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991.
A. M. Prokashev E. S. Soboleva A. S. Imenitova I. A. Vartan A. S. Matushkin N. D. Okhorzin S. L. Mokrushin I. L. Borodatyi 《Eurasian Soil Science》2018,51(7):758-771
Data on soddy-podzolic soils with the second humus horizon in the southwestern part of Kirov oblast are discussed. These soils were first studied by the authors on mantle calcareous loams of the Yarano- Kokshagskaya Plain in the eastern part of the Central Russian southern-taiga province of medium-humus soddy-podzolic soils of European Russia. The aim of this study is to reconstruct the history of the development of soil properties and soil cover in automorphic landscapes of this region. Morphology, substantive properties of mineral and organic components, soil genesis and evolution are analyzed using a set of physical, chemical, physicochemical, biochemical, and geochronological methods. The results of our study attest to the relict character of second the humus horizon and polygenetic nature of the studied soils. These soils have passed through two essentially different evolutionary stages in the Holocene: the accumulative stage in the first half of the Holocene and the accumulative-eluvial stage of erasing evolution with preservation of some inherited features in the second half of the Holocene. According to their properties, the studied soils are analogous to the earlier studied southern-taiga Vyatka–Kama province of high-humus soddy-podzolic soils of the northeast. At present, plowing of these soils leads to a partial or complete destruction of the second humus horizon; thus, spontaneous degradation processes are complemented by the human-induced soil degradation. A tendency for a gradual disappearance of these soils from the soil cover under the influence of natural and anthropogenic factors has been noted. The materials presented in this paper may be useful for organization of specially protected soil areas in the southwestern part of the Vyatka River basin. 相似文献
992.
993.
Atmospheric deposition in India is generally described as alkaline and well buffered against an increase of acidifying components. Such conclusion has been based on measurements usually performed in urban or suburban areas. Our data on deposition in NE India (in the countryside N of Bhubaneswar) obtained with wet-only and bulk collectors show that: 1) the weighted mean concentrations (and wet deposition) of H+ and HCO3 ? are almost equal, with dustfall contributing a negligible amount of HCO3 ?, 2) the deposition of potential acidity, defined as the acidity that would give the same acidity contribution to the receiving surface as the actual deposition provided that all ammonium was converted to nitrate in the soil, could be as high as 40 mmol H+ m?2 a?1 corresponding to a pH of 4.3 in precipitation. The low buffer capacity against acidification and high potential acidity were discovered from long- term measurements in a vegetation covered rural area. Similar measurements in a nearby suburban area gave a much higher input of HCO3 ? both in wet deposition and dustfall. Further increase of the emission of acidifying components in the region will increase the acid deposition. 相似文献
994.
F. Batič P. Kalan H. Kraigher H. Šircelj P. Simončič N. Vidergar-Gorjup B. Turk 《Water, air, and soil pollution》1999,116(1-2):377-382
Determination of the stresses operating on a forest ecosystem demands the use of several bioindication methods. Air quality indicators were assessed from an inventory of forest decline based on the assessment of tree crowns and epiphytic lichens. Photosynthetic pigments, ascorbic acid and major macronutrients were studied in Norway spruce needles as indicators of physiological and biochemical stress. Analyses were carried out on selected forest plots in polluted areas (Zasavje district, vicinity of thermal power plants) and predominantly unpolluted areas (Triglav National Park, Julian Alps, Slovenia). For some bioindication methods, there was good agreement with measured air quality and climatological parameters. The best agreement was found between total foliar sulphur in needles and epiphytic lichens, especially in more polluted areas. Agreement with forest decline inventories and analyses of some needle stress physiological/biochemical parameters was less convincing. The strength of agreement was further decreased by soil characteristics and climatic parameters, influenced also by biotic parameters and forest stand history and management. It was concluded that there is no simple bioindication method available to evaluate the vitality of a forest. 相似文献
995.
