摘要:

We studied sulfate adsorption by four acid forest soils to determine the adsorption capacities of these soils and to compare different adsorption equations in describing sulfate adsorption. The adsorption capacity of the iron-podzols (P1and P5) was nearly double that of the semipodzol (P4) and the brown earth (P6), but none of the soils showed a tendency to reach maximum within the SO4-2concentration range (10 to 800 μg S/ml) tested. The iron-podzols also showed a higher affinity for SO4-2adsorption than the semipodzol and brown earth. Not only the adsorption capacity but also the affinity for sulfate adsorption was reduced when the SO4-2adsorption data were corrected for isotopically exchangeable SO4-2Of the five adsorption equations—the Freundlich, extended Freundlich, Langmuir, Sibbesen, and Temkin—compared, the Freundlich equation was found to be the best in describing SO4-2adsorption. The Langmuir equation provided the alternative, if the already adsorbed SO4-2was not taken into account. The adsorption coefficients of these two equations were well correlated. For example,Aof the two equations was highly correlated (r= 0.876). The isotopically exchangeable SO4-2in these soils was found to be highly correlated (r= 0.955) with the already present SO4-2(phosphate-extractable).

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We present an accurate analytical approximation for the water profile in a soil, taking into account small but nonnegligible air effects. The method relies on using a Brutsaert-type profile and an optimization condition. The approximation is accurate enough for any practical purpose, but an iterative scheme can also be used if more accuracy is needed. The paper assesses the precision of the method for an exponential law diffusivity and, finally, presents a simpler but still accurate approximation. It is shown that water intake for constant soil water potential at the surface increases with air effects, but that it decreases for constant water pressure, as expected.

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We describe the application of least-square polynomials (trend-surface analysis) to estimate average annual soil temperatures at locations within a network of stations. The procedure is illustrated using data from Virginia and neighboring states.The third-degree polynomial gives anR2of 0.7062, small residuals, and isotherms that correspond to large local effects. Residuals indicate that areas with high elevations in the Blue Ridge and the Ridge and Valley physiographic provinces are cooler than predicted. Areas with low elevations in the Piedmont and the Ridge and Valley regions are warmer than predicted. The 14°C isotherm nearly corresponds to the Blue Ridge-Piedmont physiographic boundary throughout Virginia.

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The sorptive behavior of aniline was investigated in two Alfisols from eastern coal regions. Batch adsorption/desorption studies (soil/solution ratio 1:5, aniline concentration 25 to 400 μg/ml) were performed on the prominent genetic horizons of each soil. Sorption was evaluated as a function of equilibrium pH and ionic strength (Na2SO4) of the supporting electrolyte and on selected horizons treated to remove organic materials (H2O2oxidation) and secondary iron components (oxalate and DCB-extractable). The behavior of aniline in the B horizons was concentration-dependent, and at higher concentrations (>75 μg/ml) sorption exceeded that of the upper or A horizons and was reversible. Aniline sorption was pH-dependent, reflecting different mechanisms and sites of sorption in the A and B horizons. Binding of aniline in the A horizons was greater below the compound pKa; maximum sorption in B horizons occurred above the pKa. Sorption in the A horizon was controlled primarily by partially irreversible interaction with organic materials; the high degree of sorption in the lower horizons may have resulted from proton transfer reactions and binding of the anilinium ion to interlayer areas of phyllosilicate minerals.

