ИСТИНА

Дана оценка содержаний широкого спектра микроэлементов в почвах, образованных на наиболее распространенных для Камчатки вулканических пеплах. Установлено, что более высокие значения фоновых содержаний элементов характерны для почв, образованных на средних вулканических пеплах в сравнении с почвами, развитыми на кислых пирокластических отложениях. В целом вулканические почвы обеднены большинством микроэлементов сравнительно с их общей распространенностью в почвах континентов. При этом вблизи активных вулканов почвы обогащены растворимыми формами микроэлементов, весьма быстро вымывающимися из почв и пеплов природными водами и обуславливающими богатый зольный состав растительности, произрастающей в этих зонах, а также часто наблюдаемый всплеск биопродуктивности после вулканических извержений.

The activity of volcanic centers of different development stages influences on genetic features of soil formation on the territory of Kamchatka peninsula. During the early activity stage of volcanism the processes of current soil formation with frequent periodicity from first tens till first hundreds of years are interrupted by ash fall of basaltic and andesite compositions. Thereby the properties and processes typical for Kamchatka natural and climatic conditions don’t develop in the soils on the ashfall territories. On the contrary during the mature stage of volcanism development rare (the periodicity of 500 years and more) great caldera-forming eruptions with the fall of considerable number of acid ash occur. Long intervals between the eruptions are favorable for soil formation with well-defined ochreous illuvial horizons, mature surface organogenic formations and developed alphe-humus processes. The provinces and volcanic soils areas are selected on the peninsula territory taking into account differences of the conditions of soil formation. Regional geochemical backgrounds of a wide microelements spectrum were determined for these provinces and volcanic soils areas. The main geochemical feature of Kamchatka volcanic soils formed on the different (in accordance with petrochemical composition) volcanic ashes is low contents of many chemical elements relative to their total occurrence in continents soils. It is greatly defined by the geochemical depleted of soil-forming ashes relative to clarkes of chemical elements in magmatic rocks of similar composition. P, Cu and Se define total geochemical specialization of Kamchatka volcanic soils. It is expressed by their stable overclarke background contents. In the zones of active ashfall near active Kamchatka volcanoes the processes of soil formation are accompanied by periodical ash fall of basaltic and andesite compositions. This ash is enriched in moving forms of elements which major part is lost during the first years after the eruption. Geochemical differentiation taking place in accordance with eluvial-illuvial type was determined in soil profile. Substantially high concentrations of available forms of elements in the soils define rich microelement composition of plants biomass in such areas.