Where is Mercury found in the Environment?
On the Earth’s surface, mercury can occur in solid, liquid, or gaseous forms. Mercury can occur as elemental mercury, inorganic mercury, or organic mercury. Elemental mercury, Hgo, in liquid form is the silvery fluid used in thermometers. As a gas, elemental mercury is in the air we breathe. Inorganic mercury, Hg2+, can form a dissolved salt in water or occurs as the mineral cinnabar, HgS. Mercury also can combine with small, organic molecules, such as methane, to form organic mercury compounds like methylmercury. Since mercury can exist in so many forms on the Earth’s surface, it moves through the environment along many complex pathways. As a gas, mercury can travel from a source to many thousands of miles away. Rain removes mercury from the atmosphere to the surface of the Earth. Rivers also transport mercury to the lakes and streams where fish live. To get into the fish we eat, mercury must first be converted to the organic methylmercury form.
