Zwischenmolekulare Kräfte und die Struktur von Huminstoffen

Intermolecular forces and the structure of humic substances This study endeavors to draft a scheme for a system of humic substances with regard to interatomic and intermolecular forces. Hence are to distinguish two states with prevailing interatomic forces in the statu nascendi and otherwise with intermolecular forces in the stationary condition.     

Wechselwirkungen von Huminstoffen mit Peptiden

Interactions of Humic Substances with Peptides By means of the model reaction of p-benzoquinone with a number of peptides it has been shown that electron donor acceptor complexes between the reactants are formed. This mechanism could be verified by spectroscopic measurements and gas exchange investigations. The takings of differential spectra in the ultraviolett region are showing modifications which are caused by the reaction of the peptides with the humic substances of a peaty soil. They are traced back to the enlarged dissociation of the phenolic hydroxyl of the L-tyrosyl-glycine, which is caused by the formation of the charge transfer complexes with the humic substances. By gel permeation chromatography in equilibrium state the binding of peptides to the humic substances is verified and quantitative statements are possible.     

Wechselwirkungen von Huminstoffen mit Aminosäuren

Interaction of Humic Acid with Amino Acids By means of the charge-transfer complexes between p-benzoquinone and a number of amino acids, this possible mechanism of the reaction of humic acids with amino acids has been pointed out in principle. The mechanism has been confirmed for the humic acids by the absorption spectra in the ultraviolett and visible range and an increase of the dissoziation of the phenolic hydroxyl of the tyrosine molecule. The quantitative aspect of this binding has been dealt with by gelfiltration in a state of equilibrium. 70 μmol of tyrosine were found to be bound by one gram of a synthetic humis acid.     

Cyanidadsorption an Sesquioxiden,Tonmineralen und Huminstoffen

Cyanide adsorption on sesquioxides, clay-minerals and humic substances The adsorption of cyanide (KCN) on sesquioxides, clay minerals, and humic substances at different pH-values was studied. Moreover we looked for the CN-adsorption on L-layers of the humus forms mull, moder and mor. Cyanide was only adsorbed by humic acid. The amount of CN adsorbed increased with increasing pH of the reaction solution. IR-spectroscopic investigations of CN treated humic acids revealed that the cyanide was adsorbed at low pH (<7) as HCN-molecules by formation of hydrogen bonds with COOH-, COH-, OH- and NH₂-groups of the humic acid. At pH > 7 the cyanide was mainly adsorbed as CN^? by charge transfer with acceptor-molecules such as chinones. The cyanide adsorption of L-layers of humus forms decreased in the order mor > mull > moder. It is surmised that the HCN-molecules were not only adsorbed by humic acids in these layers but also by oxidation products of lignin, pectin, protein, cellulose, and carbon-hydrates of fulvic acids. Solutions of K₂HPO₄ did not desorb cyanides from humic acids to any great extent.     

Zusammensetzung und Eigenschaften von Sickerwasser aus Stallmiststapeln

Composition and properties of leachates from farmyard manure heaps Besides some rheological characteristics, the N_total, NH₄⁺-N, NO₃^? -N, P, K⁺, dry matter and ash content, as well as chemical oxygen demand and conductivity of farmyard manure leachates were examined. The K⁺ concentration was highest with an average of 5921 mg l^?1, followed by N_total (1139 mg l^?1, 66% of it as NH₄⁺-N and 4% NO₃^?-N) and P (334 mg l^?1). All parameters were highest in leachates of fresh manure and lowest at the end of a 6 months storage period. During the storage, the P concentration in leachates showed a decrease of 67.7%, followed by a decrease in N_t (-57.3%) and K⁺ (-24.0%). In leachates from a manure with an relatively high initial N_t content of 0.51% and a low C:N ratio of 16.8 the N_t concentration was 0.5–1 times higher than that of a manure with 0.44% N_t and a C:N ratio of 19.9. The viscosity and the thixotropy of leachates were both relatively high at the beginning of the manure's storage period, which led to a strongly developed blocking of porous systems. These properties that contribute to explain the high retention rate of nutrients in the top soil layer at manure storage sites, decreased with an increase in storage time.     

