Selenium in Water
Selenium in Water is analogous to sulfur in many of its chemical combinations.
Selenium occurs in some soils as basic ferric selenite, as calcium selenate, as elemental selenium and in organic compounds derived from decayed plant tissue.
Selenium may be introduced into the environment through the burning of coal and application of phosphate fertilizers and selenium containing insecticides.
Biologically, selenium is an essential beneficial element recognized as a metabolic requirement in trace amounts for animals. But selenium can be toxic at higher concentrations.
Selenium bioaccumulates in the aquatic food chain and chronic exposure in fish and aquatic invertebrates can cause reproductive impairments (e.g., larval deformity or mortality).
The concentration of selenium in surface waters is proportional to the concentrations in the ambient soil. Selenium concentrations in natural waters may be as high as 1 mg/L, but generally concentrations are below 100 micrograms/Liter.
Minute concentrations of selenium appear not to be harmful to fish during an exposure period of several days. However, constant exposure to traces of selenium has caused disturbances of appetite and equilibrium, pathological changes and even death of fish after several weeks.
Concentrations that are considered safe for human beings have been toxic to fish. It is believed that selenium is passed up through the food chain to the fish which accumulate this element in the liver in lethal concentrations.
End of Selenium in WaterEach of the non-metals is discussed briefly.
Bromine in Water
Boron in Water
Cyanide in Water