Nitrates in groundwater
Natural nitrate levels in groundwater are generally very low (typically less than 10 mg/l NO3), but nitrate concentrations grow due to human activities, such as agriculture, industry, domestic effluents and emissions from combustion engines. The following table  shows the causes of nitrates pollution in groundwater.
Nitrates generally moves relatively slow in soil and groundwater: there is a lag time of approximately 20 years between the pollution activity and the detection of the pollutant in groundwater. For this reason, it is predicted that current polluting activities will continue to affect nitrate concentrations for several decades. However if the pressure in the aquifer is high, transport can be very rapid within the saturation zone.
The sources of nitrates pollution in groundwater are:
For more information and for the heath effects of nitrate in drinking water click on our nitrate web page.