Characterization of relict Late Pleistocene and Early Holocene paleosols buried in wedge-shaped structures on the southern coast of the Finnish Gulf     

A. V. Rusakov  A. A. Nikonov 《Eurasian Soil Science》2010,43(7):737-747

The physical and physicochemical properties and morphogenetic characteristics of the buried soddy gleyic and gleyed paleosols developed from the glaciolacustrine loamy sediments on the southern coast of the Finnish Gulf in the Late Pleistocene and Early Holocene (12–9 ka, calibrated) are considered. It is shown that the morphology and properties of these paleosols sharply differ from those of the enclosing gravelly sands deposited in the ancient basins. The latter substrates serve as the major type of soil-forming materials for the modern surface soils. The studied paleosols fill wedge-shaped structures dissecting the gravelly sediments. Their profiles are well preserved, though their normal horizontal orientation is disturbed; large soil blocks were displaced into the open wedges. The presence of these soils attests to the fact that the initial soil cover in the studied region was formed in the Late Glacial epoch soon after the retreat of the glacial sheet. The good degree of preservation of the paleopedogenic information recorded in the profiles of these paleosols is of great value for the paleoenvironmental reconstructions.  相似文献   

Alternative methods in the development of pedotransfer functions for soil hydraulic characteristics     

H. Merdun 《Eurasian Soil Science》2010,43(1):62-71

Soil hydraulic properties are needed in the modeling of water flow and solute movement in the vadose zone. Pedotransfer functions (PTFs) have received the attention of many researchers for indirect determination of hydraulic properties from basic soil properties as an alternative to direct measurement. The objective of this study was to compare the performance of cascade forward network (CFN), multiple-linear regression (MLR), and seemingly unrelated regression (SUR) methods using prediction capabilities of point and parametric PTFs developed by these methods. The point PTFs estimated field capacity (FC), permanent wilting point (PWP), available water capacity (AWC), and saturated hydraulic conductivity (Ks) and the parametric PTFs estimated the van Genuchten retention parameters. A total of 180 soil samples was extracted from the UNSODA database and divided into two groups as 135 for the development and 45 for the validation of the PTFs. The model performances were evaluated with three statistical tools: the maximum error (ME), the model efficiency (EF), and the D index (D) using the observed and predicted values of a given parameter. Despite the fact that the differences among the three methods in prediction accuracies of the point and parametric PTFs were not statistically significant (p > 0.05) except θ_r and α (p < 0.05) based on the ANOVA test, overall MLR and SUR were somewhat better than CFN in prediction of the point PTFs, whereas CFN performed better than the other two methods in prediction of the parametric PTFs. The F.F values of FC and θ_r for CFN, MLR, and SUR methods were 0.705. 0.805, 0.795 and 0.356, −0.290, −0.290, respectively, which refer to the best and worst predictions. Properties (Ks, θ_r, α) having some difficulty in prediction were better predicted by CFN and SUR methods, where these methods predict all hydraulic properties from basic soil properties simultaneously rather than individually as in MLR. This suggests that multivariate analysis using such functional relationships between hydraulic properties and basic soil properties can be utilized in developing more accurate point and parametric PTFs with less time and effort.  相似文献   

Water stability of aggregates in subtropical and tropical soils (Georgia and China) and its relationships with the mineralogy and chemical properties     

T. V. Alekseeva  Z. Sokolowska  M. Hajnos  A. O. Alekseev  P. I. Kalinin 《Eurasian Soil Science》2009,42(4):415-425

Water-stable aggregates isolated from three subtropical and one tropical soil (Western Georgia and China) were studied for their organic carbon, cation exchange capacity (CEC), specific surface area, magnetic susceptibility, and total chemical elements. The soils were also studied for their particle-size distribution, mineralogy, and nonsilicate Fe and Al oxides. Describe the water stability, three indices have been used: the content of water-stable macroaggregates (>0.25 mm), the mean weighted diameter of the aggregates, and the numerical aggregation index. The yellow-cinnamonic soil (China) was neutral, and the three other soils were acid. The soils were degraded with a low content of organic matter. The yellow-cinnamonic soil was characterized by the lowest water stability due to the predominantly vermiculite composition of the clay. The high water stability of the Oxisol structure was determined by the kaolinites and high content of oxides. In three out of the four soils studied, the hierarchical levels of the soil structure organization were defined; they were identified by the content of organic matter and the Ca + Mg (in Oxisols). Iron oxides mainly participated in the formation of micro-aggregates; Al and Mn contributed to the formation of macroaggregates. The water-stable aggregates acted as sorption geochemical barriers and accumulated Pb, Zn, Cd, Cs, and other trace elements up to concentrations exceeding their levels in the soil by 5 times and more. The highest correlations were obtained with CEC, Mn, and P rather than with organic carbon and Fe.  相似文献   

