Eutrophic urban ponds suffer from cyanobacterial blooms: Dutch examples

Ponds play an important role in urban areas. However, cyanobacterial blooms counteract the societal need for a good water quality and pose serious health risks for citizens and pets. To provide insight into the extent and possible causes of cyanobacterial problems in urban ponds, we conducted a survey on cyanobacterial blooms and studied three ponds in detail. Among 3,500 urban ponds in the urbanized Dutch province of North Brabant, 125 showed cyanobacterial blooms in the period 2009–2012. This covered 79 % of all locations registered for cyanobacterial blooms, despite the fact that urban ponds comprise only 11 % of the area of surface water in North Brabant. Dominant bloom-forming genera in urban ponds were Microcystis, Anabaena and Planktothrix. In the three ponds selected for further study, the microcystin concentration of the water peaked at 77 μg l^?1 and in scums at 64,000 μg l^?1, which is considered highly toxic. Microcystin-RR and microcystin-LR were the most prevalent variants in these waters and in scums. Cyanobacterial chlorophyll-a peaked in August with concentrations up to 962 μg l^?1 outside of scums. The ponds were highly eutrophic with mean total phosphorus concentrations between 0.16 and 0.44 mg l^?1, and the sediments were rich in potential releasable phosphorus. High fish stocks dominated by carp lead to bioturbation, which also favours blooms. As urban ponds in North Brabant, and likely in other regions, regularly suffer from cyanobacterial blooms and citizens may easily have contact with the water and may ingest cyanobacterial material during recreational activities, particularly swimming, control of health risk is of importance. Monitoring of cyanobacteria and cyanobacterial toxins in urban ponds is a first step to control health risks. Mitigation strategies should focus on external sources of eutrophication and consider the effect of sediment P release and bioturbation by fish.     

Evaluation and improvement of a method for assessing HSMS from the resilience engineering perspective: A case study of an electricity distributor

This article presents an evaluation and proposals for improving a method for assessing health and safety management systems. This method takes resilience engineering (RE) as its underlying philosophy and was originally devised and tested in a case study of a manufacturing plant. Four main changes were proposed in comparison with the original version of the method: (a) a framework for assessing the use of RE principles more systematically; (b) guidelines for developing an action plan as a result of the assessment; (c) re-organization of the data collection tools in order to increase their ease of use; and (d) procedures for facilitating the assignment of scores to the items assessed. The evaluation of the method, which was not restricted to the changes described in this article, was conducted based on seven criteria for evaluating safety assessment tools. Both the evaluation and the impact of the changes are discussed based on a case study, in which the method was applied in a company that distributes electricity.     

Are older workers more active copers? Longitudinal effects of age‐contingent coping on strain at work

This study addresses coping processes as explanation of age‐related differences in strain experience. Based on the life‐span theory of control, we posit that older workers employ more active problem‐focused and more active emotion‐focused coping strategies than younger workers, which should mediate age effects on strain at work. The correlation between age and passive avoidance coping, in contrast, is expected to be qualified by external resources such as job control. Hypotheses were tested in a two‐wave panel study (8 months lag) with 634 workers (age range 16–65 years). Job demands were considered as control variables. As predicted, older as compared with younger workers reported more active problem‐focused coping, which mediated age differences on strain in the longitudinal analysis. No mediation was found for active emotion‐focused coping. Moreover, age‐contingent effects of passive avoidance coping were moderated by job control. When job control was low, younger as compared with older workers reported more avoidance coping, which in turn decreased strain in the longitudinal analysis. Finally, reverse longitudinal effects of age‐contingent strain on active problem‐focused and active emotion‐focused coping provide initial evidence for age‐contingent resource spirals. Together, the results reveal specific strengths of older workers for stress management at work. Copyright © 2015 John Wiley & Sons, Ltd.     

Chemical defense and evolution in the Sacoglossa (Mollusca: Gastropoda: Opisthobranchia)

Summary. Recent advances in both the systematics and the natural products chemistry of the order Sacoglossa (=Ascoglossa) in the gastropod subclass Opisthobranchia suggest a revised and improved historical account of the evolution of the group. Although the algal genus Caulerpa makes a suitable model for the ancestral food of the order, other siphonaceous algae are consistent with both morphological and chemical data. At an early evolutionary stage terpenoids are sequestered from the food, and used defensively, often with modification. With an evolutionary switch to different kinds of algal food, there is often a shift to other, related defensive chemicals. A switch to new food source sometimes leads to the abandonment of chemical defense, but in other cases there is de-novo synthesis of defensive metabolites. The synthesis of polypropionates, which are used defensively, occurs in some other gastropods, but otherwise is known only in fungi. The systematic distribution of the defensive polypropionates suggests that their defensive use has evolved several times among gastropods. Failure to detect them may mean that synthetic capacity has evolved more than once, or it may mean that they exist at low levels, perhaps having a non-defensive function. Received 9 February 1998; accepted 20 March 1998.     

Removal of hydrogen chloride from gaseous streams using magnesium-aluminum oxide

Magnesium-aluminum oxide (Mg-Al oxide) obtained by thermal decomposition of Mg-Al layered double hydroxide (Mg-Al LDH) effectively removed HCl from gaseous streams. HCl removal was greater in the presence of added water vapor at all temperatures examined and increased with decreasing temperature in both the presence and absence of added water vapor. Wet and dry removal of gaseous HCl were attributed to the production of MgCl2 . 6H2O and MgCl2 . 4H2O, respectively. For the wet scrubbing process, the reconstruction reaction of Mg-Al LDH from Mg-Al oxide was the primary mechanism for increased HCl removal.