Distribution characteristics and assessment of the content of heavy metals in small rivers of the Ulba riv. basin in the mining regions of East Kazakhstan.

Water quality of small rivers in the Ulba basin has been assessed in the impact zone of the mining industry of the Ridder region in East Kazakhstan. Sixteen elements in the waters of small rivers and general chemical water indices were determined using mass spectrometry. The waters of the small rivers under investigation were primarily ultra-fresh and slightly alkaline. The chemical composition of the examined waters was characterised as a sodium-potassium sulphate type, a calcium-magnesium bicarbonate type, and a mixed chemical type, namely, sodium-calcium bicarbonate-sulphate. These waters do not conform to the Health Standards established by the Republic of Kazakhstan, as indicated by the hardness indices for the Filippovka and Bystrukha riv. The cadmium content exceeded the MPC set by the Health Standards of the Republic of Kazakhstan in the waters of the Ulba riv. (up to 21 MPC), Tikhaya (up to 5 MPC) and Filippovka riv. (up to 3 MPC) in 65%, 88% and 18% of water samples, respectively. Single samples were also found to contain elevated concentrations of manganese (Filippovka riv. and Breksa riv.) and ferrum (Breksa riv.). According to the standards set by the World Health Organization (WHO) and the US MPC, exceedances of manganese, aluminium, iron, and cadmium contents in the waters of the Ulba, Filippovka, Breksa, and Bystrukha rivers were observed, ranging from 1 to 7 times. The highest exceedances were recorded in the waters of the Ulba river, with manganese concentrations exceeding the WHO standards by 4 times and US EPA standards by 6.4 times and cadmium concentrations exceeding the WHO standards by 7 times and US EPA standards by 4.2 times. In most water samples from Tikhaya and Ulba riverbeds and in the upper reach of the Filippovka riv, high and average levels of water contamination were revealed (according to the pollution index of heavy metals (HPI)). Alternatively, low contamination levels (<15) with no elevated concentrations of heavy metals were observed in the waters of Zhuravlikha, Malaya Zhuravlikha, Gromotukha, Khariuzovka, Bystrukha and Breksa.