Difference between revisions of "Nutrient dynamics"

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</ref> . The continuing changes in land use and global urbanisation of coastal margins<ref name="Tappin 2002"> Tappin, A.D. (2002), An Examination of the Fluxes of Nitrogen and Phosphorus in Temperate and Tropical Estuaries: Current Estimates and Uncertainties, Estuarine, Coastal and Shelf Science 55, 885-901. </ref>  thus pose a continual threat to coastal waters.
 
</ref> . The continuing changes in land use and global urbanisation of coastal margins<ref name="Tappin 2002"> Tappin, A.D. (2002), An Examination of the Fluxes of Nitrogen and Phosphorus in Temperate and Tropical Estuaries: Current Estimates and Uncertainties, Estuarine, Coastal and Shelf Science 55, 885-901. </ref>  thus pose a continual threat to coastal waters.
  
=CONTINENTAL NUTRIENT SOURCES=
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==Continental Nutrient Sources and Nutrient Transformation==
==Rivers==
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Nutrients in coastal environments come from various sources - through rivers, groundwater or atmospheric deposition. The main species - Nitrogen, Phosphorus and Silicon - undergo different transformation processes and states. Nutrient dynamics is further discussed in [[Continental Nutrient Sources and Nutrient Transformation]].
  
On a global scale, riverine inputs of N and P to coastal seas have possibly increased by factors of 2 to 3 <ref name=”Howarth”>Howarth, R., H. Jensen, R. Marino, and H. Postma, in Phosphorus in the Global Environment:Transfers, Cycles and Management, H. Tiessen, Ed., Scientific Committee on Problems of the Environment 54. (Wiley, New York, 1995), pp. 323–356.</ref> ,<ref name=”Duce”> Duce, R., P.S. Liss, J.T. Merrill, E.L. Atlas, P. Buat-Menard, B.B. Hicks, J.M. Miller, J.M. Prospero, R. Arimoto, T.M. Church,. W. Ellis, J.N. Galloway, L. Hansen, T.D. Jickells, A.H. Knap, K.H. Reinhardt, B. Schneider, A. Soudine, J.J. Tokos, S. Tsunogai, R. Wollast, and M. Zhou (1991), The atmospheric input of trace species to the world ocean, Global Biogeochemical Cycles 5, 193-296.</ref> ,<ref name="Jickells 1998">Jickells T.D. (1998), Nutrient Biogeochemistry of the Coastal Zone, Science, 281 217 – 222</ref>. Agriculture, in the form of fertilizers, leachates and animal wastes, is the largest contributor of N and P in aquatic systems <ref name=”Howarth”>Howarth, R., H. Jensen, R. Marino, and H. Postma, in Phosphorus in the Global Environment:Transfers, Cycles and Management, H. Tiessen, Ed., Scientific Committee on Problems of the Environment 54. (Wiley, New York, 1995), pp. 323–356.</ref> . Other major inputs include point-source discharges of wastewater from urban sewer networks<ref name=”B&G2007”> Billen, G., J. Garnier, J. Nemery, M. Sebilo, A. Sferratore, S. Barles, P. Benoit, and M. Benoit (2007), A long-term view of nutrient transfers through the Seine river continuum, Science of the Total Environment 375, 80-97.</ref> ,<ref name=”EEA1999”> European Environment Agency (1999), Nutrients in European Ecosystems. Environmental Assessment Report No. 4, Office for Official Publications of the European Communities, Luxembourg, pp.  156.</ref>  and industrial wastes. The direct discharge of P exchanged with soils and sediments<ref name=”B1991”> Billen, G., C. Lancelot, and M. Meybeck (1991), N, P and Si retention along the aquatic continuum from land to ocean. Ocean Margin Processes in Global Change, R.F.C Mantoura, J.-M.  Martin, and R. Wollast, Eds. (John Wiley & Sons Ltd.), pp. 19-44.</ref>  also contributes significantly to the budget of this element.   
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==European Context of Nutrient Dynamics==
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Nutrient budgets and fluxes have been established at the local (major rivers) and regional (coastal seas) scales across Europe. The article [[European Context of Nutrient Dynamics]] provides examples.   
  
Riverine Si fluxes, originating predominantly from weathering, have generally been altered little by human activity<ref name="Jickells 1998"/> .
 
