Filamentous scum bacteria in activated sludge plants: detection and identification quality by conventional activated sludge microscopy versus fluorescence in situ hybridization.

Detection of filamentous bacteria morphotypes involved in scum formation in activated sludge wastewater treatment plants by conventional sludge microscopy is often doomed to fail because of morphological and taxonomical variations. The aim of this study is to compare detection, identification, and quantification quality of filamentous "scum bacteria" found by conventional activated sludge microscopy and fluorescence in situ hybridization (FISH). In the case of filamentous Microthrix parvicella and Eikelboom morphotypes 1863 and 1851, conventional activated sludge microscopy and FISH results correspond well. In contrast, conventional activated sludge microscopy overlooks nocardioform actinomycete and type 1863 single cells. On the other hand, FISH underestimates filamentous nocardioform actinomycetes and morphotypes 0041/0675 or 0092 because of insufficient cell wall permeability or because of their taxonomic variability, with a resulting inadequacy of previously published probes. Nostocoida limicola morphotype results are still inconclusive because of low bacteria numbers being available in situ and the enormous taxonomic variability within this group.     

Impact of Climate Change on Fish Population Dynamics in the Baltic Sea: A Dynamical Downscaling Investigation

Understanding how climate change, exploitation and eutrophication will affect populations and ecosystems of the Baltic Sea can be facilitated with models which realistically combine these forcings into common frameworks. Here, we evaluate sensitivity of fish recruitment and population dynamics to past and future environmental forcings provided by three ocean-biogeochemical models of the Baltic Sea. Modeled temperature explained nearly as much variability in reproductive success of sprat (Sprattus sprattus; Clupeidae) as measured temperatures during 1973-2005, and both the spawner biomass and the temperature have influenced recruitment for at least 50 years. The three Baltic Sea models estimate relatively similar developments (increases) in biomass and fishery yield during twenty-first century climate change (ca. 28 % range among models). However, this uncertainty is exceeded by the one associated with the fish population model, and by the source of global climate data used by regional models. Knowledge of processes and biases could reduce these uncertainties.     

Photoinduced reduction of divalent mercury in ice by organic matter

Reduction of divalent mercury and subsequent emission to the atmosphere has been identified as loss process from surface snow, but its mechanism and importance are still unclear. The amount of mercury that stays in the snow pack until spring is of significance, because during snow melt it may be released to the aquatic environment and enter the food web. Better knowledge of its fate in snow might further assist the interpretation of ice core data as paleo-archive. Experiments were performed under well-controlled laboratory conditions in a coated wall flow tube at atmospheric pressure and irradiated with light between 300 nm and 420 nm. Our results show that the presence of benzophenone and of oxalic acid significantly enhances the release of mercury from the ice film during irradiation, whereas humic acid is less potent to promote the reduction. Further it was found that oxygen or chloride, and acidic conditions lowered the photolytically induced mercury release in the presence of benzophenone, while the release got larger with increasing temperatures.     

Determination of polyfluoroalkyl compounds in water and suspended particulate matter in the river Elbe and North Sea, Germany

The distribution of polyfluoroalkyl compounds (PFCs) in the dissolved and particulate phase and their discharge from the river Elbe into the North Sea were studied. The PFCs quantified included C₄-C₈ perfluorinated sulfonates (PFSAs), 6:2 fluorotelomer sulfonate (6:2 FTS), C₆ and C₈ perfluorinated sulfinates (PFSiAs), C₄-C₁₂ perfluorinated carboxylic acids (PFCAs), perfluoro-3,7-dimethyl-octanoic acid (3,7m₂-PFOA), perfluorooctane sulfonamide (FOSA), and n-ethyl perfluroctane sulfonamidoethanol (EtFOSE). PFCs were mostly distributed in the dissolved phase, where perfluorooctanoic acid (PFOA) dominated with 2.9–12.5 ng/L. In the suspended particulate matter FOSA and perfluorooctane sulfonate (PFOS) showed the highest concentrations (4.0 ng/L and 2.3 ng/L, respectively). The total flux of ΣPFCs from the river Elbe was estimated to be 802 kg/year for the dissolved phase and 152 kg/year for the particulate phase. This indicates that the river Elbe acts as a source of PFCs into the North Sea. However, the concentrations of perfluorobutane sulfonate (PFBS) and perfluorobutanoic acid (PFBA) in the North Sea were higher than that in the river Elbe, thus an alternative source must exist for these compounds.     

Determination of polyfluoroalkyl compounds in water and suspended particulate matter in the river Elbe and North Sea, Germany

The distribution of polyfluoroalkyl compounds (PFCs) in the dissolved and particulate phase and their discharge from the river Elbe into the North Sea were studied. The PFCs quantified included C₄-C₈ perfluorinated sulfonates (PFSAs), 6:2 fluorotelomer sulfonate (6:2 FTS), C₆ and C₈ perfluorinated sulfinates (PFSiAs), C₄-C₁₂ perfluorinated carboxylic acids (PFCAs), perfluoro-3,7-dimethyl-octanoic acid (3,7m₂-PFOA), perfluorooctane sulfonamide (FOSA), and n-ethyl perfluroctane sulfonamidoethanol (EtFOSE). PFCs were mostly distributed in the dissolved phase, where perfluorooctanoic acid (PFOA) dominated with 2.9–12.5 ng/L. In the suspended particulate matter FOSA and perfluorooctane sulfonate (PFOS) showed the highest concentrations (4.0 ng/L and 2.3 ng/L, respectively). The total flux of ΣPFCs from the river Elbe was estimated to be 802 kg/year for the dissolved phase and 152 kg/year for the particulate phase. This indicates that the river Elbe acts as a source of PFCs into the North Sea. However, the concentrations of perfluorobutane sulfonate (PFBS) and perfluorobutanoic acid (PFBA) in the North Sea were higher than that in the river Elbe, thus an alternative source must exist for these compounds.     

