bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption of Parathion, Fenitrothion, Methyl Parathion, Aminoparathion and Paraoxon by Na+, Ca2+, and Fe3+ Montmorillonite Suspensions
Authors: Bowman B. T. , Sans W. W. 
Published: July 2010

AbstractThis study was conducted to investigate the influence of the saturating cation on the adsorption of parathion, methyl parathion, fenitrothion, aminoparathion, and paraoxon by montmorillonite suspensions. In all cases the saturating cation distinctly influenced the Freundlich‐type adsorption, with adsorption decreasing in the following sequence: Fe3+ − >Ca2+‐ > Na+‐montmorillonite. Adsorption of parathion, methyl parathion, fenitrothion and aminoparathion at low concentrations varied inversely with their water solubilities in Na+ − and Ca2+‐montmorillonite suspensions, i.e. parathion > fenitrothion > methyl parathion > aminoparathion > fenitrothion > methyl parathion > aminoparathion adsorption. Paraoxon adsorption was slightly greater than the compound with the next lower solubility, aminoparathion. The water solubility of parathion at 20°C was 12.9 µg/ml. Aminoparathion was more than 99.9% adsorbed from solution by Fe3+‐montmorillonite, suggesting the possibility of protonation of the ‐NH2 group by the acidic clay surfaces. In Na+ − and Ca2+‐montmorillonite suspensions, there was some conversion of paraoxon to p‐nitrophenol. Parathion adsorption‐desorption exhibited greater hysteresis effects in Fe3+‐montmorillonite than in Ca2+‐montmorillonite. The desorption pathway was dependent only on the initial concentration. The volume of solution removed in each cycle did not alter the desorption pathway, but only the rate at which the desorption proceeded down the desorption isotherm.
Behavior of Vapam and Methylisothiocyanate in Soils
Authors: Gerstl Z. , Mingelgrin U. , Yaron B. 
Published: July 2010

AbstractAn investigation was undertaken to study the behavior of the fungicide Vapam (sodium‐N‐methyldithiocarbamate) and its toxic degradation product MIT (methylisothiocyanate) in soils to obtain the necessary parameters for predicting the distribution of these compounds when applied in irrigation water. These parameters include absorption by the soil components, the degradation of Vapam to MIT and the subsequent breakdown of MIT to nontoxic substances, and the distribution of MIT between the liquid, gaseous, and adsorbed phases in the soil. Adsorption was determined by both batch and flow methods. The results indicated that degradation of both Vapam and MIT followed first‐order kinetics. The breakdown of Vapam to MIT was rapid, half‐life generally < 30 min at moisture contents below saturation, while MIT was found to persist for 2 weeks or more. The rapid breakdown of Vapam will result in a soil solution containing mainly MIT. MIT adsorption was relatively low (Kads = 0.41 and 0.57 ml/g for the soils higher in clay and organic matter content). The soils with the lower adsorption coefficients (Kads < 0.05) will give a practically uniform MIT distribution with depth when Vapam is applied at a constant concentration in the irrigation water. The behavior of Vapam in heavy textured soils needs further investigation.
Differences in Exchangeable Aluminum and Soil Acidity in Loess Soils of Iowa
Authors: Richardson J. L. , Riecken F. F. 
Published: July 2010

AbstractThe relationship of soil natural drainage, native vegetation, and textural development to exchangeable aluminum, exchange acidity, pH (CaCl2), total carbon and clay was studied in selected loess soils in Iowa. Greatest differences in measured properties in the laboratory were observed along biosequences. Prairie soils had only trace amounts of exchangeable aluminum, but usually had the most A‐horizon exchange acidity. Forest soils had both maximum exchangeable aluminum and exchange acidity in the B‐horizon, corresponding to maximum clay accumulation. “Transition” soils, presumably an encroachment of forest on a former prairie, were similar to forest soils. Only minor differences in measured properties were observed in natural drainage sequences. Acidity correlates with organic matter in prairie soils and with clay content in forest soils. The organic matter appears to act as a buffer in prairie soils and in the A‐horizon of transition and forest soils. Aluminum acts to buffer the forest and transition soil B‐horizons.
Numerical Evaluation of Granule Size Effect on Dissolution Rate of Potassium Silicates and Potassium Polyphosphate in Aqueous Solution
Authors: Miwa Eitaro , Kurihara Kiyoshi 
Published: July 2010

