Impacts of mining on Central Red Sea environment

Abstract

The mining of the Atlantis II deep will result in a significant input of heavy metals into the Red Sea. Quantities of dissolved compounds will result in major changes in the trace element composition of the water masses. The dissolution of minerals resulting in the release of toxic chemicals including zinc, copper, cadmium and mercury remains of fundamental concern which will require further study. The regime for discharge of tailings must be designed to minimise the dispersal of the solids, and also the fluids together with their dissolved leached constituents. If the discharges occur deep down the waste will be confined to the deep waters in the central graben, where the absence of significant upwelling combined with the natural chemical processes of removal via sorption will restrict the dispersal of the toxic substances. Research on biological activity within the epipelagic and mesopelagic zones has led to the recommendation that all wastes should be restricted to the bottom water below 1100 metres. A consideration of the likely effect upon benthos and water chemistry has demonstrated that tailings will have to be confined to the central graben, in order to protect local fisheries and the vulnerable reef and seabed environments of the coasts and the Central Trough. However, discharge of the tailings at depth would also limit the transmission of the tailing pollutants through the food web. It should, therefore, confine the effects of mining to a limited portion of the Red Sea biota. The shallower release of tailings within the zone of diel migration by plankton and nekton would expose a large community of organisms to the pollutants and result in the vertical transport of heavy metals up the water column.