BG Biogeosciences BG 1726-4189 Copernicus GmbH Göttingen, Germany 10.5194/bg-7-3901-2010 Diagenetic control of nitrogen isotope ratios in Holocene sapropels and recent sediments from the Eastern Mediterranean Sea Möbius J. 1 Lahajnar N. 1 Emeis K.-C. 1 Institute of Biogeochemistry and Marine Chemistry, University of Hamburg, Bundesstr. 55, 20146 Hamburg, Germany 30 11 2010 7 11 3901 3914 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.biogeosciences.net/7/3901/2010/bg-7-3901-2010.html The full text article is available as a PDF file from http://www.biogeosciences.net/7/3901/2010/bg-7-3901-2010.pdf

The enhanced accumulation of organic matter in Eastern Mediterranean sapropels and their unusually low &delta;<sup>15</sup>N values have been attributed to either enhanced nutrient availability which led to elevated primary production and carbon sequestration or to enhanced organic matter preservation under anoxic conditions. In order to evaluate these two hypothesis we have determined Ba/Al ratios, amino acid composition, N and organic C concentrations and &delta;<sup>15</sup>N in sinking particles, surface sediments, eight spatially distributed core records of the youngest sapropel S1 (10–6 ka) and older sapropels (S5, S6) from two locations. These data suggest that (i) temporal and spatial variations in &delta;<sup>15</sup>N of sedimentary N are driven by different degrees of diagenesis at different sites rather than by changes in N-sources or primary productivity and (ii) present day TOC export production would suffice to create a sapropel like S1 under conditions of deep-water anoxia. This implies that both enhanced TOC accumulation and &delta;<sup>15</sup>N depletion in sapropels were due to the absence of oxygen in deep waters. Thus preservation plays a major role for the accumulation of organic-rich sediments casting doubt on the need of enhanced primary production for sapropel formation.

 References % vor jede Referenz Altabet, M. A.: Variations in nitrogen isotopic composition between sinking and suspended particles: implications for nitrogen cycling and particle transformation in the open ocean, Deep-Sea Res. Pt. I, 35, 535–554, 1988. % vor jede Referenz Altabet, M. A.: Nitrogen and carbon isotopic tracers of the source and transformation of particles in the deep-sea, in: Particle Flux in the Ocean, edited by: Ittekkot, V., Schafer, P., Honjo, S., and Depetris, P. J., Wiley London, 155–184, 1996. % vor jede Referenz Altabet, M. A.: Constraints on oceanic N balance/imbalance from sedimentary $^15$N records, Biogeosciences, 4, 75–86, doi:10.5194/bg-4-75-2007, 2007. % vor jede Referenz Altabet, M. A. and Francois, R.: Sedimentary Nitrogen Isotopic Ratio as a Recorder for Surface Ocean Nitrate Utilization, Global Biogeochem. Cy., 8, 103–116, 1994. % vor jede Referenz Anastasakis, G. C. and Stanley, D. J.: Sapropels and organic-rich variants in the Mediterranean: sequence development and classification, in: Fine-grained Sediments: Deep-water Processes and Facies, edited by: Stow, D. A. W. and Piper, D. J. W., Geological Society London, 497–510, 1984. % vor jede Referenz Anastasakis, G. C. and Stanley, D. J.: Uppermost Sapropel, Eastern Mediterranean – Paleoceanography and Stagnation, Natl. Geogr. Res., 2, 179–197, 1986. % vor jede Referenz Arnaboldi, M. and Meyers, P. A.: Patterns