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411.
The decomposition of chloroform (CHCl3) diluted in air was studied. The experiment was carried out by using a gliding arc plasma. Different values of initial concentrations of chloroform, total gas flow rates, and input power frequencies have been used to investigate this effects on the conversion reaction products both qualitatively and quantitatively. Experimental results indicate that the maximum conversion of chloroform was 97% at a total gas flow rate of 180?L?h?1 containing 1% chloroform. Using air as carrier gas, decomposition of CHCl3 produces CCl4, CO2, CO, and Cl2 as the main products. Small amounts of HCl and COCl2 are also detected. Liquid products were also produced. 相似文献
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亚硝态氮是养殖水体中常见的胁迫因子.为探讨亚硝态氮对养殖蟹类的毒性作用,采用生物酶测定及聚丙烯酰胺凝胶电泳的方法,研究了水体中不同浓度(0.15,0.3,2,5,10,20mg/L)亚硝态氮胁迫下日本蟳肝胰腺消化酶活力的变化,以及高浓度(20mg/L)亚硝态氮胁迫对日本蟳同工酶表达的影响.结果表明:低浓度(0.15,0.3mg/L)的亚硝态氮胁迫对碱性蛋白酶,酸性蛋白酶,脂肪酶和淀粉酶活力均产生一定的诱导效应,且在处理7d时,除淀粉酶活力略低于对照组外,其他3种消化酶活力仍保持在较高的水平.较高浓度(2,5,10mg/L)亚硝态氮的短期胁迫(0.5~1d)会诱导酸性蛋白酶,碱性蛋白酶和脂肪酶活力的迅速升高,但随即快速下降.高浓度(20mg/L)的亚硝态氮胁迫对蛋白酶和淀粉酶活力表现出明显的抑制效应.处理7d时,胁迫浓度2mg/L及以上的实验组各消化酶活力与剂量浓度间均呈显著负相关关系.20mg/L亚硝态氮胁迫下,除肌肉中新增两条酶带(MDH-2和MDH-4)外,日本蟳鳃,肝胰腺,胃,心脏,卵,精子等组织中的α-淀粉酶(α-AMY)同工酶,乳酸脱氢酶(LDH)同工酶,苹果酸脱氢酶(MDH)同工酶和过氧化物酶(POD)同工酶均出现活性减弱或酶带数量减少现象.结果显示高浓度亚硝态氮胁迫对日本蟳消化酶活力和同工酶表达均表现出明显的抑制作用. 相似文献
414.
The ecological footprint (EF) is a method for measuring sustainable development through ecological impact. A methodology is presented for predicting urban ecological footprints. Urban energy use and natural resource consumption were analyzed to calculate an EF based on land type (arable, pasture, forest, fossil energy land, built-up area and water area) and consumption (food, housing, transportation, goods, services and waste). The result was then compared with the local ecological carrying capacity to develop criteria for sustainable ecological footprints. Case studies of four cities in China (Guangzhou, Ningbo, Suzhou and Yangzhou) illustrate the urban EF approach. The time series of EF in a case study of Guangzhou for 1991–2001 was analyzed and the consumption–land-use matrix of urban EF was established. The results show that the cities are ecologically unsustainable, with average ecological conflicts per capita of more than 2 ha. The urban EF method is useful to measure urban sustainable development and provides policy proposals for decision-making. However, the EF method still has limitations and weaknesses. 相似文献
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416.