  
However, human management of rivers has, in some cases, altered the Si fluxes extensively<ref name=”Humborg2002”> Humborg, C, S. Blomqvist, E. Avsan, Y. Bergensund, E. Smedberg, J. Brink, and C.-M. Morth (2002), Hydrological alterations with river damming in northern Sweden: implications for weathering and river biogeochemistry, Global Biogeochemical Cycles, 16 (3), 1039</ref> , often leading to a reduction in diatom blooms as a result of damming.
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==References==
 
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<references/>
==Groundwater==
 
 
 
The direct discharge of groundwater into the ocean, termed submarine groundwater discharge (SGD), has been recently recognized as an additional pathway of nutrients from the land to coastal waters<ref name="Johannes1980">Johannes, R.E. (1980), The ecological significance of the submarine discharge of groundwater, Marine Ecology-Progress Series 3, 365-373.</ref>,<ref name=”Capone1985”> Capone, D.G., and M.F. Bautista (1985), A groundwater source of nitrate in nearshore marine sediments, Nature 313, 214 216.</ref>. On a global scale, SGD rates vary between 0.01-10 % of river runoff<ref name=”Church1996”>Church, T.H. (1996), An underground route for the water cycle, Nature 380, 579-580.</ref>. However, the concentrations of nutrients in groundwater are typically higher than those in coastal and river waters<ref name="Johannes1980"/>,<ref name="Valiela1990">Valiela, I., J. Costa, K. Foreman, J. Teal, B. Howes, and D. Aubrey (1990), Groundwater-borne inputs from watersheds to coastal waters, Biogeochemistry 10, 177-198.</ref>,<ref name="Dollar1992">Dollar, S.J., and M.J. Atkinson (1992), Effects of nutrient subsidies from groundwater to nearshore marine ecosystems off the island of Hawaii, Estuarine, Coastal and Shelf Science 35, 409-424.</ref>,<ref name="Moore1996">Moore, W.S. (1996), Large groundwater inputs to coastal waters revealed by 226Ra enrichments, Nature 380, 612-614.</ref>,<ref name=”Uchiyama2000”>Uchiyama, Y., K. Nadaoka, P. Rolke, K. Adachi, and H. Yagi (2000), Submarine groundwater discharge into the sea and associated nutrient transport in a sandy beach, Water Resources Research 36, 1467-1479.</ref>. Therefore, in terms of fluxes, such high concentrations can compensate for the relatively low SGD rates. At the local scale, SGD of nutrients is a prominent transport pathway, particularly in enclosed bays, karstic and fractured systems (e.g., Hawaii<ref name="Garison2003">Garrison, G.H., C.R. Glenn, and G.M. McMurty (2003), Measurement of submarine groundwater discharge in Kahana Bay, O’ahu, Hawaii, Limnology and Oceanography 48, 920-928.</ref>), or at locations where rivers are small or non-existent (e.g., Yucatan peninsula<ref name="Hanshaw1980"> Hanshaw, B.B., and W. Back (1980), Chemical mass-wasting of the northern Yucatan Peninsula by groundwater dissolution, Geology 8, 222-224.</ref>).
 
  
==Atmosphere==
 
  
Atmospheric deposition is a significant source of N compounds to the coastal zone, particularly in summer and autumn, but is only a minor source of Si and P<ref name="Conley1993">Conley D.J., C.L. Schelske, and E.F. Stoermer (1993), Modification of the biogeochemical cycle of silica with  eutrophication, Marine Ecology-Progress Series 101, 179–192.</ref>,<ref name=”Conley2000”>Conley D.J., P. Stalnacke, H. Pitkanen, and A. Wilander (2000), The transport and retention of dissolved silicate by rivers in Sweden and Finland, Limnology and Oceanography 45, 1850–1853.</ref>,<ref name="Jickells 1998"/>. Nitrogen delivered by the atmospheric pathway can be either in the oxidized or reduced form<ref name=”Galloway1995”> Galloway J., W. Chlesinger, H. Levy, A. Michaels, and J. Schnoor (1995), Nitrogen fixaton: Anthropogenic enhancement and environmental response, Global Biogeochemical Cycles 9, 235-252.</ref> . For instance, atmospheric deposition amounts to 30% of the total land based nitrogen input to the North Sea, mainly as oxidized N, and 50% to the Baltic Sea<ref name=”NorthSeaTaskForce1993”> North Sea Task Force (1993), North Sea Quality Status Report, Oslo and Paris Commissions, London. Olsen & Olsen, Fredensborg, Denmark.</ref> . The N:Si:P ratio for wet deposition in the North Sea is 503:2:1<ref name=”Rendell1993”> Rendell, A. R., Ottley, C. J., Jickells, T. D. & Harrison, R. M. Tellus 45, 53−63 (1993).</ref> .
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==See also==
 +
:[[Eutrophication]]
 +
:[[Continental Nutrient Sources and Nutrient Transformation]]
 +
:[[European Context of Nutrient Dynamics]]
  
=NUTRIENT TRANSFORMATION=
 
[[Image:sources sinks.jpg|thumb|480px|Figure 1. Important sources and sinks of N in an estuary (source: Tappin, 2002)<ref name="Tappin 2002"/>]]
 
Nutrients are significantly altered by biogeochemical processes during their transport along the land-ocean transition zone, especially in estuarine systems. Figure 1 summarizes the major N sources and transformation processes in an estuary. Estuaries are usually turbid, and hence primary production is often limited by light availability. Light conditions generally improve towards the coastal zone and primary production becomes a dominant process in controlling the biogeochemical cycles of nutrients<ref name="Jickells 1998"/>.
 