of organic carbon and nitrogen isotopic compositions of latest Pliocene sapropels from six locations across the Mediterranean Sea, Palaeogeogr. Palaeocl., 235, 149–167, 2006. % vor jede Referenz Bada, J. L., Schoeninger, M. J., and Schimmelmann, A.: Isotopic Fractionation During Peptide-Bond Hydrolysis, Geochim. Cosmochim. Ac., 53, 3337–3341, 1989. % vor jede Referenz Bethoux, J. P.: Oxygen-Consumption, New Production, Vertical Advection and Environmental Evolution in the Mediterranean-Sea, Deep-Sea Res. Pt. I, 36, 769–781, 1989. % vor jede Referenz Bishop, J. K. B.: The barite-opal-organic carbon association in oceanic particulate matter, Nature, 332, 341–343, 1988. % vor jede Referenz Calvert, S. E., Nielsen, B., and Fontugne, M. R.: Evidence from nitrogen isotope ratios for enhanced productivity during formation of Eastern Mediterranean sapropels, Nature, 359, 223–225, 1992. % vor jede Referenz Cheddadi, R. and Rossignol-Strick, M.: Eastern Mediterranean Quaternary Paleoclimates from Pollen and Isotope Records of Marine Cores in the Nile Cone Area, Paleoceanography, 10, 291–300, 1995. % vor jede Referenz Coban-Yildiz, Y., Altabet, M. A., Yilmaz, A., and Tugrul, S.: Carbon and nitrogen isotopic ratios of suspended particulate organic matter (SPOM) in the Black Sea water column, Deep-Sea Res. Pt. II, 53, 1875–1892, 2006. % vor jede Referenz Dähnke, K., Serna, A., Blanz, T., and Emeis, K. C.: Sub-recent nitrogen-isotope trends in sediments from Skagerrak (North sea) and Kattegat: Changes in N-budgets and N-sources?, Mar. Geol., 253, 92–98, 2008. % vor jede Referenz Dauwe, B., Middelburg, J. J., Herman, P. M. J., and Heip, C. H. R.: Linking diagenetic alteration of aminoacids and bulk organic matter reactivity, Limnol. Oceanogr., 44, 1809–1814, 1999. % vor jede Referenz De Lange, G. J., Thomson, J., Reitz, A., Slomp, C. P., Principato, M. S., Erba, E., and Corselli, C.: Synchronous basin-wide formation and redox-controlled preservation of a Mediterranean sapropel, Nat. Geosci., 1, 606–610, doi:10.1038/ngeo283, 2008. % vor jede Referenz Dehairs, F., Chesselet, R., and Jedwab, J.: Discrete suspended \mboxparticles of barite and the barium cycle in the open ocean, Earth Planet. Sc. Lett., 49, 528–550, 1980. % vor jede Referenz Dehairs, F., Goeyens, L., Stroobants, N., Bernard, P., Goyet, C., Poisson, A., and Chesselet, R.: On Suspended Barite and the Oxygen Minimum in the Southern Ocean, Global Biogeochem. Cy., 40, 85–102, 1990. % vor jede Referenz Dymond, J., Suess, E., and Lyle, M.: Barium in deep-sea sediments: A geochemical proxy for paleoproductivity, Paleoceanography, 7, 163–181, 1992. % vor jede Referenz Emeis, K. C. and Weissert, H.: Tethyan-Mediterranean organic carbon-rich sediments from Mesozoic black shales to sapropels, Sedimentology, 56, 247–266, 2009. % vor jede Referenz Emeis, K.-C., Robertson, A. H. F., and Richter, C. (Eds.): Proceedings of the Ocean Drilling Program, Initial Reports 160, Ocean Drilling Program, College Station, TX, 972 pp., 1996. % vor jede Referenz Emeis, K.-C., Struck, U., Schulz, H.