Chromium in Water
Chromium, including hexavalent chromium, is an odorless and tasteless metallic element that occurs naturally in rocks, animals, plants, and soils. It occurs naturally in very low concentrations in most water supplies. Leaching from topsoil and rocks is the most important natural source of chromium entry into bodies of water.
The forms most common in natural waters are trivalent chromium (Cr+3) and hexavalent chromium (Cr+6).
Chromium +3 is an essential human dietary nutrient found in many vegetables, fruits, meats, grains, and yeast.
Chromium +6 occurs naturally in the environment due to erosion of natural chromium deposits. Chromium 6 is used in industrial and manufacturing processes such as electroplating, tanning, and pulp processing. It can be found in consumer products such as spray paints, tanned leather and stainless steel.
Chromium is a dietary requirement for a number of organisms. This however only applies to trivalent chromium. Hexavalent chromium is very toxic to flora and fauna.
Arsenic and Cyanide in Water