  
 
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==External links==
==Nitrogen==
 
N species in aquatic environments include dissolved (nitrate, nitrite, ammonium, organic N) and particulate (organic N) constituents<ref name="Tappin 2002"/> . The removal of N occurs by deposition and permanent burial in sediments and, most importantly, loss to the atmosphere by bacterial denitrification. This process is coupled with organic matter decomposition and reduces nitrate to gaseous N<sub>2</sub>/N<sub>2</sub>O under anoxic conditions. Part of the nitrate pool originates from coupled nitrification/denirification, in which the ammonium produced from organic matter degradation is first oxidized to nitrate, and subsequently denitrified <ref name="Jickells 1998"/>. In temperate and tropical estuaries the estimated loss of nitrate N via denitrification varies widely, and also varies in time and space within estuaries<ref name=”Barnes1998”> Barnes, J., and N.J.P. Owens (1998), Denitrification and nitrous oxide concentrations in the Humber Estuary, UK, and adjacent coastal zones,  Marine Pollution Bulletin 37, 247–26.</ref> ,<ref name=”Dong2000”> Dong, L.F., D.C.O. Thornton, D.B. Nedwell, and G.J.C. Underwood (2000), Denitrification in sediments of the River Colne estuary, England, Marine Ecology Progress Series 203, 109–122.</ref> . Because denitrification requires low oxygen concentrations, this process is particularly important in muddy sediments<ref name=”Seitzinger1998”> Seitzinger, S.P. 1988. Denitrification in freshwater and coastal marine ecosystems: ecological and geochemical importance. Limnology and Oceanography 33:702-724.</ref> ,<ref name=”Malcolm1997”> Malcolm, S.J. and Sivyer, D.B., 1997. Nutrient recycling in intertidal sediments. in
 
Jickells, T. and Rae, J.E. (Eds) Biogeochemistry of Intertidal Sediments. Cambridge University Press, pp. 59–83.</ref> . It is also quantitatively more important in ecosystems characterized by relatively long residence times<ref name=”Nixon1995”> Nixon, S.W. (1995), Coastal marine eutrophication: A definition, social causes, and future concerns, Ophelia 41, 199–219.</ref> . In groundwater systems, the nitrate supplied either by infiltrating water or produced through nitrification<ref name=”Horrigan1985”> Horrigan, S.G., and Capone, D.G (1985), Rates of nitrification and nitrate reduction in nearshore marine sediments under varying environmental conditons, Marine Chemistry 16, 317-327</ref> ,<ref name=”Nowicki1999”> Nowicki, B.L., E. Requintina, D. van Keuren, and J. Portnoy (1999), The role of sediment denitrification in reducing groundwater-derived nitrate inputs to Nauset Marsh Estuary, Cape Cod, Massachusetts, Estuaries 22, 245-259.</ref>  is also commonly removed through denitrification. As in surface estuaries, a set of conditions, namely the presence of labile organic matter, a low redox potential and sufficient time for reaction, are prerequisite for effective denitrification to occur. However, field studies often report only limited nitrate removal prior to discharge to coastal waters primarily due to a lack of labile dissolved organic matter<ref name=”Star1993”> Starr, R.C., and R.W. Gillham (1993), Denitrification and organic-carbon availability in two aquifers, Ground Water 31, 934–947.</ref> ,<ref name=”Slater1987”> Slater, J.M., and D.G. Capone (1987), Denitrification in aquifer soil and nearshore marine sediments influenced by groundwater nitrate, Applied and Environmental Microbiology 53, 1292-1297.</ref> ,<ref name=”DeSimone1996”> DeSimone, L.A., and B.L. Howes (1996), Denitrification and nitrogen transport in a coastal aquifer receiving wastewater discharge, Environmental Science and Technology 30, 1152-1162.</ref>, as is the case in many shallow groundwater aquifers or sandy nearshore sediments, or due to high groundwater velocities<ref name="Capone1990">Capone, D.G., and J.M. Slater (1990), Interannual patterns of water-table height and groundwater derived nitrate in nearshore sediments, Biogeochemistry 10, 277-288.</ref>,<ref name=”Giblin1990”> Giblin, A.E., and A.G. Gaines (1990), Nitrogen inputs to a marine embayment: The importance of groundwater, Biogeochemistry 10, 309-328.</ref> .
 
