Scientia Marina, Vol 81, No 3 (2017)

Spatial variability of nitrous oxide in the Minho and Lima estuaries (Portugal)

Célia Gonçalves
Instituto Português do Mar e da Atmosfera, IPMA, Portugal

Maria José Brogueira
Instituto Português do Mar e da Atmosfera, IPMA, Portugal


Nitrous oxide (N2O) is a potent long-lived greenhouse gas and estuaries represent potentially important sources of this biogas to the atmosphere. In this work, we analyse the first N2O data obtained in the Minho and Lima estuaries, and the processes and environmental factors that may regulate its production in these systems. In September 2006, N2O attained values of up to 20.0 nmol L–1 in the upper reaches of the Lima estuary and the river was, apparently, the main source of biogas to the system. In Minho N2O reached a maximum of 14.4 nmol L–1 and nitrification appeared to contribute to the enhancement of N2O. In the upper estuary, the relatively high concentrations of nitrification substrate NH4+, the positive correlations found between N2O level above atmospheric equilibrium (ΔN2O) and apparent oxygen utilization and NO2–, and the negative correlations between ΔN2O and NH4+ and pH can be interpreted as in situ N2O production through pelagic nitrification. Principal component analysis gave evidence of considerable differences between upper estuaries, particularly in terms of higher N2O in Lima and NH4+ in Minho. Surface waters of both estuaries were always N2O-supersaturated (101-227%) and estimated N2O emissions from Minho and Lima were 0.28 Mg N2O-N yr–1 and 0.96 Mg N2O-N yr–1, respectively, which represent a reduced fraction of N2O global emission from European estuaries.


N2O; greenhouse gas; fluxes; emission; Portuguese estuaries

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Aminot A., Chaussepied M. 1983. Manuel des analyses chimiques en milieu marin. Centre National pour l'Exploitation des Océans. CNEXO, Brest, France, 395 pp.

Bange H.W., Freing A., Kock A., et al. 2010. Marine pathways to nitrous oxide. In: Smith K.A. (ed.), Nitrous oxide and climate change. Earthscan, London. U.K. pp. 36-62.

Barnes J., Upstill-Goddard R.C. 2011. N2O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N2O source from European coastal waters. J. Geophys. Res. B. 116: G01006.

Bettencourt A., Ramos L., Gomes V., et al. 2003. Estuários Portugueses. Editions INAG - Ministério das Cidades, Ordenamento do Território e Ambiente, Lisboa, 311 pp. PMCid:PMC149316

Bianchi M., Feliatra F., Lefevre D. 1999. Regulation of nitrification in the land-ocean contact area of the Rhône River plume (NW Mediterranean). Aquat. Microb. Ecol. 18: 301-312.

Bollmann A., Laanbroek H.J. 2002. Influence of oxygen partial pressure and salinity on the community composition of ammonia-oxidizing bacteria in the Schelde estuary. Aquat. Microb. Ecol. 28: 239-247.

Burgos M., Sierra A., Ortega T., et al. 2015. Anthropogenic effects on greenhouse gas (CH4 and N2O) emissions in the Guadalete River Estuary (SW Spain). Sci. Total Environ. 503-504: 179-189. PMid:24993513

Carini S., Weston N., Hopkinson C., et al. 1996. Gas exchange rates in the Parker River estuary, Massachusetts. Biol. Bull. 191: 333-334.

Clark J.F., Schlosser P., Simpson K.J, et al. 1995. Relationship between gas transfer velocities and wind speeds in the tidal Hudson River determined by the dual tracer technique. In: Jhane B., Monahan E. (eds), Air-Water Gas Transfer. AEON Verlag and Studio, Germany, pp. 785-800. PMid:7773538 PMCid:PMC1510195

Dai M., Wang L., Guo X., et al. 2008. Nitrification and inorganic nitrogen distribution in a large perturbed river/estuarine system: the Pearl River Estuary, China. Biogeosci. 5: 1227-1244.

de Bie M.J.M., Middelburg J.J. Starink M., et al. 2002. Factors controlling nitrous oxide at the microbial community and estuarine scale. Mar. Ecol. Prog. Ser. 240: 1-9.

de Wilde H.P.J., de Bie M.J.M. 2000. Nitrous oxide in the Schelde estuary: Production by nitrification and emission to the atmosphere. Mar. Chem. 69: 203-216.

Dong L.F., Nedwell D.B. 2006. Sources of nitrogen used for denitrification and nitrous oxide formation in sediments of the hypernutrified Colne, the nutrified Humber and oligotrophic Conwy Estuaries, United Kingdom. Limnol. Oceanogr. 51(1, part 2): 545-557.

