Day 6: Iron
Chances are you have probably identified Iron (Fe) in water at one time or another by the distinctive red color of iron oxide (rust). As the second most abundant metal in the earth’s crust, Iron is prevalent in surface water, groundwater and drinking water. High levels of iron in water, above 20 parts per million, can cause health problems, but because iron is an essential component of hemoglobin and plays a role in cardiovascular health, levels below 3 parts per million are tolerable for healthy individuals. In general Iron plays a strong aesthetic role in water quality, as levels as low as 12 parts per billion in distilled water can be detected by tasted, and levels above 5 parts per trillion can result in turbidity and color detectable by the naked eye.
Iron is one of the earliest discovered elements, and in ancient times was revered as a heavenly substance due to its prevalence in meteorites that fell from the sky. Elevated iron levels in drinking water are usually found in areas with extremely concentrated deposits of iron. However the aeration of soils in areas without historically high levels of iron can lead to increased absorption of iron into groundwater tables and have a negative impact on water quality. This is more likely to occur in areas where groundwater tables are lowered, areas where excessive nitrate leaching takes place, and at times when environmental factors acidify (lowering pH) rain and surface water.