 
 
==Phosphorus==
 
 
 
P species in aquatic systems include dissolved (inorganic, organic P) and particulate (inorganic, organic P) constituents<ref name="Tappin 2002"/> . The retention of P in the land-ocean transition zone is often attributed to adsorption on solid particles, which are constantly trapped in estuarine sediments<ref name=”Jickells1991”> Jickells, T.D., T.H. Blackburn, J.O. Blanton, D. Eisma, S.W. Fowler, R.F.C. Manroura, C.S. Martens, A. Moll, R. Scharek, K.I. Suzu, and D. Vaulot (1991), What determines the fate of material within ocean margins? Ocean Margin Processes in Global Change, R.F.C Mantoura, J.-M.  Martin, and R. Wollast, Eds. (John Wiley & Sons Ltd.), pp. 211–234.</ref> , or forms part of the solid matrix in coastal aquifers. However, in the case of very large rivers that discharge directly in the continental shelf, P retention in the mixing zones between freshwater and seawater will be limited<ref name=”Milliman1991”> Milliman, J.D. (1991), in Ocean Margin Processes in Global Change, R.F.C Mantoura, J.-M.  Martin, and R. Wollast, Eds. (John Wiley & Sons Ltd.), pp. 69–90.</ref> . Adsorption onto solids such as iron and aluminum oxides is particularly effective<ref name=”Krom1980”> Krom, M.D., and R.A. Berner (1980), Adsorption of phosphate in anoxic marine sediments, Limnology and Oceanography 25, 797-806.</ref> ,<ref name=”Frossard1995”> Frossard, E., M. Brossard, M.J. Hedley, and A. Metherell (1995), Reactions controlling the cycling of P in soils. Phosphorus in the global environment, H. Tiessen, Ed. (John Wiley & Sons Ltd.), pp. 107-138.</ref> , and thus may be also coupled to the redox conditions<ref name=”Spiteri2007”> Spiteri, C., C.P. Slomp, K. Tuncay, and C. Meile (2007), Modeling biogeochemical processes in subterranean estuaries: The effect of flow dynamics and redox conditions on submarine groundwater discharge, Water Resources Research, doi:10.1029/2007WR006071.</ref> . For instance, removal of P is very efficient in subterranean estuaries characterized by zones of iron oxide accumulation, (“Iron Curtains” <ref name=”Charette2002”> Charette, M.A., and E.R. Sholkovitz (2002), Oxidative precipitation of groundwater-derived ferrous iron in the subterranean estuary of a coastal bay, Geophysical Resources Letters 29, art. no.-1444.</ref> ,<ref name=”Spiteri2006”> Spiteri, C., P. Regnier, C.P. Slomp, and M.A. Charette (2006), pH-Dependent iron oxide precipitation in a subterranean estuary, Journal of Geochemical Exploration 88, 399-403.</ref> ). The behavior of P in estuarine systems is also influenced by the strong physico-chemical gradients, which result from the variations in pH, ionic strength and solution composition between the freshwater and seawater end-members (e.g. <ref name=”Froelich1998”> Froelich, P.N. (1988), Kinetic control f dissolved phosphate in natural rivers and estuaries: A primer o the phosphate buffer mechanism, Limnology and Oceanography 33, 649-668.</ref> ,<ref name=”Lebo1991”> Lebo, M.E. (1991), Particle-bound phosphorus along an urbanized coastal plain estuary, Marine Chemistry 34, 225-246.</ref> ,<ref name=”VadderZee2007”> Van der Zee, C., N. Roevros, and L. Chou (2007), Phosphorus speciation, transformation and retention in the Scheldt estuary (Belgium/The Netherlands) from the freshwater tidal limits to the North Sea, Marine Chemistry doi:10.1016/j.marchem.2007.01.003.</ref> ). The removal of P can occur through bacterial reduction of phosphate to gaseous phosphine. However, little is known on the rate of phosphate-phosphine transformation and its contribution to overall P cycling<ref name=”Gassman1994”> Gassman, G. (1994) Phosphine in the fluvial and marine hydrosphere, Marine Chemistry 45, 197–205.</ref> , <ref name="Tappin 2002"/> .
 
