Schwermetallverteilung und -bilanzen typischer Waldböden aus nordischem Geschiebemergel

Heavy metal distribution and balances of typical forest soils out of German and Danish till The total contents of Cd, Cu, Fe, Mn, Pb and Zn were determined in different horizons as well as in clay coatings, mottles and concretions from 4 Orthic and Gleyic Luvisols around the Baltic Sea. Profile balances resulted in very small losses of Fe, small losses of Cu, Pb and Zn but higher losses of Cd and Mn. All elements were translocated by clay migration but corresponding enrichments in the B-horizons were covered by translocations in soluble form. Only Fe and Mn had been enriched in mottles of the water logged soils.     

Anorganische Schadstoffe in Böden Nordrhein-Westfalens. I. Möglichkeiten der Auswertung mehrmodaler Häufigkeitsverteilungen

Inorganic toxicants in soils of North Rhine-Westphalia. I. Evaluation of multi-modal frequency distributions In 335 soil samples from North Rhine-Westphalia the contents of 18 elements were quantified (total contents, mobilizable fraction (extraction with EDTA cocktail), mobile fraction (extraction with NH₄NO₃). An inspection of the resulting histograms revealed that the distribution of element contents in soils is not normal and even not log-normal. The appearance of several peaks indicates the existence of multi-modal distributions with various independent sub-distributions. Two methods for analysing such data sets are presented. The parametric approach assumes several single lognormal components, which are fitted by the Expectation Maximization Algorithm. In a nonparametric approach the Kernel Density Estimation is used. With this procedure five to ten concentration levels can be determined per element for our data set with corresponding groups of soil samples being characterized by common features (e.g., parent material, region of origin, specific source of pollution). This way, e.g., background concentrations for potentially toxic elements can be derived. The parametric approach is lacking sharpness of separation in the case of more than four subdistributions.     

Das Verhalten des Herbizids 2.4.5-T in deutschen Acker- und Waldböden

The behavior of the herbicide 2.4.5-T in german soils under arable land and forest Sorption, degradation and movement of trichlorphenoxy acetic acid (2.4.5-T) were investigated in 10 german soils with very different climatic and edaphic conditions in field and laboratory experiments. Under field conditions 50% of the applied herbicide were liminated in 8 to 46 days during summer time (13-18°C mean temperature), but in 40 to 220 days during (and after) winter time (4-7°C in the first weeks). Beside microbial decomposition losses due to volatility were observed. Uptake by plants (Lolium perenne) was lower than 1%. Sometimes 10% of 2.4.5-T moved downward more then 30cm during summer time but more then 50cm during winter time. Translocation in the profile was reduced by high contents of organic matter in the A horizon but not by high clay contents. Correlations between behaviour in the field and laboratory experiments were found so that the first could be predicted by the latter.     

Al-Spezies im Sickerwasser saurer Waldböden - Einfluß von Wasserbewegung und Löslichkeitsgleichgewichten

