Isotopic ratios of nitrite as tracers of the sources and age of oceanic nitrite

Dore, J. E. & Karl, D. M. Nitrification in the euphotic zone as a source for nitrite, nitrate, and nitrous oxide at Station ALOHA. Limnol. Oceanogr. 41, 1619–1628 (1996).

Kiefer, D. A., Olson, R. J. & Holmhansen, O. Another look at nitrite and chlorophyll maxima in central North Pacific. Deep-Sea Res. 23, 1199–1208 (1976).

Lipschultz, F., Zafiriou, O. C. & Ball, L. A. Seasonal fluctuations of nitrite concentrations in the deep oligotrophic ocean. Deep-Sea Res. II 43, 403–419 (1996).

Zafiriou, O. C., Ball, L. A. & Hanley, Q. Trace nitrite in oxic waters. Deep-Sea Res. A 39, 1329–1347 (1992).

Brandhorst, W. Nitrification and denitrification in the Eastern Tropical North Pacific. Journal du Conseil Permanent International pour l’Exploration de la Mer 25, 2–20 (1959).

Codispoti, L. A. & Christensen, J. P. Nitrification, denitrification and nitrous-oxide cycling in the eastern tropical South-Pacific ocean. Mar. Chem. 16, 277–300 (1985).

Codispoti, L. A. Interesting times for marine N2O. Science 327, 1339–1340 (2010).

Freing, A., Wallace, D. W. R. & Bange, H. W. Global oceanic production of nitrous oxide. Phil. Trans. R. Soc. B 367, 1245–1255 (2012).

Lomas, M. W. & Lipschultz, F. Forming the primary nitrite maximum: Nitrifiers or phytoplankton? Nature Med. 51, 2453–2467 (2006).

Dugdale, R. C. & Goering, J. J. Uptake of new and regenerated forms of nitrogen in primary productivity. Limnol. Oceanogr. 12, 196–206 (1967).

Harrison, W. G. & Harris, L. R. Isotope-dilution and its effects on measurements of nitrogen and phosphorus uptake by oceanic microplankton. Mar. Ecol. 27, 253–261 (1986).

Clark, D. R., Rees, A. P. & Joint, I. Ammonium regeneration and nitrification rates in the oligotrophic Atlantic Ocean: Implications for new production estimates. Limnol. Oceanogr. 53, 52–62 (2008).

Jenkins, W. J. Oxygen utilization rates in North-Atlantic sub-tropical gyre and primary production in oligotrophic systems. Nature 300, 246–248 (1982).

Platt, T. et al. Biological production of the oceans—the case for a consensus. Mar. Ecol. 52, 77–88 (1989).

Karl, D. M., Laws, E. A., Morris, P., Williams, P. J. L. & Emerson, S. Global carbon cycle—metabolic balance of the open sea. Nature 426, 32–32 (2003).

Luz, B. & Barkan, E. Assessment of oceanic productivity with the triple-isotope composition of dissolved oxygen. Science 288, 2028–2031 (2000).

Knapp, A. N., Sigman, D. M., Lipschultz, F., Kustka, A. B. & Capone, D. G. Interbasin isotopic correspondence between upper-ocean bulk DON and subsurface nitrate and its implications for marine nitrogen cycling. Glob. Biogeochem. Cycles 25, GB4004 (2011).

Casciotti, K. L., McIlvin, M. & Buchwald, C. Oxygen isotopic exchange and fractionation during bacterial ammonia oxidation. Limnol. Oceanogr. 55, 753–762 (2010).

Buchwald, C., Santoro, A. E., McIlvin, M. R. & Casciotti, K. L. Oxygen isotopic composition of nitrate and nitrite produced by nitrifying cocultures in and natural marine assemblages. Limnol. Oceanogr. 57, 1361–1375 (2012).

Granger, J., Sigman, D. M., Needoba, J. A. & Harrison, P. J. Coupled nitrogen and oxygen isotope fractionation of nitrate during assimilation by cultures of marine phytoplankton. Limnol. Oceanogr. 49, 1763–1773 (2004).

Granger, J., Sigman, D. M., Rohde, M. M., Maldonado, M. T. & Tortell, P. D. N and O isotope effects during nitrate assimilation by unicellular prokaryotic and eukaryotic plankton cultures. Geochim. Cosmochim. Acta 74, 1030–1040 (2010).

Casciotti, K. L., Böhlke, J. K., McIlvin, M. R., Mroczkowski, S. J. & Hannon, J. E. Oxygen isotopes in nitrite: Analysis, calibration, and equilibration. Anal. Chem. 79, 2427–2436 (2007).

