ABSTRACT

Deep-sea mining of polymetallic nodules is expected to cause directly and indirectly disturbance of the abyssal benthic ecosystem. Acquisition of baselines data of each mining area is essential for evaluation of the environmental impacts as well as for development of site-specific mining design in the way to ensure reasonable protection and conservation of the marine environment. For the purpose of this study, a perspective mineable block of about 3800 km2 was delineated within the Interoceanmetal (IOM) licensed area in the eastern part of Clarion-Clipperton Fracture Zone (NE Pacific), with average nodule abundance of 12.6 kg/m2 (dry nodules), and resources of 33700 Mt dry nodules sustaining for more than 10 years life of mining operations at the rate of 3 million tons per annum. By means of data on the local geological, geotechnical and environmental conditions, the seafloor that would be directly impacted per mining operations was sized and optimized; both the amount of mobilized sediment and the value of benthic biomass intercepted by the nodule collector were estimated. Nevertheless, in order to minimize the adverse effect on the benthic community, some technical approach in developing the mining system components and ultimate reliance on the environmentally sound exploitation strategy were proposed.

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