 
 
 
 
Tidal and marginal sediments are considered important sinks of N and P, although a quantitative estimation of their role remains uncertain<ref name=”Carpenter1997”> Carpenter, K. (1997) A critical appraisal of the methodology used in studies of material flux between saltmarshes and coastal waters. Biogeochemistry of Intertidal Sediments, T.D. Jickells,  and  J.E. Rae, Eds. (Cambridge University Press), pp. 59–83.</ref> ,. <ref name=”Ruddy1998a”> Ruddy, G., C. M. Turley, and T.E.R. Jones (1998a), Ecological interaction and sediment transport on an intertidal mudflat I. Evidence for a biologically mediated sediment-water interface. Sedimentary Processes in the Intertidal Zone, K.S. Black, D.M. Paterson, and A. Cramp, Eds. Geological Society of London Special Publications 139, pp. 135–148.</ref> ,. <ref name=”Ruddy1998b”> Ruddy, G., C.M. Turley, and T.E.R. Jones (1998b), Ecological interaction and sediment transport on an intertidal mudflat II. An experimental dynamic model of the sediment-water interface. Sedimentary Processes in the Intertidal Zone. K.S. Black, D.M. Paterson, and A. Cramp, Eds. Geological Society of London Special Publications 139, pp. 149–166.</ref> . On the global scale, it is generally accepted that intertidal sediments are more efficient for P burial than for N<ref name=”Billen1991”> Billen, G., C. Lancelot, and M. Meybeck (1991), N, P and Si retention along the aquatic continuum from land to ocean. Ocean Margin Processes in Global Change, R.F.C Mantoura, J.-M.  Martin, and R. Wollast, Eds. (John Wiley & Sons Ltd.), pp. 19-44.</ref> <ref name=”Howarth1995”> Howarth, R., H. Jensen, R. Marino, and H. Postma, Phosphorus in the Global Environment:Transfers, Cycles and Management, H. Tiessen, Ed., Scientific Committee on Problems of the Environment 54. (Wiley, New York, 1995), pp. 323–356.</ref> .
 
 
 
==Silicon==
 
 
 
Relevant Si species in the aquatic environments include dissolved Si (DSi), mainly as undissociated monomeric silicic acid, Si(OH)<sub>4</sub>, and particulate Si (biogeneic silica, BSiO<sub>2</sub>), which includes the amorphous silica in both living biomass and biogenic detritus in surface waters, soils and sediments. The main transformation processes are the uptake of DSi and the biomineralisation as BSiO2 in plants and organisms, as well as the dissolution of BSiO2 back to DSi. Over sufficiently long time scales, BSiO<sub>2</sub> may undergo significant chemical and mineralogical changes<ref name=”VanCappellan2002”> Van Cappellen, P., S. Dixit, and J. van Beusekom (2002), Biogenic silica dissolution in the oceans: Reconciling experimental and field-based dissolution rates, Global Biogeochemical Cycles 16, 1075, doi:10.1029/2001GB001431.</ref> , even including a complete diagenetic transformation of the opaline silica into alumino-silicate minerals. <ref name=”Michalopoulos2000”> Michalopoulos, P., R.C. Aller, and R.J. Reeder (2000), Conversion of diatoms to clays during early diagenesis in tropical, continental shelf muds, Geology 28, 1095-1098.</ref>.
 
 
 
The major producers of BSiO<sub<2</sub> in marine environments are diatoms. However, other organisms such as radiolarians, sponges and chrysophytes may be important local sources of BSiO<sub>2</sub><ref name=”Simpson1981”> Simpspon, T.L. and B.E. Volcani (1981), Silicon and Siliceous Structures in Biological Systems, Springer-Verlag NY, 587 pp </ref> . Large quantities of DSi are also fixed on land by higher plants, forming amorphous silica deposits, known as phytoliths<ref name=”Piperno1998”> Piperno, D.L. (1998), Phytolith analysis. An archaeological and geological perspective. London: Academic Press.</ref> . Their role in the Si cycle has only recently been studied<ref name=”Bartoli1983”> Bartoli, F. (1983), The biogeochemical cycle of silicon in two temperate forest ecosystems, Ecological Bulletins (Stockholm) 35, 469–476.</ref> ,<ref name=”Meunier1999”> Meunier, J.D., F. Colin, and C. Alarcon (1999), Biogenic silica storage in soils, Geology 27, 835-838. </ref> . In general, riverine Si fluxes have been much less altered by human activity than those of N and P. However, increased damming of major rivers has promoted siliceous phytoplankton blooms<ref name=”Billen1991”> Billen, G., C. Lancelot, and M. Meybeck (1991), N, P and Si retention along the aquatic continuum from land to ocean.</ref> ,<ref name="Humborg1997"> Humborg, C., V. Ittekot, A. Cociosu, and B. v. Bdungen (1997), Effect of Danube River dam on Black Sea biogeochemistry and ecosystem structure, Nature 386, 385 – 388.</ref> , and therefore, reduced Si fluxes to the coastal zone. For example, the damming of the Danube has reduced the DSi concentration by more than 50%<ref name="Humborg1997"/>.
 
