A Smog Chamber Facility for Qualitative and Quantitative Study on Atmospheric Chemistry and Secondary Organic Aerosol

In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists of the collapsible ～830 L FEP Teflon film main reactor, in which the atmospheric chemical reactions take place and the formation of SOA occurs under the simulated atmospheric conditions, and the diverse on-line gas- and particle-phase instrumentation, such as the proton transfer reaction mass spectrometer, the synchrotron radiation photoionization mass spectrometer, the aerosol laser time-of-flight mass spectrometer, and other traditional commercial instruments. The initial characterization experiments are described, concerning the temperature and ultraviolet light intensity, the reactivity of the pure air, the wall loss rates of gaseous compounds and particulate matter. And the initial evaluation experiments for SOA yields from the ozonolysis of α-pinene and for mass spectra of the products resulting from the photooxidation of OH initiated isoprene are also presented, which indicate the applicability of this facility on the studies of gas-phase chemical mechanisms as well as the formation of SOA expected in the atmosphere.

Construction and Characterization of an Atmospheric Simulation Smog Chamber

Currently, air pollution in Beijing has become a complex problem with two types of source pollutants： coal smoke and photochemical smog. Furthermore the maximum hourly mean concentration of O3 increases continuously, especially in the summer. In order to simulate the photochemical reaction, develop an air quality simulation model and further improve the air quality of Beijing, a precisely temperature-controlled, indoor, smog chamber facility was designed and constructed at Tsinghua University. Characterization experiments have been carried out to acquire the basic parameters of the smog chamber, such as the wall loss rates of NO2, NO, O3, C3H6 and particulate matter （PM）, the intensity of ultraviolet （UV） light in the chamber, the reactivity of the purified air and the reproducibility of the experimental results. The results indicate that the facility performs up to specifications, and can meet the demands required for simulating the photochemical reaction. The effect of high primary contaminated PM on the formation of ozone and secondary organic aerosol （SOA） is under investigation.

基于改进SMOG模型的目标跟踪算法

空间颜色混合高斯模型(SMOG)是一种优于经典颜色直方图的目标颜色表示模型。然而,SMOG模型初始化时不可避免的会引入背景象素,且极有可能被误选为一个有效的目标分布,严重影响后续的相似性度量,且各目标分布鉴别性能的发挥会受到自身权重的严重制约,当背景中出现与目标颜色相似的干扰物体时,算法的跟踪准确性仍会有所降低。针对这些不足,提出了一种改进的SMOG模型,通过衡量背景与目标分布在空间颜色域上的联合距离来剔除误引入的背景分布,同时将联合距离作为目标分布鉴别能力高低的一种度量,引人到相似性度量函数中,并在跟踪过程中根据局部背景的变化动态的进行更新,充分根据每个高斯分布的鉴别性能调整其匹配权重。实验证明,改进后的SMOG模型能有效提高目标跟踪的鲁棒性。

A Review of Atmospheric Chemistry Research in China:Photochemical Smog, Haze Pollution,and Gas-Aerosol Interactions

In this paper we present a review of atmospheric chemistry research in China over the period 2006-2010, focusing on tropospheric ozone, aerosol chemistry, and the interactions between trace gases and aerosols in the polluted areas of China. Over the past decade, China has suffered severe photochemical smog and haze pollution, especially in North China, the Yangtze River Delta, and the Pearl River Delta. Much scientific work on atmospheric chemistry and physics has been done to address this large-scale, complex environmental problem. Intensive field experiments, satellite data analyses, and model simulations have shown that air pollution is significantly changing the chemical and physical characters of the natural atmosphere over these parts of China. In addition to strong emissions of primary pollutants, photochemical and heterogeneous reactions play key roles in the formation of complex pollution. More in-depth research is recommended to reveal the formation mechanism of photochemical smog and haze pollution and their climatic effects at the urban, regional, and global scales.

一种基于SMOG模型的红外目标跟踪新算法

空间颜色混合高斯模型(SMOG)在基于颜色特征的目标跟踪中显示出比颜色直方图更强的目标鉴别能力,因为它不仅考虑了区域的颜色信息,而且也考虑了颜色的空间分布信息.本文将SMOG模型合理地引入到了红外目标的建模中,改进了原SMOG模型中的相似性度量函数,进一步提高了其对目标的鉴别能力.在粒子滤波框架内,使用简单的二阶自回归模型作为系统状态转换方程,将改进后的相似度函数作为各粒子的状态观测,给出了有效的模式更新方法以适应目标外观的变化,并设计出了一种有效的红外目标跟踪算法.实验证明,SMOG模型能有效刻画红外目标,本文提出的算法对红外目标的跟踪是稳健的.

