The effects of anion sorption on sorption and leaching of cadmium

Soil Research ◽  
1999 ◽  
Vol 37 (3) ◽  
pp. 445 ◽  
Author(s):  
N. S. Bolan ◽  
M. A. R. Khan ◽  
R. W. Tillman ◽  
R. Naidu ◽  
J. K. Syers
Keyword(s):  
Negative Charge ◽  
Silt Loam ◽  
Clay Loam ◽  
Column Studies ◽  
Phosphate Sorption ◽  
Variable Charge ◽  
Sorption Column ◽  
Chloride Sulfate ◽  
Phosphate Anions ◽  
The Difference

The effect of chloride, sulfate, nitrate, and phosphate anions on the sorption and leaching of cadmium was examined in 2 soils (Manawatu silt loam and Egmont clay loam) which differ in their variable charge components. There was a larger sorption of cadmium in the presence of phosphate than in the presence of sulfate, nitrate, and chloride, and the difference was more pronounced in the Egmont soil. In soils, specific sorption of phosphate increases the negative charge. The increase in negative charge per unit amount of phosphate sorbed decreased with increasing phosphate sorption. The sorption of cadmium increased in response to phosphate sorption. The phosphate-induced cadmium sorption resulted from the increase in negative charge due to phosphate sorption. Column studies indicated that cadmium was less susceptible to leaching in the presence of phosphate than in the presence of nitrate.

Effect of exogenous carbon on the sorption and movement of atrazine and 2,4-D by soils

Soil Research ◽  
1996 ◽  
Vol 34 (4) ◽  
pp. 609 ◽  
Author(s):  
S Baskaran ◽  
NS Bolan ◽  
A Rahman ◽  
RW Tillman
Keyword(s):  
Poultry Manure ◽  
Pig Manure ◽  
Silt Loam ◽  
Column Studies ◽  
Mushroom Compost ◽  
Organic C ◽  
Soil Material ◽  
Kd Values ◽  
The Difference ◽  
Different Levels

Sorption and movement of 2 ionic herbicides (2,4-D and atrazine) by 3 soil materials (Tokomaru silt loam, Egmont silt loam, mine tailings) which were amended with different levels of exogenous carbon (C) materials (poultry manure, sewage sludge, mushroom compost, peat, pig manure) were examined using 14C-labelled compounds. The sorption of herbicides was measured using a batch technique and the movement was examined using soil columns in which a pulse of 14C-labelled herbicide was leached with dissolved organic C (DOC). Sorption of herbicides, as measured by the distribution coefficient (Kd), increased with increasing C addition, and varied between the C sources. The difference in the effect of C sources on the sorption of herbicides was related to the difference in the amount of DOC and the pH. The increase in the Kd values per unit C addition decreased with increasing amounts of both the exogenous C addition and the indigenous C in the soil material. In a separate study, the addition of DOC to solutions of herbicides prior to sorption measurements decreased the sorption of herbicides, whereas the addition of DOC to soil increased the sorption of herbicides. Column studies have shown that DOC enhanced the movement of herbicides in soils. The effect of DOC on the movement of herbicides varied between the soil materials and may be related to the difference in the sorption of both the herbicides and the DOC.

Sorption and Desorption of Imazethapyr and 5-Hydroxyimazethapyr in Minnesota Soils

Weed Science ◽  
1994 ◽  
Vol 42 (1) ◽  
pp. 92-97 ◽  
Author(s):  
Jianying Gan ◽  
Monte R. Weimer ◽  
William C. Koskinen ◽  
Douglas D. Buhler ◽  
Donald L. Wyse ◽  
...  
Keyword(s):  
Field Experiments ◽  
Sandy Loam ◽  
Sandy Loam Soil ◽  
Silt Loam ◽  
Clay Loam ◽  
Equilibrium Studies ◽  
Limited Mobility ◽  
Loam Soil ◽  
The Difference ◽  
Plant Metabolite

Laboratory batch equilibrium studies were conducted to evaluate the sorption-desorption behavior of imazethapyr and its major plant metabolite, 5-hydroxyimazethapyr, in three Minnesota soils. Sorption of both compounds on all soils was low, and pH did not significantly influence sorption in the range of 4,8 to 7.1. Less 5-hydroxyimazethapyr was sorbed than imazethapyr on the same soil. Once sorbed, both compounds were only partially desorbable from all soils. Significant hysteresis and formation of nonextractable residues indicate that the small amount of chemical sorbed is bound to selective surfaces with strong bonds. Webster clay loam had greater irreversibility than Waukegen silt loam and Estherville sandy loam soil. The hysteresis observed in desorption may be responsible for the difference between mobility estimations made from laboratory sorption studies and the limited mobility observed in field experiments.

