EFFECTS OF URBANIZATION AND AGRICULTURAL ACTIVITIES ON THE CHEMICAL AND ISOTOPIC COMPOSITIONS OF PERCOLATING WATER
The vadose zone of the undeveloped sand dune, serving as a reference for the other, anthropologically altered land uses, and that below the residential areas had similar salt concentrations and distribution: the salts seemed to occupy primarily the upper part of the vadose zone, mainly as a result of calcite dissolution and near-surface evaporation of the percolating water. Below the cultivated areas, salt buildup was observed across the entire vadose zone down to the water table, following the application of fertilizers and the use of treated wastewater for irrigation. Calcium and bicarbonate were the dominant ions in the undeveloped, residential and industrial land uses, while sodium and sulfate prevailed below the agricultural areas. Whereas the urbanization of undeveloped areas appears to result in the deterioration of groundwater quality, the shift from cultivated to residential areas has the (surprising and unexpected) potential of improving groundwater quality due to the decreased salt load at land surface.