The fragmentation behavior of all six dicaffeoylquinic acids (diCQA) has been investigated using LC-MS(4). It is possible to discriminate between each of the isomers including those for which commercial standards are not available. For diCQA, the ease of removal of the caffeoyl residue during fragmentation is 1 approximately = 5 > 3 > 4. The distinctive fragmentation observed for the little-studied 1,4-dicaffeoylquinic acid involves elimination of the C1 caffeoyl residue, repeated dehydrations leading to the aromatization of the quinic acid moiety, and its decarboxylation. It is suggested that this process is initiated by the C1 carboxyl protonating the C5 hydroxyl in the inverted chair conformer, followed by its protonating the C1 caffeoyl residue in the favored chair conformation. The fragmentation of 1-caffeoylquinic acid is indistinguishable from that of the commercially available 5-caffeoylquinic acid, but these two isomers can be distinguished easily by their facile chromatographic resolution on reversed phase packings. The hierarchical key previously developed for characterizing chlorogenic acids has been extended to accommodate 1-caffeoylquinic acid and the 1-acyl dicaffeoylquinic acids. 相似文献
996.
R. C. Abaidoo K. E. Dashiell N. Sanginga H. H. Keyser P. W. Singleton 《Biology and Fertility of Soils》1999,30(3):187-192
Soybean cultivars capable of nodulating with indigenous Bradyrhizobium spp. have been developed by the International Institute of Tropical Agriculture (IITA) and national programs in Africa in
order to avoid artificial inoculation by resource-poor farmers in Africa. The current selection procedure for enhanced N2 fixation is based on an assessment of nodule formation which does not directly quantify the proportions of crop N derived
from the atmosphere. We have monitored N accumulation patterns and N2 fixation in nine promiscuous soybean cultivars with different maturity periods, using the 15N dilution technique. Nodule development generally peaked at the early podfill stage for all cultivars except Tgx 1519-1D
and Tgx 1447-2D in which it continued to increase. The proportion of crop N derived from fixation (%NDFA) ranged between 51%
and 67%, 77% and 84%, and 66% and 73% at full bloom, early podfill, and physiological maturity stages, respectively. Total
N accumulation increased in all soybean genotypes with increasing plant age. Significant correlations (P<0.001) were established between nodule weight and %NDFA, even though this did not explain the relationship between nodule
development and N2 fixation in cultivars such as Tgx 1519-1D. Promiscuous soybean cultivars retained between 10% and 19% of total N accumulated
at the final harvest, in belowground biomass. Our results indicated that these soybean cultivars can derive substantial proportions
of plant N from N2 fixation in soils where compatible indigenous bradyrhizobia populations are adequate and effective. Also, we have substantiated
the claims that qualitative nodulation parameters currently used to select varieties with a high N2 fixation capacity need to be validated with other measurements of N2 fixation.
Received: 5 November 1998 相似文献
997.
Mandzhieva Saglara S. Minkina Tatiana M. Chaplygin Victor A. Motuzova Galina V. Sushkova Svetlana N. Bauer Tatiana V. Nevidomskaya Dina G. 《Journal of Soils and Sediments》2016,16(4):1383-1391
Journal of Soils and Sediments - The aim of this study is the assessment of Ni, Mn, Cd, Cu, Pb, Cr and Zn accumulation by different herbaceous species and soils on the technogenic areas around... 相似文献
998.
999.
1000.
Nitrous oxide (N2O) contributes to greenhouse effect; however, little information on the consequences of different moisture levels on N2O/(N2O+N2) ratio is available. The aim of this work was to analyze the influence of different soil moisture values and thus of redox
conditions on absolute and relative emissions of N2O and N2 at intact soil cores from a Vertic Argiudoll. For this reason, the effect of water-filled porosity space (WFPS) values of
soil cores of 40, 80,100, and 120% (the last one with a 2-cm surface water layer) was investigated. The greatest N2O emission occurred at 80% WFPS treatment where conditions were not reductive enough to allow the complete reduction to N2. The N2O/(N2O+N2) ratio was lowest (0–0.051) under 120% WFPS and increased with decreasing soil moisture content. N2O/(N2O+N2) ratio values significantly correlated with soil Eh; redox conditions seemed to control the proportion of N gases emitted
as N2O. N2O emissions did not correlate satisfactorily with N2O/(N2O+N2) ratio values, whereas they were significantly explained by the amount of total N2O+N2 emissions. 相似文献