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81.
82.
The impact of dense traffic on the breeding success in pied flycatchers (Ficedula hypoleuca) was studied using roadside nest-boxes. Nest site selection and breeding success of flycatchers were observed in relation to the distance from the road. The number of occupied territories was no higher closer to the road than it was deeper inside the forest. The distance to the road had no effect on the laying date, clutch size, or brood size. However, nests closer to the road were more likely to fail at the chick stage. The number of broods that were closer to roads and were lost completely was significantly higher than those further away. As a consequence, the number of fledglings per breeding attempt decreased closer to roads. The nestlings typically died as older chicks when the parent birds were providing them with maximum quantities of food. A possible reason for the declining reproductive success was the traffic-related mortality of parent birds, as weather conditions were not especially adverse for raising healthy offspring.  相似文献   
83.
A tiered protocol for assessing ecological risks has been applied to the rice pesticide profoxydim. The initial assessment (Tier I) was based on toxicity exposure ratio (TER) calculations based on laboratory data using a worst-case rice scenario. The first refinement (Tier II) was based on direct toxicity assessment (DTA) of water samples collected during a field-mesocosm study. Finally, a higher-tier assessment on the in situ assessment of paddy community responses (field-mesocosm-Tier III) was performed. A successive application of three pesticides, the herbicides azimsulfuron, propanil and the insecticide malathion, was used as reference controls. The refined assessments indicated a lower risk than that predicted from TER estimations. DTA-based Tier II showed toxicity effects only for concentrations above the recommended dose of profoxydim. Effects for reference controls were observed in DTA which were not expected from Tier I. The field-mesocosm study confirmed these effects but also showed that they were transient and of low relevance.  相似文献   
84.
Environmental Persistence of Chemicals   总被引:1,自引:0,他引:1  
- DOI: http://dx.doi.org/10.1065/espr2006.01.008 Background The hazard criterion of persistence as it applies to chemicals in the environment is reviewed and discussed. This quantity can not be measured directly in the environment, thus it must be estimated using models that synthesise information on chemical half-lives and partitioning properties, the nature of the environment and how the chemical is released into the environment. Main Features It is suggested that the preferred criterion is the average residence time of the chemical in the environment, i.e. conceptually the sum of the life-times of all molecules (attributable only to losses by degrading reactions) divided by the number of molecules. If all chemical fate processes are first order, this persistence is independent of the quantity of chemical introduced and whether introduction is steady- or unsteady-state in nature. It is shown that in a multimedia environment persistence is affected not only by degradation kinetics, but also by mode-of-entry and partitioning. For screening level purposes a Level II equilibrium model may be adequate but a Level III model is generally preferable for estimating the average persistence. If a distribution of persistences is required a dynamic Level IV model must be used. Discussion The implications for regulating chemicals on the basis of persistence are discussed. Conclusion It is concluded that the preferred strategy is to use Level II, III, and IV models and that the use of only degradation kinetics or media-specific half-lives can be misleading and uneconomical.  相似文献   
85.
Immunoreactive metallothionein has been demonstrated in formalin fixed sections of rat and human tissue using a DNP hapten sandwich staining procedure and antibody to zinc-induced rat liver metallothionein II.MT was found in rat liver, duodenum, jejunum and ileum and in human liver and ileum both intracellularly in hepatocytes and enterocytes and extracellularly in portal vessels, sinusoids and canaliculi in the liver and in the lamina propria of the intestine.Changes in intensity of staining were related in the rat to the feeding/fasting status of the animal and whether exogenous zinc had been administered. In man least MT was found in the ileum of patients with Crohn's disease and most in patients with non-inflammatory bowel disease.These results confirm that MT is an important physiological metal-binding protein in man and animals and is concerned in zinc transport and binding in rats.  相似文献   
86.
在中东欧,人、商品、金钱与时间之间的关系发生了迅速的变化 .货币流通速度加快了,日常生活更紧张了,产品和人本身与 10年前都不同了 .耗能多的国产旧冰箱已经被效率更高(价格更高)的新冰箱所代替;老式的苏联 "拉达"和波兰 "菲亚特"已经被"欧宝"和"现代"所代替;街道和媒体充斥着广告;菜单上的国产食品越来越少 .洗碗机和衣物干燥机等先前不知道的新产品以及新包装文化代替了资源消耗少的朴素的消费行为 .  相似文献   
87.
