Predicting exchangeable cation distributions in soil by using exchange coefficients and solution activity ratios

Soil Research ◽  
1991 ◽  
Vol 29 (3) ◽  
pp. 403 ◽  
Author(s):  
IR Phillips ◽  
AS Black
Keyword(s):  
Simple Model ◽  
Cation Exchange ◽  
Activity Ratio ◽  
Soil Layer ◽  
Clay Mineralogy ◽  
Exchangeable Cation ◽  
Exchange Coefficient ◽  
Cation Composition ◽  
Physical And Chemical ◽  
Equilibrium Activity

A simple model which predicts the distribution of surface-applied chemicals in soil following leaching is described. The applied cation is considered to reach equilibrium between the solution and exchange phases prior to moving into the underlying soil layer. The distribution between the solution and exchange phases is defined by the Gapon relationship. The Gapon exchange coefficient is derived from exchange isotherms determined using a batch technique. Movement of the applied cation through successive layers and cation exchange with the soil continues until the activity ratio in solution equals the equilibrium activity ratio determined from the exchange isotherm. The applied cation remaining in solution is then considered to move 'freely'. A number of physical and chemical processes have been omitted in developing the model to retain simplicity and to ensure that the required parameters can readily be obtained using simple and well established laboratory procedures. In particular, only a binary cation exchange system is considered, and it is assumed that the rate of exchange is instantaneous. The inputs to the model are the amount of cation added, the Gapon exchange coefficient and corresponding solution activity ratio, the equilibrium activity ratio, the initial exchangeable and solution cation concentrations, and the average volumetric moisture content of soil during leaching. The simple model satisfactorily predicted the distribution of exchangeable K+ and Mg2+, and percentage of applied K+ or Mg2+ leaching 'freely' in the soil solution in homogeneous columns of soil having varying texture, clay mineralogy, and initial cation composition.

scholarly journals Mineralogical and Geochemical Trends in the Residual Soils above Basement Rocks in Ore Area, Southwestern Nigeria

2017 ◽  
Vol 9 (3) ◽  
pp. 42
Author(s):  
Adewole John Adeola ◽  
Emmanuel Tamunobelema Tubonemi
Keyword(s):  
Inductively Coupled Plasma ◽  
Soil Layer ◽  
Clay Mineralogy ◽  
Lateritic Soil ◽  
Residual Soils ◽  
Southwestern Nigeria ◽  
Thin Sections ◽  
Tropical Regions ◽  
Basement Rocks ◽  
Parent Rocks

Residual clays and laterite of economic values often occur within weathering profiles above basement rocks in tropical regions due to supergene enrichment and leaching of liable components. Previous studies in Ore area mainly on geochemistry of the basement rocks with scanty information on the weathered profiles. This study was carried out to determine the compositional characteristics of the basement rocks, the geochemical trends within the profiles above the parent rocks and the evaluation of their economic potentials.Petrographic study was carried out on thin sections of the rock samples. Elemental compositions of the rocks, clay, laterite, and top-soil were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Clay mineralogy was determined using X-ray Diffraction (XRD) analysis. Chemical index of Alterations (CIA) was calculated from geochemical data.Weathering of granite and banded gneiss in Ore resulted in the formation of soil layer, which ranged 0-0.5m, laterite 1.2-3m and clayey zone 2.9-3.0m. Quartz, plagioclase feldspars, microcline, biotite and hornblende were the essential minerals in the parent rocks. Granite and banded gneiss is high SiO2 (>65%) but low in MgO (<2.0%) and CaO (<4.0%). Kaolinite (60-80%), goethite (3-12%) and microcline (4-10%) were the dominant minerals in the XRD of the weathering profiles. Traces of illite were present only in granite. The CIA was generally > 85 indicating advanced state of weathering producing lateritic soil. The lateritic profiles over granite and banded gneiss of Ore area varied with the composition of the parent rocks. The clay layer has economic potential for ceramics, fertilizer and structural wares.

