Lac Dufault sediment core trace metal distribution, bioavailability and toxicity to Hyalella azteca

To determine changes in metal distribution, bioavailability and toxicity with sediment depth, two 20-cm-long replicate cores were collected from a lake historically subjected to the influence of metal mining and smelting activity. The vertical distribution of Pb, Cd and Cu in sediment was similar for all three metals, with the surface layers showing enrichment and the deeper (pre-industrial) layers showing lower concentrations. Toxicity of each sediment core section was determined in laboratory tests with the freshwater amphipod Hyalella azteca. Bioavailable metal in each sediment slice was estimated from metal concentrations in overlying water in these toxicity tests and, for Cd, also from metal bioaccumulation. The profile for Cd in tissue was comparable to Cd in sediment and overlying water, but relative Cd bioavailability from sediment increased with sediment depth. Survival increased with increasing sediment depth, suggesting that surface sediments were probably less or non-toxic before industrialization.     

Effects of humidity and filter material on diffusive sampling of isocyanates using reagent-coated filters

Diffusive sampling of methyl isocyanate (MIC) on 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ)-coated glass fibre (GF) filters is strongly affected by high relative humidity (RH) conditions. It is shown that the humidity interference is a physical phenomenon, based on displacement of reagent from the filter surface. In this paper, this drawback has been overcome by changing the filter material to the less polar polystyrene divinyl benzene (SDB). A series of experiments was performed to compare the analyte uptake on the two filter materials for different sampling periods and analyte concentrations at both low and high RH conditions. Additionally, the materials were investigated as well for passive sampling of ethyl (EIC) and phenyl isocyanate (PhIC) with NBDPZ and 1-(2-methoxyphenyl) piperazine (2-MP) as an alternative derivatising agent. Using 2-MP, the mean GF/SDB response ratios were determined to be 1.02 for MIC (RSD: 6.1%) and 1.03 for EIC (RSD: 6.8%), whereas PhIC could only be determined on SDB filters. Using NBDPZ as reagent, the negative influence of high humidity disappeared when SDB filters were used instead of GF filters. Even at low RH conditions, sampling with SDB material generally resulted in a higher analyte uptake than with GF filters. The GF/SDB response ratios were independent of sampling time or analyte concentration and were determined to be 0.70 (RSD: 4.7%) for MIC, 0.84 (RSD: 4.5%) for EIC and 0.95 (RSD 5.4%) for PhIC, meaning that the NBDPZ diffusive sampler based on SDB can be used at all humidity conditions without any restrictions.     

Grey Box and Component Models to Forecast Ozone Episodes: A Comparison Study

For the purpose of short-term forecasting of high ozone concentration episodes stochastic models have been suggested and developed in the literature. The present paper compares the quality of forecasts produced by a grey box and a component time-series model. The summer ozone patterns for three European urban areas (two continental and one mediterranean) are processed. By means of forecast performance indices according to EC and WHO guidelines, the following features of the models could be found: The grey box model is highly adaptive and produces forecasts with low error variance that increases with the time horizon of forecast. The component model is more 'stiff' that results in a higher forecast-error variance and poorer adaption in detail. The forecast horizon, however, could be enlarged with this model. The accuracy of predicting threshold exceedance is similar for both models. This can be understood from the assumption of a cyclical time development of ozone that was made for both models.     

Behaviour and redox sensitivity of pharmaceutical residues during bank filtration - Investigation of residues of phenazone-type analgesics

The behaviour of residues of phenazone-type pharmaceuticals during bank filtration was investigated at a field site in Berlin, Germany, where bank-filtered water is used for drinking water production. The concentrations of the pharmaceutical residues in the shallow, young bank filtrate (travel times相似文献   

Arbeitskreis der Landesanstalten und-Ämter: Konzeption der künftigen Aufgabenbereiche

The expert panel for biological indication and effect research of the state institutes and agencies, pursues the harmonisation and optimisation of methods used for biological indication since 1980. This demonstrated increased significance after the fall of the Berlin Wall and the admission of the new German states, formerly East Germany. The publication of recommendations and the co-operation with other panels of experts (for example the VDI (association of German engineers) build the basis for the expert panel’s effect on the public. As first federal biological indication system, the expert panel, together with the federal institute for the environment, introduced moss-monitoring in the Federal Republic of Germany. For the future, the main point of effort will still lie in the exchange of information between state agencies and the harmonisation of methods. Above this, the expert panel should control the co-ordination of biological indication for a federal environment surveillance, develop evaluation strategies and methods, point out research deficiencies and develop new methods when necessary. Thus, for example, the expert panel has to point out possible connections and co-operations towards the monitoring of genetically manipulated organisms and changes in climate. Existing biological indication methods, including moss-monitoring, are to be screened for actuality and, when necessary, are to undergo further developments. The expert panel will also work on the development of effect-related environmental indicators as tools for an indication of ecological sustainability.     

Advantages and possibilities of solid recovered fuel cocombustion in the European energy sector

The 1999/31 Elemental Carbon Directive sets strict rules on the disposal of untreated municipal solid waste in the European Union countries and forces a reduction of the biodegradable quantities disposed off to landfills up to 35% of the amount produced in 1995 in the coming decade. More environmentally friendly waste management options shall be promoted under the framework of the Community Waste Strategy ([96] 399 Final). In this context, the production and thermal use of solid recovered fuels (SRFs), derived from nonhazardous bioresidues and mixed- and mono-waste streams, could be a key element in a future waste management system. Within the scope of the European Demonstration Project, RECOFUEL, SRF cocombustion was demonstrated in two large-scale lignite-fired coal boilers at RWE power station in Weisweiler, Germany. As a consequence of the high biogenic share of the cocombusted material, this approach can be considered beneficial following European Directive 2001/77/EC on electricity from renewable energy sources (directive). During the experimental campaign, the share of SRF in the overall thermal input was adjusted to approximately 2%, resulting into a feeding rate of approximately 25 t/hr. The measurement campaign included boiler measurements in different locations, fuel and ash sampling, and its characterization. The corrosion rates were monitored by dedicated corrosion probes. The overall results showed no significant influence of SRF cocombustion on boiler operation, emissions behavior, and residues quality for the thermal shares applied. Also, no effect of the increased chlorine concentration of the recovered fuel was observed in the flue gas path after the desulfurization unit.     

Displaced honey bees perform optimal scale-free search flights

Honey bees (Apis mellifera) are regularly faced with the task of navigating back to their hives from remote food sources. They have evolved several methods to do this, including compass-directed "vector" flights and the use of landmarks. If these hive-centered mechanisms are disrupted, bees revert to searching for the hive, but the nature and efficiency of their searching strategy have hitherto been unknown. We used harmonic radar to record the flight paths of honey bees that were searching for their hives. Our subsequent analysis of these paths revealed that they can be represented by a series of straight line segments that have a scale-free, Lévy distribution with an inverse-square-law tail. We show that these results, combined with the "no preferred direction" characteristic of the segments, demonstrate that the bees were flying an optimal search pattern. Lévy movements have already been identified in a number of other animals. Our results are the best reported example where the movements are mostly attributable to the adoption of an optimal, scale-free searching strategy.