How Does Mercury (specifically methylmercury) Enter the Environment?
Mercury has become a contaminant of great concern. Mercury is found in the air, waterways, lakes, and the ocean. It is released into the air by the combustion of coal for electricity, and may be transported from the air to soil and water by rain. The mercury in urban storm water sediment results in part from improperly discarded fluorescent lights, electrical switches, thermometers, other mercury-containing devices, and historical and ongoing industrial activities. Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans. Methylmercury builds up more in some types of fish and shellfish than others. The levels of methylmercury in fish and shellfish depend on what they eat, how long they live and how high they are in the f
