Nitrate and Nitrite Nitrogen

Nitrate nitrogen is a commonly used lawn and agricultural fertilizer.  It is also a chemical formed in the decomposition of waste materials, such as manure or sewage.  If infants less than six months of age drink water (or formula made with water) that contains more than 10 mg/L nitrate nitrogen, they are susceptible to methemoglobinemia.  This disease interferes with the blood’s ability to carry oxygen.  Recent studies also suggest that high nitrate water may be linked to birth defects and miscarriages, so pregnant women should avoid drinking high nitrate water.  High nitrate levels also suggest that other contaminants might be present.  The natural level of nitrate in Wisconsin’s groundwater is less than 0.2 mg/L. 
Nitrite is an unstable form of nitrogen that might be found in small amounts along with nitrate.  Sometimes results of nitrate and nitrite are reported together.
0              2                               5                                            10
Natural     Human influence on water quality             Unsafe
Acceptable results: 10 mg/L or less nitrate nitrogen (NO3G-N) or nitrate and nitrite nitrogen (NO2G + NO3G-N).  Less than 2 mg/L is preferred.  When reported as nitrate (NO3G ), the acceptable level is 45 mg/L or less.
Sources: Fertilizer, septic system effluent
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