Langzeitwirkungen potentieller anorganischer Schadstoffe auf die mikrobielle Aktivität einer sandigen Braunerde

Long-term effects of inorganic pollutants on microbial activity of a sandy cambisol Long-term effects of twelve inorganic pollutants on soil microbial activity were studied in a sandy cambisol. As, Be, Br, Cd, Cr, F, Pb, Hg, Se, Sn, and V were added as inorganic salts to the soil in a field plot in 1975 and 1976. Soil samples were taken in 1984 and 1985 to determine dehydrogenase, alkaline phosphatase, saccharase, and protease activity as well as biomass- and ATP-content. All pollutants except selenium and tin inhibited microbial activity of the soil. Br, F, Ni, and V reduced microbial biomass, protease, and dehydrogenase activity although their total contents did not exceed maximum recommended levels in the FRG very much. Br was even effective below the “tolerable” concentration of 10 mg/kg. Dehydrogenase activity and microbial biomass content were the most sensitive parameters to detect negative effects of inorganic pollutants on microflora in the test soil.     

Der Fe(III)-Reduktionstest - ein einfaches Verfahren zur Abschätzung der Wirkung von Umweltchemikalien auf die mikrobielle Aktivität in Böden

The Fe(III)-reduction test - a simple procedure to determine the effects of environmental chemicals on the microbial activity in soils A new simple microorganism test is described. The test is based on the fact that the degree of microbial reduction in waterlogged soils is influenced by the addition of different amounts of toxic chemicals. The microbial activity under reducing conditions can be measured by the degree of the microbial reduction of easily reducable Fe(III)-oxides (ferrihydrites) to soluble Fe²⁺-ions. The influence of different test parameters, the reproducibility and limitations of the proposed test are described. Toxicity indices of the investigated chemicals are derived graphically from the resulting dose effect curves. Values are determined for those concentrations which cause no (Non Effect Level, NEL) and a 50%-inhibition (ED₅₀) of the microbial activity in soil samples. By representing some results for 2,4-D, 2,4,5-T, LAS, Cd and Hg the scope of the test is described. First results show that the effective toxicity of chemicals is strongly influenced by the adsorption capacity of the soils. Furthermore the relation of toxic substances to nutrients in the soil solution causing competition or antagonistic and synergistic effects during uptake and also within the organisms can substantially influence the toxicity of chemicals.     

Einfluß polychlorierter Biphenyle auf die mikrobielle Aktivität in Böden

Effects of polychlorinated biphenyls on soil microbial activity In laboratory experiments the microbial toxicity of the PCB congeners 5 (2, 3-Dichlorobiphenyl), 8 (2, 4′-Dichlorobiphenyl), 29 (2. 4, 5-Trichlorobiphenyl) and 77 (3, 3′, 4, 4′-Tetrachlorobiphenyl) which is supposed to be extremely toxic to wildlife was investigated using Parabrownearth-Ap and Podsol-Ahe horizon material. In addition the technical PCB mixtures Arochlor 1242 and 1260 were tested. Microbial toxicity was measured by means of long-term respiration (CO₂-evolution), short-term respiration (CO₂-evolution 12 h, after addition of glucose), and dehydrogenase activity (TTC reduction) tests. 1 mg/kg of the Dichlorobiphenyls 5 and 8 reduced the long-term and short-term respiration of the Podsol-Ahe during the whole experiment (35 and 28 days, respectively). The Trichlorobiphenyl 29 became effective after addition of 10 mg/kg. No effect except a short stimulation of long-term respiration was observed for PCB 77 (Tetrachloro-PCB). Due to its higher sorption capacity, all PCB congeners reduced the microbial activity of the Parabrownearth-Ap to a lower degree. In general the toxicity of PCBs decreased with increasing degree of chlorination in both soil horizons. The technical mixtures reduced the long-term respiration only after high additions of 50 mg/kg (Podsol-Ahe) and 100 mg/kg (Parabrownearth-Ap), respectively. Arochlor 1242 proved to be more toxic than Arochlor 1260.     

