ALBERT

Description: Rivers represent a transition zone between terrestric and aquatic environments, and between methane rich and methane poor environments. The Elbe River is one of the important rivers draining into the North Sea and with the Elbe potentially high amounts of methane could be imported into the water column of the North Sea. Twelve cruises from October 2010 until June 2013 were conducted from Hamburg towards the Elbe mouth at Cuxhaven. The dynamic of methane concentration in the water column and its consumption via methane oxidation was measured. In addition, physico-chemical parameters were used to estimate their influence on the methanotrophic activity. We observed high methane concentrations at the stations in the area of Hamburg harbor ("inner estuary") and about 10 times lower concentrations in the outer estuary (median of 416 versus 40 nmol/L). The methane oxidation (MOX) rate mirrowed the methane distribution with high values in the inner estuary and low values in the outer estuary (median of 161 versus 10 nmol/L/d respectively) Methane concentrations were significantly influenced by the river hydrology (falling water level) and the trophic state of the water (biological oxygen demand). In contrast to other studies no clear relation to the amount of suspendended particulate matter (SPM) was found. Methane oxidation rates were significantly influenced by methane concentration and to a weaker extent by temperature. Methane oxidation accounted for 41 ± 12% of the total loss of methane in summer/fall, but only for 5 ± 3% of the total loss in winter/spring. We applied a modified box model taking into account the residence times of a water parcel depending on discharge and tidal impact. We observed almost stable methane concentrations in the outer estuary, despite a strong loss of methane through diffusion and oxidation. Thus we postulate that in the outer Elbe estuary a strong additional input of methane is required, which could be provided by the extensive salt marshes near the river mouth.

Description: The MOSES Elbe 2023 experiment aims at following a water mass from the spring of the Elbe River in the Czech Republic, through the freshwater and tidal sections of the river, into the North Sea, where three ships (Mya II, Littorina, and Ludwig Prandtl) were used covering the marine environment in the German Bight (Sternfahrt 10). In order to follow the water mass from the Elbe estuary numerical simulations were performed to determine the likelihood of a variety of starting points for a drifter release experiment. At the first morning of the cruise model forecasts were used to determine the exact locations where drifters were to be released. The drifters were initially released in groups of three drifters and then supplemented at a later point of time. During the following two and a half weeks, the current drifter positions were revisited from the ships involved to take water samples.

Description: The dataset contains temperature, salinity, oxygen saturation, chlorophyll a and turbidity data from the Helgoland MarGate underwater observatory from the year 2020 in a temporal resolution of 1 hour. The cabled observatory is located in 10m water depth and comprises single or multiple sensors for a specific parameter (see https://www.awi.de/en/science/biosciences/shelf-sea-system-ecology/main-research-focus/cosyna/underwater-node-helgoland.html). For a detailed description of the data see associated metadatafile "Metadata_description_heluwobs_data_2020.pdf"

Description: The dataset contains temperature, salinity, oxygen saturation, chlorophyll a and turbidity data from the Helgoland MarGate underwater observatory from the year 2018 in a temporal resolution of 1 hour. The cabled observatory is located in 10m water depth and comprises single or multiple sensors for a specific parameter (see https://www.awi.de/en/science/biosciences/shelf-sea-system-ecology/main-research-focus/cosyna/underwater-node-helgoland.html). For a detailed description of the data see associated metadatafile "metadata_heluwobs_2018_hydrography.pdf".

Description: The dataset contains temperature, salinity, oxygen saturation, chlorophyll a and turbidity data from the Helgoland MarGate underwater observatory from the year 2017 in a temporal resolution of 1 hour. The cabled observatory is located in 10m water depth and comprises single or multiple sensors for a specific parameter (see https://www.awi.de/en/science/biosciences/shelf-sea-system-ecology/main-research-focus/cosyna/underwater-node-helgoland.html). For a detailed description of the data see associated metadatafile "metadata_heluwobs_2017_hydrography.pdf"