Global air quality monitoring: Trends and levels of sulphur dioxide and suspended particulate matter in selected urban areas

An overview is presented of the development and ongoing activities of the WHO/UNEP air quality monitoring project. The project started in 1973 and is part of the Global Environmental Monitoring System. An analysis of the sulphur dioxide and suspended particulate matter is also included. The results show that the annual mean concentration for sulphur dioxide has decreased since 1973; for suspended particulate matter, however, a gradual increase is observed since 1976.     

Application Of Artificial Neural Network Models To Analyse The Relationships Between Gammarus pulex L. (Crustacea, Amphipoda) And River Characteristics

This study aimed at analysing the relationship between river characteristics and abundance of Gammarus pulex. To this end, four methods which can identify the relative contribution and/or the contribution profile of the input variables in neural networks describing the habitat preferences of this species were compared: (i) the ‘PaD‘ (‘Partial Derivatives‘) method consists of a calculation of the partial derivatives of the output in relation to the input variables; (ii) the ‘Weights‘method is a computation using the connection weights of the backpropagation Artificial Neural Networks; (iii) the ‘Perturb‘method analyses the effect of a perturbation of the input variables on the output variable; (iv) the ‘Profile‘ method is a successive variation of one input variable while the others are kept constant at a fixed set of values. The dataset consisted of 179 samples, collected over a three-year period in the Zwalm river basin in Flanders, Belgium. Twenty-four environmental variables as well as the log-transformed abundance of Gammarus pulex were used in this study. The different contribution methods gave similar results concerning the order of importance of the input variables. Moreover, the stability of the methods was confirmed by gradually removing variables. Only in a limited number of cases a shift in the relative importance of the remaining input variables could be observed. Nevertheless, differences in sensitivity and stability of the methods were detected, probably as a result of the different calculation procedures. In this respect, the ‘PaD‘method made a more severe discrimination between minor and major contributing environmental variables in comparison to the ‘Weights‘, ‘Profile‘ and ‘Perturb‘ methods. From an ecological point of view, the input variables ‘Ammonium‘ and to a smaller extent ‘COD‘, were selected by these methods as dominant river characteristics for the prediction of the abundance of Gammarus pulex in this study area.     

Dichloromethane Marine Risk Assessment with Special Reference to the Osparcom Region: North Sea

This risk assessment on dichloromethane was carried out specifically for the marine environment, following methodology given in the EU risk assessment Regulation (1488/94) and Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of 'predicted environmental concentrations' (PEC) to 'predicted no-effect concentrations' (PNEC) for the marine aquatic environment. In total, 23 studies for fish, 17 studies for invertebrates and 6 studies for algae were evaluated. Both acute and chronic toxicity studies were taken into account and appropriate assessment factors used to define a PNEC value of 830 microg/l. Most of the available monitoring data apply to rivers and estuaries and were used to calculate PECs. The most recent data (1983--1995) support a typical PEC for dichloromethane lower than 0.2 microg/l and a worst case PEC of 13.6 microg/l. Dichloromethane is not a 'toxic, persistent and liable to bioaccumulate' substance sensu the Oslo and Paris Conventions for the Prevention of Marine Pollution (OSPAR-DYNAMEC). The calculated PEC/PNEC ratios give margins of 60 to 4000 between the PNEC and PEC, dilution within the sea would further increase these margins. It can be concluded that the present use of dichloromethane does not present a risk to the marine aquatic environment.     

Seasonal effects on the air-water carbon dioxide exchange in the Hooghly estuary,NE coast of Bay of Bengal,India

Monthly variation of CO2 fugacity (fCO2) in surface water and related atmospheric exchanges were measured in the Hooghly estuary which is one of the most important estuaries, since it is fed by one of the world's largest rivers, the Ganges with a flow of 15,646 m3 s-1 (1.6% of the world's combined river flow). Carbon dioxide fluxes averaged over the entire estuary are in the range of -2.78 to 84.4 mmol m-2 d-1. This estuary acts as a sink for CO2 during monsoon months and seasonal variation of its flux is controlled by dilution of seawater by river water. Since the solubility of CO2 and the disassociation of carbonic acid in estuarine water are controlled by temperature and salinity, the observed variations of CO2 fluxes are compared with those predicted from seasonal changes in temperature, salinity and the ratio of gross primary production to community respiration using empirical equations with an explained variability of 55%.     

