Formation and growth of indoor air aerosol particles as a result of d-limonene oxidation

Oxidation of d-limonene, which is a common monoterpene, can lead to new aerosol particle formation in indoor environments. Thus, products containing d-limonene, such as citrus fruits, air refresheners, household cleaning agents, and waxes, can act as indoor air aerosol particle sources. We released d-limonene into the room air by peeling oranges and measured the concentration of aerosol particles of three different size ranges. In addition, we measured the concentration of d-limonene, the oxidant, and the concentration of ozone, the oxidizing gas. Based on the measurements we calculated the growth rate of the small aerosol particles, which were 3–10 nm in diameter, to be about , and the losses of the aerosol particles that were due to the coagulation and condensation processes. From these, we further approximated the concentration of the condensable vapour and its source rate and then calculated the formation rate of the small aerosol particles. For the final result, we calculated the nucleation rate and the maximum number of molecules in a critical cluster. The nucleation rate was in the order of and the number of molecules in a critical-sized cluster became 1.2. The results were in agreement with the activation theory.     

Insights into metals in individual fine particles from municipal solid waste using synchrotron radiation-based micro-analytical techniques

Excessive inter-contamination with heavy metals hampers the application of biological treatment products derived from mixed or mechanically-sorted municipal solid waste (MSW). In this study, we investigated fine particles of < 2 mm, which are small fractions in MSW but constitute a significant component of the total heavy metal content, using bulk detection techniques. A total of 17 individual fine particles were evaluated using synchrotron radiation-based micro-X-ray fluorescence and micro-X-ray diffraction. We also discussed the association, speciation and source apportionment of heavy metals. Metals were found to exist in a diffuse distribution with heterogeneous intensities and intense hot-spots of < 10 μm within the fine particles. Zn-Cu, Pb-Fe and Fe-Mn-Cr had significant correlations in terms of spatial distribution. The overlapped enrichment, spatial association, and the mineral phases of metals revealed the potential sources of fine particles from size-reduced waste fractions (such as scraps of organic wastes or ceramics) or from the importation of other particles. The diverse sources of heavy metal pollutants within the fine particles suggested that separate collection and treatment of the biodegradable waste fraction (such as food waste) is a preferable means of facilitating the beneficial utilization of the stabilized products.     

青岛地区大气气溶胶海洋因子贡献研究

本文对青岛地区大气气溶胶海洋因子的贡献进行了分析研究，得出以下结构：（１）复季受海洋影响要比冬季明显得多；（２）就质量浓度而言，ＩＰ（ｉｎｈａｌａｂｌｅ ｐａｒｔｉｃｌｅ）中的海盐源要高于ＴＳＰ（ｔｏｔａｌ ｓｕｓｐｅｎｄｅｄ ｐａｒｔｉｃｕｌａｔｅｓ）；（３）海洋影响的程度和离海边的距离有关。离海逾远，受海洋影响就逾小；离海连逾近，受其影响就逾大；（４）ＩＰ冬季海盐源为２％－４％，夏季为１０％－     

环境中的轮胎磨损颗粒:从路面到海洋

轮胎磨损颗粒是环境中微塑料的主要来源之一,目前全球轮胎磨损颗粒的释放量在590万t·a^-1左右,约占海洋微塑料总量的15%.轮胎磨损颗粒产生于路面,通过雨水径流迁移,进而存在于路面、土壤、沉积物、水体、生物体等环境介质中.当前轮胎磨损颗粒的检测主要通过检测标记物来实现,因此,标记物的选择是关键.同时,轮胎磨损颗粒会通过吸附和浸出污染物产生污染,对人体和生物体都有一定的健康风险.对于环境中轮胎磨损颗粒的控制,最直接的方式就是在迁移路径中截留轮胎磨损颗粒和加速轮胎磨损颗粒的分解;而改进轮胎配方,降低磨损率可从源头减少轮胎磨损颗粒的释放.目前,人们对轮胎磨损颗粒的认识不足,检测方法还需要完善,其环境行为和风险评价也缺乏相关的研究.获得轮胎磨损颗粒从路面到海洋迁移的规律性认识,对于了解其生态风险和潜在污染问题十分重要.基于此,本文归纳总结了轮胎磨损颗粒的产生、检测方法、环境分布、潜在风险和缓解措施等方面的研究成果,分析了轮胎磨损颗粒研究今后应予以关注的方向.     

膜生物反应器膜污染的水力学控制实验研究

叙述了膜污染是影响膜-生物反应器处理技术推广应用的关键因素，采用水动力学方法是控制膜污染的有效方法。在不同污泥浓度条件下。对不同曝气强度下膜污染的发展速率及其形成机理进行了试验研究，研究结果表明：对应于不同污泥浓度均存在一个经济曝气强度，其大小随污泥浓度升高呈线性增加，膜生物反应器在经济曝气强度条件下运行可控制膜污染的发展；并从理论上推导出一个临界污泥浓度，其值为5．15g／L。对应于临界污泥浓度，并且污泥絮体在膜面可形成比较稳定的动态膜，膜过滤压差上升的速率最慢，膜生物反应器在此临界污泥浓度条件下运行膜污染发展最为缓慢。     

Investigation of the hydrodynamic behavior of diatom aggregates using particle image velocimetry

