Key points
- A new peer-reviewed study in Nature used in-field thorium-tracing data to test claims that seafloor sediment plumes travel “thousands of kilometers,” a claim the study says was never grounded in scientific data.
- Thorium, a radionuclide naturally present in sediment, attaches to disturbed sediment particles; measuring its radioactivity shows how far those particles have traveled.
- Researchers collected sediment cores with a multicore device at varying distances from the directly mined area to measure plume spread.
- Plume concentrations return to background levels, comparable to a single grain of sand in a liter of water, within 1-2 km of the mined area.