-M., Rosenberg, R., Bernasconi, S., Erlenkeuser, H., Sakamoto, T., and Martinez-Ruiz, F.: Temperature and salinity variations of Mediterranean Sea surface waters over the last 16 000 years from records of planktonic stable oxygen isotopes and alkenone unsaturation ratios, Palaeogeogr. Palaeocl., 158, 259–280, 2000. % vor jede Referenz Farrell, G., Pedersen, T. F., Calvert, S. E., and Nielsen, B.: Glacial-interglacial changes in nutrient utilization in the equatorial Pacific Ocean, Nature, 377, 514–517, 1995. % vor jede Referenz Francois, R., Honjo, S., Manganini, S. J., and Ravizza, G. E.: Biogenic Barium Fluxes to the Deep-Sea – Implications for Paleoproductivity Reconstruction, Global Biogeochem. Cy., 9, 289–303, 1995. % vor jede Referenz Freudenthal, T., Wagner, T., Wenzhöfer, F., Zabel, M., and Wefer, G.: Early diagenesis of organic matter from sediments of the eastern subtropical Atlantic: evidence from stable nitrogen and carbon isotopes, Geochim. Cosmochim. Ac., 65, 1795–1808, 2001. % vor jede Referenz Fry, B.: Stable Isotope Ecology, Springer-Verlag, Berlin, 308 pp., 2007. % vor jede Referenz Fry, B., Jannasch, H. W., Molyneaux, S. J., Wirsen, C. O., Muramoto, J. A., and King, S.: Stable Isotope Studies of the Carbon, Nitrogen and Sulfur Cycles in the Black-Sea and the Cariaco Trench, Deep-Sea Res. Pt. I, 38, 1003–1019, 1991. % vor jede Referenz Fuchsman, C. A., Murray, J. W., and Konovalov, S. K.: Concentration and natural stable isotope profiles of nitrogen species in the Black Sea, Mar. Chem., 111, 90–105, 2008. % vor jede Referenz Ganeshram, R. S., Pedersen, T. F., Calvert, S. E., and Francois, R.: Reduced nitrogen fixation in the glacial ocean inferred from changes in marine nitrogen and phosphorus inventories, Nature, 415, 156–159, 2002. % vor jede Referenz Garvin, J., Buick, R., Anbar, A. D., Arnold, G. L., and Kaufman, A. J.: Isotopic Evidence for an Aerobic Nitrogen Cycle in the Latest Archean, Science, 323, 1045–1048, 2009. % vor jede Referenz Gaye-Haake, B., Lahajnar, N., Emeis, K. C., Unger, D., Rixen, T., Suthhof, A., Ramaswamy, V., Schulz, H., Paropkari, A. L., Guptha, M. V. S., and Ittekkot, V.: Stable nitrogen isotopic ratios of sinking particles and sediments from the northern Indian Ocean, Mar. Chem., 96, 243–255, 2005. % vor jede Referenz Giunta, S., Negri, A., Morigi, C., Capotondi, L., Combourieu-Nebout, N., Emeis, K. C., Sangiorgi, F., and Vigliotti, L.: Coccolithophorid ecostratigraphy and multi-proxy paleoceanographic reconstruction in the Southern Adriatic Sea during the last deglacial time (Core AD91-17), Palaeogeogr. Palaeocl., 190, 39–59, 2003. % vor jede Referenz Higgins, M. B., Robinson, R. S., Carter, S. J., and Pearson, A.: Evidence from chlorine isotopes for alternating nutrient regimes in the Eastern Mediterranean Sea, Earth Planet. Sc. Lett., 290, 102–107, 2010. % vor jede Referenz Hoch, M. P., Fogel, M. L., and Kirchman, D. L.: Isotope Fractionation Associated with Ammonium Uptake by a Marine Bacterium, Limnol. Oceanogr., 37, 1447–1459, 1992. % vor jede Referenz Holmes, M. E., Muller, P. J., Schneider, R. R., Segl, M., Patzold, J., and Wefer, G.: Stable nitrogen isotopes in Angola Basin surface sediments, Mar. Geol., 134, 1–12, 1996. % vor jede Referenz Holmes, M. E., Müller, P. J., Segl, M., and Wefer, G.: Reconstruction of past nutrient utilization in the eastern Angola Basin based on sedimentary 15N/14N ratios, Paleoceanography, 12(4), 604–614, 1997. % vor jede Referenz Howell, M. W. and Thunell, R. C.: Organic carbon accumulation in Bannock Basin: Evaluating the role of productivity in the formation of eastern