Bell-jar experiments and suspension measurements for the quantification oxygen consumption and nitrogen conversion in sediments of the Elbe estuary

1990 ◽  
pp. 253-258 ◽  
Author(s):  
F. Schroeder ◽  
D. Klages ◽  
H.-D. Knauth
Keyword(s):  
Oxygen Consumption ◽  
Elbe Estuary ◽  
Nitrogen Conversion ◽  
Suspension Measurements

Pelagic oxygen consumption rates in the Elbe estuary: Proxies and spatial patterns.

2021 ◽  
Author(s):  
Justus E.E. van Beusekom ◽  
Dorothee Fehling ◽  
Sina Bold ◽  
Tina Sanders
Keyword(s):  
Organic Matter ◽  
Oxygen Consumption ◽  
Land Reclamation ◽  
Salinity Gradient ◽  
Elbe Estuary ◽  
Low Oxygen ◽  
Port Area ◽  
Consumption Rates ◽  
Gradient Based ◽  
The Elbe River

<div> <div><span>The Elbe estuary is strongly impacted by human activities including dredging, land reclamation and eutrophication. Since about 30 years, water quality improved leading to major phytoplankton blooms in the Elbe river. When these blooms enter the upper estuary including the Hamburg port area, they collapse leading  to low oxygen conditions. During a cruise in September 2020 we measured oxygen consumption rates in water samples of the Elbe Estuary between the coastal North Sea (Wadden Sea) and  the weir in Geesthacht including a large freshwater part of the Elbe estuary. In addition, suspended matter samples were taken and analysed for chlorophyll, particulate C (PC) and particulate N (PN). Oxygen consumption rates reached maximum values at both the marine side (~0.3 µmol/(l*h)) and the freshwater  side of the estuary (~0.65 µmol/(l*h)) and a distinct minimum near the Estuarine Turbidity Maximum near the onset of the salinity gradient. Based on specific weights of phytoplankton and PC content, we estimated the contribution of newly formed organic matter. This estimate correlated significantly with the observed oxygen consumption rates. We suggest that most of the riverine organic matter is degraded within the freshwater part of the Elbe estuary before reaching the salinity gradient. This is in line with significant amounts of nitrate being released within the freshwater part of the estuary.</span></div> </div>

scholarly journals Oxygen Consumption of Resuspended Sediments of the Upper Elbe Estuary: Process Identification and Prognosis

2021 ◽  
Author(s):  
M. Spieckermann ◽  
A. Gröngröft ◽  
M. Karrasch ◽  
A. Neumann ◽  
A. Eschenbach
Keyword(s):  
Oxygen Consumption ◽  
Mean Squared Error ◽  
Water Injection ◽  
Elbe Estuary ◽  
Overlying Water ◽  
Oxygen Budget ◽  
Port Area ◽  
Lower Oxygen ◽  
Negative Effect ◽  
Prognosis Model

AbstractThe resuspension of sediment leads to an increased release of nutrients and organic substances into the overlying water column, which can have a negative effect on the oxygen budget. Especially in the warmer months with a lower oxygen saturation and higher biological activity, the oxygen content can reach critical thresholds in estuaries like the upper Elbe estuary. Many studies have dealt with the nutrient fluxes that occur during a resuspension event. However, the sediment properties that influence the oxygen consumption potential (OCP) and the different biochemical processes have not been examined in detail. To fill this gap, we investigated the biogeochemical composition, texture, and OCP of sediments at 21 locations as well as the temporal variability within one location for a period of 2 years (monthly sampling) in the upper Elbe estuary. The OCP of sediments during a seven-day resuspension event can be described by the processes of sulphate formation, nitrification, and mineralisation. Chlorophyll, total nitrogen (Ntotal), and total organic carbon showed the highest correlations with the OCP. Based on these correlations, we developed a prognosis model to calculate the OCP for the upper Elbe estuary with a single sediment parameter (Ntotal). The model is well suited to calculate the oxygen consumption of resuspended sediments in the Hamburg port area during the relevant warmer months and shows a normalised root mean squared error of < 0.11 ± 0.13. Thus, the effect of maintenance measures such as water injection dredging and ship-induced wave on the oxygen budget of the water can be calculated.

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