CHROMIUM, NICKEL AND COBALT IN BOTTOM SEDIMENTS OF AGRICULTURAL RESERVOIRS OF KOSTANAY REGION: ENVIRONMENTAL SAFETY AND MONITORING METHODS

Abstract

In this study, the geochemical characteristics of bottom sediments in two major reservoirs of the Northern Kazakhstan – Verkhnetobol and Karatomar, located within the boundaries of Kostanay region – were investigated. These reservoirs are vital water bodies that serve the irrigation needs of agricultural lands in the region. Therefore, ecological monitoring of the reservoirs is essential to support the quality of agricultural products produced in the Kostanay region. Samples were collected during the winter period under stable ice cover conditions, which allowed the shoreline zones to be examined in their seasonally stable natural state. Particular attention was given to determining the concentrations of key elements – chromium, nickel, and cobalt – that may affect ecosystem processes in the benthic environment. The elemental concentrations recalculated from their oxide forms, did not exceed the background values typical of the Earth’s crust (Clarke values). This indicates the absence of significant anthropogenic load in the studied areas. The obtained results are consistent with international standards, including the guidelines of the UNECE, which state that coarse-grained components of bottom sediments are typically assotiated with low levels of heavy metal accumulation. The practical relevance of the work lies in establishing a foundational database for further monitoring of agricultural water bodies. The data can be used as a reference for assessing the ecological state of temperate freshwater systems and for developing rapid methods of X-ray fluorescence analysis of the solid-phase fractions of precipitation.