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1.  Characteristics and anthropogenic sources of carbonyl sulfide in Beijing  
   Ye Cheng  Chenglong Zhang  Yuanyuan Zhang  Hongxing Zhang  Xu Sun  Yujing Mu《环境科学学报(英文版)》,2015年第28卷第2期
   Atmospheric mixing ratios of carbonyl sulfide(COS) in Beijing were intensively measured from March 2011 to June 2013. COS mixing ratios exhibited distinct seasonal variation, with a maximum average value of 849 ± 477 pptv in winter and a minimal value of 372 ± 115 pptv in summer. The seasonal variation of COS was mainly ascribed to the combined effects of vegetation uptake and anthropogenic emissions. Two types of significant linear correlations(R2> 0.66) were found between COS and CO during the periods from May to June and from October to March, with slopes(ΔCOS/ΔCO) of 0.72 and 0.14 pptv/ppbv, respectively. Based on the emission ratios of COS/CO from various sources, the dominant anthropogenic sources of COS in Beijing were found to be vehicle tire wear in summer and coal burning in winter. The total anthropogenic emission of COS in Beijing was roughly estimated as 0.53 ± 0.02 Gg/year based on the local CO emission inventory and the ΔCOS/ΔCO ratios.    

2.  Characteristics and anthropogenic sources of carbonyl sulfide in Beijing  
   Ye Cheng  Chenglong Zhang  Yuanyuan Zhang  Hongxing Zhang  Xu Sun  Yujing Mu《环境科学学报(英文版)》,2015年
   Atmosphericmixing ratios of carbonyl sulfide (COS) in Beijingwere intensivelymeasured from March 2011 to June 2013. COS mixing ratios exhibited distinct seasonal variation, with a maximumaverage value of 849 ± 477 pptv in winter and a minimal value of 372 ± 115 pptv in summer. The seasonal variation of COS was mainly ascribed to the combined effects of vegetation uptake and anthropogenic emissions. Two types of significant linear correlations (R2 > 0.66) were found between COS and CO during the periods from May to June and from October to March, with slopes (ΔCOS/ΔCO) of 0.72 and 0.14 pptv/ppbv, respectively. Based on the emission ratios of COS/CO from various sources, the dominant anthropogenic sources of COS in Beijing were found to be vehicle tire wear in summer and coal burning in winter. The total anthropogenic emission of COS in Beijing was roughly estimated as 0.53 ± 0.02 Gg/year based on the local CO emission inventory and the ΔCOS/ΔCO ratios.    

3.  Wintertime peroxyacetyl nitrate (PAN) in the megacity Beijing: Role of photochemical and meteorological processes  
   Hualong Zhang  Xiaobin Xu  Weili Lin  Ying Wang《环境科学学报(英文版)》,2014年第26卷第1期
   Previous measurements of peroxyacetyl nitrate(PAN) in Asian megacities were scarce and mainly conducted for relative short periods in summer. Here, we present and analyze the measurements of PAN, O3, NOx, etc., made at an urban site(CMA) in Beijing from 25 January to 22 March 2010. The hourly concentration of PAN averaged 0.70 × 10 9mol/mol(0.23 × 10 9–3.51 × 10 9mol/mol) and was well correlated with that of NO2but not O3, indicating that the variations of the winter concentrations of PAN and O3in urban Beijing are decoupled with each other. Wind conditions and transport of air masses exert very significant impacts on O3, PAN, and other species. Air masses arriving at the site originated either from the boundary layer over the highly polluted N-S-W sector or from the free troposphere over the W-N sector. The descending free-tropospheric air was rich in O3, with an average PAN/O3ratio smaller than 0.031, while the boundary layer air over the polluted sector contained higher levels of PAN and primary pollutants, with an average PAN/O3ratio of 0.11. These facts related with transport conditions can well explain the observed PAN-O3decoupling. Photochemical production is important to PAN in the winter over Beijing. The concentration of the peroxyacetyl(PA) radical was estimated to be in the range of 0.0014 × 10 12–0.0042 × 10 12 mol/mol. The contributions of the formation reaction and thermal decomposition to PAN's variation were calculated and found to be significant even in the colder period in air over Beijing, with the production exceeding the decomposition.    