Characteristics of variably saturated granular bentonite after long-term storage at near-field relevant temperatures

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 343-361 ◽  
Author(s):  
M. Valter ◽  
M. Plötze
Keyword(s):  
Physicochemical Properties ◽  
Cation Exchange ◽  
Surface Area ◽  
Cation Exchange Capacity ◽  
Elevated Temperatures ◽  
Near Field ◽  
Exchange Capacity ◽  
Hydraulic Permeability ◽  
Cation Composition ◽  
Retention Capacity

AbstractBentonite is a potential material for use in the engineered barrier of radioactive waste repositories because of its low hydraulic permeability, self-sealing capability and retention capacity. It is expected that bentonite would react at the elevated temperatures accompanying the radioactive decay in the nuclear waste. The presented study was started in order to improve understanding of the coupled influence of temperature and (pore) water on the physicochemical and mineralogical properties of bentonite during thermal treatment under near-field relevant conditions. Granular Na-bentonite MX-80 was differently saturated (Sr = 1–0.05) and stored at different temperatures (50–150°C) in a closed system. Upon dismantling after different periods of time (3 to 18 months), mineralogical characteristics, cation exchange capacity and content of leachable cations, as well as physicochemical properties such as surface area and water adsorption were investigated.The results showed a high mineralogical stability. A slight conversion from the sodium to an earth alkali form of the bentonite was observed. However, considerable changes in the physicochemical properties of the bentonite were observed, particularly by treatment above the critical temperature of 120°C. The cation exchange capacity decreased during heating at 150°C by approximately. 10%. The specific surface area dropped by more than 50%. The water uptake capacity under free swelling conditions showed a slight tendency to lower values especially for samples heated for more than 12 months. The water vapour adsorption ability in contrast drops by 25% already within three months at T = 120°C. These changes are mostly related to the variations in the interlayer cation composition and to smectite aggregation processes. The observed alterations are rather subtle. However, temperatures ⩾ 120°C had a remarkable negative influence on different properties of MX-80.

A model of Na-K-2Cl cotransport based on ordered ion binding and glide symmetry

1998 ◽  
Vol 274 (2) ◽  
pp. C299-C309 ◽  
Author(s):  
Christian Lytle ◽  
Thomas J. McManus ◽  
Mark Haas
Keyword(s):  
Simple Model ◽  
Blood Cell ◽  
Cation Exchange ◽  
Red Blood Cell ◽  
Ion Binding ◽  
K Cells ◽  
Ion Movement ◽  
High K

In the duck red blood cell, Na-K-2Cl cotransport exhibits two modes of ion movement: net cotransport and obligate cation exchange. In high-K cells, the predominant exchange is K/K (or K/Rb). In high-Na cells, it becomes Na/Na (or Na/Li). Both represent partial reactions in which a fully loaded carrier releases part of its cargo, rebinds fresh ions, and returns back across the membrane fully loaded. Net cotransport occurs when the carrier unloads completely and returns empty. This mode has a fixed stoichiometry of 1Na:1K:2Cl under all conditions tested. The ion requirements of the two exchanges differ: K/K exchange requires only K and Cl outside but all three ions inside. Na/Na exchange requires all three ions outside but only Na inside. We propose a simple model in which the carrier can only move when either fully loaded or completely empty and in which the ions bind in a strictly ordered sequence. For example, externally, a Na binds first and then a Cl, followed by a K and a second Cl. Internally, the first on is the first off (glide symmetry), so the Na is released first and then the first Cl, followed by the K and finally by the second Cl. Only then can the empty form return to the outside to start a new cycle.

A BIOSEQUENCE OF SOILS OF THE ROUGH FESCUE PRAIRIE – POPLAR TRANSITION IN SOUTHWESTERN ALBERTA

1966 ◽  
Vol 3 (4) ◽  
pp. 457-471 ◽  
Author(s):  
J. F. Dormaar ◽  
L. E. Lutwick
Keyword(s):  
Organic Matter ◽  
Humic Acids ◽  
Exchange Capacity ◽  
Soil Profiles ◽  
Exchangeable Cation ◽  
Spectral Pattern ◽  
Ph Dependent ◽  
Physical And Chemical ◽  
Rough Fescue ◽  
Populus Spp

