How Zinc, Cadmium and Mercury Pollutes our Environment?
Like zinc and mercury, cadmium is not a natural air pollutant but occurs in air as a result of industrialization and human activities. Some major sources of emission of cadmium in air include the metal industries engaged in extraction, refining, electroplating and welding of cadmium- containing materials, and in the refining of zinc, lead and copper.
Some cadmium can also be released into the air during the manufacture of pesticides and phosphate fertilizers and plants are known to be able to absorb cadmium from soils.
Mercury is volatile, is found in rocks and soils, and is undoubtedly present in the air as a contaminant, largely as a result of human activities such as the use of mercury-containing fungicides, paints and cosmetics.
Safety limits for mercury are not known, but less than 0.1 µg/m3 of organic mercury may be permissible provided that no methylmercury is allowed at all.