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551.
552.
为探讨高浓度臭氧(O3)对气溶胶生成与老化过程的影响,本研究利用单颗粒气溶胶质谱仪(SPAMS)于2018年10月在广东省鹤山大气环境超级监测站进行观测.观测期间根据O3浓度的高低,定义了高臭氧浓度(PH)时段和低臭氧浓度(PL)时段,其中PH时段O3平均浓度为117μg·m-3,PL时段平均浓度为25μg·m-3.依据化学组成的不同,观测期间单颗粒主要包含老化元素碳颗粒(EC-aged)、二次颗粒(Sec)和老化有机碳颗粒(OC-aged).PH时段单颗粒总数(348 085)高于PL时段(224 797),且PH时段Sec颗粒(37.1%)的占比显著高于PL时段(27.8%),而EC-aged颗粒(32.1%)则低于PL时段(44.1%),OC-aged颗粒(13.5%)略高于P... 相似文献
553.
主要气象因素对可吸入颗粒物浓度影响规律探讨 总被引:6,自引:1,他引:5
简要介绍了上海、南京、苏州和南通市区API污染指数逐月同步走向的一致性,得出环境空气质量保护目标确定条件下,影响大气污染物浓度高低的主要因素是大中尺度天气系统的气象因素以及春、夏、秋、冬和典型冬季寒潮前后,南通市区可吸入颗粒物与气象因素之间的相关变化关系.说明在政府加大力度控制大气污染物排放量并取得阶段性成果时,另一个影响可吸入颗粒物浓度高低变化的重要因素是气象因素. 相似文献
554.
研究制作了半挥发性有机物中流量采样装置,将环境空气(包括气相和颗粒物)中的半挥发性有机物采集到超细玻璃纤维滤膜及其后面的吸附剂上,用乙醚/正己烷混合溶剂提取,提取液经硅胶柱净化后,用反相液相色谱分离测定邻苯二甲酸酯类.并对色谱分离条件、样品净化方式、目标化合物在气相和颗粒物上的分布规律及采样器的捕集效率进行了实验. 相似文献
555.
利用气溶胶激光雷达观测结果,结合环境监测站污染物浓度数据、气象观测资料及HYSPLIT后向轨迹模式结果,综合分析2020年1月17—22日镇江市一次大气污染过程。结果显示,此次污染过程前期天气形势稳定,不利于污染物的清除及扩散,后期受偏北风影响,北方污染物向镇江输送,使得本地污染物持续累积,污染不断加重。特征雷达图分析表明此次污染为以PM2.5为主的二次污染。激光雷达显示污染日消光系数为0.00.9 km-1,消光系数垂直廓线日变化特征明显,气溶胶粒子主要堆积在0.6 km高度以下,并且很好地揭示了污染气团从高空逐渐下沉最终与本地污染叠加的过程,与HYSPLIT模式解析的污染气团来源结果基本一致。 相似文献
556.
557.
《International Journal of Green Energy》2013,10(1):115-122
Abstract In this work the deinking process was simulated in a small high speed blender of about 2 L capacity. The effects of polyethylene (PE) and wax-coated PE on the removal of toner particles in the pulper slurry has been experimentally investigated. The effect of one commercial surfactant (30% anionic, 5% nonionic) on the toner release efficiency was also studied. The average area of toner particles retained on filter papers were determined using an image analysis system that consists of a high-resolution video camera mounted on an optical polarizing microscope, an image software processor, a Pentium PC, and a high-resolution image monitor. The effect of low density PE on toner detachment from laser-printed standard paper was investigated over a concentration range of 0 –200% PE (relative to paper mass). It is found that PE has a certain capabilty of removing (adsorbing) toner particles. In the second phase of this research work, the effect of wax-coated PE was investigated. It was found that wax-coated PE enhances the removal of toner particles beyond that obtained using only PE. Finally, the effect of a commercial surfactant on the release of toner particles have been investigated over a range of surfactant mass percentage (relative to the paper mass). 相似文献
558.
