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N. P. Chizhikova S. E. Sirotskii G. V. Kharitonova A. S. Manucharov N. S. Konovalova E. V. Utkina 《Eurasian Soil Science》2011,44(7):781-793
The mineralogy and chemistry of the fine fractions separated from the bottom sediments (aquasols) in the Amur River were studied
in the subfractions of the fractional peptization differing in the binding strength between the water-peptized and aggregated
components. Detritus of quartz, field spars, and strongly degraded layered silicates mainly passes into the water-peptized
state. Interstratified layered silicates with different combinations of chlorite and mica layers prevail in the aggregate
subfraction. The distribution of the microelements in the bottom sediments, the water-peptized and aggregated clays, and the
residues after their separation was determined. The content of iron, manganese, zinc, and copper in the clay subfractions
was higher than in the bottom sediments and in the residue after the separation of the clay subfractions by 2–4 times, which
confirmed the functional significance of the clay minerals. The presence of diatomic algae in the components of the bottom
sediments was revealed by scanning electron microscopy. The contribution of the diatoms to the accumulation of iron, manganese,
zinc, and copper was shown. 相似文献
3.
W.G. Wielemaker 《Geoderma》1984,32(1):9-20
Effects of different quantities of Si on hydroxyl-release (at constant and freely drifting pH) were measured in samples from soils in volcanic ash in Kenya and in mixtures of pure Al- and Si-oxides after additions of NaF. In addition pHo and PZNC determinations were done.Low pHNaF values in soils are partly due to extractable Si, as follows from the correlation between the depression in pHNaF and the extractable Si content. The effect is due to the variable charges of the siliceous clay components, which also depress the level of pHo even if the extractable iron content is high. The relation between ionretention and pH shows that the siliceous soils from volcanic ash have variable charge and very low AEC's. 相似文献
4.
Hans Løkke 《Water, air, and soil pollution》1984,22(4):373-387
The use of the heat pumps connected to ground coils wins widespread interest in the heating of buildings, but in cases of leakage it may involve a risk of ground water pollution caused by anti-freeze mixture components. The adsorption of individual components, such as ethylene glycol, ethanol, methanol, and benzoic acid onto different soil types was studied at 6 °C by use of a batch procedure. No adsorption (or only slight) was observed for any of the test compounds onto samples of subhorizons of sandy till, clayey till, and melt water sand. Leaching experiments with undisturbed soil cores of sandy till showed that 14C-labelled ethylene glycol or ethanol closely followed the movement of water when cloride was used as a tracer. The percolation experiments were conducted during 79 to 154 day periods at 10 °C and under anaerobic conditions. Darcy velocities varied between 1 and 3 mm day?1. About 100% of the added amounts of 14C were recovered in the effluents, although only 74 to 77% of ethylene glycol and 84 to 89% of ethanol were determined as the parent compounds by gas chromatography. Experiments on leaching of ethanol under controlled oxygen supply showed that degradation took place dependent on oxygen availability. 相似文献
5.
A cell consisting of a chloride-selective electrode and a nitrate-selective electrode was directly put in the soil suspension to determine the concentration ratio NO3?/Cl? for studying the adsorption of these two ions by three soil samples from variable charge soils. It was found that such factors as the iron oxide content of the soil, the pH of the suspension, the concentration of the respective anion, the kind of accompanying cations, and the dielectric constant of solvent etc. can all affect the amounts and the ratio of the two anions adsorbed. The adsorption was chiefly caused by coulombic force, but another mechanism, presumably a covalent force between the anion and the metal atom on the surface of soil particles, may also be involved, at least for chloride ions. 相似文献
6.
Surface charge of mixtures of lepidocrocite and illite determined by adsorption of potential-determining and electrolyte ions is studied as a function of pH and NaCl concentration. Deviations between results obtained by both methods were a function of the illite content of the mixtures, and can be mainly attributed to coatings of hydroxyaluminium complexes on the constant charge surfaces of the clay mineral, which can react with H+ ions or release exchange sites by precipitation of well-formed hydroxides. These coatings of aluminium complexes can cause H+ consumptions similar to those due to lepidocrocite. Some ideas are put forward for modelling charge properties of mixed systems. 相似文献
7.
