Sediment Fluxes, Re-suspension and Accumulation Rates at Two Wind-exposed Coastal Sites and in a Sheltered Bay

Lund-Hansen, Lars Chresten; Valeur, Jens Rosendal; Pejrup, Morten; Jensen, Annie Aarup

doi:10.1006/ecss.1996.0163

Cited by 41 publications

(9 citation statements)

References 29 publications

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“…The depletion of nutrients from the Kattegat surface waters follows generally the spring bloom . The waters remain nutrient depleted throughout the autumn period as the vertical exchange between surface and bottom layers is strongly reduced by the stratification (Skyum et al, 1996;Lund-Hansen et al, 1997). The pycnocline was located around 12 m depth with a nutricline between 10 and 15 m depth.…”

Section: Discussionmentioning

confidence: 99%

Subsurface chlorophyll maximum (SCM) location and extension in the water column as governed by a density interface in the strongly stratified Kattegat estuary

Lund-Hansen

2011

Hydrobiologia

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The aims of the study were to analyse the relations between the physics of a water column and the location of the subsurface chlorophyll maximum (SCM) peaks in a strongly stratified estuary. Could extension and depth location of the SCM be explained by the physical conditions in terms of water column stratification and density interface? Questions were addressed by obtaining data on water column density (CTD), chlorophyll a (Chl a), nutrients, (F v /F m ), r PSII and K d (PAR) at 15 positions along a 575 km transect in the Kattegat estuary. Results showed that the estuary was strongly stratified with mixed surface and bottom layers intercepted by a layer where density increased with depth. The SCM occurred only in this density interface, and widths of SCM and density interface were highly correlated. The surface waters were nearly depleted of inorganic nitrogen, phosphate and silicate though with significant higher concentrations in the waters below the interface. The Chl a concentration was comparatively higher in the SCM peak as well as maximum quantum efficiency (F v /F m ) and functional cross sectional area (r PSII ). The SCM was maintained at very low light levels and by a diapycnal nitrogen flux, with a stratified water column and nutrient depleted surface waters as predecessors. It was concluded that the depth location and vertical extension of the SCM in the estuary were closely linked to the physical structure of the water column in terms of density interface and stratification.

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Section: Discussionmentioning

confidence: 99%

Subsurface chlorophyll maximum (SCM) location and extension in the water column as governed by a density interface in the strongly stratified Kattegat estuary

Lund-Hansen

2011

Hydrobiologia

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“…A software (PC) is used for controlling the rotation velocity of the impeller and for recording the light beam (633 nm) attenuation data (see more in detail Lund-Hansen et al 1999). Critical current velocities at 100 cm from the bottom (U 100 ) were calculated by the equation (e.g., Lund-Hansen et al 1997):…”

Section: Sediment Sampling and Critical Shear Stress Measurementsmentioning

confidence: 99%

Instantaneous Effects of Sediment Resuspension on Inorganic and Organic Benthic Nutrient Fluxes at a Shallow Water Coastal Site in the Gulf of Finland, Baltic Sea

Niemistö¹,

Lund-Hansen

2019

Estuaries and Coasts

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Climate change is leading to harsher resuspension events in shallow coastal environments influencing benthic nutrient fluxes. However, we lack information on the quantitative connection between these fluxes and the physical forces. Two identical experiments that were carried out both in May and August provided novel knowledge on the instantaneous effects of resuspension with known intensity on the benthic dissolved inorganic (phosphate: DIP, ammonium: NH 4 + , nitrite+nitrate: NO x , silicate, DSi) and organic nutrient (phosphorus: DOP, nitrogen: DON, carbon: DOC) fluxes in the shallow soft bottoms of the archipelago of Gulf of Finland (GoF), Baltic Sea. Resuspension treatments, as 2 times the critical shear stress, induced effluxes of one to two orders of magnitude higher than the diffusive fluxes from the studied oxic bottoms. The presence of oxygen resulted in newly formed iron oxyhydroxides and the subsequent precipitation/ adsorption of the redox-dependent nutrients (DIP, DSi, organic nutrients) affecting their fluxes. Resuspension-induced NH 4 + and NO x fluxes were associated with the organic content of sediments showing the highest values at the organic rich sites. NH 4 + showed the strongest responses to resuspension treatments in August, but NO x at the time of high oxygen concentrations in near-bottom water in May. Foreseen increases in the frequency and intensity of resuspension events due to climate change will most likely enhance the internal nutrient loading of the studied coastal areas. The fluxes presented here, connected to known current velocities, can be utilized in modeling work and to assess and predict the internal nutrient loading following climate change.

