Transformation products and reaction kinetics of fragrances in advanced wastewater treatment with ozone

The reaction of the fragrance compounds 4,6,6,7,8,8-hexamethyl-1,3,4,7-tetrahydrocyclopenta[g]isochromene (HHCB), 1-(3,5,5,6,8,8-hexamethyl-6,7-dihydronaphthalen-2-yl)ethanone (AHTN), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene/MX), 1-(4-tert-butyl-2,6-dimethyl-3,5-dinitrophenyl)ethanone (musk ketone/MK), and 1-(2,3,8,8-tetramethyl-1,3,4,5,6,7-hexahydronaphthalen-2-yl)ethanone (OTNE) with ozone in tap water as well as waste water treatment plant (WWTP) effluents is described. Several transformation products are characterized by means of gas chromatography coupled to mass spectrometry. One transformation product (HHCB-Lactone) was confirmed by means of a true standard. Musk xylene and musk ketone do not react with ozone under the conditions used in this study. AHTN and HHCB reacted slowly to a multitude of transformation products, while OTNE reacted quickly to several stable transformation products. The reaction constants and half lives are used to predict removal efficiencies for full scale reactors.     

Ultimate biodegradation and elimination of antibiotics in inherent tests

The biodegradation and elimination of antibiotics in municipal wastewater treatment plants is of particular concern because sewage is the main exposure route for antibiotics used in human medicine. The inherent biodegradability of 17 antibiotics was determined in a combined test design based on the Zahn-Wellens test (OECD 302 B, 1992) and the CO2-evolution test (OECD 301 B, 1992). CO2 Evolution test (Modified Sturm test). OECD Guideline for the Testing of Chemicals, Paris). Only benzylpenicillin sodium salt (Penicillin G) proved to be ultimately biodegradable, reaching ThCO2 degradation extents of 78-87%. Among the others, only amoxicillin, imipenem and nystatin showed certain ultimate biodegradation in few of the parallel flasks and can be regarded as partially biodegradable with formation of stable metabolites. The DOC-elimination of tetracycline-HCl showed a typical degradation curve starting with 18% and reaching the plateau phase at 80% after 21 days. Nevertheless, the CO2-evolution measured in parallel did not support the data, indicating that the time needed for reaching the adsorption equilibrium was underestimated. Several other antibiotics showed considerable DOC-elimination in the inherent test while only minor incidences of ultimate biodegradation were observed. The combination of CO2-evolution and DOC-elimination is a suitable instrument for assessing the behaviour of chemicals within one test. It enables one to assess both inherent ultimate biodegradability and DOC-elimination by sorption. The applicability of the test is limited to substances with a moderate toxicity.     

Seasonal source influence on river mass flows of benzotriazoles

The anticorrosive agents 1H-benzotriazole (1H-BT), 4-methyl-1H-benzotriazole (4 Me-BT) and 5-methyl-1H-benzotriazole (5 Me-BT), which are usually added to dishwasher detergents, automotive antifreeze formulations and aircraft de-icing/anti-icing fluids (ADAFs), were measured in river water. Samples were collected from 15 sampling sites in the mainstream and selected tributaries of a medium-sized catchment area during summer and winter periods. The aim of this study was to assess a seasonal source influence on mass flows of benzotriazoles (BTs). The study area was representatively selected for an area with a possible influence of airport surface runoff. River discharge measurements were also performed. Moreover, BT concentrations were measured in an anti-icing and a de-icing fluid used at German airports as well as in several dishwasher detergents. The highest concentrations of all three compounds in river water were measured during the winter seasons. The maximum BT mass flows were calculated for all three substances in January when the mean monthly air temperature was the lowest; mass flows were the lowest in July when the mean monthly air temperature was the highest. A significant seasonal influence on BT mass flows in river water was observed for monitoring stations with a possible influence of airport surface runoff and for sampling locations where such an influence could be excluded. This indicates an input of BTs from other temperature-dependent applications, e.g. the use of antifreeze formulations in automotive windscreen wiper or cooling systems. 1H-BT was detected in two dishwasher tablets; 4 Me-BT and 5 Me-BT were not detected. BTs were measured in the anti-icing fluid with concentrations of 715 ng g(-1) (1H-BT), 1425 ng g(-1) (4 Me-BT) and 536 ng g(-1) (5 Me-BT); none of the BTs were detected in the de-icing fluid. Distribution patterns of BTs in ADAF and dishwasher detergents differed from those in river water.     

