Increase in anthropogenic mercury in marginal sea sediments of the Northwest Pacific Ocean.

Over the past century, the addition of anthropogenic mercury (HgANTH) to vast areas of North Pacific marginal seas adjacent to the northeast Asian continent has tripled. Analysis of sediment cores showed that the rate of HgANTH addition (HgANTH flux) was greatest in the East China and Yellow Seas (9.1 µg m-2 yr-1) in the vicinity of China (the source continent), but was small in the Bering and western Arctic Ocean (Chukchi Sea) (0.9 µg m-2 yr-1; the regions furthest from China). Our results show that HgANTH has reached open ocean sedimentary environments over extended areas of the northwestern Pacific Ocean, via the formation of organic-mercury complexes and deposition. The implication of these findings is that the addition of HgANTH (via atmospheric deposition and riverine input) to the ocean environment is responsible for elevated Hg flux into sedimentary environments in the northwest Pacific Ocean.