Monomethylmercury (MMHg) is the toxic form of mercury that accumulates up the food chain into fish. High levels of MMHg are found at mid-water ocean depths where oxygen levels are lowest. Are bacteria making MMHg in the open ocean as they do in sediments closer to land, or are other complex processes going on? To probe this mystery, scientists collected hundreds of seawater samples above and in the low-oxygen zone. (Jack Cook, Woods Hole Oceanographic Institution)[back]
|