Potential Oxidative Stress in the Bodies of Electric Arc Welding Operators: Effect of Photochemical Smog

Objective To investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators. Methods Seventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry. Results Compared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P<0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P<0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P<0.05-0.005), the value of LPO in the WOs was increased gradually (P<0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P<0.005-0.001), but LPO increased (P<0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients?alpha (6 items) was 0.8021, P<0.0001, and that the standardized item alpha was 0.9577, P<0.0001. Conclusion Findings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.

A Study of Smog Issues and PM_2.5Pollutant Control Strategies in China

The increased occurrence of smoggy days in major Chinese cities is of major concern to the general public. This paper explores the major sources of PM2.5 pollutants, a key contributor to the smog in Beijing, one of China’s largest cities. Evidence indicates that the secondary PM2.5 particles formed through NOx, SOx, NH3, VOCs, etc. have a strong impact on human health. As a result, PM2.5 pollution control should not simply focus on controlling particulate emission, but should involve adopting an integrated multi-pollutant control strategy. In addition to identifying the major sources of PM2.5, this paper explores its impact on environmental and human health. Although the intention of this research is not to provide solutions for reducing PM2.5 pollution, the paper analyzes the United States’ experience with establishing PM2.5 standards and mandates. Specifically, this paper focuses on the air quality control strategies adopted in California since the 1940s and draws parallels with present-day China. The research suggests that adequate government regulation, public awareness, regional collaboration and industrial compliance are keys to successfully controlling PM2.5 pollution.

Preliminary study on visual recognition under low visibility conditions caused by artificial dynamic smog

AIM： To quantitatively evaluate the effect of a simulated smog environment on human visual function by psychophysical methods.METHODS： The smog environment was simulated in a 40×40×60 cm3 glass chamber filled with a PM2.5 aerosol, and 14 subjects with normal visual function were examined by psychophysical methods with the foggy smog box placed in front of their eyes. The transmission of light through the smog box, an indication of the percentage concentration of smog, was determined with a luminance meter. Visual function under different smog concentrations was evaluated by the E-visual acuity, crowded E-visual acuity and contrast sensitivity.RESULTS： E-visual acuity, crowded E-visual acuity and contrast sensitivity were all impaired with a decrease in the transmission rate（TR） according to power functions, with invariable exponents of-1.41,-1.62 and-0.7, respectively, and R2 values of 0.99 for E and crowded E-visual acuity, 0.96 for contrast sensitivity. Crowded E-visual acuity decreased faster than E-visual acuity. There was a good correlation between the TR, extinction coefficient and visibility under heavy-smog conditions.CONCLUSION： Increases in smog concentration have a strong effect on visual function.

Procreation Anxiety in Climate Crisis:Comparative Analysis of The Smog Society and Diary of an Interesting Year

The deterioration of the environment caused by climate change has been entangled with other factors to wane people’s desire for having children.This paper takes two climate short stories,The Smog Society by the Chinese SF author Chen Qiufan and Diary of an Interesting Year by the British writer Helen Simpson as case studies,comparing the writing of the climate change induced fertility anxiety in the two stories from both the individual and community perspectives.By associating the textual analysis with the social reality about fertility rate in China and Britain,the paper explores performance and coping methods of fertility anxiety in the face of climate crisis,aimed at providing possible solutions for the sustainable development of population.

Characterization of a smog chamber for studying formation of gas-phase products and secondary organic aerosol

Smog chambers provide a potent approach to explore the secondary organic aerosol formation under varied conditions.This study describes the construction and characterization of a new smog chamber facility for studying the formation mechanisms of gas-phase products and secondary organic aerosol from the photooxidation of volatile organic compounds.The chamber is a 5.4 m^(3) Fluorinated Ethylene Propylene(FEP)Teflon reactor with the potential to perform photooxidation experiments at controlled temperature and relative humidity.Detailed characterizations were conducted for evaluation of stability of environmental parameters,mixing time,background contamination,light intensity,and wall losses of gases and particles.The photolysis rate of NO_(2)(J_(NO2))ranged from(1.02-3.32)×10^(-3)sec^(-1),comparable to the average J_(NO2)in ambient environment.The wall loss rates for NO,NO_(2),and O_(3)were 0.47×10^(-4),0.37×10^(-4),and 1.17×10^(-4)min^(-1),while wall loss of toluene was obsoletely found in a 6 hr test.The particle number wall loss rates are(0.01-2.46)×10^(-3)min^(-1)for 40-350 nm with an average lifetime of more than one day.A series of toluene photooxidation experiments were carried out in absence of NO_xunder dry conditions.The results of the simulation experiments demonstrated that the chamber is well designed to simulate photolysis progress in the atmosphere.

