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Trace elements in pedosequences II. Two Pararendzina-Pseudogley-sequences on loess Total amounts and fractions of Cu, Zn, Pb, Cd, Co and Ni extractable in boiling oxalate (replacing dithionite for analytical reasons), oxalate at room temperature and EDTA were determined in two hydro-pedosequences on loess ranging between Pararendzina-Braunerde-Parabraunerde-Pseudogley. The pedogenic influence on the depth functions of these trace elements was much weaker in the loess soils than in those on slates of part I of this study. With a few exceptions external additions seem to be masked by soil cultivation. Clay movement (Alfisols) produced maxima of Fe and Cu in the Bt horizon. Carbonates of the parent loess contain trace elements which are released into the soil during solum formation. As long as they exist in carbonates they are hardly extractable with oxalate but with EDTA. In contrast, after pedogenic decomposition of the carbonates in the B horizon their trace elements are now oxalate but no longer EDTA extractable. In the A horizon, where organic matter is involved the trace elements are again EDTA extractable. As in the soils from slate (part I) Cd behaves more similarly to Pb than to Zn. The total element balance indicates a slight gain of Pb and loss of Zn whereas the total amount of the other elements was essentially unchanged. Generally, the more mobile fractions increased during soil formation. 相似文献
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Sampling seepage water with suction cups – a literature study The article presents a literature study concerning the sampling of seepage water with suction cups. It gives a general view about construction and materials of different types of suction cups as well as proposals for the installation and arrangement of sampling equipments. Furthermore the article deals with questions related to the release or the sorption of substances by the cup material. Other problems like the influence of the applied suction on the concentration of the solutants in the seepage water sample and the potential field around the suction cup are discussed. 相似文献
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U. Schwertmann 《植物养料与土壤学杂志》1984,147(3):385-399
Al-substitution in Fe-oxides This article resumes the present knowledge on Al-substitution in Fe (III)oxides. Al-substitution is known for goethite, hematite, lepidocrocite, magnetite and maghemite. The extent of substitution is mineral specific and varies for different soil environments for which it may have some indicator value. Al-substituted Fe-oxides are easily to synthesize. A number of characteristics of the synthetic samples have been measured. The result was that most of the changes in characteristics except the unit cell size is more an indirect effect of Al-substitution because Al in the system also affects crystallinity. Crystallinity will, however, also be strongly influenced by other conditions during crystallization. Therefore, thermal behaviour, X-ray line intensity and width, magnetization, dissolution, OH-content, IR absorption characteristic etc. depend more directly on crystallinity than on Al-substitution. The variation of these characteristics for soil iron oxides is essentially unknown so far. 相似文献
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In order to ascertain the existence of the apparent paradox in the behaviour of calcined sand, the ζ-potential of sand subjected to dehydroxylation (calcined sand) – hydroxylation (autoclaved sand) was studied by a streaming potential. No or insignificant differences in the behaviour of differently pretreated sands were found. At any rate, the calcined sand has no less ζ-potential than the autoclaved sand. The existence of an electric double layer with the relevant ζ-potential indicates that some instant hydroxylation takes place when calcined sand contacts water. 相似文献
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