UDS-test with freon 11 (R-11)

Trichlorofluoromethane, in concentrations of 80, 400, 2 000, 10 000 and 50 000 ppm, was administered to rats of both sexes (Sprague Dawley) by inhalation exposure. 2 000 ppm in air (= 11 200 mg/m³) amount to twice the MAK value of 1 000 ppm. At exposure times of 4 hours this corresponds to the MAK value defined for an 8 hour workday. Unscheduled DNA synthesis (UDS) was measured in single-cell suspensions of hepatocytes, pulmonary epithelial cells and lymphocytes of the spleen, respectively. In the pulmonary cells concentrations of 2 000, 10 000 and 50 000 ppm of freon 11 lead to a significantly increased mean silver grain count compared to a negative control group. In spleen and liver cells increasing concentrations of R 11 tend to increase the incorporation of thymidine into the DNA of the cells. These changes of the extent of unscheduled DNA synthesis can, however, not be statistically verified.     

The SeKT joint research project: definition of reference conditions, control sediments and toxicity thresholds for limnic sediment contact tests

- In current biotest approaches, intact organisms or in vitro systems are exposed to sediments using different exposure scenarios. The most important issue in sediment toxicity testing protocols is the question which test phase (solid or liquid) should be used. Whole-sediment exposure protocols represent the most realistic scenario to simulate in situ exposure conditions in the laboratory. However, until now there is no agreement in how to acquire and to evaluate the data of the various available sediment contact assays. The SeKT joint research project was initiated with the aim to compare recently developed sediment contact assays by addressing reference conditions, control sediments and toxicity thresholds for limnic sediment contact tests.     

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.     

Is this trail too crowded? A choice experiment to evaluate tradeoffs and preferences of park visitors in Garibaldi Park,British Columbia

Large crowds in parks can be a problem for park managers and visitors. However, perceptions of crowding are difficult to measure due to coping mechanisms deployed by park visitors. Furthermore, perceptions of crowding should not be measured in isolation, but rather as part of a suite of conditions that comprise the visitors’ outdoor experience. We used a dichotomous choice experiment with visual images and eight attributes to estimate park users’ utilities associated with their visitor experience in Garibaldi Provincial Park in British Columbia, Canada. Our visual method allowed us to control for background view and compare user preferences on hiking trails with preferences at final destinations. We find that utilities are more sensitive to crowding at viewpoints than to other aspects of the outdoor experience. Thus, visitor satisfaction and crowding perceptions are more likely to be defined by where visitors have these encounters rather than the total number of encounters.     

Future ocean acidification will be amplified by hypoxia in coastal habitats

Ocean acidification is elicited by anthropogenic carbon dioxide emissions and resulting oceanic uptake of excess CO₂ and might constitute an abiotic stressor powerful enough to alter marine ecosystem structures. For surface waters in gas-exchange equilibrium with the atmosphere, models suggest increases in CO₂ partial pressure (pCO₂) from current values of ca. 390 μatm to ca. 700–1,000 μatm by the end of the century. However, in typically unequilibrated coastal hypoxic regions, much higher pCO₂ values can be expected, as heterotrophic degradation of organic material is necessarily related to the production of CO₂ (i.e., dissolved inorganic carbon). Here, we provide data and estimates that, even under current conditions, maximum pCO₂ values of 1,700–3,200 μatm can easily be reached when all oxygen is consumed at salinities between 35 and 20, respectively. Due to the nonlinear nature of the carbonate system, the approximate doubling of seawater pCO₂ in surface waters due to ocean acidification will most strongly affect coastal hypoxic zones as pCO₂ during hypoxia will increase proportionally: we calculate maximum pCO₂ values of ca. 4,500 μatm at a salinity of 20 (T = 10 °C) and ca. 3,400 μatm at a salinity of 35 (T = 10 °C) when all oxygen is consumed. Upwelling processes can bring these CO₂-enriched waters in contact with shallow water ecosystems and may then affect species performance there as well. We conclude that (1) combined stressor experiments (pCO₂ and pO₂) are largely missing at the moment and that (2) coastal ocean acidification experimental designs need to be closely adjusted to carbonate system variability within the specific habitat. In general, the worldwide spread of coastal hypoxic zones also simultaneously is a spread of CO₂-enriched zones. The magnitude of expected changes in pCO₂ in these regions indicates that coastal systems may be more endangered by future global climate change than previously thought.     