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We determined three different forms oftrans-4-hydroxycinnamic acid in 24 samples of peat soils from Hokkaido, the northernmost Japanese island. The A form, designated as the free form, was isolated with hot ethyl acetate by repeated refluxing and is significant for allelopathic studies. The B form is a combined form; it was extracted with hot ethyl acetate. The C form, another combined form, was unextractable with hot ethyl acetate, but could be isolated with hot 2MNaOH by repeated extraction. The C form appears to be bound to the soil matrix and not to move easily in the environment. On average the relative distribution of the A, B, and C forms of the acid in the 24 samples was approximately 2, 3, and 96%, respectively. We classified the 24 peat samples into three types according to dominant peat-forming plants. The total amounts of the A, B, and C forms of the acid varied from 3600 μg/g C soil for the low moor type to 2100 μg/g C soil for the high moor one. The total phenol content in the C fraction amounted to 14.3 mg/g soil in the low moor and 14.0 mg/g soil in the high moor. Despite the small difference in the total phenol content between both peat types, the difference in the amount of acid was appreciable. The correlation coefficient (r) between the total amount of the three forms of the acid and rubbed fiber content or the pyrophosphate index was low. If calculated separately by the three types of peat, however, there were considerable good relationships in the low moor and high moor types.

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Soil samples from three watersheds of New York State were treated with simulated rain at pH 3.5, 4.1, and 5.6 daily for 14 d, at 12 3-d intervals in three separate tests, or at 22 7-d intervals. Except for one system of treating the three forest soils, simulated acid rain reduced the amount of organic matter leached from samples of soil from which more than 0.05% of the organic carbon was leached during the exposure period. In the soil samples representing the exceptions, acid rain enhanced the leaching of organic matter. Samples from the organic layer of the treated samples of acid soil were taken at two equal depths, and the rates of organic matter decomposition in the two layers were studied. As compared with simulated rain at pH 5.6, simulated acid rain reduced the decomposition of organic matter in the three soils at both depths in three of the five tests and at both depths of two of the soils in the fourth test. In some instances, organic matter decomposition was enhanced by the simulated acid rain. Except for the sample of soil at the highest initial pH, carbon mineralization was inhibited in soils and treatments in which simulated acid rain reduced the amount of organic carbon leached, and it was stimulated in soils and treatments in which the quantity of organic carbon leached was increased by the simulated acid rain.

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Two types of neutron moisture probes designed for detecting leaks in roofs were adapted to measure surface soil water content. These were calibrated as a function of soil water content under field conditions. Calibration curves were obtained for both probes to a depth increment of 30 cm. Such equipment can be used to monitor surface soil water content and its changes, and it complements the depth probes whose accuracy fails at depths shallower than 20 cm.

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

This paper reports an investigation into the applicability of the series/parallel model of heat conduction to saturated soils. The model is expressed by the thermal conductivities of solid phase and fluid, volumetric solid content, andDvalue, which is defined as the contribution ratio of the solid phase to the series flow of heat. The experimental results show that the model can be applied to saturated soils.Both the thermal conductivity of the soil solid phase and theDvalue of the model can be determined by simultaneous equations that were derived from the model. The thermal conductivity of the soil solid phase, that is, the mean thermal conductivity of the soil solid particles, can be approximated by the weighted geometric mean of the thermal conductivities of each soil solid particle. The thermal conductivities of the solid phases, which were determined by the series/parallel model, were used to calculate de Vries' equation. The calculated values agree well with the measured values. TheDvalues of the model are in the neighborhood of 0.95 for the granular materials and soils used in this work.

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

We examined cadmium sorption in three soils that were unamended, freshly amended, or preconditioned with gamma-irradiated sewage sludge. We also studied metal sorption in the same soils treated with a CaCl2-extract of the sludge. Cadmium sorption was greatest in the unamended soils, less in soils preconditioned with sludge, and least in the freshly amended soils and sludge-extract-treated soils. We attempted to explain the treatment effects on the basis of reduced free metal ion activity, but the explanations were not adequate. Despite the reduction in metal retention effected by various treatments, cadmium mobility was very limited. Short- or long-term leaching studies showed cadmium movement to be limited to 1 or 2 cm below the zone of sludge (109Cd) incorporation. Cadmium mobility is expected to be very limited in calcareous soils, regardless of sludge treatments.

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID

ISSN:0038-075X    

出版商:OVID    

年代:1984

数据来源: OVID