Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 1 1 2004 10.5194/bg-1-33-2004 http://www.biogeosciences.net/1/33/2004/ http://www.biogeosciences.net/1/33/2004/bg-1-33-2004.html http://www.biogeosciences.net/1/33/2004/bg-1-33-2004.pdf 33 61 2004-10-05 Modeling the nitrogen fluxes in the Black Sea using a 3D coupledhydrodynamical-biogeochemical model: transport versus biogeochemicalprocesses, exchanges across the shelf break and comparison of the shelf anddeep sea ecodynamics M. Grégoire m.gregoire@nioo.knaw.nl J. M. Beckers University of Liège, 1 Mare, B6c, Sart-Tilman, 4000 Liège, Belgium Netherlands Institute of Ecology (NIOO -- KNAW), Centre for Estuarine and Marine Ecology, Korringaweg 7, 4401 NT Yerseke, The Netherlands A 6-compartment biogeochemical model of nitrogen cycling and plankton productivity has been coupled with a 3D general circulation model in an enclosed environment (the Black Sea) so as to quantify and compare, on a seasonal and annual scale, the typical internal biogeochemical functioning of the shelf and of the deep sea as well as to estimate the nitrogen and water exchanges at the shelf break. Model results indicate that the annual nitrogen net export to the deep sea roughly corresponds to the annual load of nitrogen discharged by the rivers on the shelf. <P style="line-height: 20px;"> The model estimated vertically integrated gross annual primary production is 130gCm^-2yr^-1 for the whole basin, 220gCm^-2yr^-1 for the shelf and 40gCm^-2yr^-1 for the central basin. In agreement with sediment trap observations, model results indicate a rapid and efficient recycling of particulate organic matter in the sub-oxic portion of the water column (60-80m) of the open sea. More than 95% of the PON produced in the euphotic layer is recycled in the upper 100m of the water column, 87% in the upper 80 m and 67% in the euphotic layer. The model estimates the annual export of POC towards the anoxic layer to 4 10¹⁰molyr^-1. This POC is definitely lost for the system and represents 2% of the annual primary production of the open sea. Altman, E. and Kumish, N.: Interannual and seasonal variability of the Black Sea fresh water balance, \it Trudi Gos. Oceanogr. \it Inst., 145, 3-15, 1986. Andersen, V. and Nival, P.: A pelagic ecosystem model simulating production and sedimentation of biogenic particles: role of salps and copepods, \it Mar. Ecol.-Pr., 44, 37-50, 1988. Beckers, J. M.: Application of a 3D model to the Western Mediterranean, \it J. Mar. Syst., $1$, 315-332, 1991. Beckers, J. M., Grégoire, M., Nihoul, J., Stanev, E., Staneva, J., and Lancelot, C.: Hydrodynamical processes governing exchanges between the Danube, the North Western continental shelf and the Black Sea's basin, \it Est. Coast. S., $54$, 3, 459-472, 2002. Billen, G. and Lancelot, C.: Modelling benthic nitrogen cycling in temperate coastal ecosystems, in \it Nitrogen Cycling in Coastal Marine Environments, edited by Blackburn, T. H. and Sorensen, J., John Wiley and Sons Ltd., New York, 341-378, 1988. Brewer, P. and Murray, J.: Carbon, nitrogen and phosphorus in the Black Sea, \it Deep-Sea I, $20$, 803-818, 1973. Buesseler, K., Livingston, H., and Casso, S.: Mixing between oxic and anoxic waters of the Black Sea as traced by Chernobil cesium isotopes, \it Deep-Sea I, $38,$ Suppl. 2a, S725-S745, 1991. Callender, E. and Hammond, D. E.: Nutrient exchange across the sediment-water interface in the Potomac river estuary, \it Est. Coast. S., $15$, 395-413, 1982. Cociasu, A., Diaconu, V., Popa, L., Buga, L., Nae, I., Doragan, L., and Malciu, V.: The nutrient stock of the Romanian shelf of the Black Sea during the last three decades, in "Sensitivity to change: Black Sea, Baltic Sea and North Sea", edited by Ozsoy, E. and Mikaelyan, A., NATO ASI Series 2: Environment, 27, 49-63, Kluwer Academic Publishers, Dordrecht, 1997. Codispoti, L. A. and Christensen, J. P.: Nitrification, denitrification and