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211.
    
Deposition of aerosols in the respiratory system depends inter alia on their size and the respiratory tract deposition is appreciable for nanometer-sized particles. This article presents the results of measurements of size distributions of aerosols in the range of several nanometers up to about 20?μm in the underground mine excavations of an active hard coal mine. The study included practically all particles of a respirable fraction. The results showed that a high concentration of fine and ultrafine aerosols occurs in key underground workplaces especially during mining machine operations, although their contribution to total mass concentration is usually negligible.  相似文献   
212.
The existence of illegal dumping continues to be a worldwide problem, even in nature protected areas, and its distribution is not random. An understanding of the distribution of illegal dumping sites is crucial for the enhancement of effective waste management systems. Therefore, this study aims at a better understanding of spatial and temporal changes to illegal dumping sites in a nature protected area (the Ojców National Park) from 1994 to 2016. The most important spatial factors that control the distribution of illegal dumping sites were the distance from roads and from the field-forest edge. In the last two decades, the number of small dumping sites has increased, whereas the number of large illegal dumping sites has decreased. Moreover, this study presents a model of the potential occurrence of illegal dumping sites, which indicates places that should be under the control of the national park and of local authorities.  相似文献   
213.
A new efficient method for the chemical decomposition of polyamide 6.6 by the glycolysis and amino-glycolysis processes was proposed. The glycolysis was conducted using the mass excess of ethylene glycol (EG) as a decomposing agent in the presence of a catalyst. Also, a mixture of EG and triethylenetetramine was used as another decomposing agent in the amino-glycolysis process. The described process of decomposition did not require the use of elevated pressure. The hydroxyl and amine numbers, rheology behavior and the presence of characteristic chemical groups in the obtained glycolysates and aminoglycolysates were determined in order to characterize the reaction products. The decomposition products were defined as non-Newtonian fluids that could be described by suitable mathematical models. The conducted studies showed that the properties of the obtained intermediates depend on the mass excess of the decomposing agent used. The resulting semi-products are suitable for reusing in the synthesis of polyurethanes, which has been confirmed by the exemplary synthesis. In the reaction, 10 and 15 wt% of commercial polyol were replaced with the recovered intermediates.  相似文献   
214.
    

52 coal ash samples from individual households were analyzed to determine the pH and the concentrations of four toxic elements: arsenic, cadmium, lead and thallium. The method used was atomic absorption spectrometry with graphite-furnace atomization. The ash samples originated from various coal grades and statistical analysis showed existing correlations between the concentrations of studied elements, pH and the coal grades. The maximum concentrations of arsenic, cadmium, lead and thallium were 50,900, 43,500, 128,900, and 6660 µg/kg, respectively. The results were compared with the published data for the ash of industrial origin.

  相似文献   
215.
The anaerobic digestion of municipal sewage sludge (SS) with swine manure (SM) and poultry manure (PM) was undertaken. It was found that a mixture of sewage sludge with a 30% addition of swine manure gave around 400 dm3/kgVS of biogas, whereas the maximal biogas yield from ternary mixture (SS:SM:PM = 70:20:10 by weight) was only 336 dm3/kgVS. An inhibition of methanogenesis by free ammonia was observed in poultry manure experiments. The anaerobic digestion was inefficient in pathogen inactivation as the reduction in the number of E. coli an Enterobacteriaceae was only by one logarithmic unit. A substantial portion of pathogens was also released into the supernatant.  相似文献   
216.
In the United Kingdom, as with other European countries, land-based emissions of NOx and SO2 have fallen significantly over the last few decades. SO2 emissions fell from a peak of 3185 Gg S in 1970 to 344 Gg S in 2005 and are forecast by business-as-usual emissions scenarios to fall to 172 Gg by 2020. NOx emissions were at a maximum of 951 Gg N in 1970 and fell to 378 by 2005 with a further decrease to 243 Gg N forecast by 2020. These large changes in emissions have not been matched by emissions changes for NH3 which decreased from 315 Gg N in 1990 to 259 in 2005 and are forecast to fall to 222 by 2020. The Fine Resolution Atmospheric Multi-pollutant Exchange model (FRAME) has been applied to model the spatial distribution of sulphur and nitrogen deposition over the United Kingdom during a 15-year time period (1990–2005) and compared with measured deposition of sulphate, nitrate and ammonium from the national monitoring network. Wet deposition of nitrogen and sulphur was found to decrease more slowly than the emissions reductions rate. This is attributed to a number of factors including increases in emissions from international shipping and changing rates of atmospheric oxidation. The modelled time series was extended to a 50-year period from 1970 to 2020. The modelled deposition of SOx, NOy and NHx to the UK was found to fall by 87%, 52% and 25% during this period. The percentage area of sensitive habitats in the United Kingdom for which critical loads are exceeded is estimated to fall from 85% in 1970 to 37% in 2020 for acidic deposition and from 73% to 49% for nutrient nitrogen deposition. The significant reduction in land emissions of SO2 and NOx focuses further attention in controlling emissions from international shipping. Future policies to control emissions of ammonia from agriculture will be required to effect further significant reductions in nitrogen deposition.  相似文献   
217.
The present study deals with the application of the self-organizing map (SOM) technique in the exploration of spatiotemporal dynamics of spring and stream water samples collected in the Chocho?owski Stream Basin located in the Tatra Mountains (Poland). The SOM-based classification helped to uncover relationships between physical and chemical parameters of water samples and factors determining the quality of water in the studied high-mountain area. In the upper part of the Chocho?owski Stream Basin, located on the top of the crystalline core of the Tatras, concentrations of the majority of ionic substances were the lowest due to limited leaching. Significantly higher concentration of ionic substances was detected in spring and stream samples draining sedimentary rocks. The influence of karst-type springs on the quality of stream water was also demonstrated.  相似文献   
218.
    
