Geochemical specificity of volcanic soils of Kamchatka

The microelemental composition of volcanic soils of Kamchatka is specified by the composition of the volcanic ashes from which these soils are developed. It is found that the soils developing from acid and intermediate ashes are characterized by low contents of most of the studied microelements as compared with their clarke values in soils of the world. The background concentrations of microelements in the soils developed from intermediate ashes of Kamchatka are higher than those in the soils developed from acid pyroclastic deposits. Differences in the microelemental composition of the soils developed from different ashes are seen against the regional background specificity of the volcanic soils of Kamchatka. These soils are enriched in the elements typical of mafic magnetic rocks. In particular, this concerns Cu, Mn, Sc, V, and Ag; the concentrations of these elements in the soils of Kamchatka are higher than their average concentrations in soils of the world. This is related to the common geochemical properties of volcanic ashes in Kamchatka, whose composition reflects the geochemical specificity of the multistage volcanism on this peninsula.     

Chemical composition of soils in the areas of volcanic ashfalls around active volcanoes in Kamchatka

The geochemical features of volcanic soils (Andosols) in the northern soil province of Kamchatka are identified. The background regional concentrations (Cb_r) of most of chemical elements in the studied soils are lower than their average concentrations in soils of the world and in the European volcanic soils. Only Na, Ca, and Mg are present in elevated concentrations in all the studied soils in the north of Kamchatka. Regional background concentrations of elements are exceeded by 1.6 times in the area of active ashfalls of the Tolbachik volcano and by 1.3 times in the area of active ashfalls of the Shiveluch volcano. The concentrations of mobile forms of elements in these areas exceed their regional background concentrations by 2.1 and 2.6 times, respectively.     

Soil formation on acid and basic volcanic ashes of different ages in Kamchatka

The use of tephrochronological data on the ages of volcanic eruptions and the corresponding ash layers buried in the profiles of forest soils in Kamchatka makes it possible to distinguish between two groups of volcanic soils related to different stages of the volcanic activity. In the Holocene, the southern group of volcanoes was characterized by the ejection of acid pyroclasts typical of the mature stage of volcanism (the stage of caldera formation). The northern group of volcanoes ejected basic pyroclasts typical of the early (basaltic) stage of volcanism. Thus, the effect of the full cycle of volcanism on the soil formation can be traced in the soil profiles. It is shown that soil formation in volcanic areas depends on the frequency and intensity of ash falls and on the composition of the pyroclastic material.     

Regional clarkes of chemical elements in soils of southern European Russia

Distribution patterns of 19 elements in soils of the southern part of European Russian were estimated on the basis of the analysis of more than 9000 soil samples; regional clarkes of the elements were compared with their global clarkes, The obtained data attest to the fact that southern Russia is characterized by increased concentrations of most of the microelements with a tendency for their rise in the recent decades. The great role of the aerial migration and deposition of elements results in the enrichment of the soils with technophilic elements, so that the geochemical convergence of the soils is observed. It can be concluded that natural element abundances in soils are subjected to the technogenic transformation reflecting the high rate of contamination of the biosphere.     

Composition and pools of humus in natural and agrogenic soils of the Kamchatka Peninsula

Differentiation of Kamchatka soils with respect to the composition and pools of humus is discussed. Very low and low pools of humus of the fulvate type are typical of the ocherous and stratified ocherous volcanic soils of the eastern coastal zone and the Central Kamchatka Depression. Ocherous volcanic soils of the Western Kamchatka Lowland are characterized by the low and moderate pools of the humate–fulvate humus. Agrogenic soils are characterized by the higher pools of humus in the upper 20 cm in comparison with their natural analogues, which is largely related to changes in the physical properties of the soils under the impact of tillage.     