Flame propagation behaviors of nano- and micro-polymethyl methacrylate (PMMA) dust explosions were experimentally studied in the open-space dust explosion apparatus. High-speed photography with normal and microscopic lenses were used to record the particle combustion behaviors and flame microstructures. Simple physical models were developed to explore the flame propagation mechanisms. High-speed photographs showed two distinct flame propagation behaviors of nano- and micro-PMMA dust explosions. For nano-particles, flame was characterized by a regular spherical shape and spatially continuous combustion structure combined with a number of luminous spot flames. The flame propagation mechanism was similar to that of a premixed gas flame coupled with solid surface combustion of the agglomerates. In comparison, for micro-particles, flame was characterized by clusters of flames and the irregular flame front, which was inferred to be composed of the diffusion flame accompanying the local premixed flame. It was indicated that smaller particles maintained the leading part of the propagating flame and governed the combustion process of PMMA dust clouds. Increasing the mass densities from 105 g/m3 to 217 g/m3 for 100 nm PMMA particles, and from 72 g/m3 to 170 g/m3 for 30 μm PMMA particles, the flame luminous intensity, scale and the average propagation velocity were enhanced. Besides, the flame front became more irregular for 30 μm PMMA dust clouds. 相似文献
559.
Seasonal variation and source apportionment of organic and inorganic compounds in PM2.5 and PM10 particulates in Beijing, China 总被引:3,自引:0,他引:3
The distribution and source of the solvent-extractable organic and inorganic components in PM 2.5(aerodynamics equivalent diameter below 2.5 microns),and PM 10(aerodynamics equivalent diameter below 10 microns) fractions of airborne particles were studied weekly from September 2006 to August 2007 in Beijing.The extracted organic and inorganic compounds identified in both particle size ranges consisted of n-alkanes,PAHs(polycyclic aromatic hydrocarbons),fatty acids and water soluble ions.The potential emission sources of these organic compounds were reconciled by combining the values of n-alkane carbon preference index(CPI),%waxC n,selected diagnostic ratios of PAHs and principal component analysis in both size ranges.The mean cumulative concentrations of n-alkanes reached 1128.65ng/m3 in Beijing,74% of which(i.e.,831.7ng/m3) was in the PM 2.5 fraction,PAHs reached 136.45ng/m3(113.44ng/m3 or 83% in PM 2.5),and fatty acids reached 436.99ng/m3(324.41ng/m3 or 74% in PM 2.5),which resulted in overall enrichment in the fine particles.The average concentrations of SO42-,NO3-,and NH4+ were 21.3±15.2,6.1±1.8,12.5±6.1μg/m3 in PM 2.5,and 25.8±15.5,8.9±2.6,16.9±9.5μg/m3 in PM 10,respectively.These three secondary ions primarily existed as ammonium sulfate((NH4)2SO4),ammonium bisulfate(NH4HSO4) and ammonium nitrate(NH4NO3).The characteristic ratios of PAHs revealed that the primary sources of PAHs were coal combustion,followed by gasoline combustion.The ratios of stearic/palmitic acid indicated the major contribution of vehicle emissions to fatty acids in airborne particles.The major alkane sources were biogenic sources and fossil fuel combustion.The major sources of PAHs were vehicular emission and coal combustion. 相似文献
560.
以腐殖酸为研究对象,采用硫酸铝为混凝剂进行混凝杯罐实验,借助PDA在线监测系统、图像解析法及粒子图像测速技术分析评价絮凝体的构造特征,着重探讨了混凝过程中初期快速搅拌条件对絮凝体形态结构的影响.结果表明,快速搅拌条件对腐殖酸絮凝体的形成过程及形态结构有着显著影响.最佳快速搅拌条件为:搅拌历时l min,搅拌强度300 r·min-,此时形成的絮凝体结构密实,抗剪切能力强,整体性能最优,絮凝体分形维数、强度及平均粒径分别为1.8842、0.164 N·m-2、0.43 mm.腐殖酸絮凝体的形成包括不溶性微粒的产生及初期颗粒的形成与结合等过程,其中,不溶性微粒的形成及初期颗粒的致密化过程是决定最终絮凝体形态构造的重要环节,而快速搅拌条件影响着混凝剂扩散混合效果和初期颗粒的形成速率与致密化程度,这也是初期快速搅拌条件对于腐殖酸混凝过程有显著影响的一个重要因素. 相似文献