Nitrogen level: Pros and Cons

Nitrogen is one of the most abundant elements. About 80 percent of the air we breathe is nitrogen. It is found in the cells of all living things and is a major component of proteins. Inorganic nitrogen may exist in the free state as a gas N2, or as nitrate NO3-, nitrite NO2-, or ammonia NH3+. Organic nitrogen is found in proteins and is continually recycled by plants and animals. What is the environmental impact of nitrogen: Nitrogen-containing compounds act as nutrients in streams and rivers. Nitrate reactions [NO3-] in fresh water can cause oxygen depletion.

Nitrogen Level

Thus, aquatic organisms depending on the supply of oxygen in the stream will die. The major routes of entry of nitrogen into bodies of water are municipal and industrial wastewater, septic tanks, feedlot discharges, animal wastes (including birds and fish) and discharges from car exhausts. Bacteria in water quickly convert nitrites [NO2-] to nitrates [NO3-]. Nitrites can produce a serious condition in fish called "brown blood disease." Nitrites also react directly with hemoglobin in human blood and other warm-blooded animals to produce methemoglobin. Methemoglobin destroys the ability of red blood cells to transport oxygen. This condition is especially serious in babies under three months of age. It causes a condition known as methemoglobinemia or "blue baby" disease.

Water with nitrite levels exceeding 1.0 mg/l should not be used for feeding babies. Nitrite/nitrogen levels below 90 mg/l and nitrate levels below 0.5 mg/l seem to have no nutrients are essential for plant and animal growth and nourishment, but the overabundance of certain nutrients in water can cause a number of adverse health and ecological effects. To determine the extent of nutrient and other types of contamination in the Nation's streams and groundwater, we analyzed data from about 12,000 ground-water samples and more than 22,000 surface-water samples collected at more than 300 sites between October 1979 and September 1990.

Most samples had been collected within NAWQA study units. Nutrient concentrations in water generally are related to land use in the upstream watershed or the area overlying a groundwater aquifer. Nitrate concentrations were generally higher in groundwater than in streams. Concentrations were highest in the Northeast, Great Plains, and along the West Coast. Drinking water from public-supply wells and domestic-supply wells outside of agricultural areas is not likely to have high levels of nitrate. Domestic supply wells in agricultural areas are more prone to increased concentrations. Ammonia and phosphorus concentrations in surface watersurface water are highest downstream from urban areas. Where these concentrations are high, they warrant concerns about decreased oxygen in the water, toxicity to fish, and accelerated eutrophication.

Read Next: Protect your Baby from Nitrates & Nitrites

Effect on warm water fish?

Contamination of water by nutrients has been a national concern for several decades. The earliest public interest was in lake and reservoir eutrophication, which produces unsightly scums of algae on the water surface and can occasionally result in fish kills. Beginning in the 1970s, additional concern focused on nutrients discharged to streams from sewage-treatment plants. Nutrients in treatment-plant effluent adversely affect aquatic life through direct toxicity and by removing oxygen from water during chemical transformations. The Water Pollution Control Act of 1972, later known as the Clean Water Act, mandated improvements in sewage-treatment technology, to be funded jointly by the Federal, State, and local governments. Twenty years later, the EPA reported that nutrients still were among the two leading causes of water-quality degradation in rivers, lakes, and estuaries throughout the Nation.

Also, one particular nutrient compound, nitrate, was reported to be the most prevalent contaminant in groundwater nationwide. The other nutrients of concern in water pollution are ammonia and phosphorus. The EPA has established a maximum contaminant level (MCL) of 10 mg/L (as nitrogen) for nitrate in drinking water. Excessive nitrate can result in the restriction of oxygen transport in the bloodstream. Infants under the age of 4 months lack the enzyme necessary to correct this condition. Fatalities from methemoglobinemia ("blue baby syndrome") occur infrequently and are most common in rural areas. Illness and death caused by methemoglobinemia are not always recognized; therefore, its occurrence might be underreported. Although one case in Colorado was attributed to infant formula made from public-supply water that had a nitrate concentration of 13.3 mg/L, most cases involve concentrations that are somewhat higher. In parts of Eastern Europe where groundwater is contaminated with 50-100 mg/L nitrate, pregnant women and children under 1 year of age are supplied with bottled water. Nitrogen, in the form of nitrate, nitrite, or ammonium, is a nutrient needed for plant growth.

About 78% of the air that we breathe is composed of nitrogen gas, and in some areas of the United States, particularly the northeast, certain forms of nitrogen are commonly deposited in acid rain. Although nitrogen is abundant naturally in the environment, it is also introduced through sewage and fertilizers. Chemical fertilizers or animal manure is commonly applied to crops to add nutrients. It may be difficult or expensive to retain on-site all nitrogen brought on to farms for feed or fertilizer and generated by animal manure. Unless specialized structures have been built on the farms, heavy rains can generate runoff containing these materials into nearby streams and lakes.

Wastewater-treatment facilities that do not specifically remove nitrogen can also lead to excess levels of nitrogen in surface or groundwater. Two of the major problems with excess levels of nitrogen in the environment are: Excess nitrogen can cause overstimulation of growth of aquatic plants and algae. Excessive growth of these organisms, in turn, can clog water intakes, use up dissolved oxygen as they decompose, and block light to deeper waters. This seriously affects the respiration of fish and aquatic invertebrates, leads to a decrease in animal and plant diversity, and affects our use of the water for fishing, swimming, and boating; Too much nitrate in drinking water can be harmful to young infants or young livestock.

Read Next: Protect your Baby from Nitrates & Nitrites

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