Dosis- Wirkungs-Beziehungen zur Erfassung von Chemikalienwirkungen auf die mikrobielle Aktivität von Böden: I. Kurvenverläufe und Auswertungsmöglichkeiten

Dose response curves: their use in soil microbiological research and possibilities of evaluation The relation between different concentrations of a toxicant in soils and the resulting effects on biological parameters can be described with dose response curves. Dose response curves make it possible to determine the concentrations of a chemical that create definite effects (?Effective Doses”?, e.g. ED₁₀ and ED₅₀ for 10- and 50% inhibitory effects) or to evaluate the rate of increase of inhibition with increasing concentrations. Some of the mostly used ways to extract these parameters from dose response curves are presented and examined with regard to their suitability in soil microbiological research. Besides graphical procedures for the evaluation of dose response curves a mathematical model for fitting quantitative dose response curves is introduced. With this model the confidence intervals of effective doses can be computed. By showing eight frequently appearing shapes of dose response curves the advantages and limitations of different ways to calculate effective doses are discussed.     

Sorption und Wirkung von Arsen auf die mikrobielle Aktivität von Waldhumusformen

Arsenate adsorption and effects of arsenate pollution on microbial activity of different types of humus soils Perfusion experiments using Na₂HAsO₄ were carried out in order to investigate adsorption and effects of arsenate on microbial activity of L-, O-, and A-horizons of a mull, a moder, and a mor soil. Arsenic adsorption of mineral A-horizons was positively influenced by their contents of amorphous Al- and Fe-oxides. It is assumed that arsenic was mainly precipitated as Al-, Mn- or Ca-arsenate in the organic layers during the perfusion experiments. The Freundlich equation was valid to describe As-adsorption of all layers under investigation. Microorganisms seemed to be very tolerant to arsenate pollution. Soil respiration and enzyme activities were reduced when liquid concentrations exceeded 8 μg As/ml. Extremely high As-additions (up to 10 mg As/g) did not reduce microbial processes to a greater degree than lower ones of 0,5 mg As/g.     

Der Einfluß von Fungiziden auf die mikrobielle Aktivität eines Bodens

The influence of fungicides on microbial activity in soil The objective of this work was to investigate the influence of the fungicides copper, sulfur, mancozeb, captan-folpet-folcid, quintozene and benomyl on CO₂-evolution and on the dehydrogenase-, xylanase- and urease-acitivities of an acid soil. The investigations showed that a recommended dosage of fungicide caused an increase in CO₂-evolution. After the second and third fungicide application this ‘stress reaction’ was followed by a decrease in CO₂-release below the value of the untreated control soil. Up to the tenth week after pesticide application again an increase of the activity could be shown. This increase might be explained by an inactivation of fungicides, a selection of resistant species, a decreasing competition of microorganisms and mineralization of dead organisms. Finally, after 10 to 14 weeks the activity returned to the value of the untreated soil, that was probably due to the recovery of the affected microflora and/or a new adapted microflora. The various enzyme activities did not follow this scheme exactly. The course was influenced by the mode of action of the particular compound used. Brassicol (Quintozene) differed because of the severe and continous inhibition of the xylanase activity. It can be concluded that the fungicides applied to the soil influence both the CO₂-release and the activities of the soil enzymes tested. Consequently litter decomposition and metabolic activities may be affected for 3 to 4 months.     

Ein Mischzellenmodell zur Abschätzung der Nitratauswaschung aus landwirtschaftlich genutzten Böden im Winterhalbjahr

A mixing-cell model for estimating nitrate seepage losses from agricultural soils in winter A mixing-cell model is developed with which the leaching of nitrate from agricultural soils in temperate regions during winter can be estimated. The model assumes steady-state flow conditions and takes nitrogen mineralization in the upper soil as well as nitrate deposition from the atmosphere into consideration. Model results are compared with results from a convective-dispersive solute flow model. They show that for common field soil dispersivities mixing-cell model results compare well with those obtained from convective-dispersive theory. With the mixingcell model nitrate leaching calculations were carried out for a variety of soil and climatic conditions. They show that the combined effect of N-mineralization and N-deposition may influence the amount of leached nitrate in winter considerably, especially in regions with light soils and high seepage rates. It is shown that the model can be used to derive late fall site-specific upper limits for soil mineral nitrogen for groundwater protection purposes. Such upper limits should reflect the crop-specific rate of N-mineralization that can be expected during winter.     

