The physio-chemical conditions of surface and groundwater resources in water scarce areas - how droughts affect ions migration

Mediterranean countries are characterized by high temperatures, low rainfall along with frequent catastrophic, prolonged droughts. In the short run lack of water-limits the amount needed for domestic use, while in the long run it leads to deterioration of the quality. In addition to the quantity of available water resources, its quality is of extreme importance. The objective of the study was to compare suitability of groundwater with that of surface water in order to use it. An additional goal was to determine the possibility of estimating conservative ion migration time as well as determine nitrate ion migration cycle. Data available from 2015 to 2019 was divided into two groups: groundwater (being under limited influence of climatic conditions and not exposed to direct evaporation) and surface water (exposed to direct sunlight and significant evaporation). It has been shown that, with the exception of nitrate ions, the physicochemical composition of groundwater is less variable than that of surface waters; however, it is strongly spatially diversified across the country. It has been established that in a dry and hot climate, with a high share of artificial irrigation of crops (with deliberate limitation of evaporation and intensification of infiltration) along with the introduction of fertilizers, migration cycle of nitrogen compounds in the environment is different than that from temperate and humid climate. The final conclusion is the unexpected: surface waters are much safer when used for consumption. For irrigation of crops, groundwater with high nitrate content may also be used; however, over-fertilization should be avoided.