Summary Previous work in our laboratory indicated that the slow rate of denitrification in Iowa subsoils is not due to a lack of denitrifying microorganisms, but to a lack of organic C that can be utilized by these microorganisms for reduction of NO
3
–
. This conclusion was supported by studies showing that drainage water from tile drains under agricultural research plots contained only trace amounts of organic C and had very little, if any, effect on denitrification in subsoils. Aqueous extracts of surface soils promoted denitrification when added to subsoils, and their ability to do so increased with increase in their organic C content. Amendment of surface soils with corn and soybean residues initially led to a marked increase in the amounts of organic C in aqueous extracts of these soils and in the ability of these extracts to promote denitrification in subsoils, but these effects were short-lived and could not be detected after incubation of residue-treated soils for a few days. We conclude from these observations that water-soluble organic C derived from plant residues is decomposed so rapidly in surface soils that very little of this C is leached into subsoils, and that this largely accounts for the slow rate of denitrification of nitrate in subsoils. 相似文献
8.
The saturated hydraulic conductivity, Ksat, was measured on soil samples collected from the plough layer and the subsoil. A range of naturally occurring soil bulk densities was obtained by sampling in different years, with different crops and within and without wheel-tracks, etc. It was found that, for the plough layer, quite good linear relationships exist between the logarithm of Ksat and the bulk density. However, for the subsoils, the value of Ksat usually lies above the regression line for found for the corresponding plough layer. This “excess” hydraulic conductivity of subsoils is attributed to the presence of biopores, especially root channels. The lower hydraulic conductivity of the plough layer, relative to the subsoil, is attributed to the destruction of these biopores by tillage. A simple model for the separate contributions of soil texture and root channels to the overall value of Ksat is presented. It is concluded that subsoil tillage could cause significant reductions in Ksat with potentially serious environmental consequences unless it is repeated periodically. 相似文献
9.
《Communications in Soil Science and Plant Analysis》2012,43(11-12):2201-2214
Abstract Solubility and kinetic data indicated that concentrations of aluminum (Al) extracted with 1 M KCl are determined by the solubility of a precipitated A1(OH)3 phase in soils dominated by variable charge minerals. Kinetic studies examining the release of Al on non‐treated and KCl treated residues indicated the precipitation of an acid‐labile Al phase during the extraction procedure. The log ion activity products estimated for the KCl extracts ranged between 8.1–8.6 for the reaction Al(OH)3 + 3H+ < = > Al3++ 3H2O, which was similar to the solubility product of several Al(OH)3phases. The mechanism proposed for Al precipitation indicated that Al released by exchange with added K+ hydrolyzed and released H+ that was readily adsorbed on surfaces of variable charge minerals. The increased ionic strength of the extracting solution further increased the amount of H+adsorbed to the variable charge surface and reduced the H+ concentration in the aqueous phase. Consumption of H+ induced further hydrolysis of Al, resulting in supersaturation of the extracting solution and formation of polynuclear hydroxy Al species. It was concluded that the 1 M KCl extraction does not quantitatively extract salt exchangeable Al from variable‐charge soils. 相似文献
10.
Katsutoshi Sakurai Akinori Nakayama Tsutomu Watanabe Kazutake Kyuma 《Soil Science and Plant Nutrition》2013,59(4):623-633
Influence of Al dissolution on soil ZPC (zero point of charge) measured by a potentio-metric titration (PT) method and a modified salt titration (STPT) method was examined using two strongly weathered soils from Thailand and two volcanic ash soils from Japan. The amount of dissolved Al ions increased with the increase in the concentration of a supporting electrolyte for the strongly weathered soils, while the increase was negligible for the volcanic ash soils. ZPC value of the strongly weathered soils determined by the PT method was lower than that by the STPT method, due to the greater Al dissolution associated with the higher electrolyte concentration used in the PT method. Al ions adsorbed onto the soil surface would shift the ZPC to a higher pH value not as a result of the formation of hydroxy Al polymers, but due to the blocking of permanent negative charge sites, which could otherwise lower the ZPC. The σp value, as a measure of permanent charge or the amount of 11 or O11 adsorbed by a soil required to attain the ZPC, could be used to describe this phenomenon. In the STPT method, the salt concentration was not high enough to causc a significant Al dissolution at the ZPC, which is considered to be a more suitable condition than in the PT method because the ZPC value can be evaluated at a low salt concentration as in the ease of field conditions for crop production. Thus, the STPT method is rccommendcd for the determination of the ZPC. 相似文献
11.
