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Long-Term Ocean Climate Observations (LOCO) – D301/302
Cruise Diary – 25th March 2006	Sediment trap from the top of the mooring     Sediment trap that stands on the seafloor
Saturday - Busy day. During the night 2 CTD stations were done and at 5.30 am the mooring team started. Again, everything with the mooring recovery went smoothly, although the mooring with sediment traps (see pictures) caused some stress. When we arrived at the site with this 'special' mooring late in the morning, Sander, who is responsible for the releasing the moorings, could not make contact with the releases. Making contact means that sound at a specific frequency is sent to the mooring. If everything is OK, the releases at the mooring should respond with a specific sound signal and the instrument on board then shows how far the release is away from the ship. The normal procedure is that first 'contact is made', followed by the release procedure (by sending a specific sound code). However the releases from this mooring did not respond at all. Despite this we decided to send the release code, but again, no response. After moving to another site, almost above the mooring, the whole procedure was repeated many times, also with the spare instruments that were on board. Did we use wrong codes, was the position wrong? Finally, about one hour after our first trials the Mozambican observer shouted. He had sighted the top of the drifting mooring. Of course every body happy and especially GeertJan and Ulrike, the scientists involved. This 'trap' mooring is a special one since data from this mooring are not used for studies on the currents (physical) but for studies on the vertical flux of particles (geological/chemical). On the pictures the sediment trap on the top of the mooring, 250 m above the seafloor and on the seafloor itself, is shown. The top of these traps is a funnel? (trechter) in which particles that fall down through the water column are collected.
Below the funnel is a series of small bottles. These bottles close about every 4 weeks so that the content of each of these bottles is representative for the vertical particle flux during that period. Many analyses are done on the content of these bottles, mainly to derive the origin of the particles. Results from these studies also give insight in the processes that have formed the upper layer of the seafloor. Anyhow, it was a successful day. Almost all moored instruments seem to have functioned properly.