A synthesis of environmental data compiled over the past 25 years is reviewed and organized. We describe the anticipated activities associated with exploration for commercial deposits, with engineering tests of recovery and mining systems, and with basic metallurgical processing. Basic description of the manganese nodule oceanographic environment is presented, including the occurrence of nodule deposits, relative sediment properties, benthic currents, and biological community. Environmental impacts from previous studies are summarized. Studies to date support the original concerns for environmental impact identified in the DOMES research, including impact on the benthic community where nodules are removed; impacts of the discharged plume on the near-surface biota; and impacts on the benthos due to deposition of suspended sediment. Future studies should address the establishment of quantitative relationships between resedimented thickness and benthic community response; integration of mining-related research efforts on benthic communities; establishment of clear guidelines for monitoring of precommercial mining test; and comparison of impacts from deep seabed mining with alternative land-based mining scenarios. |
