: to make (something) more attractive usually by putting something on it.
There are several types of mercury. They include metallic mercury, and both inorganic and organic mercury compounds. Many of these forms are found in our environment, however, the most common natural forms include metallic mercury, mercury sulfide, mercuric chloride, and methylmercury (http://www.atsdr.cdc.gov/toxprofiles/tp46.html).
While we are exposed to many types of mercury in our environment, the type that poses the greatest risk is methylmercury. It is the most toxic form, and it is commonly found in fish due to bioaccumulation. This occurs when mercury found in the environment is fixed by microorganisms to produce methylmercury.