Image smog restoration using oblique gradient profile prior and energy minimization

Removing the smog from digital images is a challenging pre-processing tool in various imaging systems.Therefore,many smog removal(i.e.,desmogging)models are proposed so far to remove the effect of smog from images.The desmogging models are based upon a physical model,it means it requires efficient estimation of transmission map and atmospheric veil from a single smoggy image.Therefore,many prior based restoration models are proposed in the literature to estimate the transmission map and an atmospheric veil.However,these models utilized computationally extensive minimization of an energy function.Also,the existing restoration models suffer from various issues such as distortion of texture,edges,and colors.Therefore,in this paper,a convolutional neural network(CNN)is used to estimate the physical attributes of smoggy images.Oblique gradient channel prior(OGCP)is utilized to restore the smoggy images.Initially,a dataset of smoggy and sunny images are obtained.Thereafter,we have trained CNN to estimate the smog gradient from smoggy images.Finally,based upon the computed smog gradient,OGCP is utilized to restore the still smoggy images.Performance analyses reveal that the proposed CNN-OGCP based desmogging model outperforms the existing desmogging models in terms of various performance metrics.

How does smog affect firms' investment behavior? A natural experiment based on a sudden surge in the PM2.5 index

This study examines the effect of environmental regulations on the investment behavior of high-polluting enterprises.Our data are from A-share listed ?rms in China from 2006 to 2014.We use a sudden surge in the PM2.5 index as an exogenous event to conduct a natural experiment.We?nd that after the event with a series of regulatory policies introduced,investment expenditure declines signi?cantly in local state-owned enterprises(SOEs)and non-state-owned enterprises(non-SOEs),whereas investment opportunity declines signi?cantly in non-SOEs compared with SOEs.However,there are no signi?cant changes in central SOEs’investment expenditure and investment opportunity.Further analysis shows that investment expenditure and investment opportunity decline for high-polluting enterprises located in East China but increase for those located in West China.Our study is the?rst to investigate the effect of smog on enterprises’investment behavior.Our?ndings reveal that environmental regulation has in?uence on the investment behavior of enterprises with different property rights and regional differences.

Smog chamber study on the evolution of fume from residential coal combustion

Domestic coal stoves are widely used in countryside and greenbelt residents in China for heating and cooking,and emit considerable pollutants to the atmosphere because of no treatment of their exhaust,which can result in deteriorating local air quality.In this study,a dynamic smog chamber was used to investigate the real-time emissions of gaseous and particulate pollutants during the combustion process and a static smog chamber was used to investigate the fume evolution under simulate light irradiation.The real-time emissions revealed that the total hydrocarbon （THC） and CO increased sharply after ignition,and then quickly decreased,indicating volatilization of hydrocarbons with low molecular weight and incomplete combustion at the beginning stage of combustion made great contribution to these pollutants.There was evident shoulder peak around 10min combustion for both THC and CO,revealing the emissions from vitrinite combustion.Additionally,another broad emission peak of CO after 30min was also observed,which was ascribed to the incomplete combustion of the inertinite.Compared with THC and CO,there was only one emission peak for NOx,SO 2 and particular matters at the beginning stage of combustion.The fume evolution with static chamber simulation indicated that evident consumption of SO 2 and NOx as well as new particle formation were observed.The consumption rates for SO 2 and NOx were about 3.44% hr-1 and 3.68% hr-1,the new particle formation of nuclei particles grew at a rate of 16.03 nm/hr during the first reaction hour,and the increase of the diameter of accumulation mode particles was evident.The addition of isoprene to the diluted mixture of the fume could promote O 3 and secondary particle formation.

Review of the influencing factors of secondary organic aerosol formation and aging mechanism based on photochemical smog chamber simulation methods

The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and human health.However,there are still large errors between air quality model simulation results and field observations.The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences.In this paper,we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging.And all these results were mainly based the studies of photochemical smog chamber simulation.Although the properties of precursor volatile organic compounds(VOCs),oxidants(such as OH radicals),and atmospheric environmental factors(such as NOx,SO2,NH3,light intensity,temperature,humidity and seed aerosols)jointly influence the products and yield of SOA,the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process.The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research.

A large-scale outdoor atmospheric simulation smog chamber for studying atmospheric photochemical processes:Characterization and preliminary application

Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China.Thus,a large-scale outdoor atmospheric simulation smog chamber was constructed at Chinese Research Academy of Environmental Sciences(the CRAES Chamber),which was designed for simulating the atmospheric photochemical processes under the conditions close to the real atmospheric environment.The chamber consisted of a 56-m^(3) fluorinated ethylene propylene(FEP) Teflon film reactor,an electrically-driven stainless steel alloy shield,an auxiliary system,and multiple detection instrumentations.By performing a series of characterization experiments,we obtained basic parameters of the CRAES chamber,such as the mixing ability,the background reactivity,and the wall loss rates of gaseous compounds(propene,NO,NO_(2),ozone) and aerosols(ammonium sulfate).Oxidation experiments were also performed to study the formation of ozone and secondary organic aerosol(SOA),including α-pinene ozonolysis,propene and 1,3,5-trimethylbenzene photooxidation.Temperature and seed effects on the vapor wall loss and SOA yields were obtained in this work:higher temperature and the presence of seed could reduce the vapor wall loss;SOA yield was found to depend inversely on temperature,and the presence of seed could increase SOA yield.The seed was suggested to be used in the chamber to reduce the interaction between the gas phase and chamber walls.The results above showed that the CRAES chamber was reliable and could meet the demands for investigating tropospheric chemistry.

The Major Root Causes of Smog in China and Technologies and Solutions to Reduce It

This paper discusses the two major root causes of smog in China.The first one is the distributed coal combustion in many small and medium sized boilers which have no emission control systems installed.To resolve this problem,there are several ways,such as increasing the centralized coal combustion for heat and power cogeneration;or converting coal to SNG in areas where there is enough water resource and removing the pollutants of the coal in the centralized coal to SNG plant,or refining the coal and making it cleaner first before combustion.The second major cause of smog is the low quality diesel and outdated diesel engines used in China.To solve this problem,there are some ways,such as improving the diesel quality to meet the national V standard,and meanwhile,enhancing the law enforcement to eliminate these outdated diesel engines that do not meet the national emission standards;in addition,combusting cleaner and cheaper fuel such as methanol or DME in the diesel engines is also an option for certain areas where there are abundant alternative fuels such as methanol to replace diesel.

Smog chamber studies of ozone formation potentials for isopentane

The incremental reactivity and ozone formation potential of isopentane have been studied with chamber experiments and computer simulations. The chemical mechanism used in the computer simulations is an isopentane sub-mechanism from the Master Chemical Mechanism (MCM). The results from the chamber experiments suggest that the MCM can well simulate i-C5H12-NOx chamber experiments. The heterogeneous reaction of NO2 and water is an important source for OH radicals in the chamber experiments. The photolysis of HONO is responsible for the initiation of isopentane in photochemical reactions. The reaction rate constant for NO2 → HONO was determined to be 3.9×10-4―5.9×10-3 min-1 by conducting 3 sets of CO-NOx-air irradiations. 5 sets of isopentane-NOx irradiations under different conditions were performed in our chamber. Compared with the experiment with a low relative humidity (RH), an increase in RH can increase the reaction rate of NO2 with H2O, so that the peak ozone occurs earlier. When isopentane is predominant over NOx, the peak ozone concentration is largely dependent on NOx concentrations.

Investigation of the ozone formation potential for ethanol using a smog chamber

The ozone formation reactivity of ethanol has been studied using chamber experiments and model simulations. The computer simulations are based on the MCM v3.1 mechanism with chamber-dependent auxiliary reactions. Results show that the MCM mechanism can well simulate C 2 H 5 OH-NO x chamber experiments in our experimental conditions, especially on ozone formation. C 2 H 5 OH-NO x irradiations are less sensitive to relative humidity than alkane species under our experimental conditions. In order to well simulate the experiments under high relative humidity conditions, inclusion of N 2 O 5 +H 2 O=2HNO 3 in the MCM mechanism is necessary. Under C 2 H 5 OH-limited conditions, the C 2 H 5 OH/NO x ratio shows a positive effect on d(O 3 -NO)/dt and RO 2 +HO 2 . High C 2 H 5 OH/NO x ratios enhance the production of organoperoxide radical and HO 2 radical concentrations, which leads to a much quicker accumulation of ozone. By using ozone isopleths under typical scenarios conditions, the actual ozone formation ability of ethanol is predicted to be 2.3-3.5 part per billion (ppb) in normal cities, 3.5-146 ppb in cities where ethanol gas are widely used, and 0.2-3.2 ppb in remote areas. And maximum ozone formation potential from ethanol is predicted to be 4.0-5.8 ppb in normal cities, 5.8-305 ppb in cities using ethanol gas, and 0.2-3.8 ppb in remote areas.

β-罗勒烯光化学反应生成SOA和O_(3)的影响因素

β-罗勒烯(C_(10)H_(16))是BVOCs的优势物种,为明晰其光化学反应的影响因素,通过设计单因素变量、多因素变量β-罗勒烯光化学反应试验探究了β-罗勒烯光化学反应机理。结果表明:SOA粒子数和O_(3)浓度与β-罗勒烯初始浓度、NO_(2)初始浓度、光照强度之间呈正相关关系;[C_(10)H_(16)]/[NO_(2)]值为6时比其值为1的条件下更有利于提高SOA产率;利用响应曲面法分析发现,对β-罗勒烯光化学反应影响最显著的反应条件是光照强度为800μW/cm^(2),β-罗勒烯初始浓度为200 mg/m^(3),NO_(2)初始浓度为20 mg/m^(3)。