Mediterranean sapropels, Mar. Geol., 103, 461–471, 1992. % vor jede Referenz Jenkyns, H. C., Grocke, D. R., and Hesselbo, S. P.: Nitrogen isotope evidence for water mass denitrification during the early Toarcian (Jurassic) oceanic anoxic event, Paleoceanography, 16, 593–603, 2001. % vor jede Referenz Jennerjahn, T. C. and Ittekkot, V.: Changes in organic matter from surface waters to continental slope sediments off the Sao Francisco River, eastern Brazil, Mar. Geol., 161, 129–140, 1999. % vor jede Referenz Jung, M., Ilmberger, J., Mangini, A., and Emeis, K. C.: Why some Mediterranean sapropels survived burn-down (and others did not), Mar. Geol., 141, 51–60, 1997. % vor jede Referenz Kemp, A. E. S., Pearce, R. B., Koizumi, I., Pike, J., and Rance, S. J.: The role of mat-forming diatoms in the formation of Mediterranean sapropels, Nature, 398, 57–61, 1999. % vor jede Referenz Krom, M. D., Woodward, E. M. S., Herut, B., Kress, N., Carbo, P., Mantoura, R. F. C., Spyres, G., Thingstad, T. F., Wassmann, P., Wexels-Riser, C., Kitidis, V., Law, C. S., and Zodiatis, G.: Nutrient cycling in the south east Levantine basin of the eastern Mediterranean: Results from a phosphorus starved system, Deep-Sea Res. Pt. II, 52, 2879–2896, 2005. % vor jede Referenz Krom, M. D., Emeis, K. C., and Van Cappellen, P.: Why is the Eastern Mediterranean phosphorus limited?, Progr. Oceanogr., 85, 236–244, 2010. % vor jede Referenz Kuhnt, T., Schmiedl, G., Ehrmann, W., Hamann, Y., and Hemleben, C.: Deep-sea ecosystem variability of the Aegean Sea during the past 22 kyr as revealed by Benthic Foraminifera, Mar. Micropaleontol., 64, 141–162, 2007. % vor jede Referenz Kuypers, M. M. M., van Breugel, Y., Schouten, S., Erba, E., and Damste, J. S. S.: N-2-fixing cyanobacteria supplied nutrient N for Cretaceous oceanic anoxic events, Geology, 32, 853–856, 2004. % vor jede Referenz Lahajnar, N., Wiesner, M. G., and Gaye, B.: Fluxes of amino acids and hexosamines to the deep South China Sea, Deep-Sea Res. Pt. I, 54, 2120–2144, 2007. % vor jede Referenz Lehmann, M. F., Bernasconi, S. M., Barbieri, A., and McKenzie, J. A.: Preservation of organic matter and alteration of its carbon and nitrogen isotope composition during simulated and in situ early sedimentary diagenesis, Geochim. Cosmochim. Ac., 66, 3573–3584, 2002. % vor jede Referenz Macko, S. A. and Estep, M. L. F.: Microbial alteration of stable nitrogen and carbon isotopic compositions of organic matter, Org. Geochem., 6, 787–790, 1984. % vor jede Referenz Mara, P., Mihalopoulos, N., Gogou, A., Daehnke, K., Schlarbaum, T., Emeis, K. C., and Krom, M.: Isotopic composition of nitrate in wet and dry atmospheric deposition on Crete in the eastern Mediterranean Sea, Global Biogeochem. Cy., 23, GB4002, doi:10.1029/2008gb003395, 2009. % vor jede Referenz Mayer, B., Boyer, E. W., Goodale, C., Jaworski, N. A., Van Breemen, N., Howarth, R. W., Seitzinger, S., Billen, G., Lajtha, L. J., Nosal, M., and Paustian, K.: Sources of nitrate in rivers draining sixteen watersheds in the northeastern US: Isotopic constraints, Biogeochemistry, 57, 171–197, 2002. % vor jede Referenz McCarthy, J. J., Yilmaz, A., Coban-Yildiz, Y., and Nevins, J. L.: Nitrogen cycling in the offshore waters of the Black Sea, Estuar. Coast. Shelf S., 74, 493–514, 2007. % vor jede Referenz McClelland, J. W. and Valiela, I.: