What factors affect nitrate concentrations in ground water?
Although elevated nitrate concentrations in groundwater are associated with higher inputs, geochemical conditions are an important factor governing concentrations of nitrate in groundwater. For a given land use, median nitrate concentration is significantly higher in groundwater that is well oxygenated regardless of nitrogen input. For example, wells in agricultural areas had a median nitrate of about 5.5 mg/L in oxic water (oxygen concentrations greater than 0.5 milligram per liter), but barely detected in reduced water (oxygen concentrations less than 0.5 milligram per liter) despite having similar nitrogen inputs at the land surface.