Mineralogical properties of andisols of the Kitakami mountain range,Northeastern Japan

We studied the mineralogical properties of Andisols of the Kitakami mountain range. Soils of the northern and central parts of the mountain range contained higher levels of acid oxalate extractable silicon (Si_o), aluminum (A1_o), and iron (Fe_o) but smaller amounts of sodium pyrophosphate-extractable aluminum (Al_p), iron (Fe_p), and carbon (C_p) than those of the southern part. Consequently, the soils of the northern and central parts of the mountain range contained large amounts of allophane and ferrihydrite whereas in the soils of the southern part A1 (Fe)-humus complexes and 2:1 and 2:1:1 clays predominated. The amount of sand (20-2,000 μm) in the soils tended to decrease sharply from the north to the south of the mountain range. The soils of the northern and central parts of the mountain range contained larger amounts of heavy minerals in their fine sand fraction (20-200 μm). The soils of the southern part, on the other hand, contained larger amounts of fine-grained quartz (2-20 μm). All the soils of the mountain range contained substantial amounts of volcanic glass in their sand fraction. However, on a total soil basis, the amount of volcanic glass in the soils decreased from the north to the south of the mountain range and the trend was parallel to that of the sand content of the soils. From these results, we concluded that (i) the soils of the northern and central parts of the mountain range were derived mainly from tephras and (ii) the soils of the southern part were strongly influenced by long-range eolian dust.     

Differential response of mineral-associated organic matter in tropical soils formed in volcanic ashes and marine Tertiary sediment to treatment with HCl,NaOCl, and Na4P2O7

Quantitative knowledge of the amount and stability of soil organic matter (SOM) is necessary to understand and predict the role of soils in the global carbon cycle. At present little is known about the influence of soil type on the storage and stability of SOM, especially in the tropics. We compared the amount of mineral-associated SOM resistant to different chemical treatments in soils of different parent material and mineralogical composition (volcanic ashes – dominated by short-range-order aluminosilicates and marine Tertiary sediments – dominated by smectite) in the humid tropics of Northwest Ecuador. Using ¹³C isotope analyses we traced the origin of soil organic carbon (SOC) in mineral-associated soil fractions resistant to treatment with HCl, NaOCl, and Na₄P₂O₇ under pasture (C₄) and secondary forest (C₃). Prior to chemical treatments, particulate organic matter was removed by density fractionation (cut-off: 1.6 g cm^?3). Our results show that: (1) independent of soil mineralogical composition, about 45% of mineral-associated SOC was resistant to acid hydrolysis, suggesting a comparable SOM composition for the investigated soils; (2) oxidation by NaOCl isolated a SOM fraction with enhanced stability of mineral-bound SOM in soils developed from volcanic ashes; while Na₄P₂O₇ extracted more SOC, indicating the importance of Al-humus complexes in these soils; and (3) recently incorporated SOM was not stabilized after land use change in soils developed from volcanic ashes but was partly stabilized in soils rich in smectites. Together these results show that the employed methods were not able to isolate a SOM fraction which is protected against microbial decay under field conditions and that the outcome of these methods is sensitive to soil type which makes interpretation challenging and generalisations to other soils types or climates impossible.     

Available potassium in volcanic soils of Kamchatka

The distribution of available potassium in the profiles of synlithogenic volcanic soils of Kamchatka has been studied. Most of the soils in the Central Kamchatka Depression and the Western Kamchatka Lowland are characterized by a medium content of nonexchangeable potassium and a high content of exchangeable potassium. The soils of the east coast are less rich in potassium. The reserves of available potassium in the root layer of the virgin and cultivated soils of Kamchatka have been calculated. It is shown that differences in the reserves of potassium are related to different degrees of the soil tolerance toward the depletion of potassium and to the uneven application of potassium fertilizers. In most cases, soil cultivation is accompanied by a general rise in the reserves of available potassium with an increase in the portion of exchangeable potassium relative to its nonexchangeable forms.     

Calculation and mapping of critical loads of s,n and acidity on ecosystems of the Northern Asia

On the basis of modified simple steady state mass-balance equations, the critical loads for nutrient and acidifying nitrogen as well as for sulphur and acidity have been calculated for various ecosystems of northern Asia using simplified expert-modelling GIS and grid cells 150×150 km. The minimal values of critical loads of nitrogen, CL(N), (<50eq a/yr)=" were=" shown=" for=" arctic=" and=" subarctic=" ecosystems=" and=" the=" maximal=" ones=" (=">300eq/ha/yr) for ecosystems of chernozemic and chernozem-like soils in southern Siberia and the Far East. The minimal values of critical loads of sulphur, CL(S), as well as acidity were shown predominantly in the northern part of east Siberia and in the Kamchatka peninsula and the maximal ones for ecosystems having neutral and alcaline soils. The corresponding exceedances were indicated for many regions of the northern part of Asia with maximal values for regions of Ural mountains, frontery of Kazakhstan, Altai, lower Yenisei river flow, Far East, Sakhalin and South-Kurilean islands.     