Intergenerational aspects of ecotax reforms – An application to Germany

In a model of overlapping generations and majority voting, we analyze an ecotax reform consisting of the tax rate and the budgetary rule. Revenue can be recycled through a lump-sum transfer or a reduction in pension contributions. Our theoretical results as well as the calibration of our model to the German economy show that the median voter's preferred tax rate may exceed the efficient rate. This holds whenever income of the decisive voter is sufficiently high compared to the average income, as rich individuals benefit more from a reduction in pension contributions than they are harmed by an increase in ecotaxes. The calibration confirms that the median voter prefers the earmarking of tax revenue for reductions in pension contributions to the alternative lump-sum transfer. This is quite an accurate prediction of the situation in Germany. Aging of society as expected for Germany lowers the ecotax in the political equilibrium below its optimal level.     

Assessment of regional climate change impacts on Hungarian landscapes

The assessment of regional climate change impacts combined with the sensitivity of landscape functions by predictive modelling of hazardous landscape processes is a new fundamental field of research. In particular, this study investigates the effects of changing weather extremes on meso-regional-scale landscape vulnerability. Climatic-exposure parameter analysis was performed on a predicted climate change scenario. The exposure to climate change was analysed on the basis of the original data of the meso-scale IPCC A1B climate scenario from the REMO and ALADIN regional models for the periods of 2021–2050 and 2071–2100, and the regional types of climate change impacts were calculated by using cluster analysis. Selected climate exposure parameters of the REMO and ALADIN models were analysed, in particular, for extreme events (days with precipitation greater than 30 mm, heat waves, dry periods, wet periods) and for daily temperature and precipitation. The landscape functions impacted by climate change are proxies for the main recent and future problematic processes in Hungary. Soil erosion caused by water, drought, soil erosion caused by wind, mass movement and flash floods were analysed for the time periods of 1961–1990, 2021–2050 and 2071–2100. Based on the sensitivity thresholds for the impact assessments, the landscape functional sensitivity indicators were interpreted, and an integrative summary of the five indicators was made, differentiating the regions facing only a few or multiple sensitivities. In Central Hungary, the increasing exposure and sensitivity to droughts will be a serious problem when following the REMO scenario. In several regions, most indicators will change the sensitivity threshold from a tolerable risk to an increased or very high risk.     

Characterization of MSWI fly ash through mineralogy and water extraction

This paper investigates the mineralogical characteristics of fresh, aged and hot water extracted MSWI fly ash for providing the baseline information of minerals stability which controls the released heavy metals into the environment. Quantitative determination of bulk phase abundance in the fresh fly ash by the XRD Rietveld refinement method provided composition levels for amorphous and crystalline phases such as potassium tetrachlorozincate (K₂ZnCl₄), gehlenite, halite, quartz, anhydrite, and feldspar. The minerals association in the fly ash is clearly unstable and subject to mineralogical reactions. The phases of K₂ZnCl₄, halite and anhydrite in the fresh fly ash were involved in hydration and dissolution/precipitation processes to form new minerals such as the Zn-bearing mineral gordaite, syngenite, gypsum and hydrocalumite. The solubility-controlling phases and extractability of heavy metals were examined in a Soxhlet hot water-extractor. Here the soluble salts were simply removed from fly ash while Ca-, Al-, Si- and SO₄²⁻-bearing hydrate minerals were precipitated from the extraction solution. Furthermore, a low release of heavy metals Zn, Pb and Cd in hot water was noticed, indicating a strong retention of the trace metals in the mineral phases remaining in the insoluble fly ash residues.