Aqueous Aluminum Species in Acidic Forest Soils - Influence of Water Pathways and Solubility Equilibria In the seepage of three typical Black Forest soils (Haplic Podzol, Dystric Cambisol, Dystric Planosol) the fractions ‘Labile-Monomeric Al’, ‘Stabile-Monomeric Al’ and ‘Acid-soluble Al’ were analyzed. Activities of aqueous Al species and saturation indices (SI) with respect to various Al-bearing minerals were calculated from ‘Labile-Monomeric Al’, using the computer program WATEQF. Al-mobilization/immobilization processes were evaluated by means of AI/CI molar ratios. With 1.5 mg/L in average, the Al_total concentrations are relatively low in all studied soils. In the O-horizon leachates, 70 to 80% of aqueous Al occur as ‘Stabile-Monomeric’ and ‘Acid-soluble’ forms mainly consisting of organo-complexes. This portion decreases in the mineral soil to 35% in the podzol and the planosol as well as to 10% in the Cambisol. Simultaneously, Al³⁺ increases to 40% (planosol), 50 (podzol), and 70% (cambisol). In all horizons, 5 to 15% of Al_total are covered by Al-fluoride-complexes, whereas Al-sulfate-complexes are insignificant. With 5 to 10% monomeric Al-OH-ions play a role only in the subsoil. Aluminum is strongly mobilized in the upper mineral horizons of all studied soils. In the planosol and the cambisol, Al is immobilized in the subsoil. In the subsoil of the podzol, in contrast, Al reveals further mobilization due to a distinct internal production of HNO₃ and H₂SO₄ as a consequence of mineralization of organic matter. In the podzol, rapid percolation in macropores is crucial for Al dynamics, whereas in the planosol the temporal variation of the perched water table. Leachates from all O-horizons and upper mineral horizons as well as from the planosol subsoil are undersaturated with respect to the solubility of all mineral phases considered. With SI > O imogolite appears to be a permanently stable mineral in the subsoils of both podzol and cambisol. There is evidence for the Al(OH)₃ interlayer of Al-chlorites controlling Al dynamics in the subsoil of the podzol. Al(OH)SO₄ type minerals are not likely to regulate aqueous Al activities in any of the studied soils.     

Zur Bestimmung austauschbarer Kationen in sauren Waldböden

On the determination of exchangeable cations in acid forest soils Different samples from acid forest soils were percolated with large amounts of H₂O. Significant amounts of anions, especially sulfate, were found in the percolates mainly accompanied by Na. K, Ca and Mg (M_b-cations). The dissolution of Al-Sulfates and subsequent exchange of M_b-cations by Al as dominant mechanism is proposed. Thus the common method for determination of the cation exchange capacity (CEC) of acid forest soils, the percolation with NH₄Cl may overestimate the CEC. The overestimation may be related to the sulfate content of the soil and also influences the calculation of relative CEC proportions of individual cations.     

Eine Methode zur Bestimmung austauschbarer Kationen in Waldböden

A Method for the Determination of Exchangeable Cations in Forest Soils A simple extraction method with NH₄Cl was developed for determining exchangeable cations in forest soils. The influence of selected parameters (reaction time, concentration of NH₄Cl, filter medium etc.) affecting the amount of extractable cations was tested and a standardisation was done. The cation exchange was completed in less than 4 h. For a quantitative extraction of K, Mg, Ca, and Mn a concentration of 0.05 M NH₄Cl was sufficient. The extractable amount of these cations was always clearly defined. However, extracted Al and Fe increased with the NH₄Cl-concentration. Depending on the soil samples, the exchange is not quantitative even when using a saturated solution. The extractable H⁺ is nearly independent of the NH₄Cl-concentration. Probably considerable amounts are dissociated from organic acids. The optimized method is feasible and can be used for K, Mg, Ca, and Mn as an alternative to percolation methods.     

Einfluß der Probenvorbereitung auf die Adsorption von Cd und Cu in sauren Waldböden

Influence of Soil Sample Preparation on Cd and Cu Adsorption in Acid Forest Soils The influence of soil sample preparation on Cd and Cu adsorption was investigated using six acid forest soil samples and comparing adsorption isotherms for fresh and air-dried samples. While no influence of sample preparation on Cd adsorption capacity was found, air-drying resulted in a significant decrease in Cu adsorption density in all six soil samples under investigation at ecotoxicologically relevant concentrations in the soil solution.     

Über die Humusdynamik in vier österreichischen Waldböden

Humus dynamics in four Austrian forest soils The humus of four Austrian forest soils was characterized by means of a chromatographic and a mass spectrometric (δ¹³C, δ¹⁵N) method. With this combination it was possible to explain changes in the humic acid systems within the profiles. The leaching of humic acids in a Spodo-Dystric Cambisol and therefore the beginning of podsolization could be deduced. In a Stagno-Dystric Gleysol processes of dehumification were determined. The value of non humic substances was enhanced within the profile of a Fluvi-Calcaric Fluvisol. The δ¹⁵N-values increased in the four profiles much more with depth than the δ¹³C-values. This indicated the rapid mineralization of organic nitrogen.     