Effects of male sexual harassment on female time budgets,feeding behavior,and metabolic rates in a tropical livebearing fish (<Emphasis Type="Italic">Poecilia mexicana</Emphasis>)

Sexual harassment by males has the potential to affect almost any aspect of female behavior and life history. Using Atlantic mollies (Poecilia mexicana) as a model—a species in which males do not court but almost constantly try to forcefully mate with females—we asked whether and how male harassment influences (a) females’ time budgets and (b) feeding rates (e.g., through frequent flight from male approaches), and (c) whether metabolic rates are increased as a response to stress. Field observations in a natural P. mexicana population revealed that males (average feeding rate 15%) spent far less time feeding than females (60%), and clearly traded off frequent pursuit of females with foraging. Most importantly, females’ feeding times were dramatically reduced when being pursued by a harassing male. Also in standardized lab experiments, females spent significantly less time feeding when accompanied by a male as compared to being in the presence of another female. This effect was also observed when partner fish (male or female) were presented only visually, but could not interact physically with the focal female. It seems, therefore, that females increase vigilance when a harassing male is around, which keeps them from feeding even before males actually approach them. Based on the latter result, we asked whether a stress-induced increase in metabolic rates would be discernible. We measured oxygen consumption and gill ventilation frequencies (opercular rates) of females in different social contexts (alone, with another female, or a male). The predicted, strong body mass dependency of both physiological parameters was uncovered, but no evidence for an effect of social context was detected. We argue that male harassment represents such a constant (but non-lethal) stressor for poeciliid females that their metabolic stress responses have adapted to this through habituation.     

Occurrence of benzotriazoles in the rivers Main,Hengstbach, and Hegbach (Germany)

Background, aim, and scope  

Benzotriazoles (BT) as 1H-benzotriazole (1H-BT), 5-methyl-1H-benzotriazole (5Me-BT), and 4-methyl-1H-benzotriazole (4Me-BT) are frequently used as corrosion inhibitors in dish washer detergents, aircraft de-icing/anti-icing fluids (ADAF), automotive antifreeze formulations, brake fluids, fluids for industrial cooling systems, metal-cutting fluids, and in solid cooling lubricants. Discharge of treated municipal waste water and controlled over-runs of combined waste water sewers are potential point sources for BT in rivers. The aim of this monitoring study was to yield an overview on exposure concentrations and loads of BT in the German rivers Main, Hengstbach, and Hegbach.     

Inheritance of dominance in honeybees (Apis mellifera capensis Esch.)

Summary Hierarchies in worker dominance are well developed in reproductive workers of the Cape honeybee (Apis mellifera capensis Esch.). Elements that influence worker dominance (trophallactic behaviour, fecundity, queen substance content) are mainly genetically determined. The estimated values for the heritabilities in the broader sense range from 0.27 to 0.89. This genetically based hierarchy leads to new insight into the theory of natural selection in honeybees. Besides selection at the colony level, or selection at the level of reproductives, natural selection also operates at the level of the individual worker bee within a colony.     

Colony performance in honeybees (Apis mellifera capensis Esch.) depends on the proportion of subordinate and dominant workers

Summary Individual worker dominance correlated with trophallactic behavior, which affects several social behaviors related to colony fitness, shows a high genetic variance in worker bees. In a bioassay we tested trophallactic behavior of workers and selected dominant (receiving) and subordinate worker bees (offering) of Apis mellifera capensis to establish genetic lines of both kinds. Queenright test colonies were experimentally composed of 100% subordinate workers, 100% dominant workers, 50% dominant plus 50% subordinate workers, and 100% hybrid workers from the two genetic lines. The chosen test parameters were brood-rearing, comb building and hoarding behavior. In all cases, the colonies of pure subordinate bees showed the best colony performance, whereas the colonies composed of only dominant bees were nearly unproductive. The mixed colonies (50% dominant + 50% subordinate) ranked in the middle and did not differ significantly from the hybrid colonies. The results indicate that colony performance under queenright conditions depends on the proportion of subordinate workers. This result supports a selection model based on the combination of individual selection and on group selection at the colony level, which explains the high genetic variance of individual worker reproduction.