 
 
=EUROPEAN CONTEXT=
 
Nutrient budgets and fluxes have been established at the local (major rivers) and regional (coastal seas) scales across Europe. Two examples are provided below: (1) a N budget of the continental inputs to the North Sea<ref name="Galloway1995"> Galloway, J., W. Chlesinger, H. Levy, A. Michaels, and J. Schnoor (1995), Nitrogen fixaton: Anthropogenic enhancement and environmental response, Global Biogeochemical Cycles 9, 235-252.</ref>  and (2) a N budget of major riverine inputs and transformations along the Western Scheldt river-estuarine system<ref name="Vanderborght"/> . Other nutrient budgets have been established, among others, for the Western shelf of the Black Sea <ref name=”Gregoire2004”> Gregoire, M., and J. Friedrich (2004), Nitrogen budget of the northwestern Black Sea shelf inferred from modeling studies and in situ benthic measurements, Marine Ecology Progress Series 270, 15-39.</ref>  and the Baltic Sea<ref name=”Wulff2001”> Wulff, F., L. Rahm, A. - K. Hallin, and J. Sandberg (2001), A nutrient budget model of the Baltic Sea. Chapter 13 A systems analysis of the Baltic Sea. Ecological Studies, F. Wulff, L. Rahm, and P. Larsson Eds., (Springer Verlag) Vol 148, pp 353-372.</ref> . At a smaller scale, detailed estimates of the nutrient sources, transport and transformations are also available for the Seine and Humber continuums<ref name=”Garnier1995”> Garnier, J., G. Billen, and M. Coste (1995), Seasonal succession of diatoms and Chlorophyceae in the drainage network of the Seine River: observations and modeling, Limnology and Oceanography 40, 750-765.</ref> ,<ref name=”Tappin2003”> Tappin, A.D., J.R.W. Harris and R.J. Uncles (2003) The fluxes and transformations of suspended particles, carbon and nitrogen in the Humber Estuary (UK) from 1994 to 1996 : results from an integrated observation and modelling study. The Science of the Total Environment 314/316, 665-713.</ref> .
 
 
 
==North Sea==
 
[[Image:N dep atm.jpg|thumb|px380|Figure 2. Total atmospheric nitrogen deposition to North Sea, 1999, in ton N per km2(source: Hertel et al, 2002)<ref name="Hertel2002"/>]]
 
The continental inputs of nitrogen to the North Sea originate from rivers, atmospheric inputs and, to a much smaller extent, direct discharges and dumping<ref name="Galloway1995"/>. The riverine contributions are summarized in Table 1 and, collectively, amount to almost twice that of atmospheric inputs<ref name="Jickells 1998"/>. Figure 2 shows the spatial distribution of the total atmospheric N deposition to the North Sea. The spatial pattern results from the distribution of the source areas and precipitation rates. On average, deposition amounts to 0.9 ton N per km2, with deposition up to 50% higher than average around territorial waters of Belgium, the Netherlands and Germany. Approximately 60% of total atmospheric N deposition results from combustion (nitrogen oxides) and approximately 40% from agricultural activities (ammonia) <ref name="Hertel2002"> Hertel, O., C. Ambelas Skjøth, L.M. Frohn, E. Vignati, J. Frydendall, G. de Leeuw, U. Schwarz, and S. Reiset  (2002), Assessment of the atmospheric nitrogen and sulphur inputs into the North Sea using a Lagrangian model, Physics and Chemistry of the Earth 27 ,1507 – 1515.</ref> .
 
 
 
 
 
 
 
{|border="1" cellpadding="5" cellspacing="0" align="center"
 
|+Table 1: Annual river inputs (ton per year) of nitrogen for all relevant rivers around the North Sea (source: Radach and Lenhart, 1995) <ref name="Radach1995">Radach, G., and H.J. Lenhart (1995), Nutrient dynamics in the North Sea: Fluxes and budgets in the water derived from ERSEM, Netherlands Journal of Sea Research 33, 301-335.</ref> . P and S fluxes are also shown
 
