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儿童呼吸健康与颗粒物中元素浓度的关联分析 总被引:3,自引:0,他引:3
通过两步回归法研究了儿童呼吸健康与PM2.6和PM2.5-10中元素浓度的统计关联,发现了哮喘、支气管炎、气喘,慢性咳嗽和慢性咳痰与污染元素,土壤元素的某些关联性,比较了粗、细颗粒物中元素与呼吸健康反应之间的异同,提出了解释土壤元素与健康反应之间正向关联性的“土壤粒子团”假设。 相似文献
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Occurence and Distribution of Polycyclic Aromatic Hydrocarbons in Ankara Precipitation 总被引:1,自引:0,他引:1
Urban atmospheric environment contains many trace organic pollutants that are related to the incomplete fuel combustion in domestic heating, industrial plants and automobile traffic. Removal of these pollutants from the atmosphere takes place through wet and dry deposition as well as chemical transformations. In this study, concentrations of polycyclic aromatic hydrocarbons (PAHs) in wet deposition samples were determined at an urban site of Turkey. Wet and dry deposition samples were collected using Andersen Rain Sampler. The sampler was modified accordingly for the collection of organic pollutants. Collected samples were preconcentrated by using solid phase extraction (SPE) disks and consecutively analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). Among the 13 compounds quantified in this study, anthracene, fluoranthene, and pyrene were found more frequently and at elevated concentrations (202, 271 and 260 ng L-1 mean concentrations, respectively).Concentrations of PAHs were found to be high in winter period. 相似文献
107.
废水中甲酸萃取回收的研究 总被引:9,自引:1,他引:9
以ZYM混合溶剂为萃取剂,以含4.5%的甲酸的废水进行萃取试验,结果表明,ZYM具有良好的热稳定性和再生性,对废水中的甲酸有较高的萃取率。采用本萃取技术,不但具有显著的环境效益,而且还可回收甲酸,获得较好的经济效益。 相似文献
108.
Ken’ichiro Matsumoto Yuko Arai Rina Nagao Takaaki Murata Kazuma Takase Hideo Nakashita Seiichi Taguchi Hiroaki Shimada Yoshiharu Doi 《Journal of Polymers and the Environment》2006,14(4):369-374
In this paper, the photosynthetic production of short-chain-length/medium-chain-length polyhydroxyalkanoate (PHA) copolymers is reported. The wild-type and highly active doubly mutated PHA synthase 1 (S325T/Q481K, abbreviated ST/QK) genes from Pseudomonas sp. 61-3 were introduced into Arabidopsis thaliana. Peroxisome targeting signal 1 (PTS1) was used to target PHA synthases into the peroxisome to synthesize PHA from the intermediates of the β-oxidation pathway. The transgenic Arabidopsis produced PHA copolymers consisting of 40–57 mol% 3-hydroxybutyrate, 21–49 mol% 3-hydroxyvalerate, 8–18 mol% 3-hydroxyhexanoate, and 2–8 mol% 3-hydroxyoctanoate. The maximum PHA contents were 220μ g/g cell dry weight (cdw) in leaves, and 36μ g/g cdw in stems, respectively. The expression of the ST/QK mutated PHA synthase in leaves gene did not lead to significant difference in PHA content and monomer composition of PHAs, compared to the wild-type PHA synthase gene, suggesting that the supply of monomers may be a rate-determining step of PHA biosynthesis in the peroxisome. However, in stems, there were significant differences dependent on whether the wild-type or ST/QK mutated PHA synthase was expressed. These results suggest that tissue-specific monomer availability is important in determining the final mol% composition of PHA copolymers produced by the peroxisome in plants. 相似文献
109.
In multiphase systems capillary pressures play a significant role on fluid movement and retention. The facility to predict
the effect of different thermal remediation strategies requires the knowledge of the effect of temperature on capillary pressure-saturation
relationships in the soils.
The objective of recent study was (a) to develop a technique for routinely measuring the pressure-saturation curves of soil
samples saturated with a nonpolar liquid at different regulated temperatures (b) to build a database using the measured pressure-saturation
curves and the physical, chemical properties of the model soils (c) to establish the dependence of nonaqueous phase liquid
retention on the soil properties and the temperature.
The retention curves (extraction isotherms) with nonaqueous phase liquid were determined using a modified
pressure plate extractor. The wetting phase was a non-aromatic hydrocarbon distillation product. Pressure plates were designed and constructed in
the laboratory of our department. The temperature was held constant at 20, 40 and 60 ∘C.
Statistical analysis was performed involving selected soil parameters and the measured nonaqueous phase liquid retention data.
The results show that knowing some easily measurable soil parameters (bulk density, particle size distribution, humus and
lime content) we can estimate the nonaqueous phase liquid retention of the soils. The measured “extraction isotherms” provide
essential information about the temperature-dependency of pressure-saturation curves. 相似文献
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