摘要:

A study was conducted to evaluate the suitability of selected analytical methods for correlating the uptake of copper (Cu) and zinc (Zn) by grasses on soils exposed to sewage and industrial effluents and automobile exhausts. Samples of soils and selected grasses, such asCynodon dactylonandCyperus rotundusgrowing on these polluted soils, were taken and analysed for their Cu and Zn contents by extraction. Four extractants, 4M HNO3, DTPA‐CaCl2(pH 7.3), 1N NH4OAc (pH 4.8), and 0.001N HCl were used. The results revealed that for the extraction of Cu and Zn from these soils, the efficiency of extraction was in the order of 4M HNO3> 1N NH4OAc > DTPA‐CaCl2> 0.001N HCl. Significant positive correlationns were found between all the extracting methods and the Cu and Zn uptake by the grasses. The DTPA‐CaCl2and 0.001N HCl extractants were found to be most promising extractants for the determination of Cu and Zn in the polluted soil in view of their high statistical relationship with the uptake of these elements by the grasses.

ISSN:0010-3624    

DOI:10.1080/00103629409369117

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Resistance muffle furnace dry ashing process is commonly used for plant tissue sample analysis. It takes from four to eight hours to complete the ashing process. A microwave muffle furnace, however, can reduce ashing time to about 20 minutes. Comparisons of the ashing effectiveness between the two techniques were made on six different plant tissue samples. Plant macro‐ and micro‐nutrients were determined by an inductively coupled plasma emission (ICP) spectrometer. Determination of all the major nutrients ashed by the microwave furnace for 40 minutes were comparable to those ashed in conventional muffle furnace for four hours. Results showed that microwave ashing technique can speed up analysis significantly.

ISSN:0010-3624    

DOI:10.1080/00103629409369118

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A method based on use of ion exchange resin capsules was evaluated for simultaneous extraction of plant available nutrients (N, P, K, Ca, Mg, and Na) to determine its utility as a general soil testing procedure for soils of world‐wide origin. Nutrient release kinetics of soils representing many soil orders were measured in saturated soil paste during 14 d incubation periods. Suppressed ion chromatography was suitable for simultaneous determination of five cations in extracts from the resin capsules. The fractional power equation described well the cumulative nutrient adsorption by the resin as a function of time for all nutrients. The constantsaandbin this equation combine quantitative levels of nutrient availability as well as transport and release mechanisms in the soil. Ranges ofaandbin soil are presented and their relationships to other soil properties are discussed. A simple method for calculating kinetic constants in the power function based on only two incubation times is proposed. The Phytoavailability Soil Test method offers great potential for standardized, multi‐element soil testing in many environments. Some aspects of its suitability for use in standard soil testing for rice are discussed.

ISSN:0010-3624    

DOI:10.1080/00103629409369119

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Kinetics of K desorption was studied on Alfisol Haploxeralf samples of central Greece. Calcium‐saturated samples were equilibrated with different potassium concentrations and pH for 96 hours at pH 5.0, 6.0, 7.0 and 8.0 and initial potassium concentrations of 7, 35, 54 and 112 ppm. Samples were continuously leached with 0.01 M CaCL2until K was not detected in the leachate. Desorption was nearly complete in approximately 3 to 4 hours for the Alfisol Haploxeralf. When the initial K concentrations varied between 0–7, 7–35, 35–54 and 54–112 ppm, then approximately 95–97%, 93–98%, 75–96% and 18–75%, respectively, was subsequently desorbed from Alfisol Haploxeralf samples. Three mathematical models (first order, power function and parabolic diffusion) were used to describe cumulative potassium release at different values of pH and initially adsorbed K. Comparisons of coefficients of determination (r2) indicated that the first order, power function and parabolic diffusion equations adequately described cumulative potassium release for all studied pH and initially adsorbed potassium. Apparent potassium desorption rate coefficients (k) ranged from 4.3 x 10‐3to 11.43× 10‐3min‐1. The magnitude of the k values decreased as adsorbed potassium and pH increased. Finally all the studied models were transformed to pH‐dependent forms.

ISSN:0010-3624    

DOI:10.1080/00103629409369120

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The one‐ and two‐surface Langmuir, the Freundlich and the Temkin isotherms were fitted to potassium sorption data for Alfisol Haploxeralf at pH range of 4.0 to 8.0. Each was found to describe potassium sorption data with comparable success, with the Freundlich model being slightly superior. The effect of pH on the potassium adsorption was studied and Langmuir, Freundlich and Temkin isotherms were converted to pH‐dependent forms. The amount of adsorbed potassium increased as pH and initial concentration increased. From the Landmuir isotherm, the maximum amount (Xm) that can be sorbed in a monolayer was estimated. It is noteworthy that the maximum amount (Xm) of K increases by increasing pH. The four isotherms were transformed into pH‐dependent forms.

