The geochemical composition of waters of the Mzymta River is subjected to sharp seasonal changes. In summer, the waters are enriched in 34 elements (mainly REE, Fe, Mn, Cs, Al, and Cd) relative to their average contents in river waters. REEs in the waters show steady relations MREE > HREE > LREE with a general positive trend to the mouth. In spring, they are enriched only in 14 elements. They have the poorer REE composition and less fractionated REE patterns. In summer, their contamination significantly increase relative to MPC, with growth from the upper reaches to the river mouth. A general geochemical specialization of bottom sediments is determined by 27 elements, contents of which insignificantly exceed their average contents in rocks exposed in the basin for the upper continental crust. Disagreement between the high level of water contamination in summer and a weak contamination of the bottom sediments of the river is related to the low contents of finely dispersed mineral and organic matter in the latters. It was determined that chemical elements are supplied in water from three main sources: natural, natural–technogenic, and anthropogenic–technogenic. The maximum contribution to the water contamination over the entire river extent is provided by natural sources: rocks that compose the basin. The anomalous increase of concentrations of chemical elements, including Th and Y, in the middle and lower reaches of the river is related to the natural–technogenic sources at the adjacent slopes of the valley. These are technogenic areas and talus, as well as highway and railway roads, and sometimes building embankments, which are made up of disintegrated rocks devoid of soil–vegetation layer. The anthropogenic–technogenic factors make only a limited contribution to the contamination of water and bottom sediments of the river. The radioecological state of waters and bottom sediments of the Mzymta River is safe.

The paper presents the first data on the zoning of modern volcanic soils on the Kamchatka Peninsula according to the age and composition of volcanic ashes in which the surface organogenic horizons of the soils were formed. The following soil provinces are recognized: Northern, Central, Western, and Southeastern. Parameters of their regional geochemical background (concentrations of trace elements) are determined. The main factor controlling the background concentrations of trace elements in these soils is the composition of the ashes underlying the soils. The geochemical specifics of the surface organogenic horizons of volcanic soils on Kamchatka may be variably affected only by the concentrations of trace elements whose average contents in magmatic rocks are the highest: Cr, Cu, Mn, Sc, Zn, Co, V, and Ag. The maximum concentrations of excess elements were determined in the soils underlain by ashes of basic composition, and the minimum concentrations of these elements occur in the soils formed in silicic ashes. All soil provinces recognized on Kamchatka are characterized by pervasively elevated Cu concentrations. It is proposed to identify volcanic soils formed in the peninsula in ashes of various composition with the application of a multiplicative geochemical coefficient.

The link of the chemical composition of the plant with the active volcanism of Kamchatka, is determined by the stable occurrence into the composition of the priority chemical elements for plants, volcanic ashes and soils: Ca, Mg, Mn, P, Cu, Zn and Sr. An elevated geochemical background of Kamchatka plants relative to the bulk chemical composition of the peninsula’s soils was established. The contents of Br, Hg, Hf, Sb, Ga, W, K relative to the clarks for living matter in the plants of the region are exceeded by 3–5 times. Against the background of small variations in the contents of chemical elements in plants of different regions, the relatively rich biogeochemical background of the Western region of the southern province (the western coast of Kamchatka) is determined, where most ancient near-surface volcanic ashes for Kamchatka are transformed into humus-accumulative horizons. On the territory of young volcanic ash fallout in the immediate vicinity of volcanoes, the relative richness of vegetation with chemical elements and the poverty of soils by mobile forms of elements have been established. On the contrary, at a distance from the volcanoes in the zone of far transfer fallout ashes, there is a marked relative poverty of plants and soil richness of available chemical elements.

The Mzymta and Sochi watersheds, located on the southern slopes of the Caucasus Mountains on Russia’s Black Sea coast, are characterized by a remarkably complex geological setting. The predominant rocks are mudstones, siltstones, and shales, with smaller amounts of carbonate and clay-carbonate rocks, and occasionally igneous rocks. The area is also characterized by the occurrence of polymetallic, gold, sulfide, rare metal, and rare-earth mineralizations in addition to hosting a thermal hydrogen sulfide groundwater aquifer. The objective of this study was to determine groundwater genesis patterns in an area with such contrasting geological and hydrogeological structures. Based on the chemical analysis of 33 natural groundwater springs, five chemical types of water were identified dictated by the composition of the host rock as well as the occurrence of mineralizations, seepage of mineralized water, and local geochemical features of the host rock. The high sodium concentration and mineralization of groundwater near the thermal hydrogen sulfide groundwater aquifer are due to the infiltration of seawater. The consistent presence of excessive amounts of rare-earth elements (REEs) in all groundwaters in the area is a reflection of the regional geochemical specialization of the rocks. Groundwater, like the terrestrial components of the natural environment, inherits rare-earth fractionation patterns from the rocks that make up the area. Thus, rare-earth totals and fractionation patterns can be used as a reliable criterion to interpret the regional specificity of groundwater.

Under conditions of active volcanism, the soils on different geomorphic positions (from high-mountain landscapes to river valleys) are formed under the impact of periodic ashfalls. The exogenous processes affect the redistribution of volcanic ashes by the elements of the relief, so that the soils of different altitudinal zones have their own morphological specificity. It is suggested that two additional types of volcanic soils should be included in the new Russian soil classification: the type of alluvial volcanic soils in the order of volcanic soils and the type of volcanic lithozems in the order of lithozems. These soils can be considered intergrades between volcanic and alluvial soils and between volcanic soils and lithozems, respectively.

The Kamchatka volcanic soils have low concentrations of most chemical elements relative to their general abundances in continental soils and in European volcanic soils. The soils in different...