Chemische Eigenschaften von Waldböden im Nordwestdeutschen Pleistocän und deren Gruppierungen nach Pufferbereichen

Chemical properties of forest soils in the pleistocene of Northwest Germany and their classification based on soil buffering systems In order to characterize the chemical characteristics of forest soils of Hamburg, 800 soil samples and 400 root samples from 172 sites were used to obtain suitable soil chemical and ecochemical parameters. A strong and deep reaching soil acidification was observed on all sites with exception of those on till. The sulfate concentration in the equilibrium soil solution allows the conclusion that deposition of acid plays a significant role in this acidification. Classification of sites based on edaphic factors did not provide useful information on the chemical status of soils. However, grouping of soil horizons using pH measured in 0.01 M CaCl₂ lead to a stratification according to the soil buffering systems. Distinction between the exchanger and the aluminium buffer ranges was, however, not quite satisfactory.     

Schwefelformen in Waldböden SO2-belasteter Standorte des Fichtelgebirges

Sulfur fractions in forest soils of the SO₂-polluted Fichtelgebirge The sulfur status of a soil sequence (two Dystric Cambisols, Haplic Podzol, Eutric Cambisol) in SO₂-polluted coniferous and hardwood forests of the Fichtelgebirge (North-East Bavaria) is investigated. In the mineral soil layers S_t fluctuates between 37 to 943 ppm; 11–84% of S_t is S_p. Layers rich in clay contain up to 79%-S_E, whereas in sandy to silty substrates organic bound C?S-S dominates. The organic surface layers show 1.0–2.9‰ S_t, maximum in the Oh. 69–90% of S_t are C?S-S. S_p is low with a maximum in the L-horizons (9–19% of S_t). S_E is vice versa, because values increase from L (0–8% of S_t) to Oh (7–22% of S_t). The characterization of the sulfur status in a forest ecosystem by investigation of organic layers presumably is more reliable than the results of needle and mineral soil analyses.     

Zum Einfluß von pH und organischem Kohlenstoffgehalt auf die Löslichkeit von Eisen,Blei, Mangan und Zink in Waldböden

Influence of pH and organic carbon content on the solubility of iron, lead, manganese and zinc in forest soils Several soil factors determine the solubility of heavy metals in soils. The contents of exchangeable and in consequence potentially plant available heavy metals are mainly influenced by the pH and the content of organic carbon. Samples of the A_h-horizon from the stemflow area and from soil not influenced by stemflow water were investigated in beech forests. The solubility or iron, lead, manganese and zinc is described in relation to the pH and the content of organic carbon. Exchangeable iron and lead appear in significant amounts at pH below 3.5 and 4.5, respectively, regardless to the content of organic carbon. Manganese and zinc are exchangeable at pH below 5.0 and are leached for about 90% from the A_h-horizon at pH values below 3.0. The effects of higher soluble iron and lead contents on the distribution of herbaceous plants are discussed.     

Bildung schlechtkristalliner bis amorpher Verwitterungsprodukte in stark bis extrem versauerten Waldböden

Formation of poorly crystallized weathering products in strongly to extremely acid forest soils Poorly crystallized weathering products, formed as a consequence of wide-spread extrem acidification and silicate weathering in forest soils, were examined using X-ray diffraction (XRD) and fluorescence (XRF), scanning electron microscopy (SEM, EDXRA) and chemical analyses. The investigations were carried out on five extremely acid forest soils (different Luvisols, a Gleyic Luvisol and a Luvic Podzol) derived from different parent materials (loess, sand loess, glacial sands/loam) in Northrhine Westfalia and Schleswig-Holstein. The results reveal an intense destruction of clay minerals and other silicates in the extremely acid topsoils leading to an accumulation of poorly crystallized to amorphous compounds. These weathering products occur predominantly as silicic coatings on the surface of soil aggregates or as small spherical precipitates on mineral surfaces. Besides Si they contain small amounts of Al and Fe.     

