Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Celtic Explorer	CE/12/010	20.07.2012 - 06.08.2012	ECO2	North Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Linke Peter	Helmholtz Centre for Ocean Research Kiel (GEOMAR)	Bremerhaven	Hamburg

Ziel der Reise / Objectives of Cruise:

The expedition CE12010 with the Irish research vessel CELTIC EXPLORER was conducted in the framework of 2 EU projects. Whereas the ship time, costs for transport and travel are supplied through the project EUROFLEETS, scientific questions raised within the ECO2 project were addressed during the expedition. The project ECO2, supported by a team of international collaborators, investigates the environmental impact of the storage of carbon dioxide (CO2) in the sediments. This is being performed at existing CO2 storage sites in the North Sea and the Barents Sea paired with a comparison of natural gas emission at the seafloor. The first target of the researchers on board the CELTIC EXPLORER was the Norwegian gas field 'Sleipner', which has been used since 1996 to inject CO2 into a saline aquifer (Utsira formation) at ~900 m sediment depth in parallel to gas production. During the previous year, initial investigations on potential gas emission sites were conducted on board the ALKOR and subsequent cruises by G.O.SARS and JAMES COOK. Our objectives were to quantify fluxes of key chemical parameters and potentially toxic metals and study the mechanisms determining the migration of CO2, CH4, and formation waters through the sedimentary overburden by a variety of novel monitoring techniques. Included in this plan were investigations of seawater chemistry together with the near-field dispersion processes as key input parameters for our environmental studies and numerical model simulations. Furthermore, we planned to perform an assessment of the distribution of sensitive megafauna and wanted to use fingerprinting of microbial community diversity as a key indicator of environmental impacts. Thus, fluid and gas seepage will be studied as a potential precursor of CO2 leakage from the Sleipner storage site. On this cruise the prime investigation methods for leakage detection were hydroacoustic techniques, sensitive to observe single gas bubbles emitted from the seafloor, subsequently followed by video observation (ROV and towed cameras) and instruments to measure seepage fluxes (benthic lander systems, CTDs) and coring devices to study biogeochemical gradients at the seep sites. Furthermore, a CO2 release experiment was conducted at the seafloor in the vicinity of the Sleipner storage site to test the sensitivity of the sensors and to trace the near-field dispersion processes of a limited amount of CO2 in the sea water as input parameters for the environmental studies and numerical model simulations. In addition to the Sleipner storage site, the so-called blowout crater in the British sector of the North Sea was investigated, where high quantities of methane have been emitted for more than 20 years following a failed drill attempt. Ideally, this unplanned long-term release experiment can be used to estimate how much methane is emitted from the seafloor and its resultant distribution in the water column. Furthermore, it can be used as a natural laboratory to study the establishment of microbial communities, which are capable of consuming this methane and may hinder the emission of the green house gas into the atmosphere.

Messungen / Measurements

Verankerungen / Moorings