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961.
Svidén  J.  Hedbrant  J.  Lohm  U.  Tarr  J. 《Water, Air, & Soil Pollution: Focus》2001,1(3-4):167-177
The type of energy system andindustrial structure of urban areas is veryimportant for the total amounts of Cu emitted.The total per capita emission for the New Yorkarea is estimated to be approximately 4 timeslarger than Stockholm municipality between 1900–1980. The latter was mainly the result of largedifferences in energy systems and industrialstructure. Hydro-electric power and non fossilfuels were important energy sources for Stockholmwhile coal was a much more significant fuel forthe New York area. Metal processing hascharacterised the industries of Stockholm whilethe New York area was a national centre forcopper and petroleum refining as well as thechemical industry. In both cases the estimated Cuemissions from fuel combustion and industrydecreased from 1900–1980. But in the case ofconsumption related emissions the time trendsdiffer between the two urban areas. In Stockholmend use was the largest category of Cu emissionsduring the whole time period studied. In the NewYork area consumption related emissions becamethe largest source of Cu emission in the 1950s.  相似文献   
962.
Starches modified by Ophiostoma spp. have been investigated to develop bio-materials with enhanced mechanical and physical properties for thermoplastic applications. In this study, glass transition temperature (Tg) of modified starches was investigated in both dynamic mechanical analyzer (DMA) and differential scanning calorimeter (DSC) to detect molecular changes in the starch’s structure. Overall, two thermal transitions were observed in modified starches, as opposed to one in their native counterparts. Scanning electron microscopy of granular modified starch indicated visible damages and internal structural perturbations in addition to occlusion of granular pores by extraneous materials owing to possible enzymatic degradation and production of secondary metabolites. Modified starches registered two-fold improvement in storage modulus as compared to that of native starches. From the study of second derivative of the mass loss against temperature, two thermal transitions were also identified in modified starches. X-ray diffraction analyses showed that crystalline regions of the starch granules remained intact after the modification. It is proposed that the second phase transition potentially corresponds to modified amylose fractions and/or exopolysaccharides produced by the fungi.  相似文献   
963.
This research was aimed at assessing the fertilizer quality and public health implications of using digestate biofertilizer from the anaerobic digestion of food wastes and human excreta. Twelve (12) kg of food wastes and 3 kg of human excreta were mixed with water in a 1:1 w/v to make 30-l slurry that was fed into the anaerobic digester to ferment for 60 days at mesophilic temperature (22–31 °C). Though BOD, COD, organic carbon and ash content in the feedstock were reduced after anaerobic digestion by 50.0%, 10.6%, 74.3% and 1.5% respectively, nitrogen, pH and total solids however increased by 12.1%, 42.5% and 12.4% respectively. The C/N ratios of the feedstock and compost are 135:1 and 15.8:1. The residual total coliforms of 2.10 × 108 CFU/100 ml in the digestate was above tolerable limits for direct application on farmlands. Microbial analysis of the digestate biofertilizer revealed the presence of Pseudomonas, Klebsiella, Clostridium, Bacillus, Bacteroides, Penicillum, Salmollena, and Aspergillus. Klebsiella, Bacillus, Pseudomonas, Penicillum and Aspergillus can boost the efficiency of the biofertilizer through nitrogen fixation and nutrient solubility in soils but Klebsiella again and Salmollena are potential health risks to end users. Further treatment of the digestate for more efficient destruction of pathogens is advised.  相似文献   
964.
WEEE recycling: Pyrolysis of fire retardant model polymers   总被引:6,自引:0,他引:6  
Pyrolysis treatments of model polymers were made with the aim of studying the recycling of wastes from electronic, electric equipment containing brominated flame retardants. Pyrolysis of flame retarded high impact polystyrene and epoxy resins were made both in flow and closed systems. Products of pyrolysis were analysed with FT-IR spectroscopy and GC-MS and the evolution of bromine was followed with a bromine ion specific electrode. The effect of alkali on pyrolysis was also studied demonstrating, as far epoxy resin is concerned, to be effective on decreasing bromine content in oil and volatile products leading to the recovery of bromine from the residue by washing. The alkali treatment was shown to be less effective in styrenic polymers containing brominated flame retardants.  相似文献   
965.
