 8745-50. doi:10.1073/pnas.0510185103.

Needoba, J.A., D.M. Sigman, and P.J. Harrison. 2004. “The Mechanism of Isotope Fractionation During Algal Nitrate Assimilation As Illuminated by the 15N 14N of Intracellular Nitrate”. Journal of Phycology 40. Blackwell Publishing Inc.: 517-22. doi:10.1111/j.1529-8817.2004.03172.x.

Haug, G.H., K.A. Hughen, D.M. Sigman, L.C. Peterson, and U. Röhl. 2001. “Southward Migration of the Intertropical Convergence Zone through the Holocene”. Science 293: 1304-8. doi:10.1126/science.1059725.

Sigman, D.M., J. Granger, P.J. Difiore, M.F. Lehmann, R. Ho, G. Cane, and A. van Geen. 2006. “Erratum: "Coupled Nitrogen and Oxygen Isotope Measurements of Nitrate Along the Eastern North Pacific margin&Quot; (Global Biogeochemical Cycles (2005) Vol. 19 10.1029 2005GB002458)”. Global Biogeochemical Cycles 20. doi:10.1029/2005GB002682.

Hastings, M.G., D.M. Sigman, and F. Lipschultz. 2003. “Isotopic Evidence for Source Changes of Nitrate in Rain at Bermuda”. Journal of Geophysical Research: Atmospheres 108. Blackwell Publishing Ltd: 22-1. doi:10.1029/2003jd003789.

Sigman, D.M., and E.A. Boyle. 2001. “Palaeoceanography: Antarctic Stratification and Glacial CO2”. Nature 412: 606. doi:10.1038/35088132.

Hastings, M.G., D.M. Sigman, and E.J. Steig. 2005. “Glacial/Interglacial/Changes/in/the/Isotopes/of/Nitrate/from/the/Greenland/Ice/Sheet/Project/2/(GISP2)/Ice/Core”. Global Biogeochemical Cycles 19. doi:10.1029/2005GB002502.

Sigman, D.M., and G.H. Haug. 2003. The Biological Pump in the Past. Treatise on Geochemistry. Vol. 6-9. Elsevier Inc. doi:10.1016/B0-08-043751-6/06118-1.

Sigman, D.M., and E.A. Boyle. 2000. “Glacial/Interglacial/Variations/in/Atmospheric/Carbon/Dioxide”. Nature 407: 859-69. doi:10.1038/35038000.

Lehmann, M.F., D.M. Sigman, D.C. McCorkle, B.G. Brunelle, S. Hoffmann, M. Kienast, G. Cane, and J. Clement. 2005. “Origin of the Deep Bering Sea Nitrate Deficit: Constraints from the Nitrogen and Oxygen Isotopic Composition of Water Column Nitrate and Benthic Nitrate Fluxes”. Global Biogeochemical Cycles 19. doi:10.1029/2005GB002508.

Saito, M.A., D.M. Sigman, and F.M.M. Morel. 2003. “The Bioinorganic Chemistry of the Ancient Ocean: The Co-Evolution of Cyanobacterial Metal Requirements and Biogeochemical Cycles at the Archean-Proterozoic Boundary?”. Inorganica Chimica Acta 356. Elsevier S.A.: 308-18. doi:10.1016/S0020-1693(03)00442-0.

Sigman, D.M., M.A. Altabet, D.C. McCorkle, R. François, and G. Fischer. 2000. “The δ15N of Nitrate in the Southern Ocean: Nitrogen Cycling and Circulation in the Ocean Interior”. Journal of Geophysical Research: Oceans 105. Blackwell Publishing Ltd: 19599-614. doi:10.1029/2000jc000265.

Robinson, R.S., D.M. Sigman, P.J. Difiore, M.M. Rohde, T.A. Mashiotta, and D.W. Lea. 2005. “Diatom-Bound 15N 14N: New Support for Enhanced Nutrient Consumption in the Ice Age Subantarctic”. Paleoceanography 20: 1-14. doi:10.1029/2004PA001114.

Casciotti, K.L., D.M. Sigman, and B.B. Ward. 2003. “Linking Diversity and Stable Isotope Fractionation in Ammonia-Oxidizing Bacteria”. Geomicrobiology Journal 20: 335-53. doi:10.1080/01490450303895.

Haug, G.H., D.M. Sigman, R. Tiedemann, T.F. Pedersen, and M. Sarnthein. 1999. “Onset of Permanent Stratification in the Subarctic Pacific Ocean”. Nature 401: 779-82. doi:10.1038/44550.