nitrous oxide cycling in the eastern tropical South Pacific Ocean, \it Mar. Chem., $16$, 277-300, 1985. Cokacar, T. and Ozsoy, E.: Comparative analyses and modelling for regional ecosystems of the Black Sea, in "Ecosystem modelling as a management tool for the Black Sea", edited by Ivanov, L. and Oguz, T., NATO ASI Series 2: Environmental Security, 47, 323-358, Kluwer Academic Publishers, Dordrecht, 1998. Deleersnijder, E. and Nihoul, J. C. J.: Turbulent fields associated with the general circulation in the Northern Bering Sea, in "Small Scale turbulence and mixing in the ocean", edited by Nihoul, J. C. J. and Jamart, B. M., 77-93, Elsevier, Amsterdam, 1988. Delhez, E.: Reconnaissance of the general circulation of the North-Western European Continental Shelf by means of a three-dimensional turbulent closure model, Earth. Sci. R., $41$, 3-29, 1996. Deuser, W. G.: Organic-carbon budget of the Black Sea, \it Deep-Sea I, $18$, 995-1004, 1971. Devol, A. H.: Direct measurement of nitrogen gas fluxes from continental shelf sediments, \it Nature, $349$, 319-321, 1991. Dippner, J. W.: A lagrangian model of phytoplankton growth dynamics for the Northern Adriatic Sea, \it Cont. Shelf, 13, 331-355, 1993. Elderfield, H., Luedke, N., McCaffrey, R., and Bender, M.: Benthic flux studies in Narragansett Bay, \it Am. J. Sci., $281$, 768-787, 1981. Eppley, R.: New production: history, methods, problems, in "Productivity of the Ocean: Present and Past", edited by Berger, W. H., Smetacek, V. S., and Wefer, G., Dalhem Workshop report, 85-97, Wiley, Chichester, West Sussex, United Kingdom, 1989. Finenko, Z.: Principles of the biological productivity of the Black Sea, \it Naukova Dumka (in Russian), 88-89, 1979. Friedl, G., Friedrich, J., and Wehrli, B.: Nutrient fluxes in the lower Danube river, Danube delta and the coastal Black Sea, 2nd report of the E.U. INTAS project on the study of the nitrogen cycling in the oxic/anoxic environment of the Black Sea: Data analysis and numerical simulation, 144-159, Liège, 2001. Friedrich, J., Dinkel, C., Friedl, G., Pimenov, N., Wijsman, J., Gomoiu, M.-T., Cociasu, A., Popa, L., and Wehrli, B.: Benthic nutrient cycling and diagenetic pathways in the north-western Black Sea, \it Est. Coast. S., $54$, 3, 369-383, 2002. Ginzburg, A. I., Kostianoy, A. G., and Sheremet, N. A.: On the use of satellite data in the study of seasonal and interannual variations of the Black Sea sea-surface temperature, \it Issledovanie Zemli iz \it kosmosa, $1$, 51-61, 2001. Globec report: Interdisciplinary model formulation and Parameterization, report on the second meeting of the international GLOBEC Numerical Modeling Working group, Nantes, July 1995, Globec International, Plymouth, UK, 1997. Grégoire, M. and Lacroix, G.: Study of the Oxygen budget of the Black Sea waters using a 3D coupled hydrodynamical-biogeochemical model, \it J. Mar. Syst., $31$, 175-202, 2001. Grégoire, M., Beckers, J. M., Nihoul, J. C. J., and Stanev, E.: Reconnaissance of the main Black Sea's ecohydrodynamics by means of a 3D interdisciplinary model, \it J. Mar. Syst., $16$, 85-105, 1998. Grégoire, M. and Lacroix, G.: Exchange Processes and Nitrogen Cycling on the shelf and continental slope of the Black Sea basin\bf , \it Global Biog. 17, 2, 42-1-42-17, 2003. Grégoire, M. and Friedrich, J.: Nitrogen Budget of the north-western Black Sea shelf as inferred from modeling studies and in-situ benthic measurements, \it Mar. Ecol.-Pr., 270, 15-39, 2004. Grégoire M., Nezlin, N., Kostianoy, A., and Soetaert K.: Modeling the nitrogen cycling and plankton productivity in an enclosed environment (the Black Sea) using a three-dimensional coupled hydrodynamical-ecosystem model, \it J. Geophys. Res.