Salzgehalt und Photosynthese bei marinen Pflanzen

Marine plants — phanerogams as well as algae — show a proportional decrease of photosynthetic rate, when the salinity is lowered by dilution with distilled water. Using natural water instead of distilled water, it is absolutely indispensable to take into consideration the carbon supply. Normally, the photosynthetic rate decreases in freshwater with low alcalinity, in comparison to marine water. On the other hand, using water with high contents of bicarbonates, assimilation rate is higher than in marine water. These results show that salinity may indirectly affect photosynthesis due to differences in carbon supply. The direct influence is caused by exosmosis in hypotonic media and is irreversible. — The author cannot but agree with the statement by Ogata and Matsui (1965): “It may generally be said that the changes in salinity, osmotic pressure, pH, and also carbon dioxide supply, particularly in natural sea-water, are rather inseparably associated.”     

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.     

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.     

Aufnahme von Cyanid in Pflanzen

Cyanides are waste products from the pyrolysis of coal and are frequent soil pollutants in cities nowadays. Prussic acid (HCN) is a fast acting, highly toxic poison, but iron-complexed cyanides in soil are far less toxic. The phytotoxicity of free CN to basket willows (Salix viminalis) was determined with the tree transpiration test. The EC₁₀ for t=72 h is 0.76 mg KCN (0.3 mg CN) per liter, the EC₅₀ is 4.47 mg/l. 5 mg/l KCN are ultimately lethal. Balsam poplars (Populus trichocarpa) can survive concentrations of up to 2500 mg/l ferroferricyanide (Prussian blue), although with reduced growth. Willows survived in gas work soils with up to 452 mg/kg total CN. More CN was taken up from nutrient solution than from the soil. Complexed cyanide is probably translocated into the leaves as well. Free CN was readily eliminated from Erlenmeyers with plants growing in nutrient solution. Planting appropriate vegetation might be a suitable solution for many former gas work and mining sites.     

Quecksilbergasfeinreinigung mittels metall- und salzpartikelbelegter Trägermaterialien (G/S-Reaktor) Ökotoxizität von Quecksilber und seiner Verbindungen

Waste and process gases from thermal power and metallurgical plants or such products from alkali-chloride industries contain metallic, inorganic and organic mercury. Widespread processes applied to remove the greatest amount of mercury are absorption and adsorption. Caused by the lowering of the emission limit from 200 to 50 μg/m³ [STP] by national and European legislators, considerable efforts have been made to enhance the efficiency of the main separation units of flue gas cleaning plants by applying the appropriate technological measures. This article is focused on the removal of mercury from waste gases. The state of engineering is described, especially with regard to enhancing the efficiency of separation in the raw gas, in wet, dry and quasi-dry processes as well as in tail-end process units. Specially impregnated ceramic carriers can be used for the selective separation of metallic, inorganic and organic mercury. Amalgamation has been investigated as a possible separation mechanism both experimentally and in theory. Using the ceramic reactor, removal rates for gaseous mercury and its compounds can be achieved which are even lower than 50 μg/m³ [STP]. The technology, the separation mechanisms and the ecological advantages through the use of ceramic reactors are presented in the article as well.     

Quecksilbergasfeinreinigung mittels metall- und salzpartikelbelegter Trägermaterialien (G/S-Reaktor) Ökotoxizität von Quecksilber und seiner Verbindungen

Waste and process gases from thermal power and metallurgical plants or such products from alkali-chloride industries contain metallic, inorganic and organic mercury. Widespread processes applied to remove the greatest amount of mercury are absorption and adsorption. Caused by the lowering of the emission limit from 200 to 50 µg/m³ [STP] by national and European legislators, considerable efforts have been made to enhance the efficiency of the main separation units of flue gas cleaning plants by applying the appropriate technological measures. This article is focused on the removal of mercury from waste gases. The state of engineering is described, especially with regard to enhancing the efficiency of separation in the raw gas, in wet, dry and quasi-dry processes as well as in tail-end process units. Specially impregnated ceramic carriers can be used for the selective separation of metallic, inorganic and organic mercury. Amalgamation has been investigated as a possible separation mechanism both experimentally and in theory. Using the ceramic reactor, removal rates for gaseous mercury and its compounds can be achieved which are even lower than 50 µg/m³ [STP]. The technology, the separation mechanisms and the ecological advantages through the use of ceramic reactors are presented in the article as well.     

Aufnahme von 2,4,6-Trinitrotoluol in Pflanzen

Soil contaminations with the explosive 2,4,6-TNT are a major problem at many sites of former ammuniton plants in Germany. But only little is known about its environmental or metabolic fate in soil or plants. A field study was conducted on a former ammunition plant in Stadtallendorf/Hessen. Three areas with different TNT concentrations were planted with 8 different crops. After harvest plants were analyzed for TNT, ADNTs and DNTs. Soil contamination decreased in the rhizosphere compared to unplanted areas and there was a transfer of TNT from soil to the plants. Accumulation in plants was dependent on soil contamination and also specific for different plant parts or plant species. The contamination spectrum of TNT and derivatives was different in soil or plant tissue, respectively. After acid hydrolysis of bean roots, 2,6-DNT and 2,4-DNT could be identified in the extract.     

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.     

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.