E. V. Abakumov

Changes in some physical properties of soils in the chronosequence of self-overgrown dumps of the Sokolov quarry-dump complex, Czechia

The water-physical properties (bulk density, air conductivity, texture, water content, and temperature dynamics) were studied in a chronosequence of soils developing on self-overgrowing quarry-dump complexes in the area of Sokolov, Czechia. The area overgrown for 12 years was covered by a thin grass cover; osiers were observed after 20 years of overgrowth; a broadleaved forest was found on a plot after 45 years of overgrowth. The particle-size distribution in the soil was determined using peptization by pyrophosphate and the FAO method. When the soil was prepared by the FAO method, a predominance of physical clay (62–72%) in the dump material was revealed; at the use of pyrophosphate peptization, the content of this fraction was lower (18–19%). The observed differences can be due to the incomplete degradation of the microaggregates composed of clay particles during the peptization by pyrophosphate. A decrease in the field water content of the soils with the increasing time of the dump’s overgrowth was observed. This could be attributed to the more significant evapotranspiration of the perennial woody vegetation compared to the herbaceous plants, which agreed with the data on the projective cover of plants and their root biomass. A decrease in the soil temperature in the root-inhabited layer (in the diurnal variation) with the age of succession was also observed. The analysis of the data on the field soil water content and their comparison with the results of the laboratory measuring of the wilting points indicated that the development of plants could be restricted by a water deficit at the 20- and 45-year-old stages of the succession.

Particle-size distribution in soils of West Antarctica

The particle-size distribution in soils sampled near Russian polar stations in West Antarctica has been studied. It is shown that the soils of the Subantarctic zone (the Bellingshausen Station on King George Island) are characterized by a higher content of silt and clay in the fine earth fraction and by a higher content of the fine earth fraction in comparison with the soils of the proper Antarctic tundra barrens near the Lenin-gradskaya Station and the Antarctic cold desert near the Russkaya Station. In the latter soils, the content of rock fragments is higher than that in the soils of the Antarctic tundra barrens. In the soils of the tundra barrens, a considerable accumulation of fine earth may take place in large cavities (hollows) on the stony bedrock surface. Desert pavements are formed in both types of Antarctic landscapes.

The Sources and Composition of Humus in Some Soils of West Antarctica

Original data on humus-forming substances and their elemental and biochemical compositions in Antarctic soils are discussed. Mosses, lichens, algae, remains of higher vascular plants, and penguin guano of two types differ considerably in their chemical compositions. This leads to significant differences in the formation of humic substances in plant materials themselves in the course of their transformation. However, no significant differences in the composition of humus in the fine earth of soils developing under different humus-forming materials have been revealed, which may be related to the extremely low rates of humification. Significant differences between the soils of Antarctic landscapes proper and the soils of the Subantarctic King George Island are only observed in the humus enrichment with nitrogen. The soils of Antarctica are low-humus soils with the humate-fulvate or fulvate types of humus.

Humic acid characteristics in podzol soil chronosequence

Humic acid (HA) characteristics were studied in a natural revegetation chronosequence of 10-, 20-, 60-year-old and mature podzol soils under a pine forest, along the spoil heaps of a sand quarry. The elemental composition of HAs showed a trend towards carbon increase and hydrogen decrease with soil age. Essential differences in the atomic ratios between humic acids extracted from the different soils may be due to the intensity of the humification process as related to soil age. Compared with HAs extracted from organic horizons, those from mineral horizons showed lower C/N and H/C ratios, whereas O/C ratios were higher. Electrophoretic data showed that the proportion of the more-mobile fraction (L-MS) was higher in the mineral horizons than in the organic horizons and, among organic layers, in the Oe and Oa horizons compared with Oi. Intensive transformation of pine remains may have occurred and led to HAs with an increasing degree of humification in only 60 years. Moreover, progressive accumulation of the L-MS fraction in the E and Bs horizons with soil age might be the result of the ongoing migration of the most-polar organic compounds down through the soil profiles.

Soils of Marie Byrd Land, West Antarctica

Soils of Marie Byrd Land-one of the remotest and difficultly accessible regions of Antarctica-were investigated in the area of the mothballed Russkaya station located to the south of 74° S. Despite the extremely severe wind regime (the average wind velocity is 13 m/s, and the maximum wind velocity is up to 60 m/s), the projective cover of vegetation in the area of the station averages 25–40% and reaches 60–80% in some places. The phenomena of physical weathering of the bedrock-exfoliation, stone pavements, residual rocks exposed by wind (hoodoos), and others-are clearly manifested. In most of the described soils, normal organic and organomineral horizons are absent. The soil profiles represent the mixture of the residues of mosses and lichens and the gravelly eluvium. The fine earth material is blown out of the surface horizons by strong winds; its residual accumulation takes place in the middle and lower parts of the profiles. The classification position of these soils is open to argument; they are close to Petrozems and Lithozems. Most of the profiles are underlain by the massive or slightly disintegrated bedrock with dry permafrost at a depth of 20 to 50 cm. Soils with dry permafrost comprise about 75% of the surveyed area. In separate loci in the depressions of the local mesorelief and on gentle slopes, the soils with clearly expressed cryoturbation features are developed; their profiles are underlain by the ice-rich permafrost and compose about 15% of the surveyed area. Anthropogenically disturbed soils and soils polluted with petroleum hydrocarbons, heavy metals, and other pollutants occupy about 10% of the surveyed area.