Linking nitrogen in estuarine producers to land-derived sources, Limnol. Oceanogr., 43, 577–585, 1998. % vor jede Referenz McCoy, F. W.: Late Quaternary sedimentation in the eastern Mediterranean Sea, Harvard University, 1974. % vor jede Referenz Mercone, D., Thomson, J., Abu-Zied, R. H., Croudace, I. W., and Rohling, E. J.: High-resolution geochemical and micropalaeontological profiling of the most recent eastern Mediterranean sapropel, Mar. Geol., 177, 25–44, 2001. % vor jede Referenz Meyers, P. A. and Bernasconi, S. M.: Carbon and nitrogen isotope excursions in mid-Pleistocene sapropels from the Tyrrhenian Basin: Evidence for climate-induced increases in microbial primary production, Mar. Geol., 220, 41–58, 2005. % vor jede Referenz Milder, J. C. and Montoya, J. P.: Carbon and nitrogen stable isotope ratios at Sites 969 and 974: interpreting spatial gradients in sapropel properties, in: Proc. ODP, Scientific Results, edited by: Zahn, R., Comas, M., and Klaus, A., Ocean Drilling Programm College Station, 161, 401–411, 1999. % vor jede Referenz Minagawa, M. and Wada, E.: Nitrogen Isotope Ratios of Red Tide Organisms in the East-China-Sea – a Characterization of Biological Nitrogen-Fixation, Mar. Chem., 19, 245–259, 1986. % vor jede Referenz Moodley, L., Middleburg, J. J., Herman, P. M. J., Soetaert, K., and de Lange, G. J.: Oxygenation and organic-matter preservation in marine sediments: Direct experimental evidence from ancient organic carbon-rich deposits, Geology, 33, 889–892, 2005. % vor jede Referenz Murat, A. and Got, H.: Organic carbon variations of the eastern Mediterranean Holocene sapropel: a key for understanding formation processes, Palaeogeogr. Palaeocl., 158, 241–257, 2000. % vor jede Referenz Pantoja, S., Repeta, D. J., Sachs, J. P., and Sigman, D. M.: Stable isotope constraints on the nitrogen cycle of the Mediterranean Sea water column, Deep-Sea Res. Pt. I, 49, 1609–1621, 2002. % vor jede Referenz Ren, H., Sigman, D., Meckler, A. N., Plessen, B., Robinson, R. S., Rosenthal, Y., and Haug, G. H.: Foraminiferal Isotope Evidence of Reduced Nitrogen Fixation in the Ice Age Atlantic Ocean, Science, 323, 244–248, 2009. % vor jede Referenz Reschke, S.: Biogeochemie der Schwebstofffracht der Donau und deren Einfluß auf das Sedimentationsgeschehen im nordwestlichen Schwarzen Meer, Ph.D thesis, Universität Hamburg, Hamburg, 109 pp., 1999. % vor jede Referenz Rohling, E. J.: Review and new aspects concerning the formation of eastern Mediterranean sapropels, Mar. Geol., 122, 1–28, 1994. % vor jede Referenz Rohling, E. J., Hopmans, E. C., and Damste, J. S. S.: Water column dynamics during the last interglacial anoxic event in the Mediterranean (sapropel S5), Paleoceanography, 21, PA2018, doi:10.1029/2005Pa001237, 2006. % vor jede Referenz Rossignolstrick, M., Nesteroff, W., Olive, P., and Vergnaudgrazzini, C.: After the Deluge – Mediterranean Stagnation and Sapropel Formation, Nature, 295, 105–110, 1982. % vor jede Referenz Ryan, W. B. F.: Stratigraphy of Late Quarternary sediments in the eastern Mediterranean, in: The Mediterranean Sea: a Natural Sedimentation Laboratory, edited by: Stanley, D. J., Dowden, Hutchinson and Ross, Stroudsburg, Pa, 149–169, 1972. % vor jede Referenz Sachs, J. P. and Repeta, D. J.: Oligotrophy and Nitrogen Fixation During Eastern Mediterranean Sapropel