Key points
- TMC’s 2022 test mining campaign found that up to 98% of sediment stirred up during collection resettles directly on the seafloor, with more than 95% settling within 1-2 kilometers of the collector vehicle.
- Sediment discharged at 2,000 meters depth dilutes to background concentrations within a few kilometers, and the plume forms a turbidity current that hugs the seabed rather than spreading widely through the water column.
- One year after mining, monitoring showed many previously sediment-covered nodules had become uncovered and available again as habitat, with some organisms found alive at the same tracked spots.
- Microscopic foraminifera had recovered to 30% of pre-disturbance density and 50% of diversity within 12 months, and community composition changes were limited to areas within about 500 meters of collector tracks.