A small but growing body of literature adds to our understanding of the role of team reflexivity (i.e., reflecting upon team functioning) in predicting team performance. Although many studies conclude that reflexivity is an asset for teams, the contingencies of team reflexivity have received far less research attention. In this respect, we argue that team reflexivity may be especially helpful for teams with relatively low performance. Teams that are reflexive tend to learn from previous mistakes, errors, and group processes, which in turn will improve the performance of the team. We propose that this relationship will most likely positively affect learning and final team performance under conditions of relatively poor prior performance. When a team is doing relatively well, the relationship between reflexivity and final team performance will be less clear, as reflexivity and learning is less needed. In a longitudinal study (N = 73 teams), we found support for this idea. As predicted, results indicated that this interaction between team reflexivity and initial team performance on future performance was mediated by team learning. We outline how these findings are important for our understanding of the contingencies of team reflexivity and team performance dynamics. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
219.
The capacity of laboratory-scale aerated biofilters to oxidize methane was investigated. Four types of organic and mineral-organic materials were flushed with a mixture of CH4, CO2 and air (1:1:8 by volume) during a six-month period. The filter bed materials were as follows: (1) municipal waste compost, (2) an organic horticultural substrate, (3) a composite of expanded perlite and compost amended with zeolite, and (4) the same mixture of perlite and compost amended with bentonite. Methanotrophic capacity during the six months of the experiment reached maximum values of between 889 and 1036 g m−2 d−1. Batch incubation tests were carried out in order to determine the influence of methane and oxygen concentrations, as well as the addition of sewage sludge, on methanotrophic activity. Michaelis constants KM for CH4 and O2 were 4.6-14.9%, and 0.7-12.3%, respectively. Maximum methanotrophic activities Vmax were between 1.3 and 11.6 cm3 g−1 d−1. The activity significantly increased when sewage sludge was added. The main conclusion is that the type of filter bed material (differing significantly in organic matter content, water-holding capacity, or gas diffusion coefficient) was not an important factor in determining methanotrophic capacity when oxygen was supplied to the biofilter.  相似文献   
220.
The key issue in achieving a high extent of biodegradation of beet molasses vinasse is to establish the conditions for the assimilation of betaine, which is the main pollutant in this high-strength industrial effluent. In the present study, aerobic batch biodegradation was conducted over the temperature range of 27-63°C (step 9°C), at a pH of 6.5 and 8.0, using a mixed culture of bacteria of the genus Bacillus. Betaine was assimilated at 27-54°C and the pH of 8.0, as well as at 27-45°C and the pH of 6.5. The processes where betaine was assimilated produced a high BOD(5) removal, which exceeded 99.40% over the temperature range of 27-45°C at the pH of 8.0, as well as at 27°C and the pH of 6.5. Maximal COD removal (88.73%) was attained at 36°C and the pH of 6.5. The results indicate that the process can be applied on an industrial scale as the first step in the treatment of beet molasses vinasse.  相似文献   
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