    
ABSTRACT: Much of north-central Iowa is characterized by flat topography, shallow depressions, and poor natural surface drainage. Land drainage systems comprising of tile drains and agricultural drainage wells (ADWs) are used as outlets for subsurface drainage of cropland under corn and soybean production. Studies have shown that these drainage systems, mainly the ADWs, are potential routes for agricultural chemicals to underground aquifers. To protect the region's vital groundwater resource, researchers are evaluating alternative outlets ranging from complete closure of existing ADWs (and creation of wetlands) to continued use of ADWs and chemical management in a comprehensive policy framework. This paper presents the results of a study designed to provide government jurisdictions, farmers, and land managers information for assessing the impact of closing ADWs on crop production. The study couples a geographic information systems database for a 471-hectare watershed in Humboldt County, Iowa, with a groundwater flow model (MODFLOW) and an empirical crop yield loss model to predict long-term effects of complete closure of ADWs on crop production. The cropland areas inundated and the relative crop yield loss due to ADW closure are determined as a function of long-term climatic data. The results indicate that elimination of drainage outlets in the watershed could result in ponding of low-lying areas and poorly drained soils, making them unsuitable for crop production. Such wetness also decreases the efficiency of production in the no-ponding areas by isolating fields, and the crop yield loss can be reduced by an annual average of about 18 percent.  相似文献   
966.
The biodegradation behavior of PCL film with high molecular weight (80,000 Da) in presence of bacterium Alcaligenes faecalis and the analysis of degraded polymer film have been carried out. Thin Films of PCL were prepared by means of solution casting method and the bacterial degradation behavior was carried in basal medium, in presence of bacteria with time variation after UV treatment. It was observed that after UV treatment the degradation of polymer film was increased and the degradation rate followed a three steps degradation mechanism. The degraded polymer film was analyzed by means of Differential Scanning Calorimeter (DSC), Thermo Gravimetric Analyzer (TGA) and Fourier Transform Infrared Spectroscope (FTIR). DSC results revealed that at the initial stages of the degradation up to 15–20 days, the bacterium preferentially degrades the amorphous parts of the polymer film over the crystalline zone. Thermo gravimetric analysis highlighted the low temperature stability of degraded films with extent of degradation. FTIR results showed the chain scission mechanism of the polymer chains and also supported the preferential degradation of amorphous phase over crystalline phase in the initial stages of the degradation.  相似文献   
967.
The fate of chlorothalonil, chlorpyrifos and profenofos in sandy loam soil under tropical condition was studied in a vegetable plot in the Cameron Highlands, Malaysia. The plot was treated with chlorothalonil, chlorpyrifos and profenofos according to normal agricultural practices of the Cameron Highlands. Water (runoff and lysimeter), soil and bedload sediment samples were taken according to a sampling schedule. Residues in water, soil and bedload sediment samples were laboratory analysed to determine amount. Chlorothalonil residues were detected in the range of < 0.01–0.08 mg/kg in the soil, < 0.01–0.02 ng/mL in the leachate, < 0.01–0.02 ng/mL in the runoff and < 0.01–0.11mg/kg in the sediment. Field studies of chlorpyrifos showed residue levels of < 0.01–0.06 mg/kg in the soil, < 0.01–0.07 ng/mL in the leachate, < 0.01–0.08 ng/mL in the runoff and < 0.01–0.62 mg/kg in the sediment. Residue levels of profenofos were detected in the range of < 0.01–0.02 mg/kg in the soil, < 0.01–0.87 ng/mL in the leachate, < 0.01–0.08 ng/mL in the runoff and < 0.01–0.35 mg/kg in the sediment. The three pesticides dissipated rapidly, with DT50 (time for 50% loss) of less than two days. The study showed that these pesticides dissipated rapidly under the climatic conditions of the Cameron Highlands in Malaysia.  相似文献   
968.
Phase space prediction is a feature selection method which triesto exploit non-linear dynamics of an underlying system. We describe and offer a critical reconsideration of this approach,discuss questions of whether non-linear methods are justified by the data, and apply them to ozone time series from single locations. Our main objectives are to obtain air quality forecasts in order to provide public health warnings and to provide an insight into the dynamics of the underlying system.Interestingly, comparable linear data sets (surrogates)have very similar structure and give similar predictionaccuracy to that of the ozone data. In this instance theredoes not appear to be any advantage to applying the phasespace approach to univariate time series.  相似文献   
969.
Screenings from municipal sewage treatment plants have increased in importance in recent years, particularly in Germany, where laws prohibit depositing of screenings in landfill. This paper presents basic investigations of sewage screenings, especially the structure and dewatering behavior. Two standard experiments are conducted. First, the relationship between pressure and water content is determined. Secondly the flow resistance as a function of pressure is evaluated. The results help to derive simulation models in order to understand how the material behaves inside a wash press.  相似文献   
970.
    
Journal of Material Cycles and Waste Management - With sky-rocketing demand and unrestricted global production, plastics have become an inseparable part of daily human life and the circular economy...  相似文献   
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