|-
 
! style="background:#efefef;" | River
 
! style="background:#efefef;" | N
 
! style="background:#efefef;" | P
 
! style="background:#efefef;" | Si
 
|-
 
|Firth of Forth
 
|20
 
|186
 
|11
 
|-
 
|Tyne/Tees
 
|14735
 
|593
 
|9309
 
|-
 
|
 
Humber
 
|60636
 
|5891
 
|17928
 
|-
 
|Thames
 
|26214
 
|3786
 
|14931
 
|-
 
|Ems
 
|25736
 
|614
 
|6805
 
|-
 
|Noordzeekanaal
 
|10877
 
|1767
 
|3912
 
|-
 
|Lauwer
 
|333
 
|143
 
|25
 
|-
 
|Lake IJssel/Kornwerderzand
 
|12320
 
|461
 
|3588
 
|-
 
|
 
Lake IJssel/Den Oever
 
|21232
 
|80
 
|5170
 
|-
 
|Meuse
 
|91159
 
|4400
 
|34402
 
|-
 
|Rhine
 
|191543
 
|14194
 
|69623
 
|-
 
|Scheldt
 
|31670
 
|2116
 
|15077
 
|-
 
|Yzer
 
|267
 
|109
 
|37
 
|-
 
|Elbe
 
|126314
 
|3822
 
|34520
 
|-
 
|Jade
 
|8
 
|3
 
|2
 
|-
 
|Schleswig-Holstein river
 
|8
 
|3
 
|2
 
|-
 
|Weser
 
|52862
 
|3420
 
|18470
 
|-
 
|Danish rivers
 
|1227
 
|513
 
|136
 
|-
 
|}
 
 
 
==The Western Scheldt Estuary==
 
[[Image:Mass budget AandB.jpg|thumb|650px|Figure 3. Mass budget for (A) ammonium and (B) nitrate in the tidal rivers (right) and in the saline estuary of the Western Scheldt (left) in the summer of 1990, 2002 and 2010. Processes: resp=aerobic respiration; nitrif=nitrification; denit=denitrification; npp=net primary production. Transport fluxes are positive seawards. All fluxes are given in kmol day<sup>-1</sup>. Top arrow: Riverine and lateral inputs; Left arrow: export to the coastal zone. (source: <ref name="Vanderborght"/> Vanderborght et al., 2007]]
 
The Scheldt River and its tributaries drain 21,580 km<sup>2</sup> in northwestern France, northern Belgium and southwestern Netherlands<ref name=”Wollast1988”> Wollast, R. (1988), The Scheldt estuary. Pollution of the North Sea: An Assessment, W. Salamons,  B.L. Bayne, E.K. Duursma, and U. Forstner Eds., (Springer-Verlag, Berlin) pp. 183-193.</ref> . The Scheldt estuary is a a macrotidal system, with an average residence time in brackish waters of 1 to 3 months. The mixing zone of fresh and salt waters extends over a distance of 70 to 100 km. The area of tidal influence goes up to 160 km from the river mouth and includes the major <ref name=”Regnier1997”>Regnier, P., R. Wollast, and C.I. Steefel (1997), Long-Term Fluxes of Reactive Species in Macrotidal Estuaries. Estimates from a Fully Transient, Multi Component Reaction-Transport Model, Marine Chemistry 58, 127-145.</ref> .
 
 
 
The hydrographical basin includes one of the most heavily populated regions of Europe, where highly diversified industrial activity has developed. As a consequence, the whole catchment was heavily polluted until the mid 1970s, when water degradation culminated due to the continuous increase of nutrient and organic mater inputs. The level of wastewater treatment, especially in the upstream zones, was an important factor contributing to this degradation. The estuary was particularly affected by domestic and industrial inputs from the great Brussels, Antwerp and Gent areas<ref name="Vanderborght"/>  . Since then, better management of industrial and domestic wastewater point sources has led to a progressive improvement of the environmental conditions in the estuary. Billen et al. (2005) <ref name=”B&G2005”> Billen, G., J. Garnier, and V. Rousseau (2005), Nutrient fluxes and water quality in the drainage network of the Scheldt basin over the last 50 years. Ecological structures and functions in the Scheldt Estuary: from past to future. P. Meire,  and S. Van Damme Eds. Hydrobiologia 540(1-3), 46-67.</ref>  and Soetaert et al. (2006) <ref name=”Soetaert 2006”> Soetaert, K. J.J. Middelburg, C. Heip, P. Meire, S. Van Damme, and T. Maris (2006), Long-term change in dissolved inorganic nutrients in the heterotrophic Scheldt estuary (Belgium, The Netherlands), Limnology and Oceanography 51, 409-423.</ref>  provide two recent comprehensive reviews of this long term evolution.
 
 
 
A mass budget for nitrogen has been established for the saline estuary (km 0 to100) and for the tidal river network (km 100 to 160) of the Western Scheldt for the summer months<ref name="Vanderborght"/> . Three periods have been analyzed (1990, 2002 and 2010). This allows for the assessment of the influence the secondary and tertiary wastewater treatment in the catchment on the N dynamics. Figure 3 shows that the tidal river and the estuary contribute almost equally to the overall biogeochemical cycling of N, despite the very different volumes involved. For the simulated periods, the large decrease in N input (> 55 %) expected between 1990 and 2010 will not lead to a significant decrease of N export to the coastal zone during the summer period.
 
