Water Quality Problems Analysis and Assessment of the Ecological Security Level of the Transboundary Ural-Caspian Basin of the Republic of Kazakhstan

Both the insufficiency of water resources and the contamination of even transboundary water bodies are serious problems. Water quality analyses of the transboundary (between Russia and Kazakhstan) Ural River and the Kazakh sector of the Caspian Sea, and their assessment are the main research questions of this study. It is shown that the Ural River is heavily contaminated by polychlorinated biphenyls, heavy metals, oil contaminants, and pesticides, arising from industrial enterprises and agricultural objects. The results show that these toxicants are not only present in water, but they are also accumulated in the muscular tissues of all fish (Abramis brama, Sander lucioperca, Aspius aspius). The Caspian Sea is heavily contaminated by petroleum hydrocarbons due to off shore oil production. A sufficiently high level of accumulation of petroleum hydrocarbons, organochlorine pesticides and heavy metals was determined in the muscles of Caspian fish. All these contaminations lead to the loss of biodiversity and bio-productivity of the Caspian Sea. The authors propose a methodology for a quantitative assessment of the environmental safety level in relation to the Kazakh part of the Caspian Sea, based on bioindication methods. Recommendations, aimed for maintaining acceptable values of water resources quality, are suggested.

Automated summary

This study focuses on the water quality analysis and assessment of the Ural River and the Kazakh sector of the Caspian Sea, which are transboundary water bodies between Russia and Kazakhstan. The results reveal heavy contamination of the Ural River by pollutants such as polychlorinated biphenyls, heavy metals, oil contaminants, and pesticides, originating from industrial activities and agriculture. The Caspian Sea is heavily polluted by petroleum hydrocarbons from offshore oil production, leading to a significant accumulation of pollutants in the muscles of fish. These contaminants have adverse effects on biodiversity and bio-productivity. The study proposes a methodology for quantitatively evaluating environmental safety in the Kazakh part of the Caspian Sea and puts forward recommendations for maintaining acceptable water quality.