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“…1, particulate matter there is formed from suspended matter entering the coastal environment with river run-off, produced by abrasion of the shore and shallow sea bottom, primary production, atmospheric deposition, autogenic mineral formation, and direct anthropogenic discharges Jones et al, 1998;Bianchi et al, 2002;Pempkowiak et al, 2002). En route from the high-energy, shallow, coastal environment to the low-energy, deep, depositional basins the matter is a subject to later resuspension, migration driven by near-bottom currents, and sedimentation .Wind-induced currents (Lund-Hansen et al, 1997) and aggregation of suspended matter particles (Thomsen and Ritzrau, 1996) are thought to be major factors influencing near bottom transport. However, in periods of calm weather, suspended-matter sedimentation leads to the formation of a high-density fluffy suspended matter (FLSM) layer resting on the sea bottom.…”

Section: Introductionmentioning

confidence: 99%

Factors influencing fluffy layer suspended matter (FLSM) properties in the Odra River - Pomeranian Bay - Arkona Deep System (Baltic Sea) as derived by principal components analysis (PCA), and cluster analysis (CA)

Pempkowiak

Bełdowski

Pazdro

et al. 2005

Hydrol. Earth Syst. Sci.

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Abstract. Factors conditioning formation and properties of suspended matter resting on the sea floor (Fluffy Layer Suspended Matter -FLSM) in the Odra river mouth -Arkona Deep system (southern Baltic Sea) were investigated.Thirty FLSM samples were collected from four sampling stations, during nine cruises, in the period 1996-1998. Twenty six chemical properties of the fluffy material were measured (organic matter-total, humic substances, a variety of fatty acids fractions, P, N, δ13C, δ15N; Li; heavy metalsCo, Cd, Pb, Ni, Zn, Fe, Al, Mn, Cu, Cr). The so obtained data set was subjected to statistical evaluation.Comparison of mean values of the measured properties led to conclusion that both seasonal and spatial differences of the fluffy material collected at the stations occured. Application of Principal Component Analysis, and Cluster Analysis, to the data set amended with environmental characteristics (depth, salinity, chlorophyll a, distance from the river mouth), led to quantification of factors conditioning the FLSM formation. The five most important factors were: contribution of the lithogenic component (responsible for 25% of the data set variability), time dependent factors (including primary productivity, mass exchange with fine sediment fraction, atmospheric deposition, contribution of material originating from abrasion-altogether 21%), contribution of fresh autochtonous organic matter (9%), influence of microbial activity (8%), seasonality (8%).

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Sediment Fluxes, Re-suspension and Accumulation Rates at Two Wind-exposed Coastal Sites and in a Sheltered Bay

Cited by 41 publications

References 29 publications

Subsurface chlorophyll maximum (SCM) location and extension in the water column as governed by a density interface in the strongly stratified Kattegat estuary

Subsurface chlorophyll maximum (SCM) location and extension in the water column as governed by a density interface in the strongly stratified Kattegat estuary

Instantaneous Effects of Sediment Resuspension on Inorganic and Organic Benthic Nutrient Fluxes at a Shallow Water Coastal Site in the Gulf of Finland, Baltic Sea

Factors influencing fluffy layer suspended matter (FLSM) properties in the Odra River - Pomeranian Bay - Arkona Deep System (Baltic Sea) as derived by principal components analysis (PCA), and cluster analysis (CA)

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