Guannan Liu Juan Wang Wei Xue Jinbo Zhao Jing Wang Xinhui Liu 《Journal of Soils and Sediments》2017,17(12):2810-2821
Purpose
The size of soil particles strongly affects the accumulation and adsorption of heavy metals which partly controls the co-transport of heavy metals by soil colloids. However, the effect of the size of soil particles on the accumulation and adsorption of heavy metals in the colloidal dimension has seldom been studied. In this study, variable charge soils were selected and separated into five size fractions to elucidate the effect of the size of soil particles on Cd accumulation and adsorption.Materials and methods
Five soil particle size fractions (>10, 10–1, 1–0.45, 0.45–0.2 and <0.2 μm) were obtained from Cd-contaminated soil by natural sedimentation and fractional centrifugation. The concentrations and species of Cd were measured in various sized soil particles. Batch adsorption experiments of Cd on the obtained soil particles were conducted under different pH values and concentrations of NaCl.Results and discussion
Generally, the concentration of Cd increased with decreasing soil particle sizes, and the Cd proportion of exchangeable and carbonate fraction decreased from 43.84 to 17.75% with decreasing particle size. The soil particles with a size of 10–1 and <0.2 μm possessed a stronger adsorption ability than the other fractions in most cases. Moreover, the Cd adsorption capacities of the soil particles increased with increasing pH values and decreasing concentrations of NaCl, especially for soil particles containing more organic matter (OM) and variable charge minerals.Conclusions
Smaller soil particles are more capable of accumulating Cd and make Cd more stable. The adsorption capability of Cd is negatively related to the particle size and NaCl concentration and is positively related to the pH. The effects of the size of variable charge soil particles on Cd accumulation and adsorption are attributed to the differences in the physicochemical properties among various soil particle size fractions. This study contributes to the understanding of the co-transport of heavy metals in soil by soil colloids.12.
Sulfate adsorption by variable charge soils: Effect of low-molecular-weight organic acids 总被引:1,自引:0,他引:1
C. E. Martinez A. W. Kleinschmidt M. A. Tabatabai 《Biology and Fertility of Soils》1998,26(3):157-163
Sulfate (SO4
2–) movement and transport in soils has received considerable attention in recent years. In most soils, SO4
2– coexists with a variety of natural organic compounds, especially organic acids. Studies were conducted to assess the effect
of low-molecular-weight organic acids (eight aliphatic and five aromatic acids) on SO4
2– adsorption by variable charge soils from Chile and Costa Rica. The effects of type of organic acid, pH, type of soil, and
organic acid concentration were investigated. In one experiment, a 1.0 g soil sample was equilibrated with 25 ml 0, 0.5, 1.0,
2.0, 4.0, or 6.0 mM K2SO4 in 1 mM NaCl in the presence or absence of 5 mM citric acid. In the second set of experiments, the adsorption of 2 mM SO4
2– in soils at pH 4 or pH 5 in the presence or absence of one of 13 organic acids at a concentration of 2 mM or 5 mM was studied. Results showed that citric acid significantly decreased SO4
2– adsorption by the two soils. Sulfate adsorption decreased with increasing pH of the equilibrium solution. Aliphatic acids,
with the exception of cis-aconitic acid, decreased the amount of SO4
2– adsorbed by the two soils, with oxalic, tartaric, and citric acid showing the greatest effect. The differences in pH values
of the equilibrium solutions in the presence and absence of organic acids were significantly, but negatively, correlated with
the amount of SO4
2– adsorbed, suggesting chemisorption of SO4
2– and the release of hydroxide ions. The ionization fraction values of the organic acids at the equilibrium pH were correlated
with the amounts of SO4
2– adsorbed, suggesting that the protonation of surface hydroxyl groups of the mineral phase increased as the strength of the
ionization of the acid increased, thus creating more positively charged surfaces.
Received: 12 February 1997 相似文献
13.
《Communications in Soil Science and Plant Analysis》2012,43(15-16):2441-2457
Abstract The charge properties of three soils developed on granulite and serpentinite were investigated. These soils contain large amounts of organic matter, free iron oxide, and clay, and are therefore a good medium for measuring the interactions between those components. Cation‐ and anion‐exchange capacities (CEC and AEC) were measured in percolation experiments with and without ammonium acetate buffer pretreatment, using various electrolyte concentrations. The measurements were repeated after removal of sesquioxides and/or organic matter. In addition, potentiometric titrations were carried out to determine the ‘point of zero salt effect’ of each sample. Untreated samples showed a mutual blocking of positive charge on sesquioxides and negative charge on organic matter, leading to decreased CEC and negligible AEC values. Because the AEC is fully blocked, the natural soils do not have a ‘point of zero net charge’ (PZNC), and the apparent ‘points of zero salt effect’ (PZSE) obtained in potentiometric batch titrations are artifacts. Positive charge appeared only after the removal of organic matter. Percolation with acetate buffer strongly increased the measured CEC in samples containing organic complexes. After removal of organic matter, a slight buffer effect remained. This is attributed to the release of sesquioxides from organic complexes and clay surfaces by preferent binding to the acetate anion. 相似文献
14.
