Assessing and minimizing environmental impacts of deep-sea polymetallic nodule harvesting, processing, and transport

The process of harvesting nodules from the seabed and transporting them to a surface ship will inevitably cause some environmental impact.  In Blue Nodules we have identified all the possible environmental pressures and we are working to minimise these by improved equipment design and by developing optimal environmentally friendly working practices.  The most obvious impacts will be:

• Compaction of the seabed by the mining vehicle
• Loss of hard substrate – the nodules themselves – which provide habitat and anchorage points for many species
• The removal of the surface sediment layer, which together with the nodules hosts the benthic community
• The generation of plumes of sediment-laden water, which may travel some distance beyond the mined area. Such plumes are known to smother organisms
• Issues related to the large areas to be mined that may cause loss of connectivity between populations of organisms and also disrupt ecosystem function
• Noise generated by the seabed vehicles, riser pipe and surface operations
• The water that needs to be returned to the ocean from dewatering of the ores on the surface vessel
• Light pollution from the mining vehicles and from the surface vessel
• Production of and disposal of waste material during the processing of the ores

Measurements of a number of these impacts will be made during testing of the equipment both in the laboratory and during sea trials planned for 2017 and 2018.  These data will be used to identify areas where engineering improvements can be made.