Bestimmung von Mineralölkohlenwasserstoffen im Boden

The infra-red (IR) and the gas Chromatographic (GC) methods for the determination of mineral oil hydrocarbons in soils were examined in collaborative trials with regard to their accuracy and reproducibility. Natural, homogenized soils and soils spiked with mineral oil were used as standards. The soil matrix was composed relatively simply. The repeatability and reproducibility values obtained were about 5 % und 23 %, respectively. In contrast, the GC method revealed a considerably higher error range, especially by using the split/splitless technique. The degradation of mineral oil hydrocarbons in soils under different temperatures was investigated by IR throughout one year. The degradation rate at room temperature was about 25 %; at lower temperatures no degradation was detected. Thus, the spiked soils may be used as calibration standards for the mineral oil analysis.     

Mineralölkohlenwasserstoffe im Boden bei der Sanierung von Altlasten

Various analyses and evaluative procedures are used to provide evidence of success using remediation procedures. Because of the lack of standardized procedures for soil assessment, general practice has unfortunately propagated the use of DIN standards for determining the level of similar parameters in water as well as for other heterogeneous matrices (e.g. in soil). A precise auditing of quality, however, has not been possible with this method, this procedure has even put the success of such a remediation into question. This article describes the problems of determining mineral hydrocarbon concentrations on soil as well as portraying the remediation of oil damages which has occurred on a site of a former waste oil redestillation facility [1, 2]. This procedure has been proved in practice and serves as a model because an adequately defined, standardized method (DIN standard) is lacking.     

Ausbreitungs- und Abbauverhalten von Pestiziden im unterirdischen Wasser unter Boden

Pesticide leaching from subsoil to underground water can be effected through bypass flows and particle-bound-transport. The seepage and ground water zone have a certain barrier effect too, but the sorption and transformation of pesticides is less than in the subsoil. Dissolved and bound organic carbon content is decisive for the migration behaviour of pesticides in seepage and groundwater zone as well. Pesticides are subject to a measurable degradation in these compartments. Metabolites are usually transported faster than pesticides.     

Bestimmung und Bewertung adverser Effekte von Industriechemikalien im Umweltkompartiment Boden

The assessment of adverse effects in terrestrial ecosystems is of central importance to any Environmental Risk Assessment of Industrial Chemicals at an EU level. A conceptual proposal in this regard is clearly outlined in the ‘Technical Guidance Document’ which is currently undergoing revision; nonetheless, from an industrial point of view, there are still some unresolved questions: The design of ecotoxicological tests should not focus exclusively on reproducibility under defined laboratory conditions; of equal if not greater importance is the ecological relevance of tests, i.e. the ability of a (chronic) test system to adequately reflect substance-related effects on wild species at the population level. In readily biodegradable substances in particular, the choice of an appropriate test substrate and an optimized feeding regime as well as the analytical confirmation of nominal test concentrations is vital. Bioaccumulation of industrial chemicals in soil-dwelling organisms usually takes place via the pore water phase. Oligochaete worms such as Eisenia and Lumbricus have proven to be promising candidates for an experimental approach. However, there is still an urgent need for the development of a balanced understanding of how to evaluate the results of those studies. Variability is inherently high in terrestrial systems, making any differentiation between natural fluctuations of parameters and substance-induced effects on the structures and functions of ecosystems a difficult task. In order to strengthen their predictive value for population or ecosystem-related effects, any experimental study has to fulfill specific quality criteria (e.g. acknowledged test procedure; Good Laboratory Practice; appropriate methodological approach (including statistics); meaningful endpoints; clear linkage of results and experimental design). Only if these criteria are met can test results be used for regulatory purposes.     

Phytovolatilisation organischer Chemikalien

During the phytoremediation of contaminated soils and water, a multitude of pathways, partly not yet quantified, are activated. ‘Phytovolatilisation’ is considered to be a process, where primarily organic compounds are emitted from the above-ground sections of the plant into the atmosphere. Thus, all compounds are included which are taken up by the root, partly transformed within the roots and transported into the sprout. The phytovolatilisation is particularly suitable for the elimination of volatile compounds in shallow groundwater contaminations. In gas exchange experiments, the dynamics of these emissions were examined and, on the basis of a model, the compounds which are preferentially emitted by plants due to their physical characteristics was estimated.     

Quecksilber in Boden und Pflanzen

The former mercury mining districts in Platina (Rheinland-Pfalz, Germany) are now overgrown with a more-or-less dense cover of vegetation. Much of the area is in agricultural use. Cultivated fields around the community of Mörsfeld have been analyzed. The mercury concentration in soil samples exceeds the threshold values set for sewage sludge by up to 10. 000 fold. Wheat grain cultivated in this area has a Hg content of up to 100 times higher than the threshold values set by the WHO/FAO. The accummulation was found to be organ specific and varies by species. The highest Hg concentration was measured in mosses, the lowest in leaves of shrubs.     

Adsorption anionischer Azofarbstoffe an Boden/Sediment

The adsorption behavior of three anionic azo dyes (Acid Orange 6, Acid Orange 10 andAcid Orange 12) on different soil/sediment components (quartz sand, clay and organic matter) was investigated with a flow-through method using a simplified HPLC apparatus. Organic matter had the highest adsorption capacity for all three dyes, followed by clay and sand. The adsorption on different components in mixtures was not additive. The adsorption of similar aniomic azo dyes decreased with increasing negative charge. The affinity of equally charged dye molecules to the adsorbents was also strongly influenced by the remaining chemical structure. While adsorption on organic matter could always be described by Freundlich isotherms, S-shaped isotherms were often measured with quartz sand and clay. For that reason one must assume different adsorption mechanisms for organic matter and mineral adsorbens. Lower pH values always led to stronger adsorption of the anionic azo dyes. On the other hand, ionic strength effects cannot be characterized so clearly. Adsorption was generally lowered by decreasing ionic strengths but sometimes the opposite effect was observed. Moreover, there were some unusual cases of partly irreversible adsorption on quartz sand and organic matter when the dyes were not dissolved in an aqueous solution containing additional inorganic ions but in double distilled water. The adsorption of anionic azo dyes on soil and sediment materials turned out to be a very complex process. Although some interesting coherences could be pointed out, much more research is required to recognize general principles, concerning for example the influence of the chemical structure or the surrounding aqueous solution.     

Biokonzentration von persistenten superlipophilen Chemikalien in aquatischen Organismen

According to generally accepted theory, persistent superlipophilic chemicals with logn-octanol/water partitioning coefficient (log K_ow) >6 and molecular sizes >9,5 Å, such as octachlorodibenzo-p-dioxin, decachlorobiphenyl, Mirex etc., do not significantly bioconcentrate in aquatic organisms from ambient water. In the light of new results and considerations, this hypothesis has to be revised. The most convincing argument against this hypothesis is that in all bioconcentration experiments with superlipophilic chemicals compound concentrations have been applied which exceeded water solubility by several orders of magnitude. In this paper we describe various methods how to determine bioconcentration (BCF) factors of superlipophilic compounds. As exemplified with octachlorodibenzo-p-dioxin and Mirex, BCF values evaluated by this means match well those calculated by QSARs for fish and mussels based on log K_ow and water solubility as well. As expected these BCF values exceed previous ones by several orders of magnitude. As practical consequences, we recommend for BCF evaluations of superlipophilic chemicals:

1. flow-through systems, kinetic method (OECD guideline No 305 E)
2. ambient concentrations≤water solubility.

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