Heavy metal pollution of urban soils   总被引：1，自引：0，他引：1  

O. V. Plyaskina  D. V. Ladonin 《Eurasian Soil Science》2009,42(7):816-823

The chemical properties of urban soils (southeastern administrative district, Moscow) affecting the behavior of heavy metals were studied. The current heavy metal pollution level of the soils was assessed. The use of different approaches for the pollution standardization is shown to produce different results. The fractional composition of the metal compounds in the soils and the factors affecting its formation under technogenic pollution were investigated. In the district studied, the distribution of heavy metals by the fractions primarily depended on the chemical properties of the heavy metals themselves; the pollution level; and, to a lesser degree, on the soil properties. Zinc and cadmium were the most mobile metals in the soils studied.  相似文献   

Nomenclature and genetic relationships of apples and pears from Terceira Island     

Nahla Bassil  Kim E. Hummer  Joseph D. Postman  Gennaro Fazio  Angela Baldo  Isabel Armas  Roger Williams 《Genetic Resources and Crop Evolution》2009,56(3):339-352

Heritage apple (Malus domestica Borkh. hybrids) and pear (Pyrus communis L. hybrid) trees grow in villages throughout Terceira Island, Azores, Portugal. Some of these pears have different names but similar morphology. The objective of this study was to determine synonymy, homology, and phylogeny of apples and pears from Terceira and to examine potential relationships of the island pears with standard apples and pears of Portuguese or American descent. Nine apple microsatellite markers were used to determine genetic relationships. Distance- and parsimony-based cluster analysis grouped these genotypes into separate apple and pear clades. The Terceira apples were divided into two clades: the maçā and the reineta-reinette. Among the 17 heritage apple genotypes, seven unique accessions were identified and four groups of synonyms, or possibly clones, were detected including: ‘Reineta Agosto’ and ‘Reineta Verde’ from Altares; ‘Reineta Castanha’ and ‘Reineta Verde Miuda’; ‘Maçā Pêra,’ ‘Maçā Calhau’, ‘Pêro Branco’ from Salga and from Terra-Chā and ‘Maçā Marmelo’; and the five genotypes ‘Maçā Sao Joao’, ‘Malápio Rosa’, ‘Maçā Gaspar’, ‘Maçā Branca’ and ‘Maçā Pato’. In addition, two homonyms were detected. ‘Pêro Vermelho’ from Terra Chā was a separate genotype from a tree from Doze Ribeiras of the same name, but Pêro Branco from Terra Chā appears to be a clone that can be distinguished by an additional allele at CH1F07a from a tree with that name from Salga. One pair of apple clones, ‘Reineta Agosto’ and ‘Reineta Verde’ from Altares appear to be derived from an unreduced gamete of ‘Golden Delicious.’ Another apple genotype ‘Maçā Acida’ could be a sibling of the ‘Maçā Pêra’ clonal group. Other tested standard apples from the US genebank were unrelated to Terceira genotypes. Of the seven heritage pears, five unique genotypes and one pair of synonyms were detected. ‘Pêra Papo Pintassilgo’ from Raminho and ‘Pêra Vermelha’ from the nursery of Serviço de Desenvolvimento Agario da Terceira (SDAT) were synonyms. ‘Passans du Portugal’ was related to ‘Pêra Cabaca’ but other standard pears from the US genebank were unrelated to Terceira genotypes. Future studies will include additional apple and pear cultivars from other Islands of the Azores and continental Portugal, and wild Asian species to further explore genetic relationships.  相似文献   

The effect of low-molecular-weight organic acids and inorganic phosphorus concentration on the determination of soil phosphorus by the molybdenum blue reaction   总被引：1，自引：0，他引：1  

L. L. Wei  C. R. Chen  Z. H. Xu 《Biology and Fertility of Soils》2009,45(7):775-779

Low-molecular-weight organic acids play an important role in the mobilization of soil phosphorus (P). The molybdate blue colorimetric method, based on the formation of P molybdenum blue compound, is commonly used for analysis of phosphate in soil and environmental samples. However, some organic acids can act as a ligand to bond with molybdenum acid, which subsequently interfere with the colorimetric reaction. The recoveries of P were inhibited by the addition of oxalic (>2 mM) and citric acids (>3 mM) both in standard P solutions and soil extracts, but formic and maleic acids did not interfere with the P determination. The inhibition of oxalic and citric acids on P recovery remained even at higher level of P (up to 100 μg P 100 ml⁻¹) though such interferences decreased by increasing P concentration. Comparison between oxalic and citric acids revealed the more pronounced interference by the addition of oxalic acid. The results suggested that the interference of organic acids with P determination is related to the types of organic acids and the ratio of organic acid ligands to P anions in the solutions. Thus, analysis of P using the molybdate blue colorimetric method should be undertaken cautiously in the presence of relative strong ligands like oxalic and citric acids.  相似文献   

Salinity and sodicity effects on respiration and microbial biomass of soil   总被引：2，自引：2，他引：2  

Vanessa N. L. Wong  Richard S. B. Greene 《Biology and Fertility of Soils》2008,44(7):943-953