Bedeutung der Aktinomyceten für den Abbau von Cellulose,Lignin und Huminstoffen im Boden

Importance of Actinomycetes for the decomposition of cellulose, lignin, and humic substances in soil Actinomycetes are a group of microorganisms frequently occurring in neutral soils. They are part of the autochthonous microflora. A great number of families and genera which exhibit various and partly unusual physiological behaviour, belong to the Actinomycetales. Thermophilic actinomycetes in particular play an important role in the degradation of organic matter, e.g. Thermoactinomyces and Thermomonospora. Arthrobacter and Nocardia contain species which are able to decompose aromatic lignin-precursors and lignin itself. Even humic acids being composed by aromatic compounds can be utilized by Nocardiae as C- and N-source. Streptomycetes by their phenoloxidases take part in the formation of humic acids from the residues of slowly degradable organic substances. Referring to the succession fungi are the first while actinomycetes are the last colonizers of organic matter (Mischustin 1978).     

Ergebnisse aus gefassversuchen mit graskomposten und messungen von gasemissionen aus einer graskompostanlage

In den Jahren von 1993 bis 1995 wurde die Wirkung verschiedener Graskomposte auf den Haferertrag (oberirdische Masse und Wurzeln) in Mitscherlich‐Gefäßen geprüft. Schwerpunkte waren: gemahlener gegenüber ungemahlenem Kompost, verschiedene Zusätze wie Muttererde, Stalldung, Laub, Äste und Nährlösungen. Ab 1994 wurde zusätzlich eine Kompostprobe der Berliner Stadtreinigungsbetriebe zum Vergleich untersucht. Kompost von auszuhagernden Wiesen enthält keine Schadstoffe und kann unbedenklich eigesetzt werden. Signifikant gesicherte Mindererträge hatten die gemahlenen Kompostvarianten. Graskompost ersetzt die Wirkung von P und K. Das Kompostgut mit einem Stickstoffdünger anzureichern, wird empfohlen. Im Jahre 1994 wurden Gasemissionen bei Ammoniak (NH₃), Lachgas (N₂O), Methan (CH₄) und Kohlendioxid (CO₂) in verschiedenen Schichten der Varianten Gras und Muttererde sowie Gras und Stalldung der Versuchskompostanlage gemessen.     

Isolierung und Kennzeichnung von Lignin aus einem Podsol-B-Horizont

Isolation and characterisation of lignin from a podsol B-horizon A method was worked out to isolate a representative sample of lignin from the B-horizon of a sand podsol. All analyses were also carried out on lignin from straw (Triticum aestivum). The podsol lignin belongs mainly to the guaiacyl/syringyi-p-coumar type, only a very small part is guaiacyl type lignin. Compared with lignin of straw the podsol lignin is more polar and better suspendable in water. It has less chromatophore groups like aliphatic double bonds in propene side chains, phenyl coumarone systems and stilbenoid structures as well as conjugated aldehyde and keto groups. The primary and secondary hydroxy groups increased, also the bonds between the phenylpropane units by esterification and condensation. New carboxyl groups were built up to a large extent and nitrogen was bound covalently in primary and secondary form.     