Der Einfluß der Fauna auf die Stoffverlagerung sowie die Homogenität und die Durchlässigkeit von Böden

The influence of the fauna on displacement and on homogeneity and permeability of soils The influence of the most important soil animals (mammals, ants, termites, woodlice and earthworms) on displacement and on homogeneity and permeability of soils is discussed in reference to both older and more recent literature. Nearly all soil animals cause displacement of organic and mineral soil particles. The quantity, intensity and direction of this activity depends upon the morphological characters of the species involved. The homogeneity of soils is positively influenced only by the earthworms (and related forms) whereas the activity of the other soil fauna mostly has a contrary effect as far as shorter periods are concerned. The permeability of soils increases in different dimensions due to the activity of all species discussed. Permanent vegetation and non-tilling for the most part favour the activity of the soil fauna. Recent field experiments dealing with minimum or zero tillage have made this fact fairly evident.     

Verhalten von Schwermetallen in Böden 1. Untersuchungen zur Schwermetallmobilität

Behaviour of heavy metals in soils. 1. Heavy metal mobility 158 soil samples with widely varying composition were analysed for their total, EDTA, DTPA and CaCl₂ extractable contents of Cd, Zn, Mn, Cu and Pb. By means of single and multiple regressions the relations between the different heavy metal fractions and the pH, organic carbon and clay content were considered. The correlations between the total, EDTA and DTPA extractable contents are very close, whereas the CaCl₂ extractable contents are not or only weakly correlated with these fractions. According to these statistical results the former fractions are considered to be the total quantity (total content) and the reactive quantity (EDTA and DTPA extractable contents) of the heavy metals, whereas the CaCl₂ extractable fraction represents the mobile fraction of the heavy metals in soils. The multiple regressions show that the mobile content of heavy metals is closely correlated with each of the quantity fractions and with soil pH. In the same way the proportion of the mobile fraction (in %) of the total, EDTA and DTPA extractable heavy metal content of the soil samples is closely related to the soil pH. Hereby the proportion of the mobile content of the various elements increases in the pH range 6,5 - 3 below element-specific threshold pH values (in brackets) in the order Cd (6,5) > Mn (5,7) > Zn (5,3) > Cu (4,5) > Pb (3,5). In the pH range 6,5 - 7,5 mainly Cu and to a lesser degree also Pb show an increasing mobility due to the influence of soluble organic substances.     

Methodenvergleich zur pH-Bestimmung von Böden

Comparison of methods for determining of soil-pH Comparative studies are being described of pH-determinations in suspensions with m-KCl, 0.1 m-KCl, 0.01 m-CaCl₂ and water of soils derived from loess and sand. For a standard the pH-values in 0.01 m-CaCl₂-suspensions were chosen, considering, that such CaCl₂-solution reflects best conditions in natural soil solution. Mean differences of pH(H₂O)-, m-KCl- and 0.1 m-KCl-values as compared to pH(CaCl₂)-values were + 0.56, — 0.27 and — 0.02 for the soils derived from loess, and + 0.63, — 0.11 and + 0.18 for those from sand. Taking into account the pH-dependence of the difference pH(CaCl₂)-values were + 0.56 – 0.11, — 0.27 – 0.26 and — 0.02 – 0.21, for the soils derived from loess, and + 0.63 – 0.21, — 0.11 – 0.14 and + 0.18 – 0.10 for those from sand. Taking into account the pH-dependence of the difference of pH(H₂O)-values of sandy soils, and its dependence on the present electrolyte content with all soils, further the unequal differences of the pH(KCl)-values with soils from loess as compared to sand, and their particular large variability with soils from loess, it is being argued that the CaCl₂-method may only insufficiently be substitued by any one of these methods. pH-values obtained at a soil-to-liquid-ratio of 1:2.5 were only slightly different from those with a ratio of 1:1. A suspension effect could not be observed with the application of a glasselectrode.     

