Influence of Trace Elements Translocation from Cryoconite on Local Soil Pollution Level at the Mount Elbrus Region
摘要
Cryoconites are supraglacial organomineral sediments that can accumulate various pollutants and release them into downstream ecosystems during the melting period. The influence of cryoconites on the pollution of local soils was studied in many mountainous regions, including the Tibetan Plateau, the Alps, and others. However, this information is lacking for the Caucasus Mountains and, particularly, their highest peak – Mount Elbrus, even though it is an important region for agriculture and tourism. We studied the content of Cu, Zn, Pb, Ni, and Cd in cryoconites at the Garabashi and Maliy Azay glaciers as well as in the soils of adjacent gorges. The content of trace elements was studied by atomic absorption spectroscopy, and pollution indices were calculated further. Our findings showed that sediments mostly accumulate trace elements in the cryoconite holes at the Garabashi Glacier (Zn max. 80.00 mg/kg, Cu max. 31.20 mg/kg, Ni max. 31.20 mg/kg, Pb max. 41.90 mg/kg, Cd max. 0.54 mg/kg). The highest content of trace elements in local soils of the Terskol Gorge, especially Zn (65.40 mg/kg) and Cd (max. 0.47 mg/kg), was found at the grazing meadow and wetland at the Terskol River floodplain while all trace element more polluted more remote soils at the Baksan Gorge. According to indices of geoaccumulation and ecological risk, most of the samples were unpolluted, while the pollution index indicated a high pollution load with Zn and Cu. These results showed that local anthropogenic activities increase trace element content in samples. Soils of wetlands and floodplains act as a natural geochemical barrier for translocated pollutants. High pollution by Zn and Cu is probably associated with metal-sulfite mineral ores at the Baksan Gorge and the transfer of polluted material. Currently, this pollution may not affect local ecosystems; however, it should be taken into account for the development of agriculture. Therefore, cryoconites play an important role in the geochemical flows of the Mount Elbrus periglacial zone, which should be taken into account in future human activities and the conservation of mountain ecosystems.