Adsorption von Pflanzenschutzmitteln und DOC an Saugkerzen aus Glas und Keramik

Sorption of pesticides and DOC on glass and ceramic suction cups Suction cups are widely used for the sampling of soil solution. Due to sorption and desorption processes the concentration of dissolved substances in the samples may vary considerably depending on the material of the suction cups. In order to minimize these losses, a new glass suction cup was developed. In laboratory studies, aqueous solutions of pesticides and DOC were percolated through both types of suction cups; the concentration of pesticides and DOC in the percolates was examined. The pesticides pendimethaline, terbuthylazine, metolachlor and chlortoluron were tested at concentrations of 2, 20, and 200 μg 1⁻¹. The average losses due to sorption by the suction cups were 10% (1.1—31%) for the ceramic cups and 3.1% (0—11%) for the glass cups. Sorption effects increased with increasing hydrophobicity of the pesticides and decreasing pesticide concentrations. Thus, at a concentration of 2 μg 1⁻¹ ceramic cups sorbed 31% of pendimethaline compared with 7.7% in the case of glass cups. Corresponding tests with soilborne DOC solutions yielded comparable results. Ceramic suction cups adsorbed up to 50% of the DOC input concentration, while glass cups retarded 2.4% on average. These results are especially noteworthy because soilborne dissolved organic substances are effective sorbents and carriers for pesticides. The new type of glass suction cups may help to improve the results of pesticide field studies and, in consequence, the assessment and prediction of the leaching behavior of pesticides.     

Molekülkomplexe bei Huminstoffen durch e-Donator- und e-Acceptor-Strukturen

Molecule-complexes on Humic-substances by Structures with ?-Donor- and ?-Acceptor-Qualities For many considerations with reference to the biosynthesis of humic-substances it is useful to formulate radicals prevailing for certain phases. Some interesting conclusions can be drawn from this conception based on a great number of experiments. The formation of humic-substances requires radicable materials, i.e. aromatic substances (initial reactants first order, e.g. lignins). The interpretation of X-ray diffraction allows to estimate the distributation of aromatic and aliphatic share in humic-substances. The immense possibilities of chemical reactions therefore form extremely complex materials. But their uniformity makes impossible to separate them exactly. Further, with the formation of particles possessing additional properties of mesomerism the stability of the radicals increases, whilst the humification rate decreases.     

Chromatographische Trennung von teerbürtigen PAK in einem Boden

Chromatographic separation of tarborne PAH in a soil At coal gas production sites soils are frequently infiltrated by fluid coal tar. From tar-filled pores a further diffusive and/or convective dispersion of PAH into the soil matrix occurs. Results from a contaminated site indicate, that the systematic change of the PAH congener pattern along the transport vector is due to differences in solubility and adsorption. This leads to a chromatographic fractionation of the initial PAH mixture with the least adsorbed congeneres forming the front of PAH translocation and the strongest adsorbed congeneres moving clearly slower.     

Unterscheidung der Subtypen Humus-, Eisenhumus- und Eisenpodsol

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.     

Verdichtung von proben eines dystrandepts und palehumults aus südchile

Samples were taken from one of the upper layers in each of four profiles, two of each of a Dystrandept and a Palehumult. One profile of each kind of soil was in a lightly grazed and the other in a heavily grazed area. The samples were then loaded and unloaded at three different moisture contents. From the compression curves for the samples, the maximum pressure applied to the soil in the past, the compression index, the volumetric compressibility coefficient, the expansion index and the modulus of elasticity were computed.The mechanical coefficients for the Palehumult samples are correlated under both light and heavy loadings with bulk density, moisture contents and past levels of grazing. For the Dystrandept samples under light loadings, however, the coefficients are correlated with degree of aggregation and the nature of the mineral components. In contrast, the relations of the Dystrandept under heavy loading with bulk density and moisture levels are similar to those for the Palehumult samples.     

Abbau von Huminstoffen durch Bodenmikroorganismen — eine Übersicht

Degradation of humic substances by soil microorganisms — a review Humic substances which represent differently extractable fractions of the soil organic matter exert multifarious effects on soil as a site for plant growth and a part of terrestrial environments. Among them especially humic acids and fulvic acids are subject to degradation and/or transformation by soil microorganisms. Several authors demonstrated the participation of different species of fungi, actinomycetes and also of non-mycelial aerobic or anaerobic bacteria in those processes under laboratory conditions. Indications exist that humic substances irrespective of their structure undergo degradation on cell surfaces due to the activity of exoenzymes. In this respect microbial phenoloxidases play an extraordinarily important role. The degradation rate of humic substances can be followed by optical, gravimetric and chemoanalytical methods as well as using biochemical and microbiological procedures (CO₂ release, microbial growth, biomass formation). An objective evaluation, however, can be hindered by the adsorption of humic substances on microbial biomass and sometimes also by formation of novel humic-like microbial metabolites. Therefore it is necessary to apply a multifactorial approach in the study of the degradation of humic substances which includes both quantitative and qualitative parameters. To better elucidate how these processes may occur under natural conditions, mixed populations of soil microorganisms should be predominantly involved in future studies.     

