CARBONATE MUD IN MATAIVA-ATOLL, FRENCH-POLYNESIA - SUSPENSION AND EXPORT

Large quantities of carbonate mud are found in suspension, with concen trations reaching 80 mg l(-1), in the lagoon of Mataiva Atoll, French Polynesia. Residence time of water in the lagoon is about 73 days. Car bonate particles are exported offshore in a negatively buoyant plume t hat sinks in oceanic waters. The carbonate particles are from resuspen sion of abraded carbonate of biological origin. The negative buoyancy is induced by evaporative cooling of turbid lagoon water, turbidity re sulting from wave-driven suspension of calcareous sediment. Contaminat ed mine water should be released at depth, offshore, as a negatively b uoyant plume to sink in oceanic waters.