Trihalomethane formation in ozonated and chlorinated surface water

The relatively recent discovery of disinfection by-products has driven the main regulatory organisms to set maximum contaminant levels for certain substances in drinking water. Trihalomethanes can be deemed as the most important group of by-products in chlorinated surface waters. The present work has focused on trihalomethane formation in a full-scale water treatment plant. We studied the effect of several factors, including ozonation, on trihalomethane levels in chlorinated treated water. The treatment scheme also includes an ozonation step. Electronic Publication     

Stability and storage problems in organotin speciation in environmental samples

The stability of both tributyltin (TBT) and triphenyltin (TPT) in water, sediment, oysters and cockles was studied over a period of 18 months using several storage conditions. Butyltins were stable in unacidified sea-water stored in polycarbonate bottles in the dark at 4 degrees C for 7 months, but half of the TBT concentration was lost after 540 d. A comparable preservation time was achieved for butyltins stored on C18 cartridges at room temperature. However, phenyltins extracted from sea-water were stable for only 60 d stored on cartridges and even more pronounced losses (about 90% after 540 d) occurred when they were stored in either polycarbonate or Pyrex glass bottles. Losses of organotins were observed in sediments after air drying and pasteurization treatments using a freeze-dried sediment as a comparator, whereas both butyltin and phenyltin species remained stable in sediments stored at -20 degrees C for the 18 months tested, irrespective of the treatment used for stabilization. Air drying followed by pasteurization was shown to be superior to other treatments for the stabilization of organotin compounds in sediments stored at higher temperatures, but 30% of TBT was lost after 540 d at 25 degrees C. Finally, butyltins were stable in both frozen cockles and oysters in the dark over a 7 month period and in freeze-dried samples stored at 4 degrees C for 5 months, but TBT losses of about 70% were observed after 540 d.     

Value congruence,control, sense of community and demands as determinants of burnout syndrome among hospitality workers

Employees working in the hospitality industry are constantly exposed to occupational stressors that may lead employees into experiencing burnout syndrome. Research addressing the interactive effects of control, community and value congruence to alleviate the impact of workplace demands on experiencing burnout is relatively limited. The present study examined relationships among control, community and value congruence, workplace demands and the three components of burnout. A sample of 418 employees working in a variety of hospitality associations including restaurants and hotels in Spain were recruited. Moderation analyses and linear regressions analyzed the predictive power of control, community and value congruence as moderating variables. Results indicate that control, community and value congruence were successful buffers in the relationships between workplace demands and the burnout dimensions. The present findings offer suggestions for future research on potential moderating variables, as well as implications for reducing burnout among hospitality employees.     

Fighting rules and rival recognition reduce costs of aggression in male lizards, Podarcis hispanica

The establishment of fighting rules and the ability to recognise individual conspecifics and to assess their fighting ability and/or roles may help to reduce costs of fighting. We staged encounters between males of the lizard Podarcis hispanica to examine whether lizards used fighting strategies and whether a previous agonistic experience affects the outcome and characteristics of a subsequent encounter. The results showed that simple rules such as body size differences and residence condition were used to determine the outcome of agonistic interactions as quickly as possible. Thus, larger males were dominant in most encounters. However, when size differences between opponents are smaller, they may be more difficult to estimate and, then, residence condition was more important. In addition, the intensity of interactions between males could be explained according to the ”sequential assessment game”, supporting the idea that P. hispanica males acquire information about fighting ability gradually during the progress of a fight. Our results also showed that the second fight of the same pair of males was less aggressive, even when its outcome was the opposite of the first. This result suggests that male P. hispanica can recognise individual opponents and that they use this information to reach a contest outcome more quickly, thus reducing unnecessary aggression levels in subsequent interactions. These fighting strategies and assessment mechanisms may help to stabilise the social system of this lizard. Received: 2 November 1999 / Revised: 26 August 2000 / Accepted: 4 September 2000