Heavy metal deposition through precipitation in Kazakhstan

The active development of industry, primarily mining and metallurgical, as well as energy, is accompanied by significant emissions of pollutants into the atmosphere. We collected data and analyzed the intake of heavy metals (HM) of lead (Pb), copper (Cu) and arsenic (As), cadmium (Cd) in precipitation (wet deposition) on typical natural Kazakhstan ecosystems. The average Pb, Cu, As and Cd wet deposition was 3.80 ± 1.52, 16.11 ± 1.48, 0.96 ± 0.84 and 0.88 ± 0.44 μg/L, respectively, with a large variation among the different sites of Kazakhstan. In addition, we identified the most significant industrial areas in the republic and determined the concentrations of the listed metals in the precipitation for each of them. The relationship between these concentrations and industrial activity in the regions, and the presence of a mutual correlation between them were also investigated. We obtained that the atmospheric deposition of Pb, Cu and As were higher in the central industrial areas (Dzhezkazgan, Balkhash), as well as in the south (Chimkent) and in the east (Ust-Kamenogorsk), where large mining and metallurgical enterprises are located. In these cities, there are high concentrations of pollutants (PS) in the atmosphere, exceeding the maximum permissible concentrations (MPC) by several times. Significant sedimentation of pollutants, primarily HM, is noted, adversely affecting soils and surface runoff. The total deposition of heavy metals on snow cover was determined. We obtained that the average total deposition for Pb, Cu, As and Cd was 4.4 ± 1.28, 20.6 ± 1.43, 3.23 ± 0.81 and 1.03 ± 0.47 μg/L. Calculations performed for comparable time intervals showed that dry deposition is two to five times greater than wet deposition and the smaller the precipitation in the region, the greater the dry deposition, ceteris paribus. At the level of climate assessments, it is shown that there is a transboundary transfer of heavy metals from both the territory of Kazakhstan from the territory of Russia.