scholarly journals Characterization of Alachlor and Atrazine Desorption from Soils

Weed Science ◽  
1990 ◽  
Vol 38 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Sharon A. Clay ◽  
William C. Koskinen
Keyword(s):  
Silt Loam ◽  
Clay Loam ◽  
Adsorption And Desorption ◽  
Methanol Extraction ◽  
Application Rates ◽  
Desorption Isotherms ◽  
The Difference

Herbicide desorption isotherms may be affected by the amount of nondesorbable herbicide present in soil. Nondesorbable alachlor (as determined after methanol extraction) generally increased on a Waukegan silt loam (Typic Hapludolls) and a Ves clay loam (Udic Haplustolls) during five 0.01 M CaCl2desorptions. Atrazine was totally extracted with methanol from the Waukegan soil after one desorption using 0.01 M CaCl2. However, after five desorptions with 0.01 M CaCl2an average of 5.5 and 15.5% of the total recovered atrazine from two atrazine application rates was methanol nondesorbable from the Waukegan and Ves soils, respectively. Freundlich desorption isotherms adjusted for nondesorbable herbicide accounted for as much as 71 % of the difference between adsorption and desorption isotherms. Only a portion of the hysteresis observed can be attributable to nondesorbable herbicide.

Surface charge characteristics of variable charge soils in Thailand

Soil Research ◽  
2010 ◽  
Vol 48 (4) ◽  
pp. 337 ◽  
Author(s):  
W. Wisawapipat ◽  
I. Kheoruenromne ◽  
A. Suddhiprakarn ◽  
R. J. Gilkes
Keyword(s):  
Organic Matter ◽  
Surface Charge ◽  
Negative Charge ◽  
Clay Fraction ◽  
Base Cation ◽  
Exchange Capacity ◽  
Rate Of Change ◽  
Phosphate Sorption ◽  
Variable Charge ◽  
A Charge

Surface charge characteristics were investigated using a charge fingerprinting procedure for 90 samples from 32 profiles of highly weathered Oxisols and Ultisols derived from shale/limestone, basalt, granite, local alluvium, sedimentary, and metasedimentary rocks under tropical savanna and tropical monsoonal climates in Thailand. The charge fingerprints of 5 whole soils, after removal of organic matter and of kaolin and ion oxides from these soils, were also measured to clarify factors contributing to the variable charge behaviour. Phosphate sorption was determined and related to charge properties. Kaolin was the dominant mineral of the clay fraction with moderate amounts of goethite and hematite. Gibbsite was present in Oxisols formed on limestone and basalt under more humid conditions. All soils exhibited variable charge behaviour but the magnitude and rate of change in variable charge with pH varied greatly between Oxisols and Ultisols. Oxisols had higher amounts of variable charge than Ultisols, reflecting the differences in amounts of clay and extractable Fe and Al. Oxisols formed on basalt and limestone under more humid conditions had high values of anion exchange capacity (AEC) due to the contributions of goethite, gibbsite, and boehmite. The relationships of base cation exchange capacity (CECB) and AEC with pH were linear. Rates of change with pH of both negative and positive variable charge (Ac, Aa) were closely related to CEC, specific surface area (SSA), pH(NaF), and various forms of extractable Fe, Al, and Mn. The charge fingerprints of soil after removal of organic matter indicated that organic matter exerted a strong influence on both the magnitude of negative charge and rate of change with pH. Kaolin had permanent and variable charge, with SSA and crystal size (MCD001) being highly predictive of the rate of change in variable negative charge with pH. Iron oxide concentrates exhibited strongly pH-dependent charge and the mean coherently diffracting length (MCD110) of hematite was highly predictive of both the magnitude and rate of change in variable positive charge with pH. Charge coefficients (Ac, Ba) had highly significant (P = 0.005) positive relationships with Langmuir and Freundlich phosphate sorption maximum coefficients (Xm, k), indicating that the surfaces of amorphous, poorly ordered, and crystalline Fe and Al oxides are prime sites for both P sorption and variable charge.