Histological and biochemical bases of defense mechanisms in four species of Polybranchioidea ascoglossan molluscs

The multiple defensive strategies of four Mediterranean ascoglossan molluscan species, belonging to two different Polybranchioidea families, Cyerce cristallina (Trinchese, 1881) and Caliphylla mediterranea (Costa A., 1869) (Polybranchiidae), and Ercolania funerea (Costa A., 1867) and Placida dendritica (Alder and Hancock, 1843) (Stiligeridae), were studied. E. funerea, P. dendritica and C. mediterranea were collected from the lake Fusaro (Arco Felice, Naples) in 1992. C. cristallina was collected from Capo Miseno (Bay of Naples) in 1991. C. cristallina and E. funerea easily undergo autotomy of dorso-lateral appendages (cerata) followed by an extraordinarily quick (8 to 10 d) regeneration of the latter. Histological analyses showed the presence, at the basis of both normal and regenerated cerata of these species, of a muscular sphincter which facilitates the autotomic process. C. mediterranea and P. dendritica, which do not undergo autotomy, lack this anatomical feature but feed upon algae belonging to the Chaetomorpha and Bryopsis genera, and, as shown by electron microscopy studies, retain large quantities of chloroplasts which they use as camouflage amidst algae and to escape predation. E. funerea also exploits this behavioral defense mechanism. Histological investigations also revealed in the cerata of all four species several multi-cellular mucous glands responsible for the secretion of the slime typical for these molluscs. C. cristallina, E. funerea and P. dendritica secrete large amounts of slime, whose extracts displayed ichthyotoxic activity when assayed by the Gambusia affinis ichthyotoxicity assay, while extracts of C. mediterranea slime were not toxic. A chemical analysis of the slime, mantle and cerata led to the isolation of polypropionate - and -pyrones from all species except C. mediterranea. These secondary metabolites possess structures that differ only by the degree of methylation and the geometry of double bonds of the side chain and are specifically distributed in cerata and slime of C. cristallina and E. funerea. The pyrones also display different activities in the Hydra vulgaris regeneration assay and in the G. affinis ichthyotoxicity test and, depending on their structural features and tissue distribution, are likely to play a role either as defense allomones or as supportive inducers of cerata regeneration. In conclusion, combined biological observations and histological and chemical techniques generated valuable information on the defensive behavior of these four ascoglossan species which exploit various combinations of the same behavioral and/or chemical defensive strategies and thus successfully avoid predation.     

水生植物在滇池湿地景观设计中的应用

以滇池湿地景观设计为研究对象,介绍了水生植物在湿地景观设计中的作用和原则以及水生植物的选择、配置和生物浮岛技术的运用.     

Linking the Big Five‐Factors of personality to charismatic and transactional leadership; perceived dynamic work environment as a moderator

In this multi‐source study we investigated the relationships between the Big Five personality traits and both charismatic and transactional leadership behavior, and whether dynamism (the degree that the work environment is deemed dynamic) moderates these relationships. We also tested whether dynamism moderates the relationship between leadership behavior and effectiveness. Personality was measured through self ratings using the NEO‐PI‐R. Subordinates rated their leaders' behavior, and peers and superiors provided ratings of effectiveness. Consistent with trait activation theory, results showed that perceived dynamic work environment moderated the relationships of four of the Big Five‐Factors with both charismatic and transactional leadership. Also, charismatic leadership was positively related to perceived effectiveness, but only in dynamic contexts. Copyright © 2005 John Wiley & Sons, Ltd.     

Where intrinsic job satisfaction fails to work: national moderators of intrinsic motivation

This study sought for national characteristics that moderate the individual‐level relationship between job characteristics and job satisfaction. Data from two distinct questionnaire surveys administered to 107,292 employees in 49 countries was analyzed by employing multilevel modeling. Results showed that the link between intrinsic job characteristics and job satisfaction is stronger in richer countries, countries with better governmental social welfare programs, more individualistic countries, and smaller power distance countries. By contrast, extrinsic job characteristics are strongly and positively related to job satisfaction in all countries. In addition, we found that intrinsic job characteristics tend to produce motivating satisfaction in countries with good governmental social welfare programs irrespective of the degree of power distance, while they do not tend to work so in countries with poor governmental social welfare programs as well as a large power distance culture. Socio‐economic and cultural approaches to explaining cross‐national variation in work motivation are discussed. Copyright © 2003 John Wiley & Sons, Ltd.