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doi:10.2204/iodp.pr.347.2014

Operational strategy

Based on seismic and bathymetric data acquired during the site survey process and historical data from previous research in the BSB, seven primary drill sites and six alternate sites were proposed for paleoenvironmental objectives. Four of the primary sites were also proposed for deep biosphere investigations (See “Site summaries” for further information). Following assessment by the IODP Environmental Protection and Safety Panel, one of the primary sites (proposed Site BSB-8) was rejected because of a risk of contamination from dumped WWII chemical munitions. Instead, the alternates for this location (proposed Sites BSB-7C and BSB-7D) were approved, with the proviso that the closest alternate (Site M0065, proposed Site BSB-7C) did not core the upper 2 m of sediment to avoid any munitions residue that might have been spread by trawling activity. It was also stipulated that additional personal protective equipment be worn by those on the drill floor for the first core run following the open hole interval. For the primary site in the Ångermanälven River estuary (Site M0062, proposed Site BSB-11), an assessment of heavy metal and other contaminants was also made. As a consequence of this, restrictions on coring the upper 50 cm were put in place, although the site was given approval. Rumohr cores acquired at this location were also subject to more intensive cleaning of the outer liner and coring equipment itself prior to being brought onboard.

At Site M0059 (proposed Site BSB-3), a downpipe camera survey was conducted to assess the seabed for dumped WWII munitions prior to approving the beginning of coring operations. At Sites M0064, M0065 and M0066 (proposed Sites BSB-5, BSB-7C, and BSB-7D, respectively), a remotely operated vehicle survey was conducted at all proposed drilling locations to again survey the seabed for possible dumped munitions and chemical warfare agents from WWII prior to approving coring operations.

All holes were sited within a 20 m radius of the proposed drilling sites approved by the Environmental Protection and Safety Panel. The general locations of the sites cored are shown in Figure F1. As with all Mission Specific Plan expeditions, no cores were split during the offshore phase; therefore, a comprehensive onshore phase complements the offshore phase. Table T3 summarizes the descriptions and measurements made during Expedition 347 and indicates whether these were taken offshore or onshore.

Offshore operations

The following coring tools were carried during Expedition 347:

• Extended Coring System (ECS),
• Hammer Sampler (HS),
• Non-Coring Assembly (NCA),
• Non-Rotating Core Barrel (NRCB),
• Rotating Core Barrel (RCB),
• Push Coring Assembly (PCA),
• Piston Corer System (PCS), and
• A third-party gravity coring system known as a Rumohr Corer.

Mobilization of the vessel began on 30 August 2013 in Falmouth, UK, with the Greatship Manisha sailing for Kiel, Germany, on 8 September. The offshore phase ran from 12 September to 1 November, with embarkation/disembarkation of the science party. The vessel then transited back to Falmouth, with European Consortium for Ocean Research Drilling (ECORD) Science Operator (ESO) staff demobilizing the ESO containerized laboratories and offices en route. The vessel arrived at Falmouth on 5 November, and all ESO staff departed on 6 November.

In total, 38 days of Expedition 347 were spent operational on station, 8.5 days in transit between sites, 1.3 days in port, 1.3 days on standby at station because of weather, and 1.8 days on equipment-related downtime. See Table T4 for a summary of the offshore operations and recovery. Shipboard generated recovery plots are available on the ECORD Baltic Sea Paleoenvironment website under weekly summaries (www.eso.ecord.org/expeditions/347/daily.php).

In order to prevent degradation of living microbial samples acquired during the offshore phase, shipment of these samples was organized following completion of drilling operations at Holes M0059C, M0060B, M0063E, and M0065C, with all frozen and +4°C samples being offloaded via small boat and shipped to the scientists’ laboratories (via Aarhus University, who kindly collected the samples from the small boat transfers) in Denmark, Germany, Japan, China, and the USA. Frozen (–80°C) and +4°C microbiology samples collected at Site M0059E were shipped from Kiel to the scientists’ laboratories at the end of the expedition.

Onshore Science Party (OSP)

The cores, core catcher samples, headspace gas samples, and interstitial water splits collected offshore were transported under refrigeration to the IODP Bremen Core Repository at the Center for Marine Environmental Sciences (MARUM), University of Bremen (Germany). Natural gamma radiation was conducted on all cores and thermal conductivity on selected holes of each site before the start of the OSP.

Further analytical laboratories were accessed at MARUM (nondestructive core logging, marine geotechnics, inorganic geochemistry, and microscope laboratories) and the Department of Geosciences at the University of Bremen (paleomagnetism and hydrofluoric acid laboratories and the carbon/sulfur analysis system).

During the Expedition 347 OSP, from 22 January–20 February 2014, the cores were described in detail and the IODP minimum and some standard measurements were made (Table T3). In addition, sampling for postcruise scientific research was also undertaken.

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