Über die Sorptionseigenschaften von Waldböden bezüglich gelöster organischer Substanzen

About the sorption of dissolved organic matter to forest soils This investigation characterizes the major forest soils of the temperate climatic zones (leptosols, vertisols, cambisols, luvisols, podzols, stagnosols, gleysols) as sorbents for dissolved organic matter (DOM). Sorption isotherms were obtained for 135 soil horizons from 36 profiles. When solutions containing no DOC were added, the release of dissolved organic carbon (DOC) was highest for horizons rich in organic C (A and Bh horizons). In subsoil horizons DOC release was much lower. Most of the investigated top soils (A and E horizons) and Bh, Bg, and C horizons showed a weak DOC sorption. This was caused by low contents of sorbents (clay and sesquioxides) and/or high contents of organic C. Organic C seems to reduce the DOC sorption by occupying binding sites. Subsoils rich in clay and sesquioxides like Bs, Bt, and Bw horizons showed a strong retention of DOC. Under the aerobic conditions of the experiments, some of the subsoils of stagnosols and gleysols also showed a strong sorption of DOC. However, in sorption experiments conducted after an anaerobic incubation, the DOC sorption decreased significantly.     

Die Bedeutung von hohen Aluminiumgehalten für die Humusanreicherung in sauren Waldböden

The role of aluminium on humus accumulation in acid forest soils The impact of soil-borne aluminum on humus accumulation was investigated in a forest soil of the chestnut zone (Castanea sativa) in southern Switzerland (Ticino). Soil samples of two soils formed on bedrocks which differ mainly in their aluminum content were extracted with HNO₃, NH₄Ac.-EDTA, NH₄Cl, KCl, and NH₄F-HCl and analyzed for the most abundant elements. On gneiss which contains up to about 10% of total aluminum the common soil type in this area is a Cryptopodzol. This soil is similar to the nonallophanic Udands. It is rich in wellhumified organic matter and shows dark-colored A_h-, A(E)- and B_h-horizons. The soil samples of these horizons are extremely rich in nonexchangeable aluminum which is, however, extractable with NH₄Ac.-EDTA. It is assumed that this Al is intimately bound to the organic matter. The soil samples of these horizons contain large amounts of HNO₃-extractable phosphorus. Up to 90% of this P appears in the organic fraction. The content of NH₄F-HCl-extractable P is only 0.7 to 3.4 mg/kg. It is concluded that due to excessive Al in the organic matter the humus mineralization is inhibited compared to the Haplumbrepts of the region.     

Eine optimierte Methode zur Bestimmung der Proteaseaktivität in Sauren Waldböden

An optimized method for the determination of protease activity in acid forest soils A method for the determination of protease activity was tested for its applicability to acid forest soils (O-horizon and mineral soil). The influences of the following parameters on the protease activity and its determination were investigated: incubation time, substrate concentration. pH-value of the incubation solution, buffer solution, sample matrix and storage of soil samples. In consequence of the results an optimized method is proposed. The application of this modified method to two forest sites with contrasting N-transformation indicates, that also in acid forest soils the determination of protease activity allows significant differentiations.     

Bodenentwicklung und Schwermetallgehalte einer Straßenkehrichtdeponie

Soil development and heavy metal contents of a street sweepings dump Soils from an unsealed street sweepings dump of the city of Kiel are inhomogeneous in their properties and in their distribution pattern. The deposited material is contaminated with copper, zinc, lead, and at lower concentrations with cadmium. The high pH-values lead to predominating immobility of heavy metals. However, heavy metals bonded in organic complexes are liable to be leached into the underground because of a high portion of large pores in these soils. Since there are only few other possible bonding mechanisms than organics, after the leaching of lime, pH decline, and mineralization of organic matter mobilization of heavy metals may be predicted. Thus, in the unsealed dump a danger of groundwater pollution with heavy metals remains. The site should be treated accordingly permanently after closing.