Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL447	20.10.2014 - 04.11.2014	ECO2	Eckernfoerder Bucht Baltic Sea Kiel Bight

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Schneider von Deimling Jens	Helmholtz Centre for Ocean Research Kiel (GEOMAR)	Kiel	Kiel

Ziel der Reise / Objectives of Cruise:

The proposed research cruise shall cover methodological and research goals under the framework of the European joint research projects SUGAR II and ECO2. One goal of the cruise is to test new acoustic remote sensing tools for the evaluation of gas seep sites in the North Sea. In addition external controls on seepage are evaluated to better understand triggering mechanisms and to constrain the fate of the gases. Supporting geochemical records of dissolved methane concentration and CH4 gradients in the air shall be recorded to improve the understanding of the fate of gaseous and dissolved seepage methane, respective gas bubble dissolution, and potential transfer to the atmosphere. This research cruise got scheduled for late fall and given a very stormy period the work was limited to protected areas. We decided to sample the natural seepage sites in the Eckernforde Bay and the bubbling reefs off L?s? instead of the remote offshore seepage sites in the North Sea. 19.10 On the first day equipment was mobilized including installation of a new generation multibeam echosounder together with satellite GPS correction support (FUGRO) on R/V ALKOR. The cruise could begin on Monday the 20th of October. First the EK60 singlebeam system had to be calibrated. In the evening, R/V ALKOR took off to the outer Kiel Fjord to perform the first motion sensor calibration and multibeam measurements until 21st of October. The motion sensor calibration did not achieve specification and required re-sailing "eights" for several hours. Between the 21st and the 22nd the known pockmarks close to the shallow "Mittelgrund" area were surveyed with the new high resolution multibeam echosounder. A significant water level change was predicted to occur and therefore repeated surveys for free gas bubble release detection were started. This task had to be abandoned in the morning of Tuesday 23.10th due to a medical issue. The weather situation in the North Sea remained stormy. Repeated sampling in Eckernforde Bay was continued on the 24th and 25th to evaluate whether gas ebullitions are linked to water level changes. This included two in situ lander deployments covering more than 30 hours to monitor gas ebullition over varying water levels and pressure conditions. We successfully deployed the Bubble Box and captured naturally released gas bubbles. After finishing a comprehensive flare imaging survey R/V ALKOR steamed towards the Kattegat with arrival 18 hours later on the 27th of October. In co-operation with our Danish colleagues we were asked to first survey the hitherto un-surveyed areas north of L?s? with the capabilities of our newly installed multibeam echosounder. However, the motion sensor performance worsened. A port call was necessary in the harbor of Frederikshavn on the evening of the 27th for re-measurement of the static offsets and inspection of the ship's oar. R/V ALKOR left the harbor in the morning of the 28th again. Subsequently, the motion sensor unit performed fine and successfully calibrated. Work could be continued north of L?s?. On the 29th we got informed about potential contamination by legionella bacteria via the freshwater tanks of ALKOR. The Danish observer declined participation under the prevailing conditions, leading to surveying limited to outside the 3 nautical mile zone. To verify our previous results with extraordinary high methane ebullition triggered by wind driven water level lows, we decided to steam back to Eckernforde in the evening of the 31st. On the 1st and 2nd of November work off Eckernforde was continued and the GasQuant II lander got deployed for 24 hours. A sandy site for the gas elevator lander deployment on 3rd of November was identified off Schonberg (East of the outer Kiel Fjord) and confirmed by a grab sample. Subsequently we further mapped the seabed for dumped munition to meet a cooperation agreement made prior to AL447 until the end of the cruise in the morning of the 4th of November.

Messungen / Measurements

Verankerungen / Moorings