An international team, including the MIO, has described for the first time the mechanisms leading to mercury contamination of Pacific tuna. It shows the important role of bio-geochemical processes in the oceans and points to atmospheric emissions in Asia.
Power stations, steelworks, cement works... any combustion of coal releases metallic mercury into the atmosphere. The same applies to gold panning, an often clandestine activity that uses mercury to coagulate gold flakes, releasing metal into rivers and the atmosphere. The oceans are the main receptacle for this man-made mercury.
Added to this is the mercury released by volcanic eruptions and underwater hydrothermal springs. In total, the oceans are thought to contain between 300,000 and 400,000 tonnes of mercury, including around 80,000 tonnes linked to human activities, according to a vast global study conducted in 2014. New research, published on 11 January in PNASThe results of a study carried out by the European Commission and the United Nations Environment Programme (UNEP) have clarified the mechanisms by which fish are contaminated in the Pacific.