S. P. Dixit 《植物养料与土壤学杂志》1980,143(4):422-431
Most of the soil samples, on the basis of Δ pH measurements, were observed to carry net negative surface charges, except six samples, which carried net positive surface charges. In one case, the net surface charge was noticed to be zero. According to surface charge-pH curves, the colloid surfaces of soil samples of a Hapludalf and a Luvisol, were characterized as constant charge type. Their zero point of charge (zpc) was very low (near pH 3.0), and remained identical throughout the depth. The colloid surfaces of Tropudalf samples, especially those of B and C horizons, and net positively charged samples were characterized as constant potential type. In the former, the zpc increased from pH 3.45 (A horizon-D3) to 6.35 (C horizon-D1). Of all the samples studied, the highest zpc (pH 6.75) was recorded in one of the net positively charged samples (L24). The electrochemical behaviour of constant potential type colloids was therefore similar to that exhibited by many metallic oxides. ΔG° values in Hapludalf and Luvisol colloids were near to H bonding (-5 to-10 kcal mol?1), whereas in others the values were higher than that for H bonding, except for A horizons of Tropudalfs. 相似文献
15.
Effects of phthalic and salicylic acids on Cu(II) adsorption by variable charge soils 总被引:1,自引:0,他引:1
In the present study, the effect of two substituted benzoic acids on Cu(II) adsorption onto two variable charge soils was investigated, with the emphasis on the adsorption and desorption equilibrium of Cu(II). Results showed that the presence of organic acids induced an increase in Cu(II) adsorption onto the two soils. The extent of the effect was related to the initial concentrations of Cu(II) and organic acid, the system pH, and the nature of the soils. The effect of organic acids was greater for Oxisol than for Ultisol. Phthalic acid affected Cu(II) adsorption to a greater extent than salicylic acid did. The effect of organic acids varied with pH. The adsorption of Cu(II) induced by organic acids increased with increasing pH and reached a maximum value at approximately pH 4.5, and then decreased. It can be assumed that the main reason for the enhanced adsorption of Cu(II) is an increase in the negative surface charge caused by the specific adsorption of organic anions on soils because the desorption of Cu(II) adsorbed in organic acid systems was greater than that for the control. The desorption of Cu(II) absorbed in both control and organic acid systems also increased with increasing pH; it reached a maximum value at pH ∼5.25 for control and salicylic acid systems and at pH ∼5.1 for a phthalic acid system, then decreased. This interesting phenomenon was caused by the characteristics of the surface charge of variable charge soils. 相似文献
16.
Identifying the vulnerability of subsoils to compaction damage is an increasingly important issue both in the planning and execution of farming operations and in planning environmental protection measures. Ideally, subsoil vulnerability to compaction should be assessed by direct measurement of soil bearing capacity but currently no direct practical tests are available. Similarly, soil mechanics principles are not suitably far enough advanced to allow extrapolation of likely compaction damage from experimental sites to situations in general. This paper, therefore, proposes a simple classification system for subsoil vulnerability to compaction based for field use on local soil and wetness data at the time of critical trafficking, and, at European level, on related soil and climatic information. Soil data are readily available ‘in Country’ or from the European Soil Database and climatic data are stored in the agrometeorological database of the MARS Project. The vulnerability to compaction is assessed using a two-stage process. First, the inherent susceptibility of the soil to compaction is estimated on the basis of the relatively stable soil properties of texture and packing density. Second, the susceptibility class is then converted into a vulnerability class through consideration of the likely soil moisture status at the time of critical loadings. For use at local level, adjustments are suggested to take account of possible differences in the support strength of the topsoil and specific subsoil structural conditions. The vulnerability classes proposed are based on profile pit observations, on a wide range of soils examined mainly in intensively farmed areas where large-scale field equipment is employed. A map of soil susceptibility to compaction in Europe has been produced, as the first stage in developing a more rigorous quantitative approach to assessing overall vulnerability than has been possible hitherto. 相似文献
17.