Heavy metals (copper,lead, nickel,and cadmium) in the organic part of gray forest soils in the Buryat Republic

The levels of the accumulation of copper, lead, nickel, and cadmium in the parent material-soil-plants-soil organic matter system are given for gray forest soils in the Buryat Republic. The concentrations of copper, lead, and nickel in the parent materials do not exceed the corresponding clarkes, and cadmium is present in trace amounts. The concentrations of copper and nickel in the humus horizon are lower than those in the parent material; an opposite situation is observed for lead. The concentrations of copper, lead, and nickel in the soil organic matter and in the herbaceous plants correspond to their contents in the soil and do not exceed the background (clarke) values. Cadmium was not detected in the aboveground part of the plants, though it was found in the root mass and in the organic soil horizon. In the humus of gray forest soils, these heavy metals are mainly present in the acid filtrate remaining after the precipitation of humic acids.     

Chemical and mineralogical studies of volcanic ashes

The relationships between rock types and mineralogical properties of volcanic ashes were investigated using many volcanic ash samples from different volcanoes.

The heavy mineral fraction was dominated by two pyroxenes and ferromagnetic minerals In almost all the felsic and Intermediate volcanic ashes. Therefore, It was difficult to determine the rock types of felsic and intermediate volcanic ashes according to their heavy mineral composition. It was assumed that the presence of a large quantity of hornblende was related to the origins of the volcanic ashes. On the other hand, the predominant mineral in the heavy mineral fraction of mafic volcanic ashes was volcanic glass (refractive index about 1.59), followed by olivine.

The refractive indices (γ) of plagioclases and orthopyroxenes were 1.553–1,570 and 1.703–1.715 in the felsic volcanic ashes, 1.558–1.580 and 1.705–1,715 in the intermediate ashes, and 1.565–1.576 and 1.697–1.705 in the mafic ashes, respectively. These results indicate the difficulty of determining the rock types of volcanic ashes according to the optical properties of these minerals.     

Dynamics of the soil cover in the southeast of Europe and in the southern Trans-Ural region during the subboreal period

An inventory of published data on the natural evolution of forest-steppe, steppe, and semidesert soils in the southern part of the East European Plain and in the southern Trans-Ural region during the Subboreal period of the Holocene has been performed. Schematic maps of the thickness of soil humus profiles and the depth of soil carbonates have been developed for the chronosections of 5000–4200, 4100–3900, and 3800–3200 years ago. On this basis, the areas with specific patterns of natural evolution of soils in the Subboreal period are delineated.     

Clay mineralogy of some volcanic ash soils in which cristobalite predominates

The clay mineralogical composition of soils on volcanic ashes from Mashū and Kamuinupuri-dake volcanoes, Hokkaido, which are rich in cristobalite, was determined using petrological, X-ray diffraction, differential thermal, and selective dissolution and differential infrared spectroscopic methods.

The cristobalite occurred in abundance in every size of fraction from coarse sand to clay and every soli from approximately 1,700 to 8,400 years old, and was concluded to be of igneous origin. The major clay minerals were allophanelike constituents and allophane with some layer silicates as the minor clay mineral, being similar to those of andesitic ash soils and different from those of volcanic ash soils containing abundant quartz. The quartz of volcanic ashes was presumed to bederived from the groundmass-equivalent portion of the ashes which had been formed from magma at a low temperature.     

Specific features of the morphology of volcanic soils in the altitudinal zones of Kamchatka

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.     