An understanding of the effects of salinity and sodicity on soil carbon (C) stocks and fluxes is critical in environmental management, as the areal extents of salinity and sodicity are predicted to increase. The effects of salinity and sodicity on the soil microbial biomass (SMB) and soil respiration were assessed over 12weeks under controlled conditions by subjecting disturbed soil samples from a vegetated soil profile to leaching with one of six salt solutions; a combination of low-salinity (0.5dSm⁻¹), mid-salinity (10dSm⁻¹), or high-salinity (30dSm⁻¹), with either low-sodicity (sodium adsorption ratio, SAR, 1), or high-sodicity (SAR 30) to give six treatments: control (low-salinity low-sodicity); low-salinity high-sodicity; mid-salinity low-sodicity; mid-salinity high-sodicity; high-salinity low-sodicity; and high-salinity high-sodicity. Soil respiration rate was highest (56–80mg CO₂-C kg⁻¹ soil) in the low-salinity treatments and lowest (1–5mg CO₂-C kg⁻¹ soil) in the mid-salinity treatments, while the SMB was highest in the high-salinity treatments (459–565mg kg⁻¹ soil) and lowest in the low-salinity treatments (158–172mg kg⁻¹ soil). This was attributed to increased substrate availability with high salt concentrations through either increased dispersion of soil aggregates or dissolution or hydrolysis of soil organic matter, which may offset some of the stresses placed on the microbial population from high salt concentrations. The apparent disparity in trends in respiration and the SMB may be due to an induced shift in the microbial population, from one dominated by more active microorganisms to one dominated by less active microorganisms.  相似文献   

Changes in the pore space of soil constructions in physical laboratory models     

E. V. Shein  E. A. Torbik  K. N. Abrosimov 《Moscow University Soil Science Bulletin》2017,72(1):31-34

The dynamics of pore space structure in different filled soil constructions during water infiltration and wetting–drying processes is studied. Model laboratory experiments in columns physically simulate water infiltration after penetration at a rate of 600 mm with free outflow from the lower end of the column followed by multiple drying of soil constructions composed by alternating layers of sand, peat, and A and В horizons of soddy-podzolic soil. In two- and three-dimensional tomographic images, changes in the pore space and the interpenetration of solid phase at the boundaries between individual horizons of soil constructions are analyzed.  相似文献   

Patterns of SSR variation in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) seeds under ex situ genebank storage and accelerated ageing     

Yong-Bi Fu  Mo-Hua Yang  Carolee Horbach  Dallas Kessler  Axel Diederichsen  Frank M. You  Hong Wang 《Genetic Resources and Crop Evolution》2017,64(2):277-290

Maintaining seed viability and germplasm integrity is a challenging task in conservation of plant genetic resources, as seeds under storage will lose viability and genetic changes will occur. Attempt was made to analyze the patterns of genetic changes in wheat germplasm under ex situ genebank storage and accelerated ageing treatments. A set of 16 naturally aged wheat accessions under ex situ genebank storage since 1994 were sampled. Four recently regenerated wheat accessions were selected, four random seed samples were chosen from each accession, and three of them were exposed to three different accelerated ageing treatments. These 32 seed samples in two germplasm sets displayed a range of germination rates from 4 to 98 %. Thirty-seven microsatellite markers representing 21 wheat chromosomes were applied to screen 12 seeds of each sample and 449 SSR alleles were scored. Large SSR variation was found in each germplasm set. There was 73.1 % of the total SSR variation present among the naturally aged samples and 78.2 % present among the accelerated ageing samples. Several analyses for genetic association consistently revealed no clear genetic separations among samples of high or low germination rates in both germplasm sets. Samples under different accelerated ageing treatments did not show much genetic differentiations from the original sample of each accession. Mantel tests revealed non-significant associations between SSR variability and sample germination rates for both germplasm sets. These findings are useful for understanding seed deterioration under different ageing conditions and suggest that genome-wide SSR variability may not provide sensitive markers for the monitoring of wheat seed viability.  相似文献   

A Greener UV and Peroxide-Based Chemical Oxygen Demand Test     

Patricia Carbajal-Palacios  Patricia Balderas-Hernández  Gabriela Roa-Morales  Jorge G. Ibanez 《Water, air, and soil pollution》2017,228(8):313

Water quality assessment typically includes the determination of chemical oxygen demand (COD) by oxidation of organic matter with Cr(VI) in an acidic medium followed by digestion. Unfortunately, the required reagents are harmful and the reaction times are rather long. We investigated earlier the use of H₂O₂ as a more environmentally friendly oxidizing agent to replace the hazardous chromates. In the present study, we have furthered this possibility by incorporating the use of H₂O₂ in the presence of UV light. A protocol has been devised and tested with standards and real samples that replaces toxic Cr(VI), halves the amount of silver sulfate required, and greatly reduces the necessary reaction time, thus yielding a faster and more environmentally sound method.  相似文献