One thing is certain: Even for trained researchers, predicting mercury’s behavior in the
environment is challenging. Fundamentally it is one of 98 naturally occurring elements, with
natural sources, such as volcanoes, and concentrated ore deposits, such as cinnabar. Yet there
are also human-caused sources, such as emissions from both coal-burning power plants and
mining operations for gold and silver. There are elemental forms, inorganic or organic forms,
reactive and unreactive species. Mercury is emitted, then deposited, then re-emitted—thus
earning its mercurial reputation. Most importantly, however, it is ultimately transferred into
food chains through processes fueled by tiny microscopic creatures: bacteria.