Critical Technical Issues in High Voltage SiC Power Devices

2008 ◽  
Vol 600-603 ◽  
pp. 895-900 ◽  
Author(s):  
Anant K. Agarwal ◽  
Albert A. Burk ◽  
Robert Callanan ◽  
Craig Capell ◽  
Mrinal K. Das ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Carrier Mobility ◽  
Negative Charge ◽  
State Of The Art ◽  
Power Devices ◽  
Power Mosfets ◽  
Large Numbers ◽  
Technical Issues ◽  
The Difference ◽  
Difficult Issue

In this paper, we review the state of the art of SiC switches and the technical issues which remain. Specifically, we will review the progress and remaining challenges associated with SiC power MOSFETs and BJTs. The most difficult issue when fabricating MOSFETs has been an excessive variation in threshold voltage from batch to batch. This difficulty arises due to the fact that the threshold voltage is determined by the difference between two large numbers, namely, a large fixed oxide charge and a large negative charge in the interface traps. There may also be some significant charge captured in the bulk traps in SiC and SiO2. The effect of recombination-induced stacking faults (SFs) on majority carrier mobility has been confirmed with 10 kV Merged PN Schottky (MPS) diodes and MOSFETs. The same SFs have been found to be responsible for degradation of BJTs.

Influence of Various Soil Properties on the Adsorption and Desorption of ICIA-0051 in Five Soils

1992 ◽  
Vol 6 (3) ◽  
pp. 583-586 ◽  
Author(s):  
John S. Wilson ◽  
Chester L. Foy
Keyword(s):  
Sandy Loam ◽  
Clay Content ◽  
Silty Clay ◽  
Silt Loam ◽  
Clay Loam ◽  
Soil Factors ◽  
Silty Clay Loam ◽  
Freundlich Equation ◽  
General Order ◽  
Highly Correlated

The soil organic matter and/or humic matter fraction was highly correlated with the adsorption of ICIA-0051 herbicide onto five soils; clay content and other soil factors were less correlated. The Freundlich equation was used to describe the adsorption of ICIA-0051 by the various soils. Based on the K constants, the general order for adsorption for each soil was Hyde silty clay loam > Frederick silt loam > Davidson clay = Bojac sandy loam > Appling loamy sand. Across all soils, 25 to 50% of the amount adsorbed was removed by two desorptions. Appling, Bojac, and Davidson soils retained less herbicide after two desorptions than did Frederick and Hyde.

Persistence and Movement of Sethoxydim Residues in Three Minnesota Soils

Weed Science ◽  
1993 ◽  
Vol 41 (4) ◽  
pp. 634-640 ◽  
Author(s):  
William C. Koskinen ◽  
Kathryn M. Reynolds ◽  
Douglas D. Buhler ◽  
Donald L. Wyse ◽  
Brian L. Barber ◽  
...  
Keyword(s):  
Sandy Loam ◽  
Dimethyl Ester ◽  
Field Analysis ◽  
Silt Loam ◽  
Clay Loam ◽  
Ground Water Quality ◽  
Flame Photometric Detector ◽  
Additional Information ◽  
Potential Impact ◽  
Pentanedioic Acid

The persistence and movement of sethoxydim residues were determined in the top 45 cm of an Estherville sandy loam (sl), Port Byron silt loam (sil), and Webster clay loam (cl) in the field. Analysis of sethoxydim residues simultaneously quantified parent and eight metabolites by conversion to a common volatile end product, 3-[2(ethylsulfonyl)propyl]-pentanedioic acid dimethyl ester, followed by analysis using gas chromatography (GC) and a flame photometric detector. Recovery of residues from soil spiked with 100 μg kg-1was 86 ± 21%. Residues remaining in soil 21 days after treatment (DAT) in 1989 were 37, 51, and 29% of the applied sethoxydim in the sl, sil, and cl, respectively, while in 1990, 86, 52, and 24% remained in the sl, sil, and cl, respectively. Alachlor remaining 21 DAT in 1989 was 66, 52, and 65% of that applied in the sl, sil, and cl, respectively, while in 1990, it was 16, 13, and 100% in the sl, sil, and cl, respectively. Atrazine had the greatest % of applied chemical remaining 21 DAT in 1989: 100, 71, and 73% in the sl, sil, and cl, respectively. of the atrazine applied in 1990, atrazine remaining 21 DAT was 87% in the sl, 42% in the sil, and 100% in the cl. Over all soils and years, the amount of total sethoxydim residues remaining 137 DAT was the least of the three herbicides. In terms of leaching, sethoxydim residues showed least movement, with minimal detections below 0 to 15 cm. Although sethoxydim appears to be advantageous over alachlor and atrazine in terms of potential impact on ground water quality, additional information regarding composition of the detected residues is needed to better assess its environmental impact.

