Quality Assessment of Groundwater Used for Irrigation in the Steppe Crimea

Abstract

The aim of this work was to evaluate the chemical composition of underground irrigation waters of water intakes in different parts of the Crimean steppe and its dynamics with time and to demonstrate the suitability of waters for irrigating agricultural crops with different salt tolerance. The research was performed in 2022–2025 in pilot areas located in the steppe Crimea (Pervomaiskii and Sakskii districts). We determined pH, specific electrical conductivity (EC), main anions and cations, mineralization, and a number of microelements in irrigation waters by conventional methods. It was established that the mineralization of waters in the Pervomaiskii district was 2.3–3.1 g/L, and they were neutral of sulfate-chloride composition with high chloride content (1.0–1.4 g/L). With respect to mineralization and chloride content, the waters pose a risk of salinization and alkalization for dark chestnut soils with a heavy granulometric composition, and, according to existing criteria, are characterized as poor. The waters of the Sakskii region are characterized by the mineralization of 1.2–1.4 g/L of chloride-sulfate type. The waters are classified as moderately dangerous for salinization and alkalization of micellar-carbonate southern chernozem. The waters of the Pervomaiskii district tended to become salinized with time due to an increase in chloride content by 100–300 mg/L. In the Sakskii district, a decrease in water mineralization with time from 1.4 to 1.2 g/L with a decrease in sulfate content and stable chloride concentrations was seen. The iron and heavy metal content in groundwater was low, varied significantly by sampling dates, and was below the maximal permissible concentration (MPC) for irrigation water. The cadmium content in the water regularly exceeded the MPC for drinking water by two–five times. The studied waters are not useful for irrigating slightly salt-tolerant crops and are of limited suitability for moderately and highly salt-tolerant crops, the reduction in productivity of which may reach 25–100%. In this regard, it is recommended to change the structure of crop areas, depending on the mineralization of irrigation water.