Die Bestimmung von selektiv freisetzbarem Kalium in Parabraunerde aus Löß und Pelosol aus Gipskeuper-Tonmergeln

The determination of preferentially releasable potassium in hapludalf from loess and chromudert from gipskeuper clay marl Octadecylammonium-chloride (ODA)-extractable potassium and interlayer potassium (K_ZW), exchanged after thermal dissociation of adsorbed NH₄, were determined on particle size fractions of soils from gipskeuper clay marl (typic chromudert) and loess sediments (shallow hapludalf). The extraction by ODA is a diffusion controlled K-exchange process. This is shown by the increase of K-release at small sample quantity and K-concentration in the extraction solution. The ODA-potassium supplies (= Biotit-K) of the two typic chromudert were significantly higher than that of the shallow hapludalf (34000 and 30000 kg/ha vs. 22000 kg/ha, to a depth of 55 cm). Biotit-K was highest in the 2-6μm-fraction for both soils. The smaller the particle size, the larger were the amounts of K_ZW In the clay fractions of all samples they reached between 70 and 80% of total K (K_t). XRD-data give evidence of different mineral genesis processes between the two types of sediments. This is supported by the K_ZW-values of the particle-size fractions. The selectively releaseable interlayer potassium is associated with wedge shaped layers of illite. It can be differentiated from the bulk interlayer potassium by its preferential extractability in the first 3 to 5 heating treatments. This potassium quantity is, on an average, 22% of total clay interlayer potassium.     

Einfluß von Kationenaustauscherharz auf die Schwermetallaufnahme von Reben und anderen Kulturpflanzen aus kontaminierten Böden

The effect of a cation exchange resin on the uptake of heavy metals by grapevines and other cultivated plants grown in contaminated soils The effect of a cation exchange resin on the growth and heavy metal content of grapevine, sun flower, cress, wheat and Italian rye-grass was investigated in potted vineyard soil, contaminated by the long application of Cu-containing pesticides (total Cu content of the soil: 628 ppm), or a soil contaminated artificially with 20 ppm Cd. Roots of cress seedlings grown in a vineyard soil mixed with a cation exchange resin were 2.2 times longer than in the untreated soil. Rye-grass was not injured, whereas grapevine, sun flower and wheat showed varying degrees of growth reduction, chlorosis and necrosis when grown in untreated vineyard soil. However, wheat and sunflower grown in vineyard soil containing a cation exchange resin showed no injury and grapevines exhibited markedly reduced symptoms. The Cu content of the test plants decreased as follows: The Zn and Cd content of the plants also decreased considerably, whereas their Fe and Mn content was not influenced. Grapevine, grown in a calcareous soil contaminated with 20 ppm Cd, contained 447 ppm Cd in the roots (untreated: 1,9 ppm) and 0,20 ppm Cd in the leaves (untreated: 0,04 ppm). The Cd content of the roots declined to 113ppm, that of the leaves to 0,15 ppm when grown in the contaminated soil containing a cation exchanger.     

Die Komplexierung von Cu,Pb und Cd durch wasserlösliche Huminstoffe I. Der polarographische Nachweis der Komplexierung von Schwermetallen mit wasserlöslichen Huminstoffen

Complexation of Cu, Pb, and Cd by water soluble humic substances I. The polarographic proof of heavy metal complexation by water soluble humic substances The complexation of Cu, Pb, and Cd by water soluble humic substances in aqueous solution decreases the peak height of differential pulse polarograms. Using the law of mass action with respect to definite complex formulae, empirical stability constants can be calculated, which are roughly independent from the presence of other cations.