The hydrodynamic behavior of diatom aggregates has a significant influence on the interactions and flocculation kinetics of algae. However, characterization of the hydrodynamics of diatoms and diatom aggregates in water is rather difficult. In this laboratory study, an advanced visualization technique in particle image velocimetry (PIV) was employed to investigate the hydrodynamic properties of settling diatom aggregates. The experiments were conducted in a settling column filled with a suspension of fluorescent polymeric beads as seed tracers. A laser light sheet was generated by the PIV setup to illuminate a thin vertical planar region in the settling column, while the motions of particles were recorded by a high speed charge-coupled device (CCD) camera. This technique was able to capture the trajectories of the tracers when a diatom aggregate settled through the tracer suspension. The PIV results indicated directly the curvilinear feature of the streamlines around diatom aggregates. The rectilinear collision model largely overestimated the collision areas of the settling particles. Algae aggregates appeared to be highly porous and fractal, which allowed streamlines to penetrate into the aggregate interior. The diatom aggregates have a fluid collection efficiency of 10%-40%. The permeable feature of aggregates can significantly enhance the collisions and flocculation between the aggregates and other small particles including algal cells in water.     

2014年1月北京市大气重污染过程单颗粒物特征分析

利用在线单颗粒物气溶胶质谱仪(SPAMS)对2014年1月北京市典型大气重污染过程进行了连续监测,分析了具有正负离子质谱信息的颗粒物共2248225个.同时,利用ART-2a神经网络分类方法并结合Matlab统计分析,将具有质谱信息的颗粒物归为10类,分别为:矿尘类颗粒物(Dust)、元素碳颗粒物(EC)、有机碳颗粒物(OC)、元素碳和有机碳混合颗粒物(ECOC)、钠钾颗粒物(NaK)、富钾颗粒物(K)、含氮有机物(KCN)、高分子有机物(MOC,Macromolecular OC)、多环芳烃类颗粒物(PAHs)和重金属类颗粒物(Metal).结合PM_2.5质量浓度数据和HYSPLIT 4.0后向轨迹模型结果,将观测时间段划分为3个典型污染过程和1个清洁过程.结果显示,重污染期间OC、MOC和PAHs为最主要的颗粒物类型.最后,本文还比对分析了污染过程和清洁期间颗粒物的混合状态,结果表明,污染过程中硫酸盐和硝酸盐较清洁期间更容易与碳质颗粒物结合.     

南京大气细粒子中重金属污染特征及来源解析

利用2011年1月、4月、7月和10月在南京市区和北郊采集的气溶胶样品,研究了南京大气细粒子中zn、Ph、Hg、As和cd5种重金属的污染水平,通过元素相关性分析和因子分析方法,对细粒子中这些重金属的污染来源进行了初步解析。结果表明,南京大气细粒子及其重金属污染严重,北郊普遍比市区严重;As严重超标,cd在南京北郊超标约5倍,zn在市区与北郊的质量浓度均高于其他重金属元素。每种重金属的浓度均随季节而变化。市区细粒子中,As和zn可能主要与燃煤、轮胎灰尘和建筑扬尘等有关,Pb、Hg和cd主要来自交通尘、城市垃圾焚烧等。北郊细粒子中,As、Hg和zn主要来源于燃煤、钢铁冶炼等工业,Pb和cd主要与农作物秸秆燃烧、汽车尾气、道路扬尘等影响有关。     

Polychlorinated dibenzo-p-dioxin and dibenzofuran in urban air of an Andean city

Particle-bound polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in ambient air were monitored together with particulate matter less than 10 μm (PM₁₀) at three sampling sites of the Andean city of Manizales, Colombia; during September 2009 and July 2010. PCDD/Fs ambient air emissions ranged from 1 fg WHO-TEQ m⁻³ to 52 fg WHO-TEQ m⁻³ in particulate fraction. The PM₁₀ concentrations ranged from 23 μg m⁻³ to 54 μg m⁻³. Concentrations of PM₁₀ and PCDD/Fs in ambient air observed for Manizales - a medium sized city with a population of 380 000 - were comparable to concentrations in larger cities. The highest concentrations of PCDD/Fs and PM₁₀ found in this study were determined at the central zone of the city, characterized by public transportation density, where diesel as principal fuel is used. In addition, hypothetical gas fractions of PCDD/Fs were calculated from theoretical K_p data. Congener profiles of PCDD/Fs exhibited ratios associated with different combustion sources at the different sampling locations, ranging from steel recycling to gasoline and diesel engines. Taking into account particle and gas hypothetical fraction of PCDD/Fs, Manizales exhibited values of PCDD/Fs equivalent to rural and urban-industrial sites in the southeast and center of the city respectively. Poor correlation of PCDDs with PM₁₀ (r = −0.55 and r = 0.52) suggests ambient air PCDDs were derived from various combustion sources. Stronger correlation was observed of PCDFs with PM₁₀. Poor correlation between precipitation and reduced PM₁₀ concentration in ambient air (r = −0.45) suggested low PM₁₀ removal by rainfall.     

PVC附载TiO_2光催化剂的制备与评价

研究以PVC颗粒为载体、利用加热法制备附载型TiO2 光催化剂 ,并对其进行牢固性、附载率、使用寿命及活性等方面的评价