Events, Science, 286, 2485–2488, 1999. % vor jede Referenz Saino, T. and Hattori, A.: N-15 Natural Abundance in Oceanic Suspended Particulate Matter, Nature, 283, 752–754, 1980. % vor jede Referenz Sigman, D. M., Altabet, M. A., Francois, R., McCorkle, D. C., and Gaillard, J. F.: The isotopic composition of diatom-bound nitrogen in Southern Ocean sediments, Paleoceanography, 14, 118–134, 1999. % vor jede Referenz Silfer, J. A., Engel, M. H., and Macko, S. A.: Kinetic Fractionation of Stable Carbon and Nitrogen Isotopes During Peptide-Bond Hydrolysis – Experimental-Evidence and Geochemical Implications, Chem. Geol., 101, 211–221, 1992. % vor jede Referenz Slomp, C. P., Thomson, J., and de Lange, G. J.: Enhanced regeneration of phosphorus during formation of the most recent eastern Mediterranean sapropel (S1), Geochim. Cosmochim. Ac., 66, 1171–1184, 2002. % vor jede Referenz Struck, U., Emeis, K.-C., Voss, M., Krom, M. D., and Rau, G. H.: Biological productivity during sapropel S5 formation in the Eastern Mediterranean Sea: evidence from stable isotopes of nitrogen and carbon, Geochim. Cosmochim. Ac., 65, 3249–3266, 2001. % vor jede Referenz Thomson, J., Higgs, N. C., Wilson, T. R. S., Croudace, I. W., De Lange, G. J., and Van Santvoort, P. J. M.: Redistribution and geochemical behaviour of redox-sensitive elements around S1, the most recent eastern Mediterranean sapropel, Geochim. Cosmochim. Ac., 59, 3487–3501, 1995. % vor jede Referenz Thomson, J., Mercone, D., De Lange, G. J., and Van Santvoort, P. J. M.: Review of recent advances in the interpretation of eastern Mediterranean sapropel S1 from geochemical evidence, Mar. Geol., 153, 77–89, 1999. % vor jede Referenz Triantaphyllou, M. V., Antonarakou, A., Kouli, K., Dimiza, M., Kontakiotis, G., Papanikolaou, M. D., Ziveri, P., Mortyn, P. G., Lianou, V., Lykousis, V., and Dermitzakis, M. D.: Late Glacial-Holocene ecostratigraphy of the south-eastern Aegean Sea, based on plankton and pollen assemblages, Geo-Mar. Lett., 29, 249–267, doi:10.1007/s00367-009-0139-5, 2009. % vor jede Referenz Tyrrell, T.: The relative influences of nitrogen and phosphorus on oceanic primary production, Nature, 400, 525–531, 1999. % vor jede Referenz Voss, M., Nausch, G., and Montoya, J. P.: Nitrogen stable isotope dynamics in the central Baltic Sea: influence of deep-water renewal on the N-cycle changes, Mar. Ecol.-Prog. Ser., 158, 11–21, 1997. % vor jede Referenz Voss, M., Emeis, K. C., Hille, S., Neumann, T. and Dippner, J. W.: Nitrogen cycle of the Baltic Sea from an isotopic perspective, Global Biogeochem. Cy., 19, GB3001, doi:10.1029/2004GB002338, 2005. % vor jede Referenz Voss, M., Deutsch, B., Elmgren, R., Humborg, C., Kuuppo, P., Pastuszak, M., Rolff, C., and Schulte, U.: Source identification of nitrate by means of isotopic tracers in the Baltic Sea catchments, Biogeosciences, 3, 663–676, doi:10.5194/bg-3-663-2006, 2006. % vor jede Referenz Wallmann, K.: Feedbacks between oceanic redox states and marine productivity: A model perspective focused on benthic phosphorus cycling, Global Biogeochem. Cy., 17, 1084, doi:10.1029/2002GB001968, 2003. % vor jede Referenz Westley, M. B., Yamagishi, H., Popp, B. N., and Yoshida, N.: Nitrous oxide cycling in the Black Sea inferred from stable isotope and isotopomer distributions, Deep-Sea Res. Pt. II, 53, 1802–1816, 2006.