A biosequence of soil profiles, ranging from Black through various stages of Dark Gray to Eluviated Dark Gray Chernozems and a Degraded Brown Wooded soil, is found under a sequence of vegetation ranging from rough fescue prairie (Festuca scabrella association) to encroaching poplar (Populus spp.) and fir trees (Pseudotsuga taxifolia (Poir.) Britt.) in the Porcupine Hills of southwestern Alberta. Samples were gathered to establish the differential physical and chemical changes that have occurred in the soils over an 80-year period.Increased eluviation accompanied a reduction in the percentage of exchangeable calcium but it remained the dominant exchangeable cation in all horizons. Most of the exchange capacity arises from the organic matter. The exchange sites are mainly pH-dependent. The changes in the organic matter, because of the encroachment of trees, are more strikingly evident than are the changes in the mineral matter.Infrared absorption spectra of electrodialyzed humic acids display a conspicuous change in spectral pattern between 2 500 and 1 800 cm−1. There are indications of increased acidity and increased aromaticity in the humic acids of the B horizon as eluviation progresses.

scholarly journals Purification and properties of glutathione S-transferases from larvae of Wiseana cervinata

1984 ◽  
Vol 217 (1) ◽  
pp. 41-50 ◽  
Author(s):  
A G Clark ◽  
B Drake
Keyword(s):  
Cation Exchange ◽  
Ethacrynic Acid ◽  
Catalytic Properties ◽  
Exchange Chromatography ◽  
Cation Exchange Chromatography ◽  
Purification And Properties ◽  
Different Types ◽  
Glutathione S Transferases ◽  
Physical And Chemical ◽  
Kinetics Of

The glutathione S-transferases from the porina moth, Wiseanna cervinata, were purified by affinity chromatography, cation-exchange chromatography and preparative isoelectrofocusing. The major transferase (IV) was purified to homogeneity by a factor of 530-fold with a yield of 83%. Other transferases present were purified to a smaller degree (approx. 50-fold) to a stage of near-homogeneity. The transferases examined all had Mr values about 45 000-50 000. They appeared to be homodimers of either of two types of subunit, of Mr 22 800 and 24 600. Enzymes consisting of the different types of subunit were not immunologically cross-reactive. The major enzyme fractions separated by cation-exchange chromatography were both active with 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, ethacrynic acid and iodomethane, but were inactive with 4-nitropyridine N-oxide, 1,2-epoxy-3-(p-nitrophenoxy)propane, bromosulphophthalein and p-nitrobenzyl chloride. The kinetics of the enzyme-catalysed reaction with enzyme IV were non-Michaelean with respect to both substrates. Both products were inhibitory. The results appear to be compatible with a random steady-state mechanism. It is concluded that these enzymes are very similar, in their physical and chemical constitution, in their catalytic properties and in their relationships with each other, to those enzymes that have been isolated from vertebrate organisms.

Mineralogical, physical and chemical investigation of compacted Kunigel V1 bentonite in contact with a steel heater in the ABM test package 1 experiment, Äspö laboratory, Sweden

Clay Minerals ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 127-141 ◽  
Author(s):  
H. Sasamoto ◽  
T. Isogai ◽  
H. Kikuchi ◽  
H. Satoh ◽  
D. Svensson
Keyword(s):  
Exchange Capacity ◽  
Exchangeable Cations ◽  
Exchangeable Cation ◽  
Exchange Reactions ◽  
Swelling Properties ◽  
X Ray ◽  
Set Up ◽  
The Stability ◽  
High Level ◽  
Physical And Chemical

AbstractIn many countries, compacted bentonite is a candidate engineering barrier material for safe disposal of high-level radioactive waste. The Swedish Nuclear Fuel and Waste Management Company (SKB) set up an in situ experiment (the ABM project) to compare the stability of different bentonites under the conditions of exposure to an iron source and to elevated temperature (up to 130°C) at the Äspö Hard Rock Laboratory, Sweden. Results for the Japanese bentonite (Kunigel V1) are summarized in the present study.Mineralogical investigation using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) suggested no transformation of smectite or neoformed clay phases. However, a distinct change in exchangeable cations of smectite was indicated (i.e. from Na type to Fe type and/or Ca type) in the bentonite in the vicinity of the steel heater.Measurements of hydraulic conductivity and swelling properties suggest that no significant changes occurred in the bentonite even in the vicinity of the steel heater. This is attributed to the limited portion of the bentonite affected by the iron–bentonite interactions and the incomplete ion-exchange reactions. The methylene blue cation exchange capacity and the determination of the exchangeable cations showed that the lateral distribution for these parameters was constant. However, the total exchangeable cation population has changed significantly compared to the initial sample.