A study of the relationships of interactions between Asp-201, Na+ or K+, and galactosyl C6 hydroxyl and their effects on binding and reactivity of β-galactosidase

2004 ◽  
Vol 82 (2) ◽  
pp. 275-284 ◽  
Author(s):  
Julia Xu ◽  
Mary A.A McRae ◽  
Scott Harron ◽  
Beatrice Rob ◽  
Reuben E Huber
Keyword(s):  
Physical Properties ◽  
Negative Charge ◽  
Binding Pocket ◽  
Side Chain ◽  
Wild Type ◽  
Sodium Potassium ◽  
The Difference ◽  
Potassium Binding ◽  
Covalent Intermediate ◽  
Catalytic Effects

The interactions between Na+ (and K+) and Asp-201 of β-galactosidase were studied. Analysis of the changes in Km and Vmax showed that the Kd for Na+ of wild type β-galactosidase (0.36 ± 0.09 mM) was about 10× lower than for K+ (3.9 ± 0.6 mM). The difference is probably because of the size and other physical properties of the ions and the binding pocket. Decreases of Km as functions of Na+ and K+ for oNPG and pNPG and decreases of the Ki of both shallow and deep mode inhibitors were similar, whereas the Km and Ki of substrates and inhibitors without C6 hydroxyls remained constant. Thus, Na+ and K+ are important for binding galactosyl moieties via the C6 hydroxyl throughout catalysis. Na+ and K+ had lesser effects on the Vmax. The Vmax of pNPF and pNPA (substrates that lack a C6 hydroxyl) did not change upon addition of Na+ or K+, showing that the catalytic effects are also mediated via the C6 hydroxyl. Arrhenius plots indicated that Na+, but not K+, caused k3 (degalactosylation) to increase. Na+ also caused the k2 (galactosylation) with oNPG, but not with pNPG, to increase. In contrast, K+ caused the k2 values with both oNPG and pNPG to increase. Na+ and K+ mainly altered the entropies of activation of k2 and k3 with only small effects on the enthalpies of activation. This strongly suggests that only the positioning of the substrate, transition states, and covalent intermediate are altered by Na+ and K+. Further evidence that positioning is important was that substitution of Asp-201 with a Glu caused the Km and Ki values to increase significantly. In addition, the Kd values for Na+ or K+ were 5 to 8 fold higher. The negative charge of Asp-201 was shown to be vital for Na+ and K+ binding. Large amounts of Na+ or K+ had no effect on the very large Km and Ki values of D201N-β-galactosidase and the Vmax values changed minimally and in a linear rather than hyperbolic way. D201F-β-galactosidase, with a very bulky hydrophobic side chain in place of Asp, essentially obliterated all binding and catalysis.Key words: β-galactosidase, sodium, potassium, binding, aspartic acid.

Aeolian silt contribution to soils on mountain slopes (Mt. Ślęża, southwest Poland)

2017 ◽  
Vol 89 (3) ◽  
pp. 702-717 ◽  
Author(s):  
Jaroslaw Waroszewski ◽  
Tobias Sprafke ◽  
Cezary Kabala ◽  
Elżbieta Musztyfaga ◽  
Beata Łabaz ◽  
...  
Keyword(s):  
Particle Size ◽  
Trace Elements ◽  
Major And Trace Elements ◽  
Clear Relationship ◽  
Silt Loam ◽  
Clay Loam ◽  
Loess Deposits ◽  
Study Sites ◽  
Lower Silesia

AbstractThis paper evaluates the possible contribution of aeolian silt to soils of Mt. Ślęża (southwest Poland). Silt loam textures are common across Lower Silesia and are often confused with silt clay loam, especially at the outer boundaries with thin loess deposits. Eight study sites with different thicknesses of silt loam mantles that are covered and/or mixed with underlying sediments were examined in the field. To test our hypothesis, we analyzed the particle size and geochemistry of representative horizons. Concentrations of major and trace elements as well as their cross ratios confirmed the aeolian origin of silt loam materials and clearly distinguished them from basal sediments. There is a clear relationship between the presence and depth of aeolian mantles and mixing zones with the type of underlying material. Furthermore, the incorporation of aeolian silt to regoliths/soils was a main agent initiating and stimulating clay translocation leading to the formation of an argic horizon below the silt mantles. Mixing aeolian silt with acid granite regoliths and further illuviation resulted in the formation of alisols, while silt contributions to serpentine sediments resulted in development of skeletic luvisols. Soils receiving very weak input of aeolian silts remain as leptosols/cambisols.

Sign in / Sign up

Export Citation Format

Share Document