Nitrate ion concentration in well water

Significant variations in levels of nitrate ion concentration can occur in analysis of water samples collected from the same well. Variations seem to be associated with at least two factors: (1) the time lag between sampling and actual analysis and (2) time of continuous pumping prior to sampling. A nearly two-fold increase in the level of nitrate ion in water samples from Well 1 occurred within four hours, during which the pump was not running, and a 3 1/2-fold increase after 24 hours—pointing to a multiple aquifer source of water, one or more aquifers of which may be the source of NO_a concentration in the well water. The change in nitrate ion concentration, with time after sampling, suggests that some undetermined factor is involved that changes nitrates to some other form of nitrogen.