Ecological and geochemical studies of clastic material from the Bureya landslide after cyclic freezing/thawing <i>in vitro</i>

The paper presents the results of experimental study (in vitro) of the transformation of clastic material (CM) sampled from a landslide body at the Bureya water reservoir. СM samples are considered as a model for assessing the influence of abiogenic and biogenic factors on the transformation (destruction, dissolution) of Si-containing minerals under various conditions of cyclic freezing/thawing, i. e., the dry sample; the samples placed in deionized water and in the presence of a solution of low molecular weight peptides. Freezing was carried out at a temperature of –18 °C, and thawing at a different temperature range (+4°C and +23°C). The elemental composition of aqueous solutions was determined by ICP-MS, and the microstructure of the CM surface was determined using scanning electron microscopy. As a result of 5 cycles after 7 days of freezing/thawing of CM samples in deionized water, the content of water-soluble forms of chemical elements (Fe, Ni, Cu, Zn, As, Mo, Ag, Cd, Tl, Bi, As) was below the detection limits of the device ( 0.001 µg/l). However, in the presence of a nutrient medium with peptone and a natural microbial consortium that retained its viability, the concentrations of a number of elements (Al, Ca, Mg, Fe, Mn, As, Hg) in the aquatic environment increased significantly. According to SEM images, a significant change in the microstructure of the surface of the samples CM occurred regardless of the thawing temperature when microorganisms were activated by low-molecular peptides. The formation of biofilms on the surface of CM grains was accompanied by the formation of various isomorphic microaggregates.