NITRATE: AN ESCALATING CONTAMINANT IN AQUIFERS OF SEMIARID AREAS

For the past 50 years, synthetic N-fertilizer has been extensively applied to crops (Haber–Bosch process). Nitrogen that is not taken up by plants transforms into nitrate in the soil and leaks into the underlying aquifer. This contamination is becoming more prevalent with time, although the real extent is difficult to determine since many aquifers are not being monitored. Agricultural systems facing the greatest threat belong to semi-arid areas, as these aquifers are the main source for drinking water for people living in the area in addition to being used for agriculture. Since the recharge to the aquifer in these regions is limited, any nitrate contamination tends to greatly affect the water quality. A summary of nitrogen sources and sinks for semiarid areas and the analytical methods utilized in their determination are included. Selected aquifers impacted with nitrate and the proposed strategies (or lack of) for reducing the amount of nitrate leakage are discussed, as well as some of the most pressing challenges to the academic community.