-O, 109, C5, 28p, 2004. Honjo, S., Hay, B. J., Manganini, S., Asper, V. L., Degens, E. T., Ittekot, V., Kempe, S., Izdar, E., Konuk, Y. T., and Benli, H. A.: Seasonal cyclicity of lithogenic particle fluxes at a Southern Black Sea sediment trap station, in \it Particle flux in the ocean, edited by Degens, E. T., Izdar, E., and Honjo, S., 62, 1-18, Mitteilungen des Geologisch-Palaeontologischen Institutes, Universität Hamburg, 1987. Humborg, C., Ittekot, V., Cociasu, A., and van Bodungen, B.: Effect of Danube river dam on Black Sea biogeochemistry and ecosystem structure, \it Nature, $386$, 385-388, 1997. Karl, D. and Knauer, G.: Microbial production and particle flux in the upper 350m Black Sea, \it Deep Sea-II, $38$, Suppl. 2, S655-S661, 1991. Knauer, G. A.: Productivity and new production of the oceanic system, in \it Interactions of C, N, P and S Biogeochemical Cycles and Global Change, edited by Wollast, R., Mackenzie, F. T., and Chou, L., NATO ASI Series, 14, 211-231, Springer-Verlag, Berlin, 1993. Konovalov, S. and Murray, J. W.: Variations in the chemistry of the Black Sea on a time scale of decades (1960-1995), \it J. Mar. Syst., 31, 217-243, 2001. Konovalov, S., Ivanov, L. I., and Samodurov, A. S.: Oxygen, nitrogen and sulfide fluxes in the Black Sea, \it Mediterranean Marine Science, $1$, 41-59, 2000. Kubilay, N., Yemenicioglu, S., and Saydam, A.: Airborne material collections and their chemical composition over the Black Sea, \it Mar. Poll. B, $30$, 475-483, 1995. Lalli, C. M. and Parsons, T. R.: \it Biological Oceanography: An Introduction, Pergamon Press, Oxford, 301, 1993. Lancelot, C., Staneva, J., Van Eeckhout, D., Beckers, J.-M., and Stanev, E.: Modelling the Danube-influenced north-western continental shelf of the Black Sea, Ecosystem response to changes in nutrient delivery by the Danube river after its damming in 1972, \it Est. Coast. S., $54$, 3, 473-499, 2002. Lebedeva, L. and Shushkina, E.: The model investigation of the Black Sea community changes caused by Mnemiopsis, \it Oceanology, $34$, 79-87, 1994. Lein, A. and Ivanov, M.: On the sulphur and carbon balances in the Black Sea, \it in Black Sea oceanography, edited by E. Izdar and J. Murray, NATO ASI Series C, 351, 307-318, Kluwer Academic Publishers, Dordrecht, 1991. Madala, R. and Piacsek, S.: A semi-implicit numerical model for baroclinic oceans, \it J. Comput. Ph., $23$, 167-178, 1977. Mantoura, R. F. C., Law, C. S., Owens, N. J. P., Burkill, P. H., Woodward, E. M. S., Howland, R. J. M., and Llewellyn, C. A.: Nitrogen biogeochemical cycling in the north-western Indian Ocean, \it Deep Sea-I, $40$, 651-671, 1993. Martin, J. H., Knauer, G. A., Karl, D. M., and Broenkow, W. W.: VERTEX: carbon cycling in the northeast Pacific, \it Deep Sea-I, $34$, 267-285, 1987. McGillicuddy, D., Robinson, A., and McCarthy, J.: Coupled physical and biological modeling of the spring bloom in the North Atlantic (II): Three dimensional bloom and post-bloom effects, \it Deep Sea-I, 42, 8, 1389-1398, 1995. Mikaelyan, A.: Winter bloom of the diatom Nitzchia delicatula in the open waters of the Black Sea, \it Mar. Ecol.-Pr., $129$, 241-251, 1995. Minas, H. J., Minas, M., Coste, B., Gostan, J., Nival, P., and Bonin, M. C.: Production de base et recyclage; une revue de base de le Méditerranée nord-occidentale, \it Oceanol. Act., $9$, 155-162, 1988. Mullin, M.: Some factors affecting the feeding of marine copepods of the genus Calanus, \it Limn. Ocean., $8$, 239-250, 1963. Muramoto,~J. A., Honjo, S., Fry, B., Hay, B. R., Howarth, R. W., and Cisne, J. L.: Sulfur, iron and organic carbon fluxes in the Black Sea: sulfur isotopic evidence for origin of sulfur fluxes, \it Deep Sea-II, $38$, Suppl. 2, S1,151-S1,187, 1991. Murray, J., Codispoti, L., and Friederich, G.: Redox Environments: The suboxic zone in the Black Sea, in \it Aquatic chemistry: interfacial and interspecies processes, edited by Huang, C., O'Melia, C., and Morgan, J., 157-176, American Chemical Society, 1995. Nezlin, N., Kostianoy, A., and Grégoire, M.: Patterns of seasonal and interannual changes of surface chlorophyll concentration in the Black Sea revealed from the remote sensed data, \it Remot. Sen. E., $69$, 43-55, 1999. Oguz, T., Ozsoy, E., Latif, A., Sur, H., and Unluata, U.: Modeling of hydrographically controlled exchange flow in the Bosphorus strait, \it J. Phys. Ocea., $20$, 945-965, 1990. Oguz, T., La Violette, P., and Unluata, U.: The upper layer circulation of the Black Sea~: its variability as inferred from hydrographic and satellite observations, \it J. Geophys. Res.