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Deutsche Hydrografische Zeitschrift

, Volume 51, Issue 2–3, pp 313–329 | Cite as

Carbon cycling in the German Bight: An estimate of transformation processes and transport

  • A. Reimer
  • S. Brasse
  • R. Doerffer
  • C. -D. Dürselen
  • S. Kempe
  • W. Michaelis
  • H. -J. Rick
  • R. Seifert
Article

Summary

Carbon cycling in the shallow, near-coastal environment of the German Bight, south-eastern North Sea was studied during different seasons (spring, summer, winter). Special emphasis was placed on the investigation of processes: biologically induced internal transformation within the water column as well as external influences (rivers, Wadden Sea). Detailed analysis of dissolved inorganic carbon, total alkalinity, particulate organic carbon, dissolved oxygen and calculated CO2 fluxes revealed carbon cycling in the German Bight to be highly variable between seasons, with either dominance of physical processes during winter or pronounced biological control during productive times in spring and summer. During winter, enhanced input of particulate carbon was gained from the Wadden Sea by ice transport while biological processes stayed low. In spring, high primary production decreased the inorganic carbon pool and pronounced CO2 fluxes from the atmosphere into the surface water amounted to 40 mmol m-2 d-1. About sixty per cent of the produced biomass was rapidly remineralised within the surface layer, while in the bottom waters remineralisation stayed low. Degassing of CO2 to the atmosphere could only be observed during times of enhanced river discharge. During summer, high regenerated production accounted for CO2 fluxes of up to 25 mmol m-2 d-1 into the surface water. Replenishment of DIC in the surface layer through vertical mixing was hindered by strong stratification. Ninety-five per cent of the primary produced biomass was remineralised. Our investigations clearly show the German Bight to be a net carbon sink in spring and summer. Apart from degassing of CO2 as a result of late autumn vertical mixing or short term events like enhanced freshwater input, CO2 concentrations close to equilibrium during winter suggest that the German Bight constitutes a net annual sink for atmospheric CO2.

Keywords

German Bight River Plume Total Suspended Matter German Journal Particulate Organic Carbon Concentration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Der Kohlenstoffkreislauf in der Deutschen Bucht: Eine AbschÄtzung von Transformationsprozessen und Transporten

Zusammenfassung

Der Kohlenstoffkreislauf in der Deutschen Bucht wurde im Rahmen des KUSTOS Projektes in saisonaler Auflösung (Sommer, Frühjahr, Winter) wÄhrend der Jahre 1994-1996 untersucht. Die Quantifizierung des Kohlenstoffumsatzes zwischen marinem, fluviatilem, tidalem, atmosphÄrischem und sedimentÄrem Kompartiment in der Deutschen Bucht ermöglichte die Aufstellung einer Bilanz für Kohlenstoff im Küstenvorfeld.

Es konnte gezeigt werden, da\ der Kohlenstoffhaushalt in der Deutschen Bucht starken saisonalen Schwankungen unterliegt, aber auch durch kurzzeitige Ereignisse (z. B. erhöhter Abflu\ der einmündenden Flüsse oder Eisbedeckung) erheblich beeinflu\t wird. WÄhrend des Sommers dominieren biologische Prozesse (PrimÄrproduktion, Remineralisierung), die zu einem erhöhten Kohlenstoffumsatz innerhalb der WassersÄule führen. So werden bis zu 95% der produzierten Biomasse bereits in der WassersÄule wieder remineralisiert. WÄhrend des Winters konnten erhöhte Transporte von partikulÄrem Kohlenstoff aus den WattgewÄssern nachgewiesen werden. Generell überwiegen hier physikalische Prozesse. Im Frühjahr konnte detailliert die Entwicklung einer Planktonblüte verfolgt werden. WÄhrend der Zeit erhöhten Elbeabflusses im Frühjahr kommt es zu einer Entgasung von CO2 in die AtmosphÄre, generell stellt sich die Deutsche Bucht aber wÄhrend der von uns untersuchten ZeitrÄume als Senke für atmosphÄrisches CO2 dar (0.05* 109 mol d-1 im Winter bis 0.30 * 10-9 mol d-1 im Sommer).

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Copyright information

© Springer-Verlag 1999

Authors and Affiliations

  • A. Reimer
    • 1
  • S. Brasse
    • 2
  • R. Doerffer
    • 3
  • C. -D. Dürselen
    • 4
  • S. Kempe
    • 5
  • W. Michaelis
    • 6
  • H. -J. Rick
    • 7
  • R. Seifert
    • 8
  1. 1.Institut für Geologie und PalÄontologieGeorg August UniversitÄt GöttingenGöttingen
  2. 2.Institut für Biogeochemie und MeereschemieUniversitÄt HamburgHamburg
  3. 3.GKSS ForschungszentrumGeesthacht
  4. 4.Institut für Chemie und Biologie des MeeresUniversitÄt OldenburgOldenburg
  5. 5.Geologisch-PalÄontologisches InstitutTechnische Hochschule DarmstadtDarmstadt
  6. 6.ZMK Institut für Biogeochemie und MeereschemieUniversitÄt HamburgHamburg
  7. 7.Institut für MeereskundeUniversitÄt Kiel Abt. Marine BotanikKiel
  8. 8.Institut für Biogeochemie und MeereschemieUniversitÄt HamburgHamburg

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