scholarly journals Effect of homogenization and ultrasonication on the physical properties of insoluble wheat bran fibres

2015 ◽  
Vol 29 (4) ◽  
pp. 423-432 ◽  
Author(s):  
Ran Hu ◽  
Min Zhang ◽  
Benu Adhikari ◽  
Yaping Liu
Keyword(s):  
High Pressure ◽  
Cation Exchange ◽  
Wheat Bran ◽  
High Intensity ◽  
Dietary Fibre ◽  
Chemical Properties ◽  
High Pressure Homogenization ◽  
Insoluble Dietary Fibre ◽  
Physical And Chemical ◽  
Water Holding

AbstractWheat bran is rich in dietary fibre and its annual output is abundant, but underutilized. Insoluble dietary fibre often influences food quality negatively; therefore, how to improve the physical and chemical properties of insoluble dietary fibre of wheat bran for post processing is a challenge. Insoluble dietary fibre was obtained from wheat bran and micronized using high-pressure homogenization, high-intensity sonication, and a combination of these two methods. The high-pressure homogenization and high-pressure homogenization+high-intensity sonication treatments significantly (p<0.05) improved the solubility, swelling, water-holding, oil-holding, and cation exchange capacities. The improvement of the above properties by high-intensity sonication alone was marginal. In most cases, the high-pressure homogenization process was as good as the high-pressure homogenization+high-intensity sonication process in improving the above-mentioned properties; hence, the contribution of high-`intensity sonication in the high-pressure homogenization+high-intensity sonication process was minimal. The best results show that the minimum particle size of wheat bran can reach 9 μm, and the solubility, swelling, water-holding, oil-holding, cation exchange capacities change significantly.

Can soil clay content predict ammonia volatilization losses from subsurface-banded urea in eastern Canadian soils?

2018 ◽  
Vol 98 (3) ◽  
pp. 556-565 ◽  
Author(s):  
D.E. Pelster ◽  
M.H. Chantigny ◽  
D.A. Angers ◽  
N. Bertrand ◽  
J.D. MacDonald ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Negative Relationship ◽  
Clay Content ◽  
Soil Mesocosms ◽  
Dynamic Chamber ◽  
Canadian Soils ◽  
Soil Clay ◽  
Soil Clay Content ◽  
Physical And Chemical ◽  
Water Extractable

To determine how soil physical and chemical characteristics affect NH3 volatilization, we measured NH3 losses from eight different eastern Canadian soils with various soil clay contents and cation exchange capacities (CEC). Losses were measured from soil mesocosms banded (0.05 m depth) with urea (equivalent of 140 kg N ha−1) in a dynamic chamber system fitted with an acid trap; with soil properties measured in parallel mesocosms. Regression analysis indicated a negative relationship between 28 d of NH3 volatilization losses and soil clay content (P < 0.001; R2 = 0.978), CEC (P < 0.001; R2 = 0.941), and buffer capacity (P = 0.006; R2 = 0.772), and positive relations with maximum change in soil pH (P = 0.015; R2 = 0.670) and maximum water-extractable NH4+ (P = 0.010; R2 = 0.721). A 90% reduction in NH3 losses occurred when clay content increased from 10% to 20%. Also, the correlation between water-extractable NH4+ and NH3 loss and a lack of correlation between salt-extractable (1 mol L−1 KCl) NH4+ and NH3 loss indicate that NH4+ bound to cation exchange sites does not contribute to the rapid NH3 volatilization. However, more research on soils of different mineralogy is required to ascertain whether this holds in other regions as well.

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