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101.
Association of bound residues to soil humic matter may be accomplished by different binding mechanisms such as sequestration in hydrophobic interiors of the organic material or covalent linkage to the organic matter. The structures and chemical environments of compounds can be observed by NMR spectroscopy. We applied 15N-NMR spectroscopy to study the soil-bound residues of 15N-labeled simazine. As the 15N-isotope has a low sensitivity and natural abundance 15N-NMR experiments require long measurement times and often result in low signal-to-noise (S/N) ratios. Therefore, in addition to the use of 15N-labeled simazine, 15N-depleted compost was used to reduce the amount of background signal and enhance the sensitivity. The compost was produced from maize and wheat plants grown on sand with 15N-depleted NH4NO3 as sole nitrogen source. The plants were freeze-dried, ground and mixed with sand for composting. After a composting period of 224 days analysis of the compost revealed a 15N-content of 267 ppm as opposed to a natural abundance of 3650 ppm. Characterization of this artificial compost produced parameter values similar to those of a natural compost. The 13C-NMR-spectra of the humic and fulvic acids during different stages of maturity showed that there was a shift from single-bond functional groups to more complex double-bond and aromatic structures. Experiments with this compost showed an increased signal intensity. The improved sensitivity made it possible to obtain interpretable NMR signals in contrast to experiments with 15N-simazine on native soil where no signals were detectable. The data indicated that the bound residues of simazine are composed of metabolites resulting from N-dealkylation and triazine ring destruction. Silylation of the bound residues showed a very strong binding of the residues to the matrix as only a small fraction could be solubilized.  相似文献   
102.
In the Slovak Republic (SR) there has not been a complete and coordinated monitoring system for environment until now. The object of environmental monitoring in the SR has been to evaluate certain areas, e.g. components of the environment and the influences affecting it: atmosphere, water, soil, biota (fauna and flora), geological factors, physical fields, forest, wastes, settlement, landuse, contaminants of the food chain and human stress caused by environmental factors. Individual monitoring systems are being built on the basis of these projects.The Monitoring System for the Environment in the SR has been formed by linkage to the Information System on the Environment in the SR which is a basic source of the data on the state of the environment in the SR and the factors affecting it.The guarantor of both these systems is the Ministry of the Environment of the Slovak Republic.  相似文献   
103.
In countries having limited resources, it is difficult to assess urban air quality on contemporaneously, due to the absence of on-line information about air pollution levels and emission rates. An alternative approach is recommended for smaller cities with lower demands of resources. The applied scheme consists of a database of air pollution sources (NO x and CO from industry, traffic, and domestic heating), the simple Gaussian-plume model AEROPOL and a series of measurements by passive monitors. This method was used in Tartu, a small city situated in the valley of the river Emajõgi, within a landscape with noteworthy topographical variations. Simulations of annual average and maximal concentrations were performed, and a fair agreement obtained with NO2 monitoring results from passive Palmes monitors. Inventories of pollution sources in 1998 revealed that official statistics of stationary sources covered 64% of SO2,36% of CO, 37% of NO x and 32% of total particulate matter emissions. Recommendations for measures for reducing air pollution levels and for further investigations towards improving air quality assessment and management, are given.  相似文献   
104.
This paper draws upon the DISCUS (Developing Institutional and Social Capacity for Sustainable Development) research project, co-funded by the European Commission. The project was undertaken during 2001 – 2004 and involved an in-depth study of 40 European towns and cities in order to understand the institutional and social factors and conditions that might contribute to policy ‘achievement' or ‘failure' in local sustainable development policy and practice. Based on the findings of this research it proposes a conceptual framework for local sustainable development, linking the concepts of institutional capital, social capital and governance to provide a model for understanding the governing of local sustainability. The research shows that in those cases that exhibit sustainable development policy achievements, there are also greater levels of civil society activity and knowledge regarding sustainability issues, and high levels of institutional capacity. Confident local government is crucial to the development of institutional capacity and to institutional learning. One aspect of this is local authorities being equipped to address the longer-term issues and to have a strategic vision for a sustainable future.  相似文献   
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106.
It is well recognized that a trigger point is a functional, rather than an anatomical, entity. It is known that a significant fraction of both acute and chronic pain experience is myofascial in nature. This paper is aimed to discuss the potential of using permanent magnets placed over the trigger points, which are associated with that referred pain, to be a tool for pain relief. This approach is even more important in patients with various disabilities and experiencing chronic sacro-iliac and/or low back pain. It appears that the trigger points represent a plausible physiological/tissue “window” and/or pathways, which allow the magnetic fields to penetrate through physiological barriers, and thus returning injured tissues to the homeostatic state. These “tissue windows” represent physiological “entrance points” for eventual exogenous stimulations, mainly physical by nature, to enter the body. There is evidence that the application of magnetic fields (via permanent magnets) on trigger points is more effective for pain relief as compared to application to other body surface area. The systemic effects at which the results are manifested at sites distant from application area is also considered when discussing effects of magnetic fields applied on trigger points. Ion transport is considered as central to the integrity and proper functioning of nerve excitability and muscle contraction. Any disruption of their normal function would directly and markedly affect human neurosensory and neuromotor performance. Biophysical phenomena associated with modification of ion transport are in the range of weak stimuli. Therefore, electrophysiological changes in the functions of the so-called ion channels, are among the more (perhaps the most) sensitive indicators to detect and quantify physiological effects of electromagnetic fields.  相似文献   
107.
This article highlights recent research on the beneficial use of selected low frequency electromagnetic fields (EMF) as a safe alternative therapy for treatment of cancer and other health problems. It is shown that EMF therapy provides a safe alternative and adjunct modality for the treatment of cancer and other health problems, and therefore, research in this field deserves more support. The paper also discusses some reports and hypothesis of potential risk of human exposure to low frequency EMF, mainly to the power line frequency of 60 Hz.  相似文献   
108.
Out of three perceptual characteristics of the colour of any substance, the hue depends mostly on the spectral properties of a substance, while the brightness and saturation depend also on the concentration of a substance and its thickness. Here, we report that evident change of the hue of the colour (i.e., from green to red) is due to a change in concentration or the thickness of a layer in some exceptional substances such as pumpkin seed oil or an aqueous solution of bromophenol blue. In some regions of Central Europe, salad dressing is made preferably with the pumpkin seed oil, which has a strong characteristic nut-like taste and remarkable properties of the colour: it appears red in a bottle, but green when served as a salad dressing. The colour of the pumpkin seed oil was previously described as brownish yellow, dark green, dark green to red ochre or dark reddish brown to light yellow green. We elucidated the physicochemical and physiological basis of such dichromatism by Beer-Lambert law and by the characteristics of human colour perception. Our concept was corroborated by the outcome of calculations of colour from spectral properties using colour matching functions. We found that dichromatism is observed if the absorption spectrum of any substance has at least two local minima: one wide but shallow and one narrow but deep local minimum.  相似文献   
109.
Environmental Chemistry Letters - Research on plastic pollution has recently evidenced the ubiquitous presence of tiny plastic particles called microplastics. Microplastics alter organisms because...  相似文献   
110.
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