AbstractThe rate of potassium dissolution from spherical granules of K2O · 4SiO2, K2O · 5SiO2, and (KPO3)n was measured in water, NH4Cl and acetic acid solutions. Experimental results were analyzed using first‐order kinetics, involving a rate constant (k) and the concentration at saturation (Cs). The kCs values in H2O were 3.65 × 10−2, 1.17 × 10−2, and 7.08 × 10−3 mg K/mm2 per day for K2O · 4SiO2, K2O · 5SiO2, and (KPO3)n, respectively. Extremely high kCs values were obtained for the dissolution of (KPO3)n in solvents rich in H+ or NH4+. Based on these experimental data and assumed values for Cs, the whole process of K dissolution from each material at various granule sizes in aqueous solutions was calculated by the equations given by Hixson and Crowell (1931). As much as 83 mg of K from granules up to 3.22 mm in diameter will dissolve within 4 days in 100 ml of 0.001M NH4Cl solution. Only small differences in kCs values were obtained for K2O · 4SiO2 and K2O · 5SiO2 in the solvents used. Potassium dissolution from K2O · 5SiO2 in aqueous solutions will be extended beyond 2‐3 days by increasing granule size to 0.34 mm or greater.
Clay Formation from Basic Volcanic Rocks in a Humid Mediterranean Climate
Authors: Singer A. , Navrot J. 
Published: July 2010

AbstractClay minerals from soils formed on a variety of basic volcanic rocks in the northern Golan Heights, under humid Mediterranean conditions, have been examined mineralogically. The clay from basalt derived soils, mainly Rhodoxeralfs and Haploxeralfs (Red and Brown Mediterranean Soils) contains kaolinite and dioctahedral vermiculite partially interlayered with Al and Fe hydroxy layers. The presence of some illite and quartz in the upper soil horizons is explained by aeolian accretion. A scoria‐derived Rhodoxeralf contains, in addition, some hematite.The clay fraction from Rhodoxeralfs and Haploxeralfs formed on partly palagonitised tuff‐lapilli is composed primarily of b‐axis disordered kaolinite and a poorly crystalline, partly expanding, 2:1 clay mineral, presumed to represent a smectite randomly interlayered with chloritic layers. In the lower horizons of these soils the kaolinite is replaced by a hydrated, spheroidal halloysite. No distinctly amorphous clay minerals were identified. A scheme of an alteration sequence of basic pyroclastics under humid Mediterranean conditions is suggested.
A Note on the Use of Infiltration Equations
Authors: Parlange J.‐Y. 
Published: July 2010

AbstractIt is shown, with the help of an exact example, that the cumulative infiltration, i, may be represented as a function of time t by a relation of the form, st1/2 + at, which can be accurate over a finite time interval. Contrary to a recent suggestion, this expression cannot be identified in general with a time expansion of i. In addition the values of s and a depend on the time interval considered and have no a priori relationship to the soil properties. Consequently such an expression has at most some empirical value. A better suggestion is that data from infiltration experiments should be fitted with analytical expressions which approach the proper limits as t → 0 and t → ∞, whenever possible.
A Method for the Simultaneous Control of the Water Regime and Gaseous Atmosphere in Soil Columns
Authors: Wagenet R. J. , Starr J. L. 
Published: July 2010

AbstractA technique useful in laboratory soil columns which allows control of soil water content, regulation of the average composition of the soil atmosphere, and collection of leachate in variable increments is described. The design and construction of the system, as well as its advantages and disadvantages, are explained in detail and references are made to the adaptability of the technique to studies involving N transport and transformation, microbial populations, salinity, reduction‐oxidation reactions, or soil gas sampling.
Water Intake by a Water‐Filled Plexiglas Permeameter Cell
Authors: Tsuji G. Y. , Swartzendruber D. 
Published: July 2010

AbstractWater entry into a Plexiglas (acrylic plastic) permeameter cell was measured by the recession of water in capillary standpipes connected to the water‐filled cell. Submergence of the permeameter in water demonstrated that the water entry was not caused primarily by a slight leak in the permeameter or by water‐vapor diffusion through its walls. Also, the rate was essentially unaffected when the permeameter contained a water‐saturated mixture of sand, silt, and bentonite. Calculations for the permeameter in air indicated the observed intake rate to be 20 times that attributable to water‐vapor diffusion through the Plexiglas walls, and 1/8 that attributable to direct water absorption as obtained from a maximal handbook value. Hence, it appears that direct absorption by the Plexiglas is the likely cause of water entry into the permeameter.
Influence of Citric Acid on the Hydrolytic Reactions of Aluminum
Authors: Ng Kee Kwong K. F. , Huang P. M. 
Published: July 2010

