NATURAL REMEDIATION OF SOIL CONTAMINATED WITH HEAVY METALS DUE TO TOURISM IN THE ALTAI MOUNTAINS

Abstract

This article examines the natural remediation rate of soil contaminated with heavy metals from uncontrolled tourism in the Mongolian Altai Range. During the pandemic, domestic tourism surged in Kazakhstan and Mongolia, with the Altai Range becoming a popular destination. This led to an influx of 32-40 thousand vehicles to the Kazakhstani Altai and about 13 thousand to the Mongolian Altai. Due to limited infrastructure, tourists often traveled on unpaved roads, created new paths, crossed swamps to access the mountains, and caused significant environmental impact. The contamination analysis revealed that the levels of heavy metals like lead, nickel, and zinc were 2-4 times higher in affected soils compared to uncontaminated areas. In total, tourism impacted 705.7 hectares of soil in the Kazakh Altai and 182.7 hectares in the Mongolian Altai. Following the publication of this study, the authors presented their findings to the Mongolian Ministry of Environment and Tourism. Subsequently, the Mongolian Altai Specially Protected Areas Administration issued Order A/14 on July 28, 2023, which limited vehicle access in the area.

In the absence of any active remediation efforts to clean the contaminated soil or restore the environment, the authors hypothesized that the observed reduction in contamination levels may be attributed solely to natural processes. Soil samples were collected from previously recorded coordinates, and the concentrations of six heavy metals were analyzed using atomic absorption spectrometry. The results revealed that chromium levels in the soil decreased by 3.8–6.3 mg/kg above the road surface. Below the road, chromium concentrations varied, with decreases observed in some locations and increases in others. Lead concentrations showed a reduction of 2.7–6.8 mg/kg above the road, whereas below the road, lead levels increased by 5.5–8.8 mg/kg, indicating a tendency to accumulate in these areas. Zinc concentrations exhibited significant variation across different locations, but no consistent trend or stability was identified. These findings provide evidence that soil contaminated with heavy metals can undergo natural remediation through processes such as erosion and other environmental mechanisms.

Keywords: Altai mountains, soil pollution, heavy metals, natural remediation