ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

This work elucidates the effect of pH on the catalytic synthesis of humic substances by illite. Several portions of the sieved, peroxidized calcium illite (Morris, Illinois) were adjusted to pHs 4.0, 5.7, 6.9, and 8.5, respectively. A separate portion, of pH 8.5, was mixed with calcite powder (97:3). Each of the treated portions of illite was allowed to react with an adequate amount of a solution of phenolic compounds and urea on glass plates. Then all the plates were placed in a closed, sterilized glass cabinet. The rate of chemical change of the phenolic compounds increased with the pH of the illite, due to enhanced formation of free radicals and more intensified autooxidation. The neutral and alkaline illite favored the formation of humic and fulvic acids, particularly humic acids, whereas the alkaline illite containing CaCO3gave the lowest yield. At pH 4.0 and 8.5 + CaCO3, the formation of fulvic acids predominated that of humic acids. Elemental composition, functional groups, and infrared absorption spectra of the organic polymers were also presented.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

I grew wheat (Triticum aestivumL. em. Thell. ‘Osage’) with roots split between soil that had no added cadmium and was not watered and nutrient solution that contained 1 microgram per milliliter of cadmium, to see if cadmium ions and water would be transferred from the nutrient-solution side of the root system to the soil side. Roots in soil had about 25 times more cadmium than those of plants with roots split between soil and nutrient solution without cadmium. The soil remained saturated during the 50-day experiment, even though no water was added to the soil. The results showed that ions were transferred from roots in solution with cadmium ions into roots in soil not containing the ions and that water was transferred from nutrient solution into soil.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Site safety factors require that a nuclear reactor not be built over an active fault. Pedological principles have been used to assist in defining the minimum time since the last movement of a fault. Soil morphology may indicate if a fault associated with the soil last moved before or after the formation of the soil. Mineral or rock alteration within the soil may indicate the minimum amount of time represented by the soil.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To evaluate statistically the age-related changes of youthful sandy soils at a beach ridge and dune complex in northeastern Illinois, I used stepwise discriminant analysis: (1) to determine which pedogenic variables have the greatest ability to discriminate between different aged soils; (2) to evaluate whether pedogenic changes are significantly great enough to classify a majority of pedons into their predetermined groups; and (3) to attempt a quantitative assessment of the relative degree and rate of soil formation. The analyses suggested that a near steady state is attained as the soil approaches an age of about 300 years. The variables that best differentiate the soils were the thickness of the A1 horizon and the amount of clay in the B horizon. Finally, the ability to use discriminant analysis to test the probability of each sampling location belonging to a particular age is warranted because 41 of 60 sampling locations were correctly classified into their a priori age group.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

We conducted a laboratory experiment to study the effect of exchangeable cations on zinc (Zn) adsorption in soils, in order to understand better their contribution in the availability of applied Zn. Zinc adsorption in different cation-saturated soils was in the order: hydrogen < calcium ≤ magnesium < potassium < sodium. The pH of both the cation-saturated soils and the cations in question influenced Zn adsorption. The selectivity coefficient varied with the initial Zn concentration and the cations in question. The calculated values of standard free energy of adsorption for the Ca-Zn, Mg-Zn, K-Zn, and Na-Zn exchange reactions were 41.3, 41.5, 31.1, and 23.6 calories per mole, respectively. The positive values indicated the nonspontaneous nature of exchange reactions and less preference of Zn on the exchange complex at low equilibrium Zn concentrations.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Patulin was applied to Holdrege silt loam, Sharpsburg silty clay loam, Peorian loess subsoil, and fine quartz sand in concentrations of 200, 400, and 800 micrograms per gram of soil or sand. Patulin disappearance was determined by chemical analysis and bioassay techniques using winter and spring wheat (Triticum aestivumL.). After application of 400 micrograms of patulin per gram of soil, only 27 to 69 percent of the patulin was immediately extractable using ethyl acetate. The inability to extract patulin from soil or sand was related to physical and chemical properties. Patulin seemed to be inactivated biologically and nonbiologically in the soil. After 192 hours, patulin was detected in only one of the autoclaved soils treated with 400 micrograms of patulin. Ammonia vapors detoxified patulin and produced products that could be measured by fluorescence under ultraviolet light, and this method of analysis could be used to screen routinely for patulin in samples.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Representative pairs of muck and peat (sapric and hemic Histosol) samples were collected from a mildly cupriferous virgin bog under a normal mixed forest flora near Sackville, New Brunswick, Canada. Samples within each pair were similar in their physical and chemical properties except for their copper contents, in which they have varied widely for a long time. In agreement with the evidence of the mitigating effect of copper on decomposition, already in the literature, a muck (sapric) sample containing 2922 parts per million of total copper lost carbon through aerobic soil respiration at half the rate of a muck sample containing 1159 ppm Cu. Similarly the soil respiration rate of the peat (hemic) sample containing 797 ppm Cu was half that of the peat sample with 408 ppm Cu.Within each pair of samples, which were air-dried following a 6-week incubation, C1-cellulase, Cx-cellulase, cellobiase, xylanase, chitinase, lichenase, inulase, pectinase, amylase, invertase, lactase, maltase, lipase, protease, and acid phosphatase enzyme activities were all found to be lower in samples containing higher Cu. Enzyme activities were decreased on an average by 79 ± 10.5 percent and 66.2 ± 7.1 percent, apparently due to the natural increments of the Cu contents of the muck and peat samples, respectively. Assays of invertase, amylase, phosphatase, and protease activities in moist soil samples incubated at 21°C for 368 days indicated that, as expected, the mitigating effect of Cu on degradative activities of the enzymes functioned in microbially active soils also. These results thus suggest that the suppressive effect of Cu on levels of accumulated enzyme activities noted earlier in soils that contained increased concentrations of Cu for only a decade or two, in fact prevails for a long time and may, therefore, be useful in mitigating the decomposition and therefore the subsidence of some Histosols. It is suggested that, due to the greater abundance of substrates in organic soils, accumulated degradative soil enzymes normally play a more important role there than in mineral soils and, therefore, contribute to the decomposition and subsidence of some Histosols.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Estimates by 10 operators of illuvial clay in thin sections of six B horizons differed widely; coefficients of variation ranged from 39 to 64 percent. The results cast serious doubt on the usefulness of oriented, apparently illuvial, clay in thin sections as a quantitative criterion of argillic horizons unless steps are taken to ensure a greater degree of uniformity of estimates.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID