The second generation Deep Sea Sediment Resuspension System (DSSRS-II) was designed to simulate the deep sea sediment disturbances that will result from the future operation of manganese nodule mining collectors on the seafloor. In August and September 1994 the DSSRS-II was used to create the artificial resedimentation disturbance required for the Japan Deep Sea Impact Experiment (JET). This paper briefly describes the history of the DSSRS-II, its principal design and operational features and its performance during the JET study.
The Japan Deep Sea Impact Experiment (JET) is an environmental impact study being performed by the Metal Mining Agency of Japan (MMAJ) as part of the Ministry of International Trade and Industry" s project entitled Environmental Research for Manganese Nodule Development. JET is aimed at studying the chemical, biological and physical responses expected to result from deep sea mining of manganese nodules. As part of this study an artificial rcsedimentation disturbance was created in an experimental area in which numerous surveys were carried out to determine pre- and post-disturbance conditions. The device used to create the resedimentation (known as DSSRS-II) is a passively towed, sled mounted, hydraulic dredging machine.
A prototype Deep Sea Sediment Resuspension System (DSSRS-I) was designed and constructed in 1991 by the National Oceanic and Atmospheric Administration of the USA (NOAA). This special purpose passively towed vehicle, designed to simulate the sediment disturbance created by a seafloor nodule collector, was used in NOAA" s 1991 and 1992 BIE studies. Its design and operation are described by McGinnis and Petters (1993). Despite these similarities there are fundamental design differences between the prototype and second generation machines. These differences include the height at which sediment is discharged, the shape and number of dredge heads, the method of loosening or fluidising the sediment and the number of lift pumps.