《Communications in Soil Science and Plant Analysis》2012,43(9):1015-1027
Abstract A tillage system, ‘slit‐till’, has been developed that modifies plowpans and permits root penetration and proliferation into subsoil horizons. Slit‐till also provides a means of placing nutrients into subsoil zones where roots are concentrated. Greenhouse studies determined the effects of calcium nitrate, calcium phosphate, ammonium phosphate, ammonium nitrate, and dolomitic limestone on grain sorghum [Sorghum bicolor (L.) Moench] shoot and root development in a compacted layer of acid subsoil (pH 4.3), subject to a slit‐till treatment, and on chemical properties of soil adjacent to the injection site. Cylinders were prepared by layering A and B horizons of a Marvyn loamy sand (fine‐loamy, siliceous, thermic, Typic Hapludult) to form 56 cm of subsoil and 10 cm of topsoil in polyvinylchloride (PVC) tubing (20 × 66 cm). A 6‐cm‐thick hardpan (bulk density 1760 Mg.m‐3) was created at the top of the subsoil layer. The amendments, 500 μg/g of dolomitic limestone and 15 μg/g each of the other amendments, were injected into a 10 × 10 × 0.4 cm slit. Sorghum shoots and roots were harvested 49 days after plant emergence. Plant height was increased 15% by calcium nitrate, calcium phosphate, ammonium phosphate, and dolomitic limestone, but decreased 15% by ammonium nitrate. Twenty‐nine percent of the roots for the check occurred in the subsoil, but this increased to 49% with ammonium phosphate. Soil pH was increased and exchangeable aluminum was decreased by the dolomitic limestone up to 12 mm from point of injection. 相似文献
18.
The soil solution chemistry of some Oxfordshire soils: temporal and spatial variability 总被引:3,自引:0,他引:3
D. J. CAMPBELL D. G. KINNIBURGH† P. H. T. BECKETT 《European Journal of Soil Science》1989,40(2):321-339
The immiscible liquid displacement method was used to displace soil solutions from a variety of Oxfordshire soils. These included grassland, arable, and woodland soils. The results of detailed chemical analyses demonstrated that for most solutes there were significant seasonal differences as well as differences both within and between soil series. The variation over time intervals of a few days or weeks appeared to be relatively small in relation to sampling errors. Median concentrations (in mmol m−3 ) for soil solutions derived from 21 grassland sites and six arable sites sampled six or seven times throughout 1 year were: p H 7.7, alkalinity 1810, Na 465, K 390, Mg 135, Ca 2120, Sr 1.9, Ba 0.16, Mn 0.52, Fe 3.4, Cu 0.25, TON 860, Cl 1590, S 327, P 64, Si 220, B 5.1, and DOC 4250. For many solutes, the individual soil solution concentrations spanned a range from approximately five-times less than these median values to approximately five-times more. 相似文献
19.
The adsorption of Cd, Cu, Pb, and Zn from 0.025 M NaClO4 solutions by two ferruginous subsoils, Christiana silty clay loam and Dothan sandy clay, was investigated. Under acidic conditions, selective dissolution and removal of the Fe oxide soil component by dithionite-citrate-bicarbonate (DCB) generally increased heavy metal adsorption by the soils. This effect was attributed to increased electrostatic attraction of cations to the DCB-washed soils as evidenced by substantial reduction in the zero point of charge (ZPC) for the Dothan soil following DCB extraction. Alternately, the DCB extraction stripped Fe and Al species bound to structural exchange sites or eliminated coatings which reduce cation accessibility to such sites. Addition of low levels (10?6 M) of ferric iron suppressed heavy metal adsorption capacity of the DCB-extracted Christiana soil to values comparable to the unmodified whole soil system. While hydrous oxide surfaces represent highly reactive sites for cation binding, Fe oxides can modify both the pH-dependent and structural exchange sites in a manner which hinders heavy metal adsorption. Thus, a soil's Fe-oxide content is unlikely to be a reliable guide to heavy metal adsorption capacity. 相似文献
20.
L. MADRID E. DIAZ-BARRIENTOS P. J. SÁNCHEZ-SOTO 《European Journal of Soil Science》1989,40(4):799-806
A mathematical model, previously developed, is tested here for various clay minerals and their mixtures with iron oxides. The model yields good predictions of the permanent charge for non-swelling clay minerals, but clearly underestimates the permanent charge of montmorillonite. This result is interpreted as being caused by partial accessibility of the internal surface of the mineral.
In all cases, the values estimated for the permanent charge of the clay minerals fit the data for their mixtures with iron oxides. Nevertheless, important differences are found between the values of maximum densities of adsorption sites of potential-determining ions of the various minerals estimated when they are alone and when they are in mixtures, particularly in the case of montmorillonite mixtures. The differences are explained in terms of an intimate association between the particles in the mixtures, and some SEM and EDX results point to the same conclusion. 相似文献
In all cases, the values estimated for the permanent charge of the clay minerals fit the data for their mixtures with iron oxides. Nevertheless, important differences are found between the values of maximum densities of adsorption sites of potential-determining ions of the various minerals estimated when they are alone and when they are in mixtures, particularly in the case of montmorillonite mixtures. The differences are explained in terms of an intimate association between the particles in the mixtures, and some SEM and EDX results point to the same conclusion. 相似文献