BACKGROUND, AIMS AND SCOPE: In the first part of this paper the main principles which control the dehalogenation of polychlorinated aromatic compounds on municipal waste incineration fly ash (MWI-FA) have been discussed and the model fly ash of similar dehalogenation activity has been proposed. Even if both systems show comparable dehalogenation properties, the main question concerning the postulated identical reaction mechanism in both cases is left unanswered. The other very important point is to what extent is this dechlorination mechanism thermodynamically controlled. The same problem is often discussed in the literature also for the de novo synthetic reactions. From the data it is clear that metallic copper plays a decisive role in the mechanism of the dehalogenation reaction. Although the results reported in the first part strongly support the idea that copper acts in this dechlorination as the reaction component, in contrast to its generally accepted catalytic behaviour, we believed that additional support for this conclusion can be obtained with the help of a thermodynamic interpretation of the mechanism of the reaction. RESULTS AND DISCUSSION: The pathways of hexachlorobenzene dechlorination on MWI-FA and model fly ash were studied in a closed system at 260-300 degrees C under nitrogen atmosphere. These pathways were the same for both systems, with the following prevailing sequences: hexachlorobenzene --> pentachlorobenzene --> 1,2,3,5-tetrachlorobenzene --> 1,3,5-trichlorobenzene --> 1,3-dichlorobenzene. Thermodynamic calculations were carried out by using the method of minimization total Gibbs energy of the whole system. In the calculations, the following reaction components were taken into account: all gaseous chlorinated benzenes, benzene, hydrogen chloride, a gaseous trimer Cu3Cl3, and also Cu2O and CuCl2 as solid components. The effect of the reaction temperature and the amount of copper and water vapour were considered as well. The effect of reaction temperature was determined from the data calculated for the 500 to 750 K temperature region. The effect of the initial composition was determined for the molar amounts of copper = 0.01-3 moles and water vapour = 0.2 to 3 moles per mole of chlorobenzene isomer CONCLUSIONS: The results of hexachlorobenzene dechlorination by MWI-FA and model fly ash under comparable reaction conditions allow us to conclude that both dechlorinations proceed via the same dechlorination pathways, which can be taken as an evidence of the identical dehalogenation mechanism for both systems. The relative percentual distribution of the dehalogenated products depends on the temperature, but not on the initial amount of water vapour or copper metal. On the other hand, the initial amount of copper substantially affects the conversion of the dehalogenation as well as the molar ratio of Cu3Cl3 to HCl in the equilibrium mixture. Comparison of the experimental with thermodynamic results supports the idea that dehalogenation reactions are thermodynamically controlled. RECOMMENDATIONS AND OUTLOOK: Thermodynamic analysis of the dehalogenation reactions may prove useful for a wide range of pollutants. The calculations concerning polychlorinated biphenyls and phenols are under study.  相似文献   
88.
In this paper a method for the study of the qualitative similarity of extractable humic substance (EHS) in marine sediments based on the realisation of UV spectral library of EHS is described. the spectral library was built including the digitised spectra of humic substance extracted from several marine sediments (46 samples) and two samples of standard materials (lignin sulphonate and humic substance) in a Statistica data file. the data matrix was elaborated by means of different multivariate statistic techniques such as Cluster Analysis (CA), Principal Components Analysis (PCA) and the univariate technique Spectral Correlation Analysis (SCA). This approach allows us to show the contribution of different organic compounds (aromatic, lipid and acid) to the composition of EHS and moreover it evidences also the structural characteristics of EHS in terms of similarities in the qualitative composition of samples such as presence of terrestrial and/or vegetal contributions. the UV library is an objective tool to study the qualitative composition of EHS and it represents a complementary approach to the most common methods based on the application of spectroscopic (IR, 13CNMR), potentiometric and chromatographic techniques.  相似文献   
89.
Copulation in the simultaneous hermaphrodite Siphopteron sp. involves injection of prostate fluids into the mating partner with a stylet-shaped penile appendage before insemination. It has been hypothesised that such traumatic secretion transfer manipulates sex roles or the recipient’s short-term reproductive output. To test manipulative effects of traumatic secretion transfer, we ablated the stylet of male-acting individuals and then paired them to untreated focal individuals. Mating behaviour and egg output of focal individuals was then compared between this ‘no injection group’ and a ‘control group’ with sham-treated mating partners. We found that penile stylets were inserted at different areas prior to and during insemination, but prostate fluid injection was restricted to the first phase. Here, injections were into the anterior foot region, indicating that prostate secretions target the nearby male or female copulatory tracts. Our experimental manipulation of traumatic secretion transfer did not affect the exhibited mating roles. Matings in both treatments were usually reciprocal so that both partners acted in the male as well as female mating role. Moreover, sperm recipient reproductive output did not differ between treatments. We conclude that traumatic secretion transfer in this species either affects currently unmeasured traits, for instance the donor’s paternity share, or that these sea slugs are so well-adapted to traumatic secretion transfer that the effects were too subtle to be detected in our current assays.  相似文献   
90.
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