Mercury in water
Very few natural waters contain detectable concentrations of mercury.
However, the element mercury may be introduced into the water through disposal of mining and metallurgical or other industrial waste.
Mercuric salts occur in nature chiefly as the mercury sulfide (HgS) known as cinebar, but numerous synthetic, organic and inorganic salts of mercury are commonly used. These include mercuric chloride, mercuric cyanide, mercuric nitrate, mercuroorganic compounds and metalic mercury, all of which are toxic in varying concentrations to aquatic life.
Methyl and ethyl mercuric salts are also extremely toxic and hazardous to living organisms. Therefore, mercury and mercuric salts are considered to be highly toxic to humans.
They are readily absorbed by way of the gastro-intestinal tract and fatal doses for man vary from 3 to 30 grams. Mercury concentrations in living tissue should not exceed 0.5 mg/L.
The minimum lethal concentration of mercury salts has been reported for phytoplankton to range from 0.9 to 60 mg/L of mercury.
For fresh water fish, concentrations of 0.004 to 0.02 mg/L of mercury have been reported as harmful. Fish can accumulate mercury in their tissues directly from the surrounding water or through ingestion of contaminated food supplies.
Drinking water standards are set at 0.005 mg/L for the maximum limit tolerable.
The toxic effects of mercuric salts are accentuated by the presence of trace amounts of copper.
End of Mercury in WaterEach of the heavy metals is discussed briefly.
Silver in Water
Cadmium in Water
Chromium in Water
Copper in Water
Lead in Water
Nickel in Water
Zinc in Water
Non-Metals in Water