Veränderungen des NO/NO2-Verhältnisses in Nordrhein-Westfalen (1984–2004) und mögliche Ursachen

Objective and Background

The nitrogen oxides NO and NO₂ and, in particular, their ratio (NO/NO₂), play important roles in the radical-system of the atmospheric boundary layer. There were various indications upon a dropping NO/NO₂-ratio in citiex over the last years, however, no proof has been given yet Especially in densely populated areas such as the federal state of North Rhine-Westphalia (NRW), such a change can have significant influences upon various atmospheric reactions. The objective of this investigation was to prove the existence of a systematic change of the NO/NO₂-ratio, to describe the development of NO_x over the past 2 decades at different locations and to determine the causes for this development.

Methods

To detect changes of the NO/NO₂-ratio we processed the data of 11 continuously operating air quality stations of the State Environment Agency (LUA NRW) with time series reaching back up to 20 years. We investigated rural stations, stations in the urban background and heavily traffic influenced locations. It was possible to calculate and assess the NO/NO₂-ratio under consideration of the fast reaction of ozone with NO. There were clear indications towards existing trends and they could be determined as statistically significant using the nonparametric Mann-Kendall Test. The analysis of possible causes for the change of the NO/NO₂-ratio focused upon the change of the global radiation, the change of the patterns of the atmosphetic circulation, and the frequency of cyclones and anticyclones meteorological conditions in Central Europe, the introduction of automotive catalytic converters, and the development of the atmospheric oxidation-capacity.

Results and conclusions

The results are indicating a decline of the ratio at traffic-influenced stations with a statistical significance over 95%. The negative trend can also be detected at most urban background stations. It was problematic to perform the trend-analysis of the rural background station in the Egge-Mountains because of the fragmentary character of the dataset. Regional differences in the development of the NO/NO₂-ratio indicate towards various causes. Crucial for the situation at the rural areas are the changed trajectories of cyclones and anticyclones as well as the decline of the atmospheric oxidation-capacity, while the traffic plays another important role at urban stations. The negative trend at the traffic-stations was intensified by the introduction of catalytic converters, which lead to a reduction in emissions of NO_x

Recommendations and prospects

The significance of the NO/NO₂-ratio for the oxidation capacity of the atmosphere shows the necessity to further monitor this development. Previous investigations detected a decline in total NO_x without examining the relative development of the two nitrogen oxides towards each other. Gaining insight into the local differences of this ratio helps to allocate sources and to develop understanding of the atmospheric processes.     

Passive sampling in combination with thermal desorption and gas chromatography as a tool for self-assessment of chemical exposure

Diffusive samplers for monitoring of air quality are user-friendly devices that can normally be operated by the user himself. Hence these samplers are suitable for self-assessment. Practical and work organisational aspects of self-assessment of chemical exposure were studied in different occupational settings. It was found that the diffusive sampler used in these studies, the Perkin-Elmer tube in combination with thermal desorption, worked well for the purpose and could be correctly handled by the individuals using it. The results from self-assessments agreed well with expert measurements carried out by an occupational hygienist. However, in order to obtain a sustainable system of self-assessment strong organizational support is needed.     

Toxicity of nanosized and bulk ZnO, CuO and TiO2 to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus

As the production of nanoparticles of ZnO, TiO2 and CuO is increasing, their (eco)toxicity to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus was studied with a special emphasis on product formulations (nano or bulk oxides) and solubilization of particles. Our innovative approach based on the combination of traditional ecotoxicology methods and metal-specific recombinant biosensors allowed to clearly differentiate the toxic effects of metal oxides per se and solubilized metal ions. Suspensions of nano and bulk TiO2 were not toxic even at 20 g l(-1). All Zn formulations were very toxic: L(E)C50 (mg l(-1)) for bulk ZnO, nanoZnO and ZnSO4.7H2O: 1.8, 1.9, 1.1 (V. fischeri); 8.8, 3.2, 6.1 (D. magna) and 0.24, 0.18, 0.98 (T. platyurus), respectively. The toxicity was due to solubilized Zn ions as proved with recombinant Zn-sensor bacteria. Differently from Zn compounds, Cu compounds had different toxicities: L(E)C50 (mg l(-1)) for bulk CuO, nano CuO and CuSO4: 3811, 79, 1.6 (V. fischeri), 165, 3.2, 0,17 (D. magna) and 95, 2.1, 0.11 (T. platyurus), respectively. Cu-sensor bacteria showed that toxicity to V. fischeri and T. platyurus was largely explained by soluble Cu ions. However, for Daphnia magna, nano and bulk CuO proved less bioavailable than for bacterial Cu-sensor. This is the first evaluation of ZnO, CuO and TiO2 toxicity to V. fischeri and T. platyurus. For nano ZnO and nano CuO this is also a first study for D. magna.