4.  Direct radiative forcing of urban aerosols over Pretoria (25.75°S, 28.28°E) using AERONET Sunphotometer data: First scientific results and environmental impact  
   Ayodele Joseph Adesin  Kanike Raghavendra Kumar  Venkataraman Sivakumar  Derek Griffith《环境科学学报(英文版)》,2014年第26卷第12期
   The present study uses the data collected from Cimel Sunphotometer of Aerosol Robotic Network(AERONET) for the period from January to December, 2012 over an urban site,Pretoria(PTR; 25.75°S, 28.28°E, 1449 m above sea level), South Africa. We found that monthly mean aerosol optical depth(AOD, τa) exhibits two maxima that occurred in summer(February) and winter(August) having values of 0.36 ± 0.19 and 0.25 ± 0.14,respectively, high-to-moderate values in spring and thereafter, decreases from autumn with a minima in early winter(June) 0.12 ± 0.07. The Angstrom exponents(α440–870) likewise,have its peak in summer(January) 1.70 ± 0.21 and lowest in early winter(June) 1.38 ± 0.26,while the columnar water vapor(CWV) followed AOD pattern with high values(summer) at the beginning of the year(February, 2.10 ± 0.37 cm) and low values(winter) in the middle of the year(July, 0.66 ± 0.21 cm). The volume size distribution(VSD) in the fine-mode is higher in the summer and spring seasons, whereas in the coarse mode the VSD is higher in the winter and lower in the summer due to the hygroscopic growth of aerosol particles.The single scattering albedo(SSA) ranged from 0.85 to 0.96 at 440 nm over PTR for the entire study period. The averaged aerosol radiative forcing(ARF) computed using SBDART model at the top of the atmosphere(TOA) was- 8.78 ± 3.1 W/m2, while at the surface it was- 25.69 ± 8.1 W/m2 leading to an atmospheric forcing of + 16.91 ± 6.8 W/m2, indicating significant heating of the atmosphere with a mean of 0.47 K/day.    

5.  Ground-based observation of aerosol optical properties in Lanzhou, China  被引次数:1
   YU Xingn  ZHU Bin  FAN Shuxian  YIN Yan  BU Xiaoli《环境科学学报(英文版)》,2009年第21卷第11期
   Aerosol optical properties from August 2006 to July 2007 were obtained from ground-based and sky radiance measurements in Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), China. High aerosol optical thickness (AOT) associatedwith low ?ngstr¨om exponent ( ) was mainly observed in spring, which was consistent with the seasonal dust production from HexiCorridor. The maximum monthly average value of AOT 0.56 occurred in March of 2007, which was two times larger than the minimumvalue of 0.28 in October of 2006. Approximately 60% of the AOT ranged between 0.3 and 0.5, and nearly 93% of value varied from0.1 to 0.8, which occurred in spring. The significant correlation between aerosol properties and water vapor content was not observed.The aerosol volume size distribution can be characterized by the bimodal logarithm normal structure: fine mode (r < 0.6 m) and coarsemode (r > 0.6 m). Aerosols in spring of SACOL were dominated by large particles with the volume concentration ratio of coarse tofine modes being 7.85. The average values of asymmetry factor (g) in the wavelength range 440–1020 nm were found to be 0.71, 0.67,0.67 and 0.69 in spring, summer, autumn and winter, respectively.    

6.  Tropospheric NO2 vertical column densities retrieved from ground-based MAX-DOAS measurements at Shangdianzi regional atmospheric background station in China  
   Siyang Cheng  Jianzhong M  Weiping Cheng  Peng Yan  Huaigang Zhou  Liyan Zhou  Peng Yang《环境科学学报(英文版)》,2019年第6期
   Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.The tropospheric NO_2vertical column densities(VCDs)were retrieved to investigate the background condition of the Beijing–Tianjin–Hebei developed economic circle in China.The seasonal variation of mean NO_2tropospheric VCDs(VCD_(Trop))at SDZ is apparent,with the maximum(1.3×10~(16)molec/cm~2)in February and the minimum(3.5×10~(15)molec/cm~2)in August,much lower than those observed at the Beijing city center.The average daytime diurnal variations of NO_2VCD_(Trop )are rather consistent for all four seasons,presenting the minimum at noon and the higher values in the morning and evening.The largest and lowest amplitudes of NO_2VCD_(Trop)diurnal variation appear in winter and in summer,respectively.The diurnal pattern at SDZ station is similar to those at other less polluted stations,but distinct from the ones at the urban or polluted stations.Tropospheric NO_2VCDs at SDZ are strongly dependent on the wind,with the higher values being associated with the pollution plumes from Beijing city.Tropospheric NO_2VCDs derived from ground-based MAX-DOAS at SDZ show to be well correlated with corresponding OMI(Ozone Monitoring Instrument)satellite products with a correlation coefficient R=0.88.However,the OMI observations are on average higher than MAX-DOAS NO_2VCDs by a factor of 28%,probably due to the OMI grid cell partly covering the south of SDZ which is influenced more by the pollution plumes from the urban areas.    

