Abstract

Water, the vital element of the environment, considered for long time an inexhaustible and renewable resource, can have a limiting or favourable potential in the socio-economic development of a region. Given the fact that Romania's NE (Eastern Carpathians and the north-western part of Moldova Plateau) is undergoing increased competition for water resources, triggered by the intensification of agriculture and industrial development, better knowledge of the hydrological processes and the quality of surface water is required. The main purpose of the present study is to identify the hydrological processes that determine the quality of surface waters based on analyses of the stable isotopic composition of water (from precipitation, rivers and lakes) and their quality parameters. For this, water samples were collected from 29 river sections, two lakes and a precipitation monitoring point over a period of 12 months (January to December 2019). Results show that the changes in the isotopic composition of precipitation and surface water are mainly controlled by air temperature, which, in turn, is influenced by the large-scale atmospheric circulation and other factors (e.g. precipitation amount, season, altitude). At the same time, the chemical analyses indicate that the water resource of the study area is predominantly characterized by a good chemical and ecological state, except for two sampling points with a moderate state and three with a poor ecological state.