Hydrodynamic characteristics and nitrate propagation in Sparta aquifer

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