Hydrobiological Assessment of Water Quality in the Yesil River, Astana Region: An Environmental Evaluation

Abstract

This study provides an in-depth characterization of the water quality in the Yesil River in the Astana region for 2019, utilizing hydrochemical parameters and key indicators of bacterioplankton, zooplankton, and zoobenthos. Quantitative evaluation methods were employed to assess hydrobionts, including total bacterial counts, heterotrophic bacterial counts, bacterial multiplication rates, biomass, and abundance of zooplankton and zoobenthos, in addition to species identification for various organisms. The results indicated that, based on the bacterioplankton development level, the investigated section of the Yesil River is classified as a mesotrophic water body. As the river flows through the city, the average bacterial mass doubling time decreases due to an increase in the proportion of heterotrophic bacteria. Based on the saprobity index level for the zooplankton community, the water in the Yesil River is categorized as moderately polluted. Macrozoobenthos saprobity indices range from moderately polluted to polluted waters. The final assessment of the water quality classification and contamination degree, according to Z.G. Gold's unified classifier, revealed a shift from class 3 in the sections upstream of Astana to class 4 in sections downstream of the city.