A spatial assessment of the forest carbon budget for Ukraine

Mitigation and Adaptation Strategies for Global Change - The spatial representation of forest cover and forest parameters is a prerequisite for undertaking a systems approach to the full and...     

Sedimenttoxizit?t — ein inhaltlicher Schwerpunkt beim SETAC Europe 16th Annual Meeting World Forum Convention Center in Den Haag, Niederlangden, 7–11 Mai 2006

Tagungsankündigungen

Sedimenttoxizit?t — ein inhaltlicher Schwerpunkt beim SETAC Europe 16th Annual Meeting World Forum Convention Center in Den Haag, Niederlangden, 7–11 Mai 2006     

Okadaic acid: a potential defense molecule for the sponge <Emphasis Type="Italic">Suberites domuncula</Emphasis>

Sponges are sessile filter feeders that are exposed to toxic compounds/xenobiotics and a huge number of diverse pro- and eukaryotic organisms occurring in the aqueous milieu. To cope with these threats, sponges have developed a variety of chemical and immunological defense systems. Among them are potent secondary metabolites or toxins. The demosponge Suberites domuncula contains the bioactive compound okadaic acid; concentrations of ᅢ ng/g (ᅬ nM) of wet tissue have been quantified by LC/MS. In the present study, we sought to determine whether okadaic acid is beneficial for this sponge. Antibodies were raised against okadaic acid and used to localize this compound in situ. It could be demonstrated that the polyclonal antibodies/antiserum stained the sponge cells (endopinacocytes) which form the epithelium of the lacunae and the water channels. They also reacted with bacteria present in sponge tissue. Okadaic acid was found to augment the immune response of S. domuncula against the bacterial endotoxin lipopolysaccharide (LPS). If primmorphs, a special form of 3-D aggregates, are incubated with LPS at a concentration of 3 µg/ml, a reduction in the incorporation rate of [³H] phenylalanine is measured. In the presence of okadaic acid, this effect is measured already at a concentration of 1 µg/ml, suggesting that okadaic acid sensitizes this (immune) response. Okadaic acid is a known inhibitor of protein phosphatases which, as shown here, cause an increased phosphorylation of p38, a central kinase of the MAP kinase pathway; this may explain the sensitive response of the sponge cells to LPS. At higher concentrations, okadaic acid induces apoptosis, as was demonstrated here by a differential expression of the Bcl-2 homolog and the caspase gene. It is concluded that okadaic acid has two functions in the sponge; first, at low concentrations (<100 nM) a stimulation of the defense system against bacteria, and second, at concentrations above 500 nM, a differential effect on the pro-/anti-apoptotic genes.     

Congener-specific concentrations and carbon stable isotope ratios (delta13C) of two technical toxaphene products (Toxaphene and Melipax)

In this study we compared the contribution of individual congeners and the ratios of stable carbon isotopes of two technical toxaphene products. The former US-American product Toxaphene was from 1978 and the East-German product Melipax from 1979. Both technical products showed the known complexity in GC/ECD measurements. Contributions of 24 peaks to each of the technical products were determined by gas chromatography in combination high resolution electron capture negative ion mass spectrometry (GC/ECNI-HRMS). The percentages of the compounds studied in the technical mixtures ranged from approximately 0.05% to approximately 2.5% but showed some individual differences. 2,2,5,5,8,9,9,10,10-nonachlorobornane (B9-1025 or P-62) was identified as a major congener in both mixtures. 2-Endo,3-exo,5-endo,6-exo,8,8,10,10-octachlorobornane (B8-1413 or P26) and 2-endo,3-exo,5-endo,6-exo,8,8,9,10,10-nonachlorobornane (B9-1679 or P-50) were found at similar concentration in both technical products. Identical amounts of Melipax or Toxaphene were combusted to CO2 in an element analyzer and their delta13C values were determined relative to the international standard Vienna PeeDee belemnite (VPDB). The mean delta13C values of both products varied by 2.8% (determined at two different locations) which is roughly one order of magnitude more than the precision obtained in repetitive analyses of the individual products. Thus, both investigated products could be unequivocally distinguished by stable isotope ratio mass spectrometry (IRMS). IRMS analyses may thus be a suitable tool for tracing back toxaphene residues in environmental and food samples to the one or both of the products.     

Correlates of bushmeat hunting among remote rural households in Gabon, Central Africa

Hunted wild animals (i.e., bushmeat) are a main source of protein for many rural populations in the tropics, and the unsustainable harvest of these animals puts both human food security and ecosystem functioning at risk. To understand the correlates of bushmeat consumption, we surveyed 1219 households in 121 rural villages near three newly established national parks in Gabon. Through the surveys we gathered information on bushmeat consumption, income, and material assests. In addition, we quantified land cover in a 5-km radius around the village center and distance of the village center to the nearest park boundary. Bushmeat was not a source of income for most households, but it was the primary animal protein consumed. Ninety-seven percent of households consumed bushmeat at least once during a survey period of 12 days. Income or wealth, land cover, distance of village to the nearest park boundary, and level of education of the head of the household were among the factors that significantly related to the likelihood of consuming any of the 10 most commonly consumed species of bushmeat. Household size was the predictor most strongly associated with quantities of bushmeat consumed and was negatively related to consumption. Total bushmeat consumption per adult male equivalent increased as household wealth increased and decreased as distance of villages to park boundaries increased. Bushmeat consumption at the household level was not related to unit values (i.e., price estimates for a good that typically does not have a market value; estimates derived from willingness to sell or trade the good for items of known price) of bushmeat or the price of chicken and fish as potential substitutes. The median consumption of bushmeat at the village level, however, was negatively related to village mean unit values of bushmeat across all species. Our results suggest that a lack of alternative protein sources motivated even the wealthiest among surveyed households to consume bushmeat. Providing affordable, alternative protein sources to all households would likely reduce unsustainable levels of bushmeat consumption in rural Gabon.     

Toxizität und Risk Assessment fluvialer Sedimente und Schwebstoffe: Eine kurze Übersicht bisheriger und neuerer Entwicklungen

Background In recent years, sediments have become a central topic of scientific and public discussion as an important factor for determining water quality. While the quality of surface waters in Germany has significantly improved during the past years, highly contaminated sediments still create a considerable threat to the quality of several European catchment areas. Main features Here, we summarize different concepts and methods for the assessment of sediment quality and report on some novel integrative test methods for assessing sediment toxicity including contaminant re-mobilization during simulated re-suspension events. Results and discussion Currently, different approaches for assessment of sediment pollution exist. While instrumental chemical analyses are not suitable to accurately describe sediment toxicity, combinations of biological and chemical test procedures and integrated approaches, for example weight-of-evidence studies and effect-directed analysis (EDA), have the potential to identify key contaminants. Inter-disciplinary studies combining hydrodynamic and toxicological aspects coupled to real exposure of aquatic organisms to contaminants are currently being developed. Conclusions Monitoring and assessment of sediment quality are of increasing importance, not only for national legislation but also for the implementation of the European Water Framework Directive (WFD). Integrated approaches for the determination of sediment stability play a key role in the appropriate sediment-monitoring strategies.