AbstractHydrolytic reactions of Al were studied at the initial Al concentrations of 1.10 × 10−4M and 1.10 × 10−3M and at varying degrees of hydrolysis as influenced by the presence of 1.0 × 10−6M and 1.0 × 10−4M citric acid. The effect of citric acid on the formation of the readily extractable Al and moderately extractable Al by the 8‐quinolinolate method varied with the initial concentrations of Al and citric acid and OH/Al molar ratios of the system. Hindrance to the hydrolytic reaction of Al by the acidity of citric acid and its complexation with Al ions were two counteracting reactions governing its effect. Citric acid substantially promoted the formation of the nonextractable Al fraction. The precipitation of the solid phase products was invariably hindered by citric acid.Electron diffraction analysis showed that citric acid, at the concentrations used, hampered the formation of even microcrystalline bayerite and gibbsite. The data obtained from X‐ray diffraction and thermal analyses indicate that on aging, the degree of order in the solid phase improved upon the replacement of the citrate in the structure by the hydroxyl. Citric acid evidently hampered the hydroxyl bridging mechanism in the hydrolytic reaction of Al and thus imparted a rough fluffy surface to the solid phase as opposed to well‐formed crystals in its absence.The present study clearly illustrated the important role of citric acid in influencing the hydrolytic reaction of Al and the nature of the resulting solid phase reaction products which should be of concern in the study of pedogenesis and other soil physico‐chemical reactions.
Effect of Mixed Na‐Ca Solutions on the Hydraulic Properties of Unsaturated Soils
Authors: Russo David , Bresler Eshel 
Published: July 2010

AbstractThe effects of mixed Na‐Ca solutions on soil water diffusivity and unsaturated hydraulic conductivity were tested for a loamy soil from Gilat, Israel. Soil water diffusivity functions, D(θ), were determined by the horizontal infiltration method. Unsaturated hydraulic conductivity functions, K(θ), were determined both directly (by vertical infiltration for suction heads of 0–50 cm H2O) and indirectly (from diffusivity functions and soil water retention curves). Prior to determinations, soil samples were equilibrated with solutions containing a given concentration and composition of Ca and Na. The results show that D(θ) and K(θ) are independent of solution concentrations in a Ca‐saturated system. In mixed Na‐Ca systems, hydraulic conductivity and soil water diffusivity functions are highly dependent on the composition and concentration of the soil solution, in addition to their dependence on soil water content, θ. For any given θ, both K(θ) and D(θ) decrease as either soil solution concentration decreases or the sodium fraction in the soil solution increases. The negative effect of a combination of high Na‐to‐Ca ratio and low soil solution concentration on K(θ) is directly related to the degree of water saturation of the soil. Low values of θ can compensate for the negative effects of high Na‐to‐Ca ratio and low solution concentration.
Influence of Exchangeable Cation on the Sorption of Trace Amounts of Cadmium by Montmorillonite
Authors: García‐Miragaya J. , Page A. L. 
Published: July 2010

AbstractThe effect of different exchangeable cations on the sorption of trace amounts of Cd by montmorillonite (clay fraction, Upton, Wyoming) was studied by equilibrating samples of homoionic clay suspensions with CdCl2 solutions ranging from 15 to 120 µg Cd/liter. These Cd concentrations are similar to those found in natural and contaminated soil‐water systems. The amount of Cd sorbed on the montmorillonite surfaces depended on the kind of exchangeable cation, decreasing in the order Na‐montmorillonite > K‐montmorillonite > Ca‐montmorillonite > Al‐montmorillonite. Exchangeable Al was found to be particularly effective in reducing Cd sorption by high energy sites on montmorillonite.
Oxidation of Elemental Sulfur in Soils
Authors: Nor Y. M. , Tabatabai M. A. 
Published: July 2010

AbstractStudies of oxidation of elemental S in soils showed that thiosulfate and tetrathionate are produced during S oxidation in soils. In this work, unamended and elemental S‐amended soils were incubated (30°C) under aerobic conditions for various times. The amounts of S2O3‐, S4O6‐, and SO4‐S produced during incubation were determined. Results showed that S2O32‐ was produced within the first few days of incubation and that S4O62‐ accumulated in some soils. The rate of S oxidation increased with increasing incubation temperature (5, 15, and 30°C) and with increasing the rate of S application (50, 100, and 200 µg S/g soil). For 100 µg S/g soil, the rates of oxidation of elemental S in 10 Iowa surface soils ranged from 39 to 75 µg S/g soil after incubation at 30°C for 70 days; rates were more rapid in alkaline soils than in acid soils. There was little change in pH of soils even when the S application rate was increased from 50 to 200 µg S/g soil. The rate of S oxidation was lower in air‐dried soils than in field‐moist soils.
Manure Effects on Water Intake and Runoff Quality from Irrigated Grain Sorghum Plots
Authors: Mathers A. C. , Stewart B. A. , Thomas J. D. 
Published: July 2010

