Benthic Experimental Chamber

A new, large instrument had been constructed for the planned in-situ experiments of the GECOMET project: a benthic experimental chamber with an Active Sampling and Measuring System (ASMS). The instrument had been developed in cooperation of the VWS Berlin, FU Berlin and TU Clausthal. The aims of the in-situ experiments were to bring the benthic chamber onto the undisturbed deep-sea bottom, to cause a disturbance of the upper sediment layer with a stirrer, and to monitor the physico- and biochemical changes as well as the heavy metal cycle in this disturbed system over a time period of seven days. For the recording of changes of pH, Eh and dissolved oxygen, a sensor probe (Kurt-Schwabe-Institute) was integrated. Sequential sampling and storing of data is done by the ASMS (see cruise report SO106 – ATESEPP for further details).

However, during the first test of the Benthic experimental chamber all buoyancy glass spheres imploded and destroyed the system to the extent that no sensor data or samples could be recovered. The chamber itself was also damaged and could not be used anymore. Thus, the plan for in-situ experiments with the benthic experimental chamber had to be given up.

From spare parts, a second sampling system (ASMS II) with reduced capabilities was integrated in the stainless steel frame of the former ASMS. The system was equipped with four bag samples and one ion-exchange column and was tested during several deployments in different configurations. At the end of the test series the ASMS II was mounted below the water sample rosette and deployed with a 5 meter-long suction hose and a weight to whirl up seafloor sediment, which was then collected in the sampling bags as a bottom water-sediment suspension.