-O, $97$, 12 569-12 684, 1992. Oguz, T., Latun, V., Latif, M., Vladimirov, V., Sur, H., Markov, A., Ozsoy, E., Kotovschikov, B., Eremeev, V., and Unluata, U.: Circulation in the surface and Intermediate Layers of the Black Sea, \it Deep Sea-I, $40$, 1597-1612, 1993. Oguz, T., Ducklow, H. W., Malanotte-Rizzoli, P., Tugrul, S., Nezlin, N., and Unluata, U.: Simulation of annual plankton productivity cycle in the Black Sea by a one-dimensional physical-biological model, \it J. Geophys. Res.-O, $101$, 16 585-16 599, 1996. Oguz, T., Ducklow, H., Shushkina, E., Malanotte-Rizzoli, P., Tugrul, S., and Lebedeva, L.: Simulation of upper layer biochemical structure in the Black Sea, in \it Ecosystem modelling as a management tool for the Black Sea, edited by Ivanov, L. and Oguz, T., NATO ASI Series 2: Environmental Security, 47, 257-300, Kluwer Academic Publishers, Dordrecht, 1998. Oguz, T., Ducklow, H., Malanotte-Rizzoli, P., Murray, J., Shushkina, E., Vedernikov, V., and Unluata, U.: A physical-biochemical model of plankton productivity and nitrogen cycling in the Black Sea, \it Deep Sea-I, $46$, 597-636, 1999. Oguz, T., Ducklow, H., and Malanotte-Rizzoli, P.: Modeling distinct vertical biogeochemical structure of the Black Sea: Dynamical coupling of the oxic, suboxic, and anoxic layers, \it Global Biog., 14, 4, 1331-1352, 2000. \"Ozsoy, E. and \"U. \"Unl\"uata: Oceanography of the Black Sea: A Review of Some Recent Results, \it Earth Sci. R., $42$, 4, 231-272, 1997. Ozsoy, E., Cokacar, T., Mikaelyan, A., and Besiktepe, S.: Model studies and analyses of ecosystem dynamics in the Black Sea, in \it "Ecosystem modelling as a management tool for the Black Sea", edited by Ivanov, L. and Oguz, T., NATO ASI Series 2: Environmental Security, 47, Kluwer Academic Publishers, Dordrecht, 1998. Patankar, S.: \it Numerical heat transfer and fluid flow, Series in Computational Methods in Mechanical and thermal Sciences, McGraw-Hill, New-York, 197, 1980. Patsch, J. and Radach, G.: Long-term simulation of the eutrophication of the North Sea: temporal development of nutrients, chlorophyll and primary production in comparison to observations, \it J. Sea Res., 38, 275-310, 1997. Platt, T. and Jassby, A.: The relationship between photosynthesis and light for natural assemblages of coastal marine phytoplankton, \it J. Phycology, $12$, 421-430, 1976. Polat, C. and Tugrul, S.: Chemical exchange between the Mediterranean and the Black Sea via the Turkish Straits, \it Bulletin de l'Institut océanographique \it de Monaco, 37-56, 1995. Rozanov, A. G.: Redox stratification in Black Sea waters, \it Oceanology, $35$, 500-504, 1996. Ryther, J. H.: Photosynthesis and fish production in the sea. The production of organic matter and its conversion to higher forms of life vary throughout the world ocean, \it Science, $166$, 72-76, 1969. Sarmiento, J., Slater, R., Fasham, M., Ducklow, H., Toggweiler, J., and Evans, G.: A seasonal 3D ecosystem model of nitrogen cycling in the North Atlantic euphotic zone, \it Global Biog., $7$, 2, 415-450, 1993. Saydam C., Tugrul, S., Basturk, O., and Oguz, T.: Identification of the oxic/anoxic interface by isopycnal surfaces in the Black Sea, \it Deep Sea-I, $40$, 7, 1405-1412, 1993. Soetaert, K., Herman, P., and Middelburg, J.: A model of early diagenetic processes from the shelf to abyssal depths, \it Geoch. Cos. A, 60, 6, 1019-1040, 1996. Sorokin, Yu. I.: On the primary production and bacterial activities in the Black Sea, \it Journal du Conseil Permanent pour