AbstractFeedlot manure was incorporated into Pullman clay loam at rates of 0, 22, and 67 metric tons per ha annually (tons/ha/per year). Additional treatments were 67 tons/ha manure the first year only and 224‐kg N/ha/per year as anhydrous ammonia. The time required for irrigation water to advance down graded furrows was increased by the manure treatment. Also water intake and grain yields were higher on manure‐ than on ammonia‐treated plots. Runoff quality was not markedly reduced by manure treatments as indicated by NO3, P, and Cl concentrations in the runoff water.
Thermal Regime of a Prairie Snowcover
Authors: Granger R. J. , Chanasyk D. S. , Male D. H. , Norum D. I. 
Published: July 2010

AbstractAn energy budget approach was used to study the melting of a shallow prairie snowpack. In the analysis, all the terms of the energy budget were determined independently. The major source of energy for the melt was the net radiation flux. Over a continuous snowcover the contribution of sensible heat to the melt could not be represented by a simple low‐level temperature index, but was dependent on the energy content of the air mass. The latent heat flux responded to the radiation flux, with daytime evaporation and nighttime condensation, however the net daily flux was evaporative. Nighttime refreezing of the snowpack limited the runoff, with approximately 40% of the daily meltwater being retained or refrozen in the snowpack. Beneath the melting snowcover the diurnal cycle of soil heat flux was almost completely eliminated. Monitoring of soil moisture changes during the melt period showed that very little infiltration occurred until the soil had thawed.
Dissolution of Arsenic from Waterlogged and Aerated Soil
Authors: Hess R. E. , Blanchar R. W. 
Published: July 2010

AbstractSharpsburg and Menfro soils containing 320 and 160 µg As/g, respectively, were waterlogged with water or 1% dextrose. The Eh reached a minimum of −150 mV after 1 day of incubation and increased to about +300 mV after 12 days for both soils in 1% dextrose. The Eh remained constant in the Sharpsburg soil during incubation with water, but gradually decreased in the Menfro soil. In the 1% dextrose solution, As increased rapidly in both soils and became constant after 12 days. The As in solution increased more slowly when incubated with water, but also remained constant after 12 days. After freeze‐drying and exposing the soil to the atmosphere, Eh increased and As decreased to initial levels.The values of pAl + 3pOH, pAl + pAsO4, pFe + 3pOH, pFe + pAsO4, 3pMn + 2pAsO4, 3pCa + 2pAsO4, and 3pPb + 2pAsO4 were computed. These measurements indicated that the soil solution of the Menfro and Sharpsburg soils contained less As than predicted for Al, Fe, and Ca arsenates, and more As than predicted for Mn and Pb arsenates.
Homovalent and Heterovalent Cation Exchange Equilibria in Soils with Variable Surface Charge
Authors: Galindo G. G. , Bingham F. T. 
Published: July 2010

AbstractCation‐exchange equilibira involving K, Na, Ca, and Mg were studied with Chilean Dystrandepts.The K‐Na exchange and the Ca‐Mg exchange showed that K and Ca were preferentially adsorbed. Increased charge density through adsorption of phosphate resulted in a reduction in the selectivity for K in the K‐Na system. Phosphate adsorption had no apparent effect on the selectivity for Ca in the Ca‐Mg system.In heterovalent systems, these soils showed a perferential adsorption of the divalent cation. This selectivity was more pronounced at low equivalent concentration of the divalent cation. The selectivity for the divalent cation increased as the surface charge density was increased by phosphate adsorption.
Characteristics of Coatings formed on Rice Roots as Affected by Iron and Manganese Additions
Authors: Bacha R. E. , Hossner L. R. 
Published: July 2010

