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Batch and column experiments were conducted to study the effect of pore water velocity on the adsorption of cadmium (Cd) onto a homogeneous nonaggregated porous medium under controlled environmental conditions. A wide range (5-214 cm/hr) of pore water velocities was imposed to observe adsorption effects. The results of batch experiments showed that adsorption coefficients are affected by the solid-to-liquid...
In the present work, aggregation of soils containing iron oxides was investigated through dispersion treatments. Microaggregates (0.1-0.2 and 0.2-0.5 mm) of six Oxisols from Brazil and Cameroon and three Inceptisols from Mid-Europe were treated with eleven different dispersing agents and the resulting particle size distribution was measured. Dithionite (DCB), which selectively removes Fe-oxides...
Dissolved organic carbon (DOC) can be transported in soil solution through the soil, and may influence water quality. The transport of DOC in soils can be described by a convection-dispersion model in which the retardation factor is one of the important coefficients. Soil column experiments are frequently used to estimate the retardation factor. Because the retardation factor is related to the...
Xenon nuclear magnetic resonance ( 129 Xe NMR) spectroscopy is a powerful technique to study microporous solids and semi-crystalline polymers. In this pilot study we investigate the use of 129 Xe NMR spectroscopy for studying soils by applying the technique to model systems of carbon black and kaolin powders and to humified sand. In contrast to e.g. zeolites no...
The objective of this study was to assess the extent of Brilliant Blue FCF adsorption in soils and to identify soil properties that play a predominant role in adsorption of the dye. Additionally the adsorption kinetics of the dyestuff were investigated. With increasing equilibrium concentration the adsorption converged to a maximum and Langmuir isotherms were fitted to the data. The parameter Q ...
The variability of the transport characteristic of pesticides has rarely been investigated. In this study, 99 undisturbed soil columns representing a 1.8-ha field site in regular agricultural use were subjected to leaching tests with the two herbicides terbuthylazine and isoproturon. Emphasis was placed on the field-like flow conditions, such as water desaturation and moderate flow velocity (q=0.58...
Adsorption/desorption behavior of selenium (Se) was investigated in laboratory studies for surface soil samples varying in physico-chemical characteristics and mineralogical composition. In general, greater amount of Se was sorbed by acidic soils than alkaline soils; the only exception was the alkaline seleniferous soil from Barwa in northwestern India. Adsorption data for Se fitted well to Freundlich...
Phosphate adsorption and desorption studies provide insight for developing P management strategies. Very few studies have concentrated on P desorption which provides information on the reversibility of adsorbed P. Phosphate adsorption and desorption studies were carried out on seven rice-growing soils from three countries in West Africa, with the objective of relating these processes to P management...
We report on the results of investigations on the adsorption of nitrogen at 79 K and water vapor at 293 K on several Polish alluvial soils. The experimental adsorption data have been used to evaluate the surface fractal dimension from Frenkel-Halsey-Hill (FHH) equation and to evaluate the adsorption energy distribution function by using a modified numerical method that has been developed by Stanley...
1 29 Xe nuclear magnetic resonance (NMR) spectroscopy of adsorbed xenon was applied for the characterisation of soil meso- and microporosity. Model systems (Ca-montmorillonite, quartz sand) and three soil types (Luvisol Alh, Bt and Cv horizons; Gleysol Go horizon; Podzol Bvs horizon) were studied. For Ca-montmorillonite, the average intercrystallite pore size has been evaluated. In natural...
In order to gain understanding of the movement of pollutant metals in soil, the chemical mechanisms involved in the transport of zinc were studied. The displacement of zinc through mixtures of sand and cation exchange resin was measured to validate the methods used for soil. With cation exchange capacities of 2.5 and 5.0 cmol c kg −1 , 5.6 and 8.4 pore volumes of 10 mM CaCl 2 ...
The adsorption characteristics of lead on each genetic horizon of a natural brown forest soil profile were studied to recognize the possible immobilizing effect of a mineralogical diverse soil profile in the case of a possible lead contamination. Lead adsorption experiments were carried out on whole soil samples, soil clay fractions, as well as on their carbonate and organic matter free variant. TEM-EDS...
The sorption and leaching of ethametsulfuron-methyl by an acidic soil, after organic amendment with humic acid (HA) and a commercial peat, were studied in batch and soil column experiments. Adsorption capacity (K f ) values, obtained by fitting the experimental data to the Freundlich equation, ranged from 4.39 for the original soil containing 1.02% OC to 10.56 for the organic amended soils...
Genetically modified crops, which produce Bacillus thuringiensis toxins, release the toxins into soils through root exudates and upon decomposition of residues. Several studies showed that Bacillus thuringiensis toxins adsorbed on pure clay minerals and model clay-OM or oxides associations as well as on soils. We determined the adsorption of the toxin from Bacillus thuringiensis subsp. tenebrionis...
The main achievement of this paper is the determination of mineral structural changes in soils from three different sites of Paraná State, Brazil caused by heating and their effect on glyphosate (GPS) adsorption. This work has also shown that pH and point of zero charge (pH pzc ) of soils and clays change after heating because of cations (Na + , K + ) exchanges or due to changes...
Tannic acid (TA) and condensed tannin (CT) are strongly retained by mineral phases consisting of quartz (Qtz) with or without coatings of either goethite (Gt) or ferrihydrite (Fh). We investigated the impact of evaporation of the carrier solvent after addition of solutions of TA and CT to the mineral phases on tannin retention. These experiments were performed in solutions ranging from acidic to alkaline...
Fipronil, (±)-5-amino-1-(2,6-dichloro-α,α,α-trifluoro-p-tolyl)-4-[(trifluoro-methyl) sulfinyl] pyrazole-3-carbonitrile, has been applied to sugar cane plantations at stand establishment in Brazil for the past 7 years. However, there is a lack of information on fipronil dynamics in humid tropical soils, particularly its behavior at the soil–solution interface. The objectives of this study were to determine...
Elevated concentrations of heavy metals and antibiotics often coexist in soil due to land application of large amounts of animal wastes and other sources of inputs. This study aims at evaluating the interaction of Cu(II) and a widely-used veterinary antibiotic tetracycline (TC; H 3 L) regarding to their adsorption and cosorption on a Red soil (RS, Udic Ferrosols) and a Wushan soil (WS, Anthrosol)...
Organic matter (OM) in soils often associates intimately with the surfaces of fine-grained minerals. We used two measures of OM–mineral associations, based on either the energetics of N 2 gas sorption (C-constant in BET equation) or changes in mineral specific surface area (SSA) upon removal of OM, that provide complementary information on organic coverage of mineral surfaces. Undisturbed...
Adsorption isotherms of metsulfuron-methyl (MM) on thirty soils from the semiarid Pampean Region of Argentina were determined. The effect of total organic carbon (TOC) content on the adsorption was the main focus, but the effects of clay content, specific surface area and pH were also analyzed. pH is a very important factor that affects the adsorption. In fact, this article demonstrates that a good...
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