 
 
==REFERENCES==
 
<references/>
 
 
 
==EXTERNAL LINKS==
 
 
:[http://www.eloisegroup.org/themes/nutrients/contents.htm ELOISE Nutrient Dynamics in European Water Systems ONLINE]
 
:[http://www.eloisegroup.org/themes/nutrients/contents.htm ELOISE Nutrient Dynamics in European Water Systems ONLINE]
 
:[http://www.eloisegroup.org/themes/nutrients/pdf/nutrient_dynamics.pdf ELOISE Nutrient Dynamics in European Water Systems in pdf format]
 
:[http://www.eloisegroup.org/themes/nutrients/pdf/nutrient_dynamics.pdf ELOISE Nutrient Dynamics in European Water Systems in pdf format]
 
:[http://www.eloisegroup.org/themes/nutrients/casesintro.htm Case studies]
 
:[http://www.eloisegroup.org/themes/nutrients/casesintro.htm Case studies]
 
:[http://www.loicz.org/ LOICZ Land-Ocean Interactions in the Coastal Zone]
 
:[http://www.loicz.org/ LOICZ Land-Ocean Interactions in the Coastal Zone]
 
==SEE ALSO==
 
[[Eutrophication]]
 
 
  
  
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[[Category:Eutrophication]]

Latest revision as of 08:58, 30 July 2019

Nutrient export fluxes in coastal systems, primarily as nitrogen (N), phosphorus (P) and silicon (Si), have a significant impact on water quality and control the nature and magnitude of coastal productivity. In coastal areas, nutrients are delivered by rivers, groundwater discharge and atmospheric deposition. The growing impact of anthropogenic activities has profoundly affected the quality of marine waters over the last 50 years. Such alterations are well documented and have been linked to perturbations in nutrient export fluxes from the continent[1] . In areas of restricted water exchange, the export of excess N and P to coastal waters may cause coastal eutrophication, a blooming of suspended and bed-anchored algae (including toxic species), alteration of community structures, degradation in the ecosystem function and modifications of marine food webs[2] . The continuing changes in land use and global urbanisation of coastal margins[3] thus pose a continual threat to coastal waters.

Continental Nutrient Sources and Nutrient Transformation

Nutrients in coastal environments come from various sources - through rivers, groundwater or atmospheric deposition. The main species - Nitrogen, Phosphorus and Silicon - undergo different transformation processes and states. Nutrient dynamics is further discussed in Continental Nutrient Sources and Nutrient Transformation.

European Context of Nutrient Dynamics

Nutrient budgets and fluxes have been established at the local (major rivers) and regional (coastal seas) scales across Europe. The article European Context of Nutrient Dynamics provides examples.


References

  1. Vanderborght, J-P, I. Folmer, D. Rodriguez Aguilera, T. Uhrenholt, and P. Regnier (2007), Reactive-transport modelling of a river-estuarine coastal zone system: application to the Western Scheldt, Marine Chemistry 106, 92-110.
  2. Garnier, J., G. Billen, E. Hannon, S. Fonbonna, Y. Videnia, and M. Soulie (2002), Modelling the transfer and retention of nutrients in the drainage network of the Danube river, Estuarine, Coastal and Shelf Science, 54, 285-308.
  3. Tappin, A.D. (2002), An Examination of the Fluxes of Nitrogen and Phosphorus in Temperate and Tropical Estuaries: Current Estimates and Uncertainties, Estuarine, Coastal and Shelf Science 55, 885-901.


See also

Eutrophication
Continental Nutrient Sources and Nutrient Transformation
European Context of Nutrient Dynamics


External links

ELOISE Nutrient Dynamics in European Water Systems ONLINE
ELOISE Nutrient Dynamics in European Water Systems in pdf format
Case studies
LOICZ Land-Ocean Interactions in the Coastal Zone


The main author of this article is Pierre Regnier
Please note that others may also have edited the contents of this article.

Citation: Pierre Regnier (2019): Nutrient dynamics. Available from http://www.coastalwiki.org/wiki/Nutrient_dynamics [accessed on 19-11-2019]


The main author of this article is Claudette Spiteri
Please note that others may also have edited the contents of this article.

Citation: Claudette Spiteri (2019): Nutrient dynamics. Available from http://www.coastalwiki.org/wiki/Nutrient_dynamics [accessed on 19-11-2019]