AbstractRice plants (Oryza sativa ‘Brazos’) were grown with varying rates of application of Fe and Mn. Solution concentration of Fe ranged from 0.5 to 50.5 ppm and Mn from 0.1 to 12.5 ppm in an experiment designed to study the coatings formed on rice roots grown under anaerobic conditions. Root coatings were removed for analysis with citrate‐bicarbonate‐dithionite solution. Chemical analysis inidcated that the coatings were composed primarily of Fe. Manganese was present in detectable amounts only when solution concentrations were > 1.0 ppm.Scanning electron micrographs of the coatings showed a precipitate on the surface of the rice root. X‐ray diffraction analysis of coatings identified the iron oxide mineral lepidocrocite (γ‐FeOOH) as the only crystalline component of the coatings.
Adsorption of Aluminum by a Smectite: II. An Al3+‐Ca2+ Exchange Model
Authors: McBride M. B. , Bloom P. R. 
Published: July 2010

AbstractThe adsorption of Al by Ca2+‐montmorillonite has been found to be described by a Langmuir‐type equation in which the activity of Al3+ in solution is a function of the coverage of the mineral surfaces by Al. The classical mass‐action equations were inadequate in describing the exchange reaction where the Ca2+ activity was allowed to vary, weighting the effect of the Ca2+ ion activity on the equilibrium too heavily. The model suggests the relative solutionlike nature of adsorbed Ca2+ compared to the much more strongly adsorbed Al3+. Hydrolysis and precipitation reactions of Al3+ at higher pH complicated the exchange model by introducing significant quantities of adsorbed hydroxyl‐Al into the system.
Characteristics of Some Selected Soils in the Caspian Sea Region of Iran
Authors: Hakimian M. 
Published: July 2010

AbstractA physiographic sequence of soils was studied in the Caspian Sea region of Iran. This area is characterized by a warm, temperate, humid microclimate. Seven representative pedons, including 34 samples, were analyzed.Physico‐chemical determinations revealed that the Mountain and Upper Alluvial Plain soils are acid with average pH values of 5.8 and 5.9, respectively. The Lower Alluvial and Coastal Plain soils are neutral with pH's of 7.0 and 7.3, respectively. The base saturation percentages are lower for highland soils (68% for Upper Alluvial Plain area) and higher for lowland soils (99% for Coastal Plain area). The exchange acidity also follows the reverse trend. The average organic matter content of the Lower Alluvial Plain soils is the highest (9%) among the soils studied, while that of the Upper Alluvial Plain soils is lowest (2.3%). The other soils have intermediate OM content, being variable throughout the pedons 1, 3 and 7. The Mountain soil exhibits the highest CEC value (41.6 meq/100 g), while the other soils have considerably lower values. However, the average vermiculite content of the Mountain soil is lower (20%) than those of the plains (ranging from 34 to 43.8%). Clay mica content of the soils also follows the same general trend.X‐ray diffraction patterns of the clay fractions reveal that the dominant clay minerals consist of kaolinite, randomly interstratified montmorillonite‐vermiculite, and some discrete vermiculite. The clay mica (illite) is more common in the soils of the plains, while discrete chlorite as well as clay mica‐chlorite and/or vermiculite are observed in the clay fraction of the low‐land soils.The soils are classified as follows: Mountain soil as Typic Hapludoll; Upper Alluvial Plain soils as Aquic Hapludalf, Fluventic Eutrochrept, and Dystric Fluventic Eutrochrept; Lower Alluvial Plain soils as Aeric Haplaquept; and the Coastal Plain soil as Fluventic Hapludoll.
Soil Development as a Function of Time in The Punjab River Plains of Pakistan
Authors: Ahmad M. , Ryan J. , Paeth R. C. 
Published: July 2010

AbstractThree soil series; Shahdara (Ustifluent), Sultanpur, (Ustochrept) and Bhalwal (Haplustalf), representing a chronosequence from the Punjab River plains of Pakistan, were studied with respect to morphological, chemical, physical, and mineralogical properties. These soils, developed in mixed mineral alluvium, represented the late Holocene, middle Holocene, and late Pleistocene surfaces and were estimated to be less than 100 years, around 2,300 years, and between 10,000 and 20,000 years old respectively. With increasing soil age, horizon differentiation and solum thickness increased while cutans and CaCO3 concretions occurred in the oldest Bhalwal soil. Topsoil CEC and TEB values increased while both CaCO3 content and the Ca:Mg ratio decreased. Significant changes occurred in the ratio of acid oxalate to citrate‐dithionite extractable iron (Fe ratio). Textural gradation was in evidence in the two older soils. Illite and chlorite tended to decrease, and vermiculite and montmorillonite to increase with soil age. Despite variability in parent materials due to depositional stratification and preweathering, the changes in soil properties with age were mainly attributed to processes of soil formation.