l'Exploration de la Mer, $29$, 41-60, 1964. Sorokin, Yu. I.: The Black Sea, in \it Estuaries and Enclosed Seas. Ecosystems of the World, edited by Ketchum, B. H., 253-292, Elsevier, New York, 1983. Stanev, E. V.: On the mechanisms of the Black Sea circulation, \it Earth Sci. R., $28$, 285-319, 1990. Stanev, E. V. and Beckers, J. M.: Numerical simulations of seasonal and interannual variability of the Black Sea thermohaline circulation, \it J. Mar. Syst., $22$, 241-267, 1999. Staneva, J. V. and Stanev, E. V.: Oceanic Response to Atmospheric Forcing Derived from Different Climatic Data Sets. Intercomparison Study for the Black Sea, \it Oceanol. Act., $21$, 393-417, 1999. Staneva, J. V., Stanev, E. V., and Oguz, T.: The impact of atmospheric forcing and water column stratification on the yearly plankton cycle, in \it Ecosystem modelling as a management tool for the Black Sea, edited by L. Ivanov and T. Oguz, NATO ASI Series 2: Environmental Security, 47, 301-322, Kluwer Academic Publishers, Dordrecht, 1998. Stelmakh, L. V., Yunev, O. A., Finenko, Z. Z., Vedernikov, V. I., Bologa, A. S., and Churilova, T. Yu.: Peculiarities of seasonal variability of primary production in the Black Sea, in \it Ecosystem modelling as a management tool for the Black Sea, edited by Ivanov, L. and Oguz, T., NATO ASI Series 2: Environmental Security, 47, 93-104, Kluwer Academic Publishers, Dordrecht, 1998. Sur, H., Ozsoy, E., and Unluata, U.: Boundary current instabilities, shelf mixing and eutrophication processes in the Black Sea, \it Prog. Ocean, $33$, 249-302, 1994. Taguchi, K. and Nakata, K.: Analysis of water quality in Lake Hamana using a coupled physical and biochemical model, \it J. Mar. Syst., 16, 107-132, 1998. Totterdell, I., Armstrong, R., Drange, H., Parslow, J., Powell, T., and Taylor, A.: Trophic resolution, in \it Towards a model of ocean biogeochemical processes, edited by G. Evans and M. Fasham, NATO ASI Series I: Global environmental change, 10, 71-92, Springer Verlag, 1993. Tugrul, S., Basturk, O., Saydam, C., and Yilmaz, A.: Changes in the hydrochemistry of the Black Sea inferred from water density profiles, \it Nature, $359$, 137-139, 1992. Tusseau-Vuillemin, M. H., Mortier, L., and Herbaut, C.: Modeling nitrate fluxes in an open coastal environment (Gulf of Lions): Transport versus biogeochemical processes, \it J. Geophys. Res.-O, $103$, 7693-7708, 1998. Unluata, U., Oguz, T., Latif, M., and Ozsoy, E.: On the physical oceanography of the Turkish Straits, in \it The physical oceanography of Sea Straits, edited by L. J. Pratt, NATO ASI, 25-60, Kluwer Academic Publishers, Dordrecht, 1990. Vedernikov, V. I. and Demidov, A. B.: Primary production and chlorophyll in the deep regions of the Black Sea, \it Oceanology, $33$, 193-199, 1993. Wijsman, J.: Early diagenetic processes in northwestern Black Sea sediments, \it PhD thesis, Netherlands Institute of Ecology, The Netherlands, 2001. Wijsman, J., Herman, P., Gomoiu, M. T. : Spatial distribution in sediment characteristics and benthic activity on the northwestern Black Sea shelf, \it Mar. Ecol.-Pr., $181$, 25-39, 1999. Wollast, R.: The global coastal ocean. Processes and methods, in \it The Sea, edited by Brink, K. H. and Robinson, A. R., 10, 213-252, John Wiley and Sons Ltd., New York, 1998. Yakushev, E.: Mathematical Modelling of oxygen, nitrogen, sulphur and manganese cycling in the Black Sea, in \it Ecosystem modelling as a management tool for the Black Sea, edited by Ivanov, L. and Oguz, T., NATO ASI Series 2: Environmental Security, 47, 373-385, Kluwer Academic Publishers, Dordrecht, 1998. Yakushev, E. and Neretin, L.: One-dimensional modelling of nitrogen and sulphur cycles in the aphotic zones of the Black Sea and Arabian Sea, \it Global Biog., $11$, 3, 401-414, 1997. Yanagi, T., Yamamoto, T., Koizumi, Y., Ikeda, T., Kamizono, M., and Tamori, H.: A numerical model of red tide formation, \it J. Mar. Syst., 6, 269-285, 1995.