Fawcett, S. E., Lomas, M., Casey, J. R., Ward, B. B. & Sigman, D. M. Assimilation of upwelled nitrate by small eukaryotes in the Sargasso Sea. Nature Geosci. 4, 717–722 (2011).

Montoya, J. P. & Voss, M. Nitrogen cycling in suboxic waters: Isotopic signatures of nitrogen transformation in the Arabian Sea oxygen minimum zone. Past Present Water Column Anoxia 64, 259–281 (2006).

Checkley, D. M. & Miller, C. A. Nitrogen isotope fractionation by oceanic zooplankton. Deep-Sea Res. A 36, 1449–1456 (1989).

Macko, S. A., Estep, M. L. F., Engel, M. H. & Hare, P. E. Kinetic fractionation of stable nitrogen isotopes during amino-acid transamination. Geochim. Cosmochim. Acta 50, 2143–2146 (1986).

Waser, N. A. D., Harrison, P. J., Nielsen, B., Calvert, S. E. & Turpin, D. H. Nitrogen isotope fractionation during the uptake and assimilation of nitrate, nitrite, ammonium, and urea by a marine diatom. Limnol. Oceanogr. 43, 215–224 (1998).

Santoro, A. E. & Casciotti, K. L. Enrichment and characterization of ammonia-oxidizing archaea from the open ocean: phylogeny, physiology and stable isotope fractionation. ISME J. 5, 1796–1808 (2011).

Casciotti, K. L. Inverse kinetic isotope fractionation during bacterial nitrite oxidation. Geochim. Cosmochim. Acta 73, 2061–2076 (2009).

Buchwald, C. & Casciotti, K. L. Oxygen isotopic fractionation and exchange during bacterial nitrite oxidation. Limnol. Oceanogr. 55, 1064–1074 (2010).

Yool, A., Martin, A. P., Fernandez, C. & Clark, D. R. The significance of nitrification for oceanic new production. Nature 447, 999–1002 (2007).

Newell, S. E., Babbin, A. R., Jayakumar, A. & Ward, B. B. Ammonia oxidation rates and nitrification in the Arabian Sea. Glob. Biogeochem. Cycles 25, GB4016 (2011).

Lipschultz, F. et al. Bacterial transformations of inorganic nitrogen in the oxygen-deficient waters of the eastern tropical South-Pacific ocean. Deep-Sea Res. A 37, 1513–1541 (1990).

Ward, B. B., Olson, R. J. & Perry, M. J. Microbial nitrification rates in the primary nitrite maximum off Southern-California. Deep-Sea Res. A 29, 247–255 (1982).

Dore, J. E., Popp, B. N., Karl, D. M. & Sansone, F. J. A large source of atmospheric nitrous oxide from subtropical North Pacific surface waters. Nature 396, 63–66 (1998).

Santoro, A. E., Buchwald, C., McIlvin, M. R. & Casciotti, K. L. Isotopic signature of N2O produced by marine ammonia-oxidizing archaea. Science 333, 1282–1285 (2011).

Bunton, C. A., Halevi, E. A. & Llewellyn, D. R. Oxygen exchange between nitric acid and water. J. Chem. Soc. 4913–4916 (1952).

Betts, R. H. & Voss, R. H. Kinetics of oxygen exchange between sulfite ion and water. Canad. J. Chem. 48, 2035–2041 (1970).

Gomori, G. Preparation of buffers for use in enzyme studies. Methods Enzymol. 1, 138–146 (1955).

Robert-Baldo, G. L., Morris, M. J. & Byrne, R. H. Spectrophotometric determination of seawater pH using phenol red. Anal. Chem. 57, 2564–2567 (1985).

Durst, R. A. & Staples, B. R. Tris/tris HCl-standard buffer for use in physiologic pH range. Clin. Chem. 18, 206–208 (1972).

McIlvin, M. R. & Altabet, M. A. Chemical conversion of nitrate and nitrite to nitrous oxide for nitrogen and oxygen isotopic analysis in freshwater and seawater. Anal. Chem. 77, 5589–5595 (2005).

Strickland, J. D. H. & Parsons, T. R. A practical handbook of seawater analysis. Bull. Fish. Res. Board Canada 167, 1–310 (1972).

Clayton, T. D. & Byrne, R. H. Spectrophotometric seawater pH measurements—total hydrogen-ion concentration scale calibration of M-Cresol purple and at-sea results. Deep-Sea Res. I 40, 2115–2129 (1993).