Although nitrogen is an essential nutrient for living organisms, too much can be toxic. Excess nitrogen is produced by agriculture, industry, automobiles and even people striving for green lawns (see [local] and view Issue 1). Excess nitrogen in the form of nitrous oxide, nitric oxide, nitrate, nitrite or ammonia are all soluble in water and can end up in ground water and drinking water [local]. Nitrogen enrichment in groundwater from manure wastes associated with animal production have been implicated in the toxic (to humans and fish) Pfisteria outbreaks on the East Coast of the U.S. Nitrate and nitrite contamination of drinking water can be toxic for young children since nitrite (produced in the stomach from nitrate) competes very effectively with O2 for binding to fetal hemoglobin. (Children are born with hemoglobin F in which the beta chains found in adult hemoglobin are, instead, so-called gamma chains. The (alpha)2(gamma)2 tetramer is called hemoglobin F. Babies begin making adult hemoglobin A before birth but, when first born, their blood contains a preponderance of hemoglobin F.)
So how do we get rid of the nitrogen contaminating ground water? "We" don't; bacteria do. This is where the denitrifying and nitrifying bacteria are useful. They take nitrogen wastes and convert them back to atmospheric nitrogen which is not toxic. The bad news is that these bacteria thrive in anaerobic environments like swamps and wetlands which we are rapidly filling in to build more houses (with bluegrass lawns) and adjacent golf courses. Ecology is biochemistry at the global scale and we must learn to pay attention to it!
