Regional variations and geostatistical mapping of soil contamination by heavy metals in Astana city

Abstract

Urbanisation and industrial development significantly increase the risk of heavy metal contamination in soil, particularly in rapidly growing cities such as Astana, Kazakhstan. Urban soils accumulate pollutants through traffic emissions, industrial discharges, and construction activities, which may pose risks to ecosystems and human health. Therefore, it is critical to assess the spatial distribution and concentration of hazardous metals to support environmental decision-making and sustainable land management. This study focuses on evaluating the spatial distribution of cadmium (Cd), zinc (Zn), chromium (Cr), lead (Pb), and copper (Cu) in the surface soils of Astana. A total of 25 soil samples were collected from different functional zones of the city. The samples were analyzed using standard laboratory procedures. Spatial interpolation was performed using the kriging method in ArcGIS 10.8 to generate distribution maps. The results demonstrated spatial heterogeneity in heavy metal distribution across the city. Elevated concentrations of Cd, Zn, Cr, and Pb were primarily found in the Esil, Almaty, and Saryarka districts, which correspond to areas of high vehicular traffic, dense urban infrastructure, and industrial activity. Copper displayed a more localized pattern with scattered hotspots. Although all values were within national and international permissible limits, several areas showed levels exceeding natural background values, suggesting anthropogenic influence and the potential for long-term ecological impact. The study highlights key areas of concern and provides an environmental zoning approach that can aid urban planners and environmental authorities in prioritizing mitigation efforts. The integration of GIS-based spatial analysis with contamination assessment proves effective for supporting sustainable urban development and targeted soil remediation in Astana.