As the Gold Rush peaked, eager entrepreneurs built more than 100 mercury mines in California, unwittingly opening an environmental Pandora's box. When the federal government recognized the danger and prohibited mercury amalgamation of gold in the early 1970s, these same mines became unprofitable and were abandoned, often in close proximity to waterways, residential communities and recreational facilities. Most of us are familiar with quicksilver, the highly mobile, elemental form of mercury which, given half a chance, will race off in little silvery balls. These days, mythological explanations have been abandoned in favor of science. Yet scientists are discovering that mercury can be as changeable and fast-moving as its namesake.
Mercury can travel long distances in the atmosphere.
The methylmercury, Abu-Saba says, is concentrated by plankton at the base of the food chain. When filter feeders consume these plankton, the mercury is further concentrated. Consequently, eating substantial amounts of tuna or swordfish could leave you mad as a hatter. The cities won a lawsuit by arguing that the state had not sufficiently considered the economic costs of adopting its water protection laws. The dischargers complain about the prohibitive costs of treating water in the Bay Area, even with higher levels of mercury allowed.