In-situ sedimentological analysis of deep sea mining trials generated sediment plumes

The impact of polymetallic nodule mining on the deep sea environment remains poorly understood. To predict the impact of such operations, better insight into the fluid dynamics of sediment plumes produced by deep sea mining operations. In particular, accurate size and settling velocity distributions (SVD) of suspended sediments are necessary to better inform plume models of sediment transport evolution. Characterizing deep sea particles in situ is crucial in understanding the variability of deep-sea sediments through different timescales and regions. Currently, there is no instrument available that can characterize in-situ these particles with high enough resolution. The RTSSV has thus been developed to measure in real-time, the SVD of deep sea particles by Sequoia Scientific, Inc., with MIT and Scripps Institution of Oceanography. Field experiments were performed in the Belgian area of the Clarion Clipperton Fracture Zone (CCFZ), where the RTSSV was first deployed to measure particle size distribution of sediment laden plumes generated by a collector. This constitutes, to the best of our knowledge, the first in-situ direct imaging of deep-sea sediments during a deep sea mining test operation at such high resolutions and a step closer to predicting the impact of deep sea mining.