ISSN:0010-3624    

DOI:10.1080/00103629409369121

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The kinetics of potassium adsorption from solution to exchangeable phases was investigated on bentonite samples which were first saturated with calcium in the form of CaCl2. Potassium adsorption time was evaluated on Ca‐saturated samples using 125, 150, 200 and 250 μgK/ml solutions, equilibrated for 10, 15, 20, 30, 35, 45, 60, 75, 80 and 120 minutes. Sample pH levels varied between 4.0 and 9.0. Equilibrium in potassium exchange was reached faster in lower concentrations and higher pH values. Four mathematical models (first‐order rate, parabolic diffusion, Elovich and modified Freundlich equation) were used to describe potassium sorption. Comparison of coefficients of determinations (r2), and plots indicated that modified Freundlich and parabolic diffusion models provided the best fits of the adsorption data (r2> 0.979). Constants for the Freundlich equation were estimated and the model was expressed as a function of pH.

ISSN:0010-3624    

DOI:10.1080/00103629409369122

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The kinetics of potassium desorption from solution to exchangeable phases was investigated on Alfisol Haploxeralf samples, which were first saturated with calcium in the form of CaCl2. Potassium adsorption was studied using 5, 25, 100, 125, 150 and 200 μgK/ml solutions and equilibrated for 10, 20, 30, 45, 60, 120, 180 and 1440 minutes. Soil pH varied between 4.0 and 9.0. Equilibrium in potassium adsorption occurred faster in lower concentrations and higher pH values. Adsorption data Were plotted according to modified Freundlich, Elovich and parabolic diffusion equations. Comparisons of coefficients of determination (r2) indicated that all of the tested models successfully demonstrated potassium adsorption with the modified Freundlich equation and the Elovich equation being superior.

ISSN:0010-3624    

DOI:10.1080/00103629409369123

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The kinetics of potassium adsorption from solution to exchangeable phases was investigated on Entisols Herothern from central Greece. Potassium adsorption with time was evaluated on Ca‐saturated samples using 3.5, 16.8, 67.5 and 86.0 ppm initial concentrations and pH levels of 5.0, 6.0, 7.0, 8.0 and 9.0. Four mathematical models (first‐order rate, parabolic diffusion, power function and Elovich) were used to describe cumulative K adsorption. Comparisons of coefficients of determination (r2) indicated that the power function, Elovich and first‐order rate models adequately described cumulative K adsorption, whereas the parabolic diffusion model was less successful. Constants A and B were calculated from reaction time vs. quantity of K adsorbed using the four mathematical models. From all four tested models only the power function and first‐order models were found to be transformed to pH‐dependent forms.

ISSN:0010-3624    

DOI:10.1080/00103629409369124

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The soils of agricultural areas in Greece are formed from alluvial calcareous deposits, mainly classified as Entisols. The objectives of the present investigation were to elucidate the most commonly used isotherms of potassium adsorption by Entisols at pH levels of 5.0, 6.0, 7.0, 8.0 and 9.0 and initial concentrations of 3.5, 10.7, 17.8, 22.1, 32.1, 37.1, 43.6, 53.6, 60.7, 69.3, 74.3, 78.6 and 85.7 μgK/ml of potassium solution. Isotherms used included those of Langmuir, Freundlich and Temkin. They were fitted by regression to the adsorption data and compared on the basis of goodness of fit (using the correlation coefficient of Pearson r2). Each was found to describe K sorption by this soil with comparable success, with the Freundlich model being slightly superior. The effect of pH on the potassium adsorption by this soil was studied and Langmuir, Freundlich and Temkin isotherms were converted to the forms: Langmuir:

ISSN:0010-3624    

DOI:10.1080/00103629409369125

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The present project describes the planning and development of PC software for soil, plant and irrigation water analysis. Our main target was to develop user‐friendly software that is easy to handle and capable of covering all the laboratory needs. So we developed three programmes entitled “soil,”; “water,”; and “plant”; to support soil, plant and irrigation water analysis, respectively.

ISSN:0010-3624    

DOI:10.1080/00103629409369126

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor