Thia-Arenes as Pollution Source Tracers in Urban Air Particulate

Respirable air particulate samples have been analyzed using gas chromatography/mass spectrometry (GC/MS) to determine the ratios of the amounts of monomethyl and dimethyl thia-arenes to the amounts of the parent thia-arenes. Standard Reference Materials 1649, 1650 and 1597 as well as local coal tar and coke oven emissions were also examined as source samples. These thia-arene profiles were used to distinguish diesel exhaust emissions from coke oven emissions in respirable air particulate collected in Hamilton, Ontario.     

Reconstructing Primary and Secondary Components of PM2.5 Composition for an Urban Atmosphere

Total 360 samples (of 8 h each) of PM_2.5 were collected from six sampling sites for summer and winter seasons in Kanpur city, India. The collected PM_2.5 mass was subjected to chemical speciation for: (1) ionic species (NH⁺ ₄, SO^2– ₄, NO^– ₃, and Cl^–), (2) carbon contents (EC and OC), and (3) elemental contents (Ca, Mg, Na, K, Al, Si, Fe, Ti, Mn, V, Cr, Ni, Zn, Cd, Pb, Cu, As, and Se). Primary and secondary components of PM_2.5 were assessed from speciation results. The influence of marine source to PM_2.5 was negligible, whereas the contribution of crustal dust was significant (10% in summer and 7% in winter). A mass reconstruction approach for PM_2.5 could distinctly establish primary and secondary components of measured PM_2.5 as: (1) Primary component (27% in summer and 24% in winter): crustal, elemental carbon, and organic mass, (2) Secondary component (45% in summer and 50% in winter): inorganic and organic mass, and (3) others: unidentified mass (27% in summer and 26% in winter). The secondary inorganic component was about 34% in summer (NH⁺ ₄: 9%; SO^2– ₄: 16%; NO^– ₃: 9%) and 32% in winter (NH⁺ ₄: 8%; SO²⁺ ₄: 13%; NO^– ₃: 11%). The secondary organic component was 12% in summer and 18% in winter. In conclusion, secondary aerosol formation (inorganic and organic) accounted for significant mass of PM _2.5 (about 50%) and any particulate control strategy should also include control of primary precursor gases.     

Acetone in the Urban Atmosphere: A Study in Denver,Colorado

We report 4-h average concentration data for acetone, formaldehyde, acetaldehyde, and carbon monoxide measured in downtown Denver, Colorado, USA from January through December 1993. The correlations between these carbonyl compounds and CO measurements suggest that motor vehicles are a significant source for all three carbonyls, particularly during the winter. The diurnal character of the concentrations of formaldehyde and acetaldehyde suggests that there is at least a small net photochemical source for these compounds during the summer. The diurnal character of the acetone concentration suggests that there is a significant net photochemical source for acetone during the summer. An analysis of the initial photochemical production and loss processes for these carbonyls under typical atmospheric conditions suggests that the production and loss processes for formaldehyde nearly balance. This same analysis for the other carbonyls suggests that there should be a large net photochemical source for both acetaldehyde and acetone. Such a large photochemical source is not observed for acetaldehyde. Acetone is relatively unreactive in the atmosphere on a timescale of urban or regional interest. Thus, atmospheric measurements of acetone concentrations may serve as a useful indicator of the photochemical age or degree of photochemical processing of an air mass.     

Atmospheric Distribution of Gas- and Particle-Phase Quinones in Southern California

Quinones are reactive organic compounds known to initiate reactions associated with a host of toxicological events. Their presence in different atmospheres has been demonstrated although their sources remain uncertain. As a result of their reactivity and instability during chemical analysis, only a limited number of studies have reported on atmospheric concentrations of quinones in ambient air. Furthermore, besides the limited information on quinones associated with particulate matter, no previous studies have quantified vapor-phase quinones. We report vapor- and particle-phase concentrations of 1,2- and 1,4-naphthoquinones (1,2-NQ, 1,4-NQ), 9,10-phenanthraquinone (9,10-PQ), and 9,10-anthraquinone (9,10-AQ), measured over a 5-year period in Southern California. The results showed that vapor-phase concentrations of the target quinones were in general higher than those in the particle-phase. Vapor-phase concentrations ranged from 80 pg/m ³ for the AQ to 1747 pg/m ³ for the 1,4-NQ, and the particle-phase concentrations between 13 pg/m ³ for the 1,2-NQ and 250 pg/m ³ for 9,10-AQ. The target quinones were found to be distributed between vapor- and particle-phase, with the exception of 9,10-PQ found only in the particle-phase. The differences observed in the concentrations among sites and seasons suggest different source contributions; source sites were dominated by primary sources, while downwind locations showed a high contribution from photochemical activity.     

Heat Treatment of Irradiated Graphite in an Oxidizing Atmosphere

It was demonstrated that thermal treatment and decontamination methods can be used for the processing of irradiated nuclear graphite. Special features of the treatment of the irradiated graphite surface with an oxidizing agent were considered. A mathematical model of the interaction of a gaseous oxidizing agent with irradiated graphite was described with consideration for the release of stored Wigner energy. It was established that the qualitative and quantitative compositions of gaseous reaction products depend on thermal and gas-dynamic process conditions. The mathematical models and calculation algorithms proposed can be used for the process optimization of the heat treatment of irradiated graphite for the selective recovery of a number of radionuclides (mainly, ¹⁴C and ³⁶Cl), which are concentrated in a thin near-surface layer of graphite components.     

Seasonal Influence on Vapor-and Particle-Phase Polycyclic Aromatic Hydrocarbon Concentrations in School Communities Located in Southern California

Ambient concentrations of 15 vapor-and particle-phase (PM _2.5 ) polycyclic aromatic hydrocarbons (PAHs), listed by the US EPA as priority pollutants, were measured between July 2002 and November 2003 in six Southern California communities participating in a multi-year chronic respiratory health study of schoolchildren. The communities were geographically distributed over two hundred kilometers, extending from Long Beach in coastal Los Angeles, to high mountain areas to the north and west of the Los Angeles basin, and south into Eastern San Diego County. Seasonal and spatial variation in the atmospheric concentrations of PAHs is of interest because this class of compounds includes potent mutagens, carcinogens, and species capable of generating reactive oxygen species (ROS) that may lead to oxidative stress. Naphthalene accounted for 95% of the total PAH mass; annual averages ranged from 89 to 142 ng m ^{? 3} . Benzo[ghi]perylene (BGP) and the pro-carcinogen benzo[a]pyrene (BAP), present almost exclusively in the particle-phase, ranged respectively from 38 to 231 pg m ^?3 and 75 and 111 pg m ^{? 3} , with the highest values observed in Long Beach, a community with a high volume of seaport-related activities, and Lancaster, a commuter dormitory community. A considerable increase in the particle-phase PAH concentration, relative to the vapor-phase, was observed as ambient temperature decreased. Cold/hot season ratios for PAHs in PM _2.5 averaged 5.7, reaching 54 at Long Beach. The presented data underscore the importance of seasonal variations on atmospheric PAH concentrations. These observations are relevant to future interpretation and analysis of community-scale human health effects research.     

Application of Radioactive Tracers in Dehydrocyclization Reaction Mechanisms

The passage of paraffins and olefins with six or more carbon atoms over catalytic metals and metal oxides can lead to ring closure, Although this reaction was noticed first by three independent groups of Russian workers [1-3], it gained industrial importance through the work of Grosse and co-workers [4] in making toluene from heptane over alumina-supported metal oxide catalysts.     

Enhanced Reactive Uptake of Nonanal by Acidic Aerosols in the Presence of Particle-Phase Organics

An electrodynamic balance was used to examine the effect of the presence of particle-phase organics on the acid-catalyzed reactive uptake of nonanal (NL) vapor. Uptake experiments were conducted by using sulfuric acid (SA) particles, oleic acid/SA (hydrophobic), and levoglucosan/SA (hydrophilic) mixed particles with 6 ppm (approximately) gas-phase NL at about 3% relative humidity. SA reacted with the mixed organics prior to NL uptake to form organic products, denoted as OleA* and Levo*, and with NL to form hydrophobic NL* (particle-phase organics). Fresh SA particles had small mass increases (5%–13%) at the start of NL exposure (0–40 min) even though they are highly acidic. However, OleA*/SA mixed particles of about 30–70 wt% of OleA* took up NL swiftly during the first 40 min. For example, the mass increase of a 33 wt% OleA* particle jumped to 120%. As the organic product, NL*, accumulated, the uptake rate of SA particle increased and the mass increase surged to 150% at 100 min. Afterwards, the mass increase started to level off which yielded a sigmoid uptake curve. For OleA*/SA particles, the uptake rate gradually slowed down resulting in physical-absorption-like uptake kinetics. The physical uptake of NL by a pure OleA* surrogate was negligible (<1%) showing that the large uptake of OleA*/SA particles were attributed to the enhanced reactive uptake of NL in the presence of hydrophobic OleA*. Conversely, the hydrophilic Levo*/SA particles were incompatible with NL, and they showed insignificant enhanced uptake compared with the SA particles. Overall, the acidic uptake of NL is highly dependent on the chemical nature and weight percentages of particle-phase organics in mixed particles. Presence of hydrophobic organic materials in particles enhanced the reactive uptake of NL.     

Practical Olefin Metathesis in Protic Media under an Air Atmosphere

The discovery that efficient olefin metathesis reactions involving previously challenging terminal olefin substrates are possible using novel and readily available catalyst systems in non‐distilled, non‐degassed protic media in air is reported.     

基于下垫面的城市面源污染负荷监测技术研究

目前城市面源污染负荷监测只是零散的探索,缺少系统性研究,尤其对于基于下垫面监测城市面源污染负荷的研究更少。本文以文献调研为基础,在兼顾数据精度与操作方便性的总体原则下,对基于下垫面的城市面源污染负荷监测技术要点进行研究,包括监测点位布设,监测项目选取,监测频次确定,地表径流量获取方法,总量测算方法等内容,为该方法在城市面源污染负荷监测中的应用和推广提供了技术支撑。根据在试点地区开展的4次降雨监测结果,验证该方法可行。     

富集因子判定大气可吸入颗粒物元素污染来源研究方法初探

本文利用分析速度快、线性范围宽、能够多元素同时分析的电感耦合等离子体发射光谱（ICP-AES）分析技术、采用微波消解的方法检测大气颗粒物PM10样品膜中的元机元素含量,用富集因子法探讨了某地春季大气可吸入颗粒物中元素的富集程度,判断出自然与人为污染来源,对大气可吸入颗粒物的研究方法进行了初步的探讨,为相应的治理措施提供了科学的依据。     

化工原理教学中建立良好学习氛围的研究

笔者根据多年的教学经验总结了学习氛围对化工原理学习的重要性,着重论述了在教学过程中建立良好的学习氛围可采取的措施:培养学生的主体意识,丰富联想和多种教学方法手段相结合,建立浓厚的课堂学习氛围,利用网络与实验实践活动创造浓厚的课外学习氛围,希望由此提高学生学习化工原理的兴趣和积极性,改善学习的效果。     

Urban Stream Vulnerability Toward PAHs and n-Alkanes and Their Source Identification

