Hydrogeochemical Zoning of the River Network of Kamchatka

Water Resources - The hydrogeochemical features of river water in different parts of Kamchatka Peninsula have been identified in terms of a wide (57) range of macro- and microelements by...     

Zoning and geochemical characterization of volcanic soils on Kamchatka

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.     

Volcanic ash as a factor for radioecological conditions in Kamchatka part 1. The abundance and hypergene transformation of Th and U in recent volcanic ash

Concentrations of Th and U in fresh ash ejected by active volcanoes in Kamchatka are generally considerably below their Clarke values in their respective types of rock. The bulk concentrations of Th and U in andesitic and basaltic ashes do not show any obvious differences. The concentrations of their mobile forms decrease with increasing basicity of the ash. We revealed overall positive linear trends in the series of bulk concentrations for Th and U and a negative trend of Th/U in ashes that have been arranged over eruption year. Considerable quantities of mobile forms of radioactive elements fall during ashfalls in dissolved form or are sorbed by falling snow directly from the dispersive medium of volcanic aerosols. The original fractions of all of the mobile forms are 0.68–1.93% for Th and 1.16–3.21% for U. The bulk of these come to the Earth’s surface during eruptions when no snow cover was available. The quantities of mobile forms of Th and U were considerably decreased when ejected by winter-time eruptions during the time they resided in the snow.     

The geochemical transformation of natural soils and enhancement of agricenosis productivity due to volcanic ejecta entering the soil

It is found that the overwhelming majority of mobile forms of the chemical elements (up to 99%) that are thought to produce favorable effects when they arrive with volcanic ash to soils and supply additional elements that enhance the bioproductivity of ecosystems do not come in the form of ash particles, but in a gas-dissolved form directly from volcanic aerosol. Volcanic ash when considered independently of volcanic eruptions does not contain considerable amounts of accessible forms of chemical elements that would enable us to consider them as sources of nutrient elements for living organisms. However, the extensive range of elements that are contained in ash in ratios that are necessary for effective life activities invests these elements with catalytic properties that regulate the nutrient regime of plants and that can be used in agriculture in combination with lower amounts of traditional fertilizers to produce substantial (up to 72%) yield increases and to improve the quality of agricultural products.     

The role of volcanic ash in formation of soil and vegetative cover in the present-day explosive volcanism area

By the example of an area near the active Karymskii Volcano (on the eastern coast of Kamchatka) it is shown that under conditions of regular supply of pyroclastic material on the diurnal surface, organic soil matter transforms very slowly and mobile trace elements of newly fallen volcanic ashes are the major plant nutrition source. Geochemical specialization of the studied area is characterized by lower concentrations of most trace elements relative to their clarkes for soils and by an excess of trace element contents over the clarkes for living matter in plants. Newly fallen ashes are enriched in mobile trace elements, which in dissolved form pass into adjacent media due to hypergene geochemical processes.