Hydrodynamic characteristics and nitrate propagation in Sparta aquifer

During the 1994-1997 water years, a hydrogeological study was carried out on the alluvial aquifer of Sparta in the Peloponnese, where the concentration of nitrate ions in groundwater, as NO3- is well over the highest recommended WHO limits of 50 mg l(-). Under specific hydrological and chemical conditions with high amounts of dissolved oxygen, the migration of nitrate ions in the aquifer, seems to be unaffected by any hydrological process, chemical substance or reaction. Examination of the relationship between nitrate concentration and aquifer properties shows that maximum nitrate concentration values follow the main axes of groundwater movement, while zones of increased recharge coincide with zones of diluted nitrate concentration. Profiles of the evolution of chemical parameters vs depth, show that the main process causing nitrate increase in groundwater, is the oxidation of ammonia originating from the rapid leaching of inorganic fertilizers applied to cultivated areas. (C) 2000 Elsevier Science Ltd. All rights reserved.