Geochemical and microbiological features of cryoconite, sampled from glaciers of the Central Caucasus region (Kabardino-Balkarian republic, Russia)

Determination of geochemical and microbiological properties of the cryoconite, related types of sediments and periglacial soils is essential to investigate impact of glaciers on terrains development at the Central Caucasus region. The studied sediments were sampled at the Garabashi and Skhelda glaciers as well as in vertical sections of local soils at the Baksan gorge. Sampled materials were investigated in terms of physicochemical parameters and nutritional state. The trace elements concentrations (Cu, Pb, Zn, Ni, Cd) were also evaluated in samples selected. The data obtained shows much higher content of organic carbon in soils (up to 7.82%) in comparison with cryoconite (max. 1.63%) due to the effect of superficial vegetation cover, however, rates of microbial activity were similar between some samples of sediments and soils. The analysis of the particle size distribution shows a similarity of the studied materials: in almost all samples, there is a dominance of the sand fraction. Cryoconite sediments on both of the above-mentioned glaciers are found as enriched with phosphorus, essential values of potassium (298 mg/kg in K2O units) and ammonium nitrogen (N-NH4 - max. 247 mg*kg) are identified at Garabashi glacier which could be a result of long-distant transfer and anthropogenic activity. The highest content among trace elements was identified for Zn (62 mg*kg for cryoconite and 60.5 mg*kg for soils), the most contaminated materials were sediments from Garabashi glacier and Entisols, up to moderate level, which is mostly associated with anthropogenic activity. Thus, development of tourism in the Central Caucasus, which is mostly associated with construction and transport, affects the pollution status of supraglacial sediments and periglacial soils as well as their agrochemical and microbiological features.