共查询到20条相似文献，搜索用时 78 毫秒
1.
Interaction between soil humic substances and metal ions. II. Investigation of soil humic substances by gel permeation chromatography and vapour pressure osmometry By gel permeation chromatography and vapour pressure osmometry average molar masses of soil fulvic and soil humic acids from two horizons of a podzol were determined. For the fulvic acids average molar masses of 9000 g/mol were obtained by the chromatographic method, while 5000 g/mol were obtained by the osmometric method. In contrast to these results for the humic acids values were measured which are 3 - 4 times larger when measured by gel permeation chromatography and 2 - 3 times smaller when measured by vapour pressure osmometry. The average molar masses found show that the applied methods of isolation and purification as well as the different determination methods with the experimental conditions attached to them have a considerable influence on the molecular size of the isolated humic substances. 相似文献
2.
3.
Development of heavy-metal deposition by precipitation in West Germany. 2. Arsenic, chromium, cobalt, and nickel Between 1984 and 1993 the deposition of As, Cr, Co and Ni with bulk precipitation was measured on 6 open field sites in Northrhine-Westphalia/Germany. The absolute amount of As, Cr, Co and Ni deposition varies according to field sites and annual precipitation. In all studied areas, however, As deposition with bulk precipitation decreased significantly during the observation period. Considering all research stations under study, the average As deposition fell from 11.0 g ha?1 in 1984 to 3.0 g ha?1 (r = ?0.982***). The reduction in As deposition corresponds with the reduction in As emission within the same period of time prognosticated. Immission of Cr and Co also decreased significantly over the majority of the studied areas. The avarage Cr immission fell from 8.5 g ha?1 in 1984 to 3.5 g ha?1 in 1993 (r = ?0.888***), whereas the average Co immission decreased from 2.6 g ha?1 to 1.1 g ha?1 (r = ?0.869***). In contrast, no reduction in Ni deposition with precipitation was found on any of the studied areas under observation. Co shows the lowest deposition rates. On average, 2.2 times as much Cd, 2.7 times as much As, 3.2 times as much Cr, 6.5 times as much Ni, and 66 times as much Pb was deposited on the six open field sites in Northrhine-Westphalia in 1993. 相似文献
4.
Interactions between soil humic substances and metal ions I. Isolation and characterization of the soil humic substances From two horizons of a podzol humic acids and fulvic acids were isolated by two different methods. The obtained samples were characterized by elemental analysis, the determination of the ash and moisture content, functional group analysis as well as FTIR-, 1H-NMR-, and 13C-NMR-spectroscopic examinations. In spite of the different isolation methods humic and fulvic acids show great similarities. A higher oxidized state and a lower content of aromatic structural features are clearly observed in the fulvic acids in contrast to humic acids. Besides aromatic structural elements, distinct aliphatic sections were detected in the investigated samples, which showed a lower concentration in the less transformed fractions of the Ahe-horizon. 相似文献
5.
6.
H. Wiechmann 《植物养料与土壤学杂志》1981,144(2):174-180
Differentiation of the subtypes humuspodzol, humus-iron podzol and iron podzol Humic podzols are characterized by a distinct Bh-horizon and deep humus illuviation (humic bands). They may be thus recognized by morphological features. Differentiation of humic podzols on layered sands, of humus-iron podzols and of iron podzols is only possible by quantitative analytical data. For that the ratio of pyrophosphate-extractable C/Fe is proposed: humic podzols (Bh) > 10, humus-iron podzols (Bhs) 3–10, iron podzols (Bs) < 3. For differentiation of soil varieties quantities of illuviated matter in the investigated illuvial subhorizons (Bh, Bhs, Bs) may be chosen. 相似文献
7.
8.
9.
10.
Johannes Helm 《Genetic Resources and Crop Evolution》1972,19(1):73-100
Zusammenfassung Anhand von nachweisbaren Belegen wurde für die seit den historischen Zeiten bekannte ArtApium graveolens L. ein Überblick über deren Kultur bis heute sowie über die sich wandelnde Nutzung gegeben. Abschließend wurde die Taxonomie der sich seit der Mitte des 17. Jahrhunderts heraus-differenzierenden Varietäten ausführlicher dargelegt.
Apium graveloens L. History of cultivation and taxonomy
Summary All kinds of known historical documents were used to complete our knowledge about the cultivation and utilization ofApium graveolens L. since the history of our times up to this day. The specialization of distinguishing varieties in the middle of the XVIIth centuries and their taxonomy were explained in detail.
Apium graveolens L. —
(Apium graveolens L.) . , XVII .相似文献
11.
W. Bussler 《植物养料与土壤学杂志》1974,137(1):62-62
12.
13.
14.
15.
16.
17.
18.
Investigations about the availability of heavy metals in soils with lithogen and anthropogen enrichment. 1. Cd and Cu First results obtained from field experiments on two locations with high natural content of heavy metals (Cd and Cu) are described. It became evident that an anthropogen enrichment by addition of Cd oxides had a stronger effect on the Cd contents of plants (oats) than the higher lithogen soil content. In respect of the Cu it is indicated that contrary to the prevailing knowledge of high lithogen contents it seems that it leads to increased contents of the plants (barley). The CaCl2-extraction of the soil has proved to be suitable to identify the plant available Cu contents, but it is restricted to determine the available Cd fraction. The DTPA-extractable fractions showed poorer relations to the metal contents of the plants. 相似文献
19.
Quantitative estimation of the mineralogical composition from silt-fractions of soils on the basis of the chemical analysis and by application of the Karl-Fischer-titration. II. Results obtained with soils from glacial sand, boulder marl and loess The contents of micas and feldspars were quantified in the silt-fractions from horizons of a podsolic brown earth developed on glacial sand and of lessives on loess as well as on boulder marl by using a method that has been described in detail in part I. Three components each of micas and of feldspars, namely muscovite (Ms), phlogopite (Phl), annite (Ann), orthoclase (Or), albite (Ab) and anorthite (An) were determined. The silt fractions of the three investigated soils are similar in their mineralogical composition. Feldspars are composed of equally high amounts of Or and Ab. Micas are dominated by the Ms-component. Apparently the mica content of the silt fractions is reduced during soil development, whereas no significant changes can be found for feldspars. The loss of micas is responsible for the decreasing potassium content of the silt fractions. 相似文献
20.
F. Lenz 《植物养料与土壤学杂志》1973,136(2):176-176