Xiaoyan SHI Kebin HE Weiwei SONG Xingtong WANG Jihua TAN 《Frontiers of Environmental Science & Engineering》2012,6(4):463-469
The effects of a diesel oxidation catalytic (DOC) converter on diesel engine emissions were investigated on a diesel bench at various loads for two steady-state speeds using diesel fuel and B20. The DOC was very effective in hydrocarbon (HC) and CO oxidation. Approximately 90%–95% reduction in CO and 36%–70% reduction in HC were realized using the DOC. Special attention was focused on the effects of the DOC on elemental carbon (EC) and organic carbon (OC) fractions in fine particles (PM2.5) emitted from the diesel engine. The carbonaceous compositions of PM2.5 were analyzed by the method of thermal/optical reflectance (TOR). The results showed that total carbon (TC), OC and EC emissions for PM2.5 from diesel fuel were generally reduced by the DOC. For diesel fuel, TC emissions decreased 22%–32% after the DOC depending on operating modes. The decrease in TC was attributed to 35%–97% decrease in OC and 3%–65% decrease in EC emissions. At low load, a significant increase in the OC/EC ratio of PM2.5 was observed after the DOC. The effect of the DOC on the carbonaceous compositions in PM2.5 from B20 showed different trends compared to diesel fuel. At low load, a slight increase in EC emissions and a significant decrease in OC/EC ratio of PM2.5 after DOC were observed for B20. 相似文献
417.
为了揭示草地退化对三江源地区高寒草甸生态系统碳通量的影响,利用涡度相关技术,于2006年12月1日~2007年11月30日对三江源地区的退化高寒草甸生态系统的碳通量及生物和环境因子进行观测.结果发现:草地退化对高寒草甸生态系统的碳通量产生了深刻影响,与未退化的高寒草甸生态系统相比,退化高寒草甸生态系统全年总初级生产力(GPP)下降了36.6%,全年生态系统呼吸(Reco)下降了7.9%,全年净生态系统CO2交换(NEE)也由退化前的负值(碳吸收)转变为正值(碳排放),二者相差132.5gC/(m2·a),生态系统由原来的碳汇转变为目前的碳源.这些变化与高寒草甸退化后,生态系统植物地上生物量锐减、植物生长期缩短(NEE<0的天数)、植物多样性下降、土壤含水量降低等因素密切相关. 相似文献
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419.
河流流域生态安全综合评估方法 总被引:9,自引:3,他引:6
在国内外生态安全相关研究的基础上,提出了河流流域生态安全的定义. 以河流流域生态安全为研究对象,基于DPSIR(驱动力-压力-状态-影响-响应)模型框架,构建了评估指标体系,并利用多准则群体决策模型的层次分析法和熵权法确定指标权重. 以晋城市沁河流域为例,对该流域2005─2009年生态安全状况进行了综合评估. 结果表明:5年内沁河流域的生态安全综合指数从2005年的0.487升至2009年的0.641,状态从“安全”区域底部逐步提升到顶部,人均GDP增长、单位工业产值CODCr和NH3-N排放强度的降低、污水处理厂投入使用和环保投资的逐年增加是影响其变化的关键因素. 相似文献
420.
Songül Akbulut Özen Necati Celik Emrehan Dursun Halim Taskın 《Environmental geochemistry and health》2018,40(3):1111-1125
In this study, indoor and outdoor radon (222Rn) surveys were carried out in the summer and winter seasons in homes of one hundred lung cancer patients in the year 2013–2014. The aim was to investigate the relationship between radon and cancer patients. Lung cancer patients completed a questionnaire concerning their living environment, various physical parameters and living habits. Pearson correlation and t tests revealed no meaningful results between radon concentrations, on one hand, and environmental and personal living habits, on the other hand. Consequently, the BEIR VI model was adapted and 222Rn exposure was estimated to be responsible for about 12% of the lung cancer incidences in the winter season and around 5% in the summer season in the Rize Province. However, due to the limited number of data and numerous parameters that could lead to lung cancer, the estimations done with the model should be taken very lightly. The annual effective doses due to inhalation of indoor and outdoor 222Rn were estimated to be, respectively, 1.43 and 0.94 mSv y?1. The indoor and outdoor annual effective doses were, respectively, close and below the world annual effective dose (1.3 mSv y?1). At the district level, the indoor annual effective dose equivalent in the ?yidere district was 4.52 mSv y?1, which was 3.5 times greater than the world average. The number of patients in the majority of the houses in this district was more than one. 相似文献