Qualitative state of groundwater bodies in Ukraine: criteria and main problems of assessment

According to European methodological documents, assessing the qualitative state of groundwater bodies is a rather complicated procedure that involves the sequential implementation of specific studies. A prerequisite for a sound determination of the «good» or «poor» qualitative state of groundwater bodies is the properly established criteria, namely the threshold values of the pollutants – water quality indicators that correspond to the concentration of a certain pollutant or group of substances that should not be exceeded to protect the environment and human health. European countries have different approaches to setting thresholds. The differences are due to variations in national drinking water quality standards, different background levels of elements and compounds, and national environmental quality standards for surface water. The diversity of natural conditions on the territory of Ukraine requires a differentiated approach to determining pollutant thresholds. The authors have analyzed the natural hydrogeochemical characteristics of groundwater and provided recommendations for the determination and application of threshold values of pollutants, taking into account the peculiarities of the current state of groundwater monitoring in Ukraine. For those groundwater bodies in which the geochemical background level of chemical elements and compounds of natural origin exceeds the drinking water standards, it is recommended to use natural background levels to set thresholds, with emphasis on the maximum value in the background interval. The use of natural background levels as thresholds for assessing the qualitative state of groundwater bodies is also advisable when the content of controlled components is significantly lower than the drinking water quality standards. The analysis of information on substances exceeding the drinking water standards in the wells of the state monitoring network shows that until recently, insufficient attention has been paid to studying the content of a number of elements and compounds included in the mandatory list approved by the order of the Ministry of Ecology. This necessitates improving the monitoring methodology by equipping it with modern laboratory facilities.