Soil formation in the quarries for limestone and clay production in the Ukhta region

The soils forming on the overgrowing technogenic dumps of quarries for limestone and clay production were investigated in the northern taiga (the Ukhta region). The soils are formed under sparse herbaceous plant communities. In the soils on calcareous technogenic eluvium and clay dumps, the processes of humus formation and accumulation predominate. In the soils of the clay dumps, the leaching of carbonates is expressed to a greater extent than in the soils of the limestone quarries. The nitrogen content of organic matter is low in the soils on the technogenic lime substrates and very low on the clay ones. Fulvic acids predominate in the humus composition. At the stages of the soil restoration studied, the zonal trend of pedogenesis is manifested only in the humus accumulation. The calcareous technogenic eluvium is found to be more favorable for the development of microbial communities as compared to the clay substrates with their small microbial biomass. However, there are no features pointing to the development of zonal soil profiles. This fact attests that, in the first 20–30 years, the soil-forming potential in the northern taiga is insufficient for the initiation of the zonal processes.

Effect of soil invertebrates on the formation of humic substances under laboratory conditions

The complete polymerization of phenols and proteins (one of the processes involved in the formation of humic substances) was explained. It was shown that fly (Bibio marci) larvae and earthworms (Aporrectodea caliginosa) participate in the complete polymerization of phenols and proteins. In a laboratory experiment, invertebrates participated in the degradation of organic matter and the synthesis of humic substances, which was proved in experiments with 14C-labeled phenols and proteins. The same organic substances (phenols and proteins) without the impact of invertebrates were used as the control substances. The distributions of the 14C isotope in alkaline extracts separated by solubility in acids (humic and fulvic acids) was compared to those of the control substances. The portion of the 14C isotope in the humic acids in the excrements of Bibio marci was higher than that in the control substances. The content of 14C-labeled humic substances in the excrements of the earthworm Aporrectodea caliginosa exceeded the control values only in the experiment with proteins. When clay material was added to the organic substances, the portion of the 14C isotope in the humic acids increased in both experiments with phenols and proteins. When these substrates passed through the digestive tracts of the invertebrates, the polymerization of organic substances and the inclusion of proteins and phenols into humic acids occurred.

Microbial biomass and basal respiration of selected Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

Abstract. Antarctica is a unique place for soil, biological, and ecological investigations. Soils of Antarctica have been studied intensively during the last century, when different national Antarctic expeditions visited the sixth continent with the aim of investigating nature and the environment. Antarctic investigations are comprised of field surveys mainly in the terrestrial landscapes, where the polar stations of different countries are situated. That is why the main and most detailed soil surveys were conducted in the McMurdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann Hills and the Schirmacher Oasis. Our investigations were conducted during the 53rd and 55th Russian Antarctic expeditions in the base of soil pits, and samples were collected in Sub-Antarctic and Antarctic regions. Sub-Antarctic or maritime landscapes are considered to be very different from Antarctic landscapes due to differing climatic and geogenic conditions. Soils of diverse zonal landscapes were studied with the aim of assessing the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. This investigation shows that Antarctic soils are quite diverse in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod) organo-mineral horizons as well as by an upper organic layer. The most developed organic layers were revealed in peat soils of King George Island, where its thickness reach, in some cases, was 80 cm. These soils as well as soils formed under guano are characterized by the highest amount of total organic carbon (TOC), between 7.22 and 33.70%. Coastal and continental Antarctic soils exhibit less developed Leptosols, Gleysols, Regolith and rare Ornhitosol, with TOC levels between 0.37 and 4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones, which can be interpreted as a result of higher amounts of fresh organic remnants in organic and organo-mineral horizons. The soils of King George Island also have higher portions of microbial biomass (max 1.54 mg g−1) compared to coastal (max 0.26 mg g−1) and continental (max 0.22 mg g−1) Antarctic soils. Sub-Antarctic soils differ from Antarctic ones mainly by having increased organic layer thickness and total organic carbon content, higher microbial biomass carbon content, basal respiration, and metabolic activity levels.

Evolution of the soil humus status on the calcareous Neogene clay dumps of the Sokolov quarry complex in the Czech Republic

The development of the soil profile and the humus substance system was described for two chronosequences of soil restoration on the Neogene clay dumps. The chronosequences differed in the restoration type of vegetation: self-overgrowing or overgrowing intensified by planting tree seedlings (rehabilitation). It was found that the regeneration rates of the soil and humus profile were much higher in the case of the land rehabilitation than during the self-overgrowing of the dumps. The acceleration of the ecogenetic succession and the symbiotic nitrogen fixation in the soils of the plots with seedlings planted resulted in the accumulation of humus and nitrogen and increased the degree of organic matter humification. The enrichment of the organic matter in nitrogen and its increased input were the main reasons for the more intense humification under the rehabilitation conditions.

Accumulation and transformation of organic matter in different-aged dumps from sand quarries

The accumulation and transformation of organic matter were studied in chronoseries of different-aged (3-, 10-, 20-, 30-, 43-, and 60-year-old) soils and a background (reference) plot. The ecogenetic succession of plants on sand quarry dumps was characterized. It was shown that the pedogenesis rate was closely related to the rate of phytocenosis development, and the thicknesses of organic and mineral horizons increased synchronously. The profile distribution of organic matter in young soils was estimated as an ectomorphic distribution, and the humus reserves in the mineral horizons of the same soils were comparable with the reserves of organic matter in the litters. The illuvial horizons of the soils under study played a significant role in the deposition of carbon dioxide; the resistance of organic matter to mineralization increased with age. In the soil chronoseries, the combustion heat of litter organic matter increased, as well as the content of energy accumulated in the litters. The composition of humus differed strongly between the eluvial and illuvial horizons; in the chronosequence, the relative content of humic acids increased in the E horizon, and that of fulvic acids increased in the B horizon. The effect of the phytocenosis on the soil was increasingly mediated with time. The accumulation and transformation of organic matter were the leading pedogenic processes at all stages.