Sources and fate of nitrosodimethylamine and its precursors in municipal wastewater treatment plants.

To assess the occurrence and fate of nitrosodimethylamine (NDMA) and its precursors in wastewater treatment plants, samples from wastewater treatment plants and industrial sources were analyzed for NDMA, total NDMA precursors, and dimethylamine (DMA). The median concentration of NDMA in untreated wastewater was approximately 80 ng/L, with maximum concentrations up to 790 ng/L presumably occuring because of sources unrelated to domestic wastewater. Concentrations of DMA in untreated wastewater ranged from approximately 50 to 120 microg/L and accounted for a majority of the NDMA precursors. The removal of NDMA during secondary biological treatment exhibited considerable variability, with overall removal ranging from 0 to 75%. In contrast, removal of NDMA precursors and DMA generally exceeded 70%. The median concentration of NDMA in secondary effluent before disinfection was 46 ng/L. Although DMA was removed during secondary treatment, other NDMA precursors in wastewater effluent will result in formation of additional NDMA upon disinfection with chloramines.     

Lichtallergien und andere Lichtempfindlichkeitsreaktionen

Adverse reactions of the skin to light comprise a number of different dermatologic conditions. In light-‘allergies’ in the narrower sense non-ionised electromagnetic radiation (ultraviolet (UV)-A/-B radiation or visible light) provokes an immunologic or allergic skin reaction. These include solar urticaria, an, immunoglobulin E-mediated, immediate-type allergic photoreaction, photoallergic contact dermatitis and photoallergic (drug) exanthema, which are cell-mediated, delayed-type allergic photoreactions due to photosensitization, chronic actinic dermatitis and polymorphic light eruption. Beyond it there are nonimmunologic photosensitive and photoaggravated skin diseases, like exogenous and endogenous phototoxicity, xeroderma pigmentosum, which is based on a genetic defect, or the autoimmune disease lupus erythematosus.     

The bottlenose dolphin community of Doubtful Sound features a large proportion of long-lasting associations

More than 12 studies of different bottlenose dolphin populations, spanning from tropical to cold temperate waters, have shown that the species typically lives in societies in which relationships among individuals are predominantly fluid. In all cases dolphins lived in small groups characterised by fluid and dynamic interactions and some degree of dispersal from the natal group by both sexes. We describe a small, closed population of bottlenose dolphins living at the southern extreme of the species' range. Individuals live in large, mixed-sex groups in which no permanent emigration/immigration has been observed over the past 7 years. All members within the community are relatively closely associated (average half-weight index>0.4). Both male–male and female–female networks of preferred associates are present, as are long-lasting associations across sexes. The community structure is temporally stable, compared to other bottlenose dolphin populations, and constant companionship seems to be prevalent in the temporal association pattern. Such high degrees of stability are unprecedented in studies of bottlenose dolphins and may be related to the ecological constraints of Doubtful Sound. Fjords are low-productivity systems in which survival may easily require a greater level of co-operation, and hence group stability. These conditions are also present in other cetacean populations forming stable groups. We therefore hypothesise that ecological constraints are important factors shaping social interactions within cetacean societies.Communicated by D. Watts     

Evaluating stream restoration projects

River and stream restoration projects are increasingly numerous but rarely subjected to systematic postproject evaluation. Without conducting such evaluation and widely disseminating the results, lessons will not be learned from successes and failures, and the field of river restoration cannot advance. Postproject evaluation must be incorporated into the initial design of each project, with the choice of evaluation technique based directly upon the specific project goals against which performance will be evaluated. We emphasize measurement of geomorphic characteristics, as these constitute the physical framework supporting riparian and aquatic ecosystems. Techniques for evaluating other components are briefly discussed, especially as they relate to geomorphic variables. Where possible, geomorphic, hydrologic, and ecological variables should be measured along the same transects. In general, postproject monitoring should continue for at least a decade, with surveys conducted after each flood above a predetermined threshold. Project design should be preceded by a historical study documenting former channel conditions to provide insights into the processes suggest earlier, potentially stable channel configurations as possible design models.     

Training trade unionists in ergonomics: Interaction between public policies, trade union practices and the development of research

For a number of years now, enterprises have become increasingly interested in training in the area of health and safety at work. Even though trade unionists and managers see different advantages in such training, they share the same willingness to reduce occupational injuries. Even if demand for training is sometimes limited on purpose (all that is expected of it is to pass on recipes enabling work to be continued without getting hurt), training in safety and health is a privileged point of contact between researchers and trade unionists. But the contact between these two groups of actors in the process of changing working conditions does not happen without raising a number of questions: that of reciprocal mental images of each other, for instance, something which will condition the ways in which their knowledge meets; or the issue of the target groups of training: all the workers or just the delegates representing the workers in cooperation bodies? Other fundamental questions relate to the context in which training takes place: what type of training should take pride of place? What is the role of the expert in this approach? And how should the expert's knowledge be linked in with that of the workers?     

Migration caused by climate change: how vulnerable are people inn dryland areas?

Climate change has been presented as a likely trigger formigration of people, especially in dryland areas of less developed countries.The underlying research questions focus on the strength of adaptationcapacity of subsistence farmers in Northern Ethiopia, and evaluate historicalexperiences gained from drought-induced migration. Through a survey of104 peasants who had to migrant due to persistent drought, vulnerabilityto climate change has shown to be a complex issue, including themultiplicity of factors comprising a household environment. Still, to bevulnerable does not make someone a potential climate migrant, as peoplein marginal regions have developed a great variety of adaptationmechanisms, which strengthen their ability to cope with both, slow climaticchanges and extreme climatic events.     

Altitude-dependent wet,dry and occult nitrogen deposition in an Alpine Region

From November 1995 to October 1996 and from October 1997 to September 1998, samples of wet precipitation, cloud water, as well as of reactive gases and particulate matter, were collected at three elevational levels (920 m, 1280 m and 1758 m a.s.l.) in Achenkirch, Austria. The samples were analysed for ammonium and nitrate in wet precipitation and in cloud water, for ammonia, nitric acid and nitrogen dioxide in the gas phase and for particulate ammonium and particulate nitrate in aerosol. Total nitrogen deposition was calculated combining measured concentrations in wet, dry and occult depositions with the corresponding deposition fluxes. Two multilayer deposition models were used for the calculation of dry and occult deposition. The total nitrogen input in 1995/96 was estimated to be 29 kg N ha⁻¹a⁻¹ at the Christlumkopf station (1758 m), 20 kg N ha⁻¹a⁻¹ at the Christlumalm station (1280 m) and 28 kg N ha⁻¹a⁻¹ at the Talboden station (930 m). Respective data for the 1997/98 observation period were 31 kg N ha⁻¹a⁻¹ at the Christlumkopf station (1758 m) and 18 kg N ha⁻¹a⁻¹ at the Mühleggerköpfl station (920 m). Critical Loads of nitrogen for coniferous forests were exceeded significantly near-source regions represented by areas of intense agricultural use and at high elevation sites.