Movement of Water and Solutes in a Wastewater Irrigated Piedmont

In Mezquital Valley, Central Mexico, wastewater has been used to irrigate crops since early 20th century. This practice has formed a stable shallow aquifer, which nowadays supplies water to the local population. The aim of this work was to understand the water dynamics and the variation of water quality throughout the critical zone. The movement of irrigation water was followed, and major ions, nitrogen and carbamazepine were determined at different depths. The soil is functioning as a filter for pollutants, as concentration of the drug carbamazepine decreased by 97%. Ammonium-nitrogen was readily transformed into nitrate, part of which seems to be denitrified.