Jaccard, S.L., G.H. Haug, D.M. Sigman, T.F. Pedersen, H.R. Thierstein, and U. Röhl. 2005. “Glacial/Interglacial/Changes/in/Subarctic/North/Pacific/Stratification”. Science 308: 1003-6. doi:10.1126/science.1108696.

Sigman, D.M., R. Robinson, A.N. Knapp, A. van Geen, D.C. McCorkle, J.A. Brandes, and R.C. Thunell. 2003. “Distinguishing Between Water Column and Sedimentary Denitrification in the Santa Barbara Basin Using the Stable Isotopes of Nitrate”. Geochemistry, Geophysics, Geosystems 4. doi:10.1029/2002GC000384.

Sigman, D.M., M.A. Altabet, R. François, D.C. McCorkle, and J.-F. Gaillard. 1999. “The Isotopic Composition of Diatom-Bound Nitrogen in Southern Ocean Sediments”. Paleoceanography 14: 118-34. doi:10.1029/1998PA900018.

Knapp, A.N., D.M. Sigman, and F. Lipschultz. 2005. “N Isotopic Composition of Dissolved Organic Nitrogen and Nitrate at the Bermuda Atlantic Time-Series Study Site”. Global Biogeochemical Cycles 19: 1-15. doi:10.1029/2004GB002320.

Haug, G.H., D. Günther, L.C. Peterson, D.M. Sigman, K.A. Hughen, and B. Aeschlimann. 2003. “Climate and the Collapse of Maya Civilization”. Science 299: 1731-35. doi:10.1126/science.1080444.

Holmes, R.M., J.W. McClelland, D.M. Sigman, B. Fry, and B.J. Peterson. 1998. “Measuring 15N-NH4 + in Marine, Estuarine and Fresh Waters: An Adaptation of the Ammonia Diffusion Method for Samples With Low Ammonium Concentrations”. Marine Chemistry 60: 235-43. doi:10.1016/S0304-4203(97)00099-6.

Haug, G.H., A. Ganopolski, D.M. Sigman, A. Rosell-Mele, G.E.A. Swann, R. Tiedemann, S.L. Jaccard, J. Bollmann, M.A. Maslin, M.J. Leng, and G. Eglinton. 2005. “North Pacific Seasonality and the Glaciation of North America 2.7 Million Years ago”. Nature 433: 821-25. doi:10.1038/nature03332.

Sigman, D.M., S.J. Lehman, and D.W. Oppo. 2003. “Evaluating Mechanisms of Nutrient Depletion and 13C Enrichment in the Intermediate-Depth Atlantic During the Last Ice Age”. Paleoceanography 18. American Geophysical Union: 17-1. doi:10.1029/2002pa000818.

Haug, G.H., T.F. Pedersen, D.M. Sigman, S.E. Calvert, B. Nielsen, and L.C. Peterson. 1998. “Glacial/Interglacial/Variations/in/Production/and/Nitrogen/Fixation/in/the/Cariaco/Basin/During/the/Last/580/Kyr”. Paleoceanography 13. American Geophysical Union: 427-32. doi:10.1029/98PA01976.

Sigman, D.M., J. Granger, P.J. Difiore, M.M. Lehmann, R. Ho, G. Cane, and A. van Geen. 2005. “Coupled Nitrogen and Oxygen Isotope Measurements of Nitrate Along the Eastern North Pacific Margin”. Global Biogeochemical Cycles 19. American Geophysical Union. doi:10.1029/2005GB002458.

Lourey, M.J., T.W. Trull, and D.M. Sigman. 2003. “Sensitivity of δ15N of Nitrate, Surface Suspended and Deep Sinking Particulate Nitrogen to Seasonal Nitrate Depletion in the Southern Ocean”. Global Biogeochemical Cycles 17. American Geophysical Union: 7-1. doi:10.1029/2002gb001973.

Sigman, D.M., D.C. McCorkle, and W.R. Martin. 1998. “The Calcite Isyocline As a Constraint on Glacial Interglacial Low-Latitude Production Changes”. Global Biogeochemical Cycles 12. American Geophysical Union: 409-27. doi:10.1029/98GB01184.

Deutsch, C., D.M. Sigman, R.C. Thunell, A.N. Meckler, and G.H. Haug. 2004. “Isotopic Constraints on Glacial Interglacial Changes in the Oceanic Nitrogen Budget”. Global Biogeochemical Cycles 18: 1-22. doi:10.1029/2003GB002189.