Soil organic carbon in density fractions of tropical soils under forest – pasture – secondary forest land use changes

Our knowledge of effects of land use changes and soil types on the storage and stability of different soil organic carbon (SOC) fractions in the tropics is limited. We analysed the effect of land use (natural forest, pasture, secondary forest) on SOC storage (depth 0–0.1 m) in density fractions of soils developed on marine Tertiary sediments and on volcanic ashes in the humid tropics of northwest Ecuador. The origin of organic carbon stored in free light (< 1.6 g cm^?3) fractions, and in two light fractions (LF) occluded within aggregates of different stability, was determined by means of δ¹³C natural abundance. Light occluded organic matter was isolated in a first step after aggregate disruption by shaking aggregates with glass pearls (occluded I LF) and in a subsequent step by manual destruction of the most stable microaggregates that survived the first step (occluded II LF). SOC storage in LFs was greater in volcanic ash soils (7.6 ± 0.6 Mg C ha^?1) than in sedimentary soils (4.3 ± 0.3 Mg C ha^?1). The contribution of the LFs to SOC storage was greater in natural forest (19.2 ± 1.2%) and secondary forest (16.6 ± 1.0%) than in pasture soils (12.8 ± 1.0%), independent of soil parent material. The amount of SOC stored in the occluded I LF material increased with increasing silt + clay content (sedimentary soils, r = 0.73; volcanic ash soils, r = 0.58) and aggregation (sedimentary soils, r = 0.52; volcanic ash soils, r = 0.45). SOC associated with occluded I LF, had the smallest proportion of new, pasture‐derived carbon, indicating the stabilizing effect of aggregation. Fast turnover of the occluded II LF material, which was separated from highly stable microaggregates, strongly suggested that this fraction is important in the initial process of aggregate formation. No pasture‐derived carbon could be detected in any density fractions of volcanic ash soils under secondary forest, indicating fast turnover of these fractions in tropical volcanic ash soils.     

The soil cover of Central Kamchatka (GIS model)

The spatial distribution of major soil horizons and layers of pyroclastic deposits in Kamchatka was analyzed with the use of GIS technologies. For this purpose, the attribute soil database and the computer-supported cartographic database were developed. Their analysis with the help of GIS technologies made it possible to study the dependence of the morphology of soil profiles on the bioclimatic conditions and on the stratification of ash layers in the particular areas of Kamchatka and to develop the cartographic model of the areas of soil horizons. The concept of tephra stratotypes—the particular combinations of ash layers in the profiles of volcanic soils—was verified on the basis of factual materials. It was shown that tephra stratotypes affect many important soil properties and specify the direction of soil formation in Kamchatka. Several major tephra stratotypes differing in their morphology and environmentally important features were distinguished in Central Kamchatka. The method of soil mapping on the basis of the concept of tephra stratotypes with due account for the specificity of surface organic horizons of soils was developed. It is argued that this method makes it possible to reflect the specificity of soil formation in volcanic regions.     

Classification of anthrosols with vitric/andic properties derived from lignite ash

To test the applicability of the Soil Reference Base of Soil Resources (ISSS/ISRIC/FAO, 1998. World Reference Base for Soil Resources, World Soil Resources Report 84, FAO, Rome) for soils derived from anthropogenic substrates, soils developed on lignite ashes in Germany which have some similarities with andosols were compared with natural volcanic soils from different countries. Soil parameters used for comparison were bulk density, clay content, Al_o+0.5 Fe_o, and P-retention, as they serve as diagnostic criteria to define either vitric or andic horizons. For Al_o+0.5 Fe_o, and P-retention, there was no statistically significant difference between both soil groups, the bulk densities of the lignite ash-derived soils were even significantly lower than those of the natural volcanic soils. Moreover, pH, total organic carbon, cation exchange capacity as well as the contents of carbonates and gypsum were collated and differences emerged between both soil groups concerning the contents of carbonates, gypsum and total organic carbon. In case of the lignite ash-derived soils, these parameters as well as the contents of oxalate soluble oxides were strongly influenced by the composition of the anthropogenic parent material. Up to now, such soil materials are not included as soil-forming materials in the World Reference Base for Soil Resources. We therefore suggested the introduction of a new diagnostic soil material, the so-called technogenic soil material into the anthropogeomorphic soil materials and to introduce “technogenic anthrosols” as a new reference subunit. In our proposition, technogenic materials are defined as anthropogeomorphic materials which are formed by technical processes including a distinct degree of transformation and/or new formation of soil-forming materials. Soil materials are categorised as “technogenic” when they consist of more than 70% (by volume) of soil material derived from technical processes like, e.g. combustion products of fossil energy sources, sewage sludges, blast furnace slags, etc.To include as much information as possible into the name of a soil, we developed a concept of reference soil series for the WRB combining pedogenetic and lithogenic information. Within this concept, these soils should be considered to be a subunit of anthrosols (vitri- or andi-technogenic anthrosols) and the specific properties of the soil-forming material (coaly, calcaric, gypsiric) should be given as additional information as Reference Soil Series as well as texture and kind of parent material.     

