Maximum sinking velocities of suspended particulate matter in a coastal transition zone

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dc.identifier.uri Maerz, Joeran Hofmeister, Richard van der Lee, Eefke M. Gräwe, Ulf Riethmüller, Rolf Wirtz, Kai W. 2016-11-24T12:51:18Z 2016-11-24T12:51:18Z 2016
dc.identifier.citation Maerz, J.; Hofmeister, R.; Van Der Lee, E.M.; Gräwe, Ulf; Riethmüller, R. et al.: Maximum sinking velocities of suspended particulate matter in a coastal transition zone. In: Biogeosciences 13 (2016), Nr. 17, S, 4863-4876. DOI:
dc.description.abstract Marine coastal ecosystem functioning is crucially linked to the transport and fate of suspended particulate matter (SPM). Transport of SPM is controlled by, amongst other factors, sinking velocity ws. Since the ws of cohesive SPM aggregates varies significantly with size and composition of the mineral and organic origin, ws exhibits large spatial variability along gradients of turbulence, SPM concentration (SPMC) and SPM composition. In this study, we retrieved ws for the German Bight, North Sea, by combining measured vertical turbidity profiles with simulation results for turbulent eddy diffusivity. We analyzed ws with respect to modeled prevailing dissipation rates ϵ and found that mean ws were significantly enhanced around log10(ϵ (m2 s−3)) ≈ −5.5. This ϵ region is typically found at water depths of approximately 15 to 20 m along cross-shore transects. Across this zone, SPMC declines towards the offshore waters and a change in particle composition occurs. This characterizes a transition zone with potentially enhanced vertical fluxes. Our findings contribute to the conceptual understanding of nutrient cycling in the coastal region which is as follows. Previous studies identified an estuarine circulation. Its residual landward-oriented bottom currents are loaded with SPM, particularly within the transition zone. This retains and traps fine sediments and particulate-bound nutrients in coastal waters where organic components of SPM become remineralized. Residual surface currents transport dissolved nutrients offshore, where they are again consumed by phytoplankton. Algae excrete extracellular polymeric substances which are known to mediate mineral aggregation and thus sedimentation. This probably takes place particularly in the transition zone and completes the coastal nutrient cycle. The efficiency of the transition zone for retention is thus suggested as an important mechanism that underlies the often observed nutrient gradients towards the coast. eng
dc.description.sponsorship BMBF/PACE
dc.description.sponsorship BMBF/FKZ 030634A
dc.description.sponsorship BMBF/FKZ 03F0667A
dc.description.sponsorship Helmholtz Society/PACES
dc.description.sponsorship Niedersächsisches Ministerium für Wissenschaft und Kultur (MWK)
dc.description.sponsorship Niedersächsisches Ministerium für Umwelt und Klimaschutz (MUK)
dc.description.sponsorship Coastal Observing System for Northern and Arctic Seas (COSYNA)
dc.language.iso eng
dc.publisher Göttingen : Copernicus GmbH
dc.relation.ispartofseries Biogeosciences 13 (2016), Nr. 17
dc.rights CC BY 3.0
dc.subject algae eng
dc.subject.ddc 550 | Geowissenschaften ger
dc.title Maximum sinking velocities of suspended particulate matter in a coastal transition zone
dc.type article
dc.type Text
dc.relation.issn 1726-4170
dc.bibliographicCitation.issue 17
dc.bibliographicCitation.volume 13
dc.bibliographicCitation.firstPage 4863
dc.bibliographicCitation.lastPage 4876
dc.description.version publishedVersion
tib.accessRights frei zug�nglich

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