Monjolinho River is an important water body located in the central urban region of São Paulo State in southeast Brazil. The present work reports a 4-year study related to spatio-temporal distribution and source identification of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in surface water and sediment samples of Monjolinho River. A total of 25 sampling campaigns for water, and 10 sampling campaigns for sediment collection, were performed from 2011 to 2014. In sediment samples, total PAHs were found in the range of 2.25 µg kg^?1–26,253.87 µg kg^?1, while n-alkane concentrations ranged from 0.01 to 165.64 µg kg^?1. Total PAHs' concentration in surface water was in the range of 0.17–1,348.35 ng L^?1, while n-alkanes were detected in the range of 6.17–316.15 µg L^?1. Principal component analysis was used as a statistical tool for summarizing and interpreting a huge quantity of data. It was observed that concentrations of contaminants increased along the river course in urban zone. Distribution indexes were calculated to identify possible sources of carbon pool that pointed towards petrogenic, pyrogenic, and biogenic sources. The overall concentrations of PAHs and n-alkanes were low compared to many previous studies done elsewhere and were mostly below the threshold effects level except in very few occasional cases, while probable effect level was violated in 1 sample during 4 years. Although adverse impacts are unexpected due to overall low contaminant concentrations, unexpected industrial, and sewage discharges make it risky for safer use as a drinking water resource, especially in dry conditions.     

洗衣粉生产中热风炉燃烧系统的改进

针对洗衣粉生产中原燃烧系统存在的缺陷进行了改进,改变了雾化方式,更换了燃烧器,调整了工艺参数。改进后,提高了产品质量,降低了燃料消耗,经济效益显著。     

城市应急水源工程创新设计思路与实践

针对应急水源工程使用频率极低的特征,为降低工程实施难度与投资,对应急取水泵房和应急原水管道进行了创新设计.采用柴油发动机代替传统电机驱动水泵,可节省双回路10 kV电源工程量,且每年无需缴纳高昂的基本电费.优化应急原水管道的功能定位,通过增加安全可靠的切换措施,使其具备输送原水和清水的双重功能,节省道路下方有限的管位资...     

用于多段压裂的化学示踪剂性能研究

研发了新型SH-W型化学示踪剂并建立了统一的分析检测技术。为了解SH-W型示踪剂应用于多段压裂示踪技术的能力,对其溶解性、配伍性、抗干扰性、热稳定性、耐酸碱性、静态吸附量等性能进行了室内评价。实验结果表明SH-W型示踪剂各项性能较好,满足应用于多段压裂示踪技术的条件。     

The Use of Isotopic Tracers in Studying Catalysts and Catalytic Reactions

Nonradioactive tracers such as deuterium, ¹⁸O, ¹⁵N, and ¹³C and radioactive tracers such as tritium and ^l4C have been used extensively for studying the properties of catalysts and the details of catalytic reactions. In the present paper an attempt will be made to show how the uses that have been made of isotopes in catalysis can be divided into one of three categories accordingly as they are concerned with (1) the study of the chemisorption of molecules on a catalyst surface and the nature of the catalyst surface; (2) the measurement of the extent to which the atoms from the structure of the solid catalyst take part in a catalytic reaction and become a part of the product; and (3) the details of the mechanism by which the catalytic reactions take place on the catalyst surface. These three categories will now be discussed and illustrated.     

浅述城市大气颗粒物来源解析技术

大气颗粒物来源解析即是调查大气颗粒物的污染来源,为环境大气污染综合治理提供科学依据。文章将从城市污染的排放清单出发,进而分析扩展模型和受体模型,以此来对城市大气颗粒物源的解析技术进行简要的分析,最终给城市环境质量的控制提供科学的参考。     

花都区废水污染源在线监控系统日常监管中存在的问题与建议

污染源在线监控是环境监管部门日常管理的辅助手段,建设废水污染源在线监控系统平台,为节能减排、环境统计、捧污申报、排污收费等提供了参考依据.废水污染源在线监控系统的建设是容易的,但是对其的管理却是一项长期而又必须系统地开展的工作.文章主要对花都区废水污染源在线监控系统日常监管工作中所存在的问题进行归纳与分析,从而提出进一步完善在线监控系统日常监管工作的建议.     

日常生活中的化学

文章从以下几个方面论述了日常生活中的化学:食品中的化学;衣服中的化学;家居中的化学。现实生活中人们不一定能正确全面的认识并了解化学,文章对日常生活中的化学给人类带来的利与害进行了阐述。