Karsh, K.L., T.W. Trull, M.J. Lourey, and D.M. Sigman. 2003. “Relationship of Nitrogen Isotope Fractionation to Phytoplankton Size and Iron Availability During the Southern Ocean Iron RElease Experiment (SOIREE)”. Limnology and Oceanography 48. American Society of Limnology and Oceanography Inc.: 1058-68. doi:10.4319/lo.2003.48.3.1058.

Hughen, K.A., J.T. Overpeck, S.J. Lehman, M. Kashgarian, J. Southon, L.C. Peterson, R. Alley, and D.M. Sigman. 1998. “Deglacial Changes in Ocean Circulation from an Extended Radiocarbon Calibration”. Nature 391: 65-68. doi:10.1038/34150.

Hastings, M.G., E.J. Steig, and D.M. Sigman. 2004. “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”. Journal of Geophysical Research D: Atmospheres 109: 1-11. doi:10.1029/2004JD004991.

Casciotti, K.L., D.M. Sigman, M.G. Hastings, J.K. Böhlke, and A. Hilkert. 2002. “Measurement of the Oxygen Isotopic Composition of Nitrate in Seawater and Freshwater Using the Denitrifier Method”. Analytical Chemistry 74: 4905-12. doi:10.1021/ac020113w.

Sigman, D.M., M.A. Altabet, R. Michener, D.C. McCorkle, B. Fry, and R.M. Holmes. 1997. “Natural Abundance-Level Measurement of the Nitrogen Isotopic Composition of Oceanic Nitrate: An Adaptation of the Ammonia Diffusion Method”. Marine Chemistry 57: 227-42. doi:10.1016/S0304-4203(97)00009-1.

Robinson, R.S., B.G. Brunelle, and D.M. Sigman. 2004. “Revisiting Nutrient Utilization in the Glacial Antarctic: Evidence from a New Method for Diatom-Bound N Isotopic Analysis”. Paleoceanography 19: 1-13. doi:10.1029/2003PA000996.

Pantoja, S., D.J. Repeta, J.P. Sachs, and D.M. Sigman. 2002. “Stable Isotope Constraints on the Nitrogen Cycle of the Mediterranean Sea Water Column”. Deep-Sea Research Part I: Oceanographic Research Papers 49: 1609-21. doi:10.1016/S0967-0637(02)00066-3.

Thunell, R.C., D.M. Sigman, F. Muller-Karger, Y. Astor, and R. Varela. 2004. “Nitrogen Isotope Dynamics of the Cariaco Basin, Venezuela”. Global Biogeochemical Cycles 18: 1-13. doi:10.1029/2003GB002185.

Tortell, P.D., G.R. DiTullio, D.M. Sigman, and F.M.M. Morel. 2002. “CO2 Effects on Taxonomic Composition and Nutrient Utilization in an Equatorial Pacific Phytoplankton Assemblage”. Marine Ecology Progress Series 236. Inter-Research: 37-43. doi:10.3354/meps236037.

Savarino, J., J. Kaiser, S. Morin, D.M. Sigman, and M.H. Thiemens. 2007. “Nitrogen and Oxygen Isotopic Constraints on the Origin of Atmospheric Nitrate in Coastal Antarctica”. Atmospheric Chemistry and Physics 7. European Geosciences Union: 1925-45. doi:10.5194/acp-7-1925-2007.

Lehmann, M.F., D.M. Sigman, and W.M. Berelson. 2004. “Coupling the 15N 14N and 18O 16O of Nitrate As a Constraint on Benthic Nitrogen Cycling”. Marine Chemistry 88: 1-20. doi:10.1016/j.marchem.2004.02.001.

Brzezinski, M.A., C.J. Pride, V.M. Franck, D.M. Sigman, J.L. Sarmiento, K. Matsumoto, N. Gruber, G.H. Rau, and K.H. Coale. 2002. “A Switch from Si(OH)4 to NO-3 Depletion in the Glacial Southern Ocean”. Geophysical Research Letters 29. American Geophysical Union: 5-1. doi:10.1029/2001gl014349.

Silver, B.J., R. Raymond, D.M. Sigman, M. Prokopeko, Sherwood Lollar, G. Lacrampe-Couloume, M.L. Fogel, L.M. Pratt, L. Lefticariu, and T.C. Onstott. 2012. “The Origin of NO 3 - and N 2 in Deep Subsurface Fracture Water of South Africa”. Chemical Geology 294-295: 51-62. doi:10.1016/j.chemgeo.2011.11.017.

Sigman, D.M., M.P. Hain, and G.H. Haug. 2010. “The Polar Ocean and Glacial Cycles in Atmospheric CO2 Concentration”. Nature 466: 47-55. doi:10.1038/nature09149.