Mesophilic and thermotolerant actinomycetes in strongly heated soils

Mesophilic and thermotolerant actinomycetes were identified in strongly heated desert-steppe soils of Mongolia, mountainous meadow soils of the Central Caucasus, and cyanobacterial films on volcanic ash near hot springs of Kamchatka. Thermotolerant actinomycetes in these soil objects were more abundant and had a greater taxonomic diversity in comparison with mesophilic actinomycetes. Thermotolerant Streptomyces were present in all the objects, except for sample 117 from the desert-steppe soil and the cyanobacterial film on volcanic ash. Thermotolerant actinomycetes from the Micromonospora and Actinomadura genera predominated in the desert-steppe soil; representatives of the Micromonospora genus predominated in the cyanobacterial film on volcanic ash, and representatives of the Microtetraspora genus predominated in the samples of geyserite near hot springs of Kamchatka.     

Seasonal Trend of Potentially Toxic Trace Elements in Soils Supporting Medicinal Plants in the Eastern Region of Ghana

Investigation was conducted into the occurrence and extent of potentially toxic heavy metals and/or trace elements in soils from three study areas in the Eastern Region of Ghana namely Abonse, Pepease and Mamfe. A protocol for soil sampling, preparation and analysis was developed to yield sufficient information on elemental concentrations in the soils. The soil samples were analysed for As, Co, Cr, Cu, Sb, Th, U, V and Zn, using Instrumental Neutron Activation Analysis (INAA) coupled with conventional counting system. Concentrations of Co, Cr, Th and Zn positively correlate with As, and regressions performed on Co-Zn, Co-Cr, Co-Th, Cr-Th and Zn-Cr values also show strong correlations. The regressions suggest that these elements are geochemically associated and might be enriched simultaneously. Though there are relatively high concentrations of Cu (maximum; 46.3 mg/kg), Co (maximum; 9.17 mg/kg), Th (maximum; 15.1 mg/kg) and U (maximum; 2.38 mg/kg) in some of the soils compared with their levels in world average soils, the average concentrations of the trace elements in general are below or within levels in world average soils/uncontaminated soils. Also, the enrichment index computed in the soils indicates that all the study areas are not enriched with toxic elements, particularly As, Cu, Sb and Zn, and the enrichment index values decrease in the order of Pepease > Mamfe > Abonse. When the average composition of the soils was normalized to the average composition of the underlying rocks, the soils were depleted in the trace elements determined, indicative of background concentration values. Lack of correlations between soil characteristics such as texture, organic carbon, organic matter, total nitrogen and available phosphorous, and most of the trace elements suggests that the influence of these parameters on the distribution of the trace elements is not important in the surface soils.     

Is the Walkley–Black Method Suitable for Organic Carbon Determination in Chilean Volcanic Soils?

Although dry combustion (DC) carbon dioxide (CO₂) is an accurate method to measure total soil carbon (C), it is a rather expensive one. Therefore, wet oxidation by the Walkley–Black (WB) method is widely used in acidic Chilean volcanic soils, although there are no studies comparing both WB and DC. The aim of this article was to compare DC and WB in a range of volcanic soils containing between 2% and 9% of soil C on a regional scale. Results indicated that the recovery (R) of soil C by WB with respect to DC varied between 70% and 82%. Consequently, the correction factor (100 / R) ranged between 1.26 and 1.47. The standardized major axis regression analysis indicated that the slope and the intercept of the fitted line on volcanic soils were similar to 1:1 line. In conclusion, WB was an economically suitable method to determine the soil C content of Chilean volcanic soils.