Die Messung der Katalaseaktivität von Böden

The determination of Catalase Activity in Soils by Dr. Beck 1. The elaboration of a method for the determination of the activity of catalase in soils is described. The method envolves the gasvolumetric determination of oxygen released by decomposition of a H₂O₂-solution by soils, suspended in buffers in the presence and absence of the catalase inhibitor NaN₃. 2. The influences of the following factors on catalase activity were studied: Methods for the determination of developed oxygen, enzyme- and substrate concentration, inhibition of catalase by NaN₃, pH- and temperature-optima of catalase and the presence of plant residues in soils. 3. It was found, that there was only a little decrease in catalase activity when fresh or dried samples of soils were stored over a periode of 4 months under laboratory conditions. The catalase activity of different soils showed very good correspondence to the dehydrogenase activity of the soils and less correspondence to the amount of soil respiration and the amylase activity. No relation could be found to the number of microorganisms in soil.     

Einfluß verschiedener Bodeneigenschaften auf die mikrobielle Toxizität von Blei und Cadmium

Effects of different soil properties on the microbial toxicity of lead and cadmium Effects of different soil properties on the microbial toxicity of lead and cadmium were investigated in laboratory experiments on ten arable and nine preserve area soils. Microbial activity was measured by means of the dehydrogenase and the arginine-ammonification tests. The latter was not suitable to show the microbial toxicity of both metals. Effects of lead on dehydrogenase activity were mainly influenced by its concentration in soil solution (r = 0,79). Thus, all soil properties which determined the adsorption of lead correlated significantly with the relative dehydrogenase activities of the contaminated soils. The most important abiotic factors influencing the toxicity of lead were the soil pH and the CEC. Cd solubility and Cd toxicity were influenced by soil pH in a contrary way. Low Cd concentrations caused greater inhibitions of dehydrogenase activity at neutral and slightly alkaline soil reaction than under acidic conditions. Therefore, correlations between Cd concentrations of soil solutions or clay content and dehydrogenase activity were only significant if partial correlation analysis (constant pH) was used.     

Kurzmitteilung Einfluß der Qualität der organischen Substanz auf die Konsistenz landwirtschaftlicher Böden

Influence of organic matter quality on consistency of agricultural soils The soil organic matter of two samples similar in the texture and approximately in the organic C contents, but very differently in the consistency properties, were investigated by pyrolysis-field ionization mass spectrometry (Py-FIMS). The shifts of the values of the liquid and plastic limits towards higher moisture contents are explained by a different quality of soil organic matter, in particular by higher amounts of longchained lipids (C_8-32 alkanes, alkenes, fatty acids), N-compounds and lignin dimers.     

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.     

Zur Bestimmung der Kationenaustauschkapazität von Böden mittels Barium

Regarding the Determination of Cation Exchange Capacity of Soils with Barium Very often the cation exchange capacity (CEC) of soils is determined using Ba⁺⁺ as exchange cation. In soils with high contents of organic matter, Ba⁺⁺ cannot be desorbed completely by Mg⁺⁺ or H⁺ but by Ca⁺⁺. Soils containing vermiculite adsorb Ba⁺⁺ in non exchangeable form. The fixed Barium can only be determined by total digestion. Therefore in soils containing vermiculite the exchange with Ba⁺⁺ leads to an underestimation of the CEC.     

Die Standortsbewertung der biologischen Aktivität von Böden über Ermittlung der Bodenatmung und der zellulolytischen Aktivitatät im Feld

Intersite estimation of biological activity of soils by determination respiration and cellulolytical activity in the field A temperature differentiated scale of estimation is presented, which is derived from long-term investigations of respiration and cellulolytic activity. This is suitable for intersite comparison of different soil-ecosystems. Investigations in spring are representative and could be done during mapping the soil-ecosystems. It exists a strong correlation to the quality of the humus body and to the available nutrients.     

Die Verwendung von Antimon-Elektroden zur pH-Messung in Böden

The application of antimony electrodes for soil pH measurements Glass electrodes are unsuitable for long-term, micro-volume pH measurements in soils because of their form, size and drying of the glass membrane. Sb-electrodes are suited for pH measurements in soils whose oxygen saturation does not vary excessively. pH values determined with Sb electrodes decrease with increasing water tension or decreasing moisture. Colour changes of pH indicators confirm this trend.