ASSESSMENT OF HEAVY METAL INPUT INTO THE IRTYSH RIVER AND ITS TRIBUTARIES FROM THE CATCHMENT AREA

Abstract

It is essential to assess the contribution of the Republic of Kazakhstan to the flow of heavy metals intothe Irtysh River and its tributaries through transboundary stations in order to resolve the issues of improving water qualityand strengthening good neighborly relations in the basin of the transboundary Irtysh River. The paper aims to: quantitatively assess the influence that natural and anthropogenic geological and geochemical factors have on heavy metal pollution of the Irtysh River and its tributaries in the Russian and Kazakhstan parts of the catchment area; estimate the transboundary transfer of heavy metals with waters of the Irtysh, Ishim, and Tobol rivers. The study has shown that in theIrtysh River basin the main runoff of heavy metals is formed on the territory of the metallogenic zones of the EasternUrals and Kazakhstan, within the boundaries of which ore minerals are mined and processed. At transboundary sites, thewater quality of the Irtysh River and its tributaries is mainly influenced by the catchment area downstream of the cascadesof reservoirs created on the Irtysh, Tobol, and Ishim rivers in the Kazakh part of the basin. It has been established that thediffuse runoff of heavy metals into the Tobol River from the disturbed territories of the ore-bearing zone in the EasternUrals is several orders higher than their background inflow, with a significant role of heavy metal deposition in bottomsediments. The contribution of the Republic of Kazakhstan to the pollution of the Irtysh River and its tributaries is mostsignificant for the Ishim River and the Irtysh River in the section up to the confluence of the Ishim River; Kazakhstan’scontribution to the pollution of the Tobol River is insignificant; such contribution is practically not traceable below theconfluence of the Tobol River. The conclusions obtained are made on the basis of a rather limited amount of initial data,and therefore require additional justification based on comprehensive field studies into physicochemical processes ofheavy metals transformation and migration in soils and anthropogenic formations of metallogenic zones in the EasternUrals and Northern Kazakhstan.