View article

This work reviews the concentrations, the dynamics and the emissions of nitrous oxide (N₂O) in groundwater. N₂O is an important greenhouse gas (GHG) and the primary stratospheric ozone depleting substance. The major anthropogenic source that contributes to N₂O generation in aquifers is agriculture because the use of fertilizers has led to the widespread groundwater contamination by inorganic nitrogen (N) (mainly nitrate, NO₃⁻). Once in the aquifer, this inorganic N is transported and affected by several geochemical processes that produce and consume N₂O. An inventory of dissolved N₂O concentrations is presented and the highest concentration is about 18.000 times higher than air-equilibrated water (up to 4004 μg N L⁻¹). The accumulation of N₂O in groundwater is mainly due to denitrification and to lesser extent to nitrification. Their occurrence depend on the geochemical (e.g., NO₃⁻, dissolved oxygen …