St. Petersburg State University Scientists Find Heavy Metal Contamination in Soils Near Caucasus Glaciers

Environmental scientists from St Petersburg State University and the A. K. Tembotov Institute of Ecology of Mountain Territories of the Russian Academy of Sciences have found that soils near glaciers in the high-mountain areas of the Central Caucasus contain almost twice as much copper and nickel as soils in protected natural areas.

Glaciers serve as a crucial source of fresh water in mountain ecosystems. However, in recent decades, they have been melting and becoming polluted due to climate change and an increasing flow of tourists. Glacial melting leads to the formation of specific dark deposits in the soil, containing dust, soot, ash, and the waste products of microorganisms – known as cryoconite. These formations accumulate pollutants and transport them into the soils with meltwater, which can negatively impact the state of unique mountain ecosystems. Until now, it has remained unclear how the amount of pollutants differs in glaciers and soils of mountain areas with varying levels of tourism and protected status.

Researchers from St. Petersburg StateА University and the A. K. Tembotov Institute of Ecology of Mountain Territories of the Russian Academy of Sciences studied two neighboring mountain gorges in the Central Caucasus – the Tsey Gorge and the Skazsky Gorge. The first is located within a nature reserve and is accessible only to a limited number of eco-tourists, while the second is actively used for mass recreation, featuring developed infrastructure and roads.

Specialists collected samples of cryoconite, soils at different altitudes and distances from the glaciers, as well as bottom sediments from glacial streams. The research was conducted in the summer – the period of most active tourism in these areas. In the laboratory, scientists assessed the content of copper, zinc, nickel, lead, and cadmium in the obtained samples, as these metals are toxic to living organisms even in small amounts. They also studied the physicochemical properties of the mountain soils and the organic matter contained within them.

The analysis showed that in the touristic Skazsky Gorge, concentrations of copper and nickel are almost twice as high as in the protected Tsey Gorge. According to the scientists' assessment, this is primarily linked to human activity – the operation of vehicles, cable cars, cafes, and other infrastructure facilities, which increase the level of pollution in sensitive mountain ecosystems.

At the same time, zinc and lead content was found to be high in both areas. Scientists attribute this to the natural geologically determined characteristics of the Central Caucasus soils and the influence of old mining enterprises located in the region. Dust particles containing these elements can be transported by the wind and deposited on glacier surfaces, then entering the soils with meltwater.

The results of the study will be useful in developing monitoring programs for the state of glaciers and soils, planning tourist infrastructure, and creating strategies for the protection of natural resources, including in tourist regions.

"We recommend introducing seasonal restrictions on visiting vulnerable areas, developing environmentally safe construction practices, and monitoring the content of toxic elements in natural environments. In the future, we plan to study the processes of accumulation and transport of other elements in high-mountain ecosystems, as well as the characteristics of the cryoconite and soil microbiomes, to better understand the dynamics of high-mountain landscape changes under conditions of climate change and expanding human activity" said the project leader, Head of the Department of Applied Ecology at St. Petersburg State University, Evgeny Abakumov.

Calculations showed that in the protected Tsey Gorge, most soil samples fall into the category of unpolluted. In the Skazsky Gorge, the pollution level was higher and classified as weak. The overall ecological risk in both areas, however, remains moderate. These findings further confirm that a strict protection regime and the development of ecological tourism help reduce human impact on mountain areas.

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Provided by St. Petersburg State University