Interactive effects of elevated ozone and carbon dioxide on growth and yield of leaf rust-infected versus non-infected wheat

Spring wheat (Triticum aestivum L. cv. Turbo) was grown from seedling emergence to maturity (129 days) in chambers simulating the physical climate and ozone pollution of a field site in Northern Germany from 1 April to 31 July with a mean 1-h daily maximum of 61.5-62.4 nl l(-1) ozone compared to a constant low level of 21.5-22.8 nl l(-1) ozone. The two ozone levels were combined with either a current (374.1-380.2 microl l(-1)) or enriched (610.6-615.0 microl l(-1)) CO(2) atmosphere. Additionally, a leaf rust epidemic (Puccinia recondita f. sp. tritici) was induced at tillering stage by repeated re-inoculations with the inoculum formed on the plants. Leaf rust disease was strongly inhibited by ozone, but largely unaffected by elevated CO(2). Ozone damage on leaves was strongly affected by CO(2) and infection. On infected plants, ozone lesions appeared 2-4 weeks earlier and were up to fourfold more severe compared to non-infected plants. Elevated CO(2) did not delay the onset of ozone lesions but it significantly reduced the severity of leaf damage. It also enhanced the photosynthetic rate of flag leaves and increased the water use efficiency, biomass formation and grain yield. The relative increases in growth and yield induced by CO(2) were much larger on ozone-stressed than on non-stressed plants. Both ozone and fungal infection reduced biomass formation, number of grains per plant, thousand grain weight and grain yield; however, adverse effects of leaf rust infection were more severe. Elevated CO(2) largely equalized the negative effects of ozone on the photosynthetic rate, growth and yield parameters, but was not capable of compensating for the detrimental effects of fungal infection. The data imply that the impact of ozone in the field cannot be estimated without considering the predisposing effects deriving from fungal infections and the compensating effects deriving from elevated CO(2).     

Gestaltungsoptionen für handlungsf?hige Innovationssysteme zur erfolgreichen Substitution gef?hrlicher Stoffe (SubChem)

Ohne Zusammenfassung Online First: 27. 03. 2002 ‚Sustainable Substitution of Hazardous Substances‚; Projektbeschreibung unter wwwoekopolde oder wwwfh-hamburgdelpers/gleich_von bzw. www.uni-hamburgde/kooperationssteI1e-hh. Das Vorhaben wird vom Bundesministerium für Bildung und Forschung (BMBF) im F?rderschwerpunkt ‚Rahmenbedingungen für Innovationen zum nachhaitigen Wirtschaften’ (RIW) gef?rdert und von der GSF als Projekttr?ger betreut (FkZ. O7Riw4).     

Anaerobic incorporation of the radiolabeled explosive TNT and metabolites into the organic soil matrix of contaminated soil after different treatment procedures

Four bioreactor designs were performed to evaluate the level of incorporation of 14C-labeled 2,4,6-trinitrotoluene (TNT) and metabolites into the organic soil matrix of different anaerobically treated contaminated soils. The contaminated soils were amended with molasses slivers (80:20% per weight) as auxiliary substrate to enhance microbial activity. After 5 weeks (bioreactors 1 and 2), 8 weeks (bioreactor 3) and 12 weeks (bioreactor 4) of anaerobic incubation, we determined 41%, 58%, 72%, and 54%, respectively, of the initially applied radioactivity immobilized in various soil fractions. After alkaline hydrolyses of the solvent-extracted soils, low quantities of radiolabel were found in the humic and fulvic acid fractions, whereas the bulk of 14C activity was found to be strongly bound to the humin fraction (solid soil residues). The amounts of solvent extractable radioactivity were 53%, 40%, 16%, and 29% for bioreactors 1, 2, 3, and 4, respectively. The level of TNT transformation at the end of the experiments was within 90-94%. Regarding the results presented in this study, we can assume that there is the possibility of high incorporation levels of TNT metabolites into the soil organic matrix mediated by microbial cometabolism under strictly anoxic conditions.     