Ferreira J.G., Nobre A.M., Simas T.C., et al. 2005. Monitoring plan for water quality and ecology for Portuguese traditional and coastal waters: Development of guidelines for the application of the European Union Water Framework Directive. Editions INAG-Instituto da Água IMAR-Institute of Marine Research. Lisbon, Portugal, 142 pp.

Gonçalves C., Brogueira M.J., Camões M.F. 2010. Seasonal and tidal influence on the variability of nitrous oxide in the Tagus estuary, Portugal. Sci. Mar. 74S1: 57-66.

Gonçalves C., Brogueira M.J, Nogueira M. 2015. Tidal and spatial variability of nitrous oxide (N2O) in Sado estuary (Portugal). Est. Coast. Shelf Sci. 167: 466-474.

Hartman B., Hammond D. 1985. Gas exchange in San Francisco Bay. Hydrobiology 129: 59-68.

Lin H., Dai M., Kao S.J. et al. 2016. Spatio temporal variability of nitrous oxide in a large eutrophic estuarine system: The Pearl River Estuary, China. Mar. Chem. 182: 14-24.

Martens-Habbena W., Berube P.M., Urakawa H., et al. 2009. Ammonia oxidation kinetics determine niche separation of nitrifying Archaea and Bacteria. Nature 461: 976-981. PMid:19794413

Mosier A.C., Francis C.A. 2008. Relative abundance and diversity of ammonia-oxidizing archaea and bacteria in the San Francisco Bay estuary. Environ. Microbiol. 10: 3002-3016. PMid:18973621

Murray R.H., Erler D.V., Eyre B.D. 2015. Nitrous oxide fluxes in estuarine environments: response to global change. Global Change Biol. 21: 3219-3245. PMid:25752934

Myhre G., Shindell D., Bréon F.M., et al. 2013. Anthropogenic and Natural Radiative Forcing. In: Stocker T.F., Qin D., Plattner G.K., et al. (eds), Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, pp. 659-740.

Nevison C.D., Butler J.H., Elkins J.W. 2003. Global distribution of N2O and the ?N2O-AOU yield in the subsurface ocean. Global Biogeochem Cycles 17: 1119.

Prather M.J., Holmes C.D., Hsu J. 2012. Reactive greenhouse gas scenarios: Systematic exploration of uncertainties and the role of atmospheric chemistry. Geophys. Res. Lett. 39: L09803.

Ramos S., Cowen R.K., Ré P., et al. 2006. Temporal and spatial distributions of larval fish assemblages in the Lima estuary (Portugal). Est. Coast. Shelf Sci. 66: 303-314.

Raymond P.A., Cole J.J. 2001. Gas exchange in rivers and estuaries: choosing a gas transfer velocity. Estuaries 24: 312-317.

SNIRH (Sistema Nacional de Informação de Recursos Hídricos). 2013. Instituto da Água IP.

Sousa C., Vaz M.N., Alvarez I., et al. 2013. Effect of Minho estuarine plume on Rias Baixas: numerical modeling approach. J. Coast. Res. Spec. 65: 2059-2065.

Strauss E.A., Mitchell N.L., Lamberti G.A. 2002. Factors regulating nitrification in aquatic sediments: effects of organic carbon, nitrogen availability, and pH. Can. J. Fish. Aquat. Sci. 59: 554-563.

Teixeira C., Magalhães C., Joye S.B., et al. 2013. The role of salinity in shaping dissolved inorganic nitrogen and N2O dynamics in estuarine sediment-water interface. Mar. Pollut. Bull. 66: 225-229. PMid:23219528

Wanninkhof R. 1992. Relationship between wind speed and gas exchange over the ocean. J. Geophys. Res. C 97(C5): 7373-7382.

Weiss R.F. 1970. The solubility of nitrogen, oxygen, and argon in water and seawater. Deep-Sea Res. Oceanogr. Abstr. 17: 721-735.

Weiss R.F., Price B.A. 1980. Nitrous oxide in water and seawater. Mar. Chem. 8: 347-359.

Wild H.E., Sawyer C.N., McMahon T.C. 1971. Factors affecting nitrification kinetics. J. Water Pollut. Control Fed. 43: 1845-1854.

WMO (World Meteorological Organization). 2006. World Meteorological Organization greenhouse gas bulletin: The State of Greenhouse Gases in the Atmosphere Using Global Observations through 2006. Bulletin No. 3. Global Atmosphere Watch, Geneva, Switzerland, 4 pp.

Yoshinari T. 1976. Nitrous oxide in the sea. Mar. Chem. 2: 189-202.

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