?kologische Kriterien der Technik- und Stoffbewertung: Integration des Vorsorgeprinzips

Zusammenfassung  Die Erarbeitung von Kriterien zur vergleichenden Bewertung von Technologien und Stoffen über den toxikologischen Ansatz hinaus und die Entwicklung eines integrierten Kriterienrasters stehen erst am Anfang. Die hier vorgestellten Kriterien aus der Technikanalyse zur Integration des Vorsorgeprinzips in die Stoffund Technikbewertung müssen weiter operationalisiert und vervollst?ndigt werden, ebenso wie die bisher im Rahmen

Validation of estuarine gammarid collectives (Amphipoda: Crustacea) as biomonitors for cadmium in semi-controlled toxicokinetic flow-through experiments

Concentrations of chemicals in organisms are regarded as being indicators of the bioavailable fraction of those substances in the environment. Three gammarid collectives (assemblages) from the Weser-estuary (NW Germany), showing different species compositions, were used as experimental units to evaluate their suitability as biomonitors. Uptake and clearance of cadmium was investigated in semi-controlled dynamic flow-through tests. Kinetic data obtained from two compartment models confirmed a net accumulation strategy of gammarids for Cd and resulted in similar bioconcentration factors (BCFs) within the same experimental treatments. Deviations in bioconcentration factors between two treatments (BCFs: 377-542 vs 947-1190, based on dry wt) obtained under similar exposures (17 +/- 2 and 23 +/- 2 microg Cd litre(-1)) could not be assigned to significant fluctuations of both Cd levels and particulate matter in the flow-through systems. The biological half-life of Cd in gammarids was 6 to 12 days. It is concluded that gammarid collectives of different species composition may be used as experimental units in biomonitoring studies. This conclusion was confirmed by homogeneous Cd concentrations in field samples of gammarids from the Weser-estuary (0.34 +/- 0.03 mg kg(-1) dry wt., mean +/- 95% confidence intervals, N = 58).     

Modelling of diffusion-limited retardation of contaminants in hydraulically and lithologically nonuniform media

A new reactive transport modelling approach and examples of its application are presented, dealing with the impact of sorption/desorption kinetics on the spreading of solutes, e.g. organic contaminants, in groundwater. Slow sorption/desorption is known from the literature to be strongly responsible for the retardation of organic contaminants. The modelling concept applied in this paper quantifies sorption/desorption kinetics by an intra-particle diffusion approach. According to this idea, solute uptake by or release from the aquifer material is modelled at small scale by a "slow" diffusion process where the diffusion coefficient is reduced as compared to the aqueous diffusion coefficient due to (i) the size and shape of intra-particle pores and (ii) retarded transport of solutes within intra-particle pores governed by a nonlinear sorption isotherm. This process-based concept has the advantage of requiring only measurable model parameters, thus avoiding fitting parameters like first-order rate coefficients.In addition, the approach presented here allows for modelling of slow sorption/desorption in lithologically nonuniform media. Therefore, it accounts for well-known experimental findings indicating that sorptive properties depend on (i) the grain size distribution of the aquifer material and (ii) the lithological composition (e.g. percentage of quartz, sandstone, limestone, etc.) of each grain size fraction. The small-scale physico-chemical model describing sorption/desorption is coupled to a large-scale model of groundwater flow and solute transport. Consequently, hydraulic heterogeneities may also be considered by the overall model. This coupling is regarded as an essential prerequisite for simulating field-scale scenarios which will be addressed by a forthcoming publication.This paper focuses on mathematical model formulation, implementation of the numerical code and lab-scale model applications highlighting the sorption and desorption behavior of an organic contaminant (Phenanthrene) with regard to three lithocomponents exhibiting different sorptive properties. In particular, it is shown that breakthrough curves (BTCs) for lithologically nonuniform media cannot be obtained via simple arithmetic averaging of breakthrough curves for lithologically uniform media. In addition, as no analytical solutions are available for model validation purposes, simulation results are compared to measurements from lab-scale column experiments. The model results indicate that the new code can be regarded as a valuable tool for predicting long-term contaminant uptake or release, which may last for several hundreds of years for some lithocomponents. In particular, breakthrough curves simulated by pure forward modelling reproduce experimental data much better than a calibrated standard first-order kinetics reactive transport model, thus indicating that the new approach is of high quality and may be advantageously used for supporting the design of remediation strategies at contaminated sites where some lithocomponents and/or grain size classes may provide a long-term pollutant source.