7.  Characteristics of one-year observation of VOCs, NOx, and O3 at an urban site in Wuhan, China  
   Yichang Yang  Xingang Liu  Jun Zheng  Qinwen Tan  Miao Feng  Yu Qu  Junling An  Nianliang Cheng《环境科学学报(英文版)》,2019年第5期
   A continuous online observation of ozone and its precursors(NOx, VOCs) was carried out in central urban Wuhan from September 2016 to August 2017. The concentration levels of ozone,NOx, VOCs and their variations in urban Wuhan were analyzed, as well as effects of VOCs on ozone photochemical generation and the main controlling factors for ozone production. During the observation period, the average concentrations of ozone and NOx in Wuhan was 22.63 and30.14 ppbv, respectively, and the average concentration of VOCs was 32.61 ppbv(42.3% alkanes,13.0% alkenes, 10.0% aromatics, 7.3% acetylene, 9.9% OVOCs, and 10.5% halohydrocarbons).Ozone concentration was higher in spring and summer as compared with autumn and winter,wheras VOCs and NOx concentratios were lower in spring and summer but higher in autumn and winter. Aromatics and alkenes, two of VOCs species, showed the highest contributions to ozone formation potential in Wuhan(35.7% alkenes, 35.4 aromatics, 17.5% alkanes, 8.6% OVOCs,1.6% halogenated hydrocarbons, and 1.4% acetylene). Among all VOCs species, those with the highest contribution were ethylene, m-xylene, toluene, propylene and o-xylene. The contribution of these five compounds to the total ozone formation potential concentration was 43.90%.Ozone-controlling factors in Wuhan changed within one day; during the early morning hours(6:00–9:00), VOCs/NOx was low, and ozone generation followed a VOCs-limited regime.However, during the peak time of ozone concentration(12:00–16:00), the ratio of VOCs/NOx was relatively high, suggesting that ozone generation followed a NOx-limited regime.    

8.  Modeling study on seasonal variation in aerosol extinction properties over China  
   Yi Gao  Meigen Zhang《环境科学学报(英文版)》,2014年第26卷第1期
   To investigate the seasonal variation of aerosol optical depth(AOD), extinction coefcient(EXT), single scattering albedo(SSA) and the decomposed impacts from sulfate(SO4 2) and black carbon(BC) over China, numerical experiments are conducted from November 2007 to December 2008 by using WRF-Chem. Comparison of model results with measurements shows that model can reproduce the spatial distribution and seasonal variation of AOD and SSA. Over south China, AOD is largest in spring(0.6–1.2) and lowest in summer(0.2–0.6). Over north, northeast and east China, AOD is highest in summer while lowest in winter. The high value of EXT under 850 hPa which is the reflection of low visibility ranges from 0.4–0.8 km 1and the high value area shifts to north during winter, spring and summer, then back to south in autumn. SSA is 0.92–0.94 in winter and 0.94–0.96 for the other three seasons because of highest BC concentration in winter over south China. Over east China, SSA is highest(0.92–0.96) in summer, and 0.88–0.92 during winter, spring and autumn as the concentration of scattering aerosol is highest while BC concentration is lowest in summer over this region. Over north China, SSA is highest(0.9–0.94) in summer and lowest(0.82–0.86) in winter due to the significant variation of aerosol concentration. The SO4 2 induced EXT increases about 5%– 55% and the impacts of BC on EXT is much smaller(2%–10%). The SO4 2-induced increase in SSA is 0.01–0.08 and the BC-induced SSA decreases 0.02–0.18.    

9.  Number concentration and size distributions of submicron particles in Jinan urban area: Characteristics in summer and winter  被引次数:1
   GAO Jian  WANG Jin  CHENG Shu-hui  XUE Li-kun  YAN Huai-zhong  HOU Lu-jian  JIANG Yu-quan  WANG Wen-xing《环境科学学报(英文版)》,2007年第19卷第12期
   The aerosol number concentration and size distribution were measured with the newly developed Wide-range Particle Spectrometer in summer and winter of 2006 at the urban site of Jinan City.Here reported the characteristics of fine particles of the different observation seasons.Relative high number concentrations for the particles in the diameter range of 10-500 nm were observed in both seasons.It was found that the dominant number distributed in particle diameter smaller than 100 nm and the percentage over the number concentration of all air particles is much higher than what has been measured in other urban sites over the world.The number mean diameter in summer was much smaller than in winter,strongly suggesting the different origin of ultrafine particles in different seasons.That is, particles in ultrafine mode mainly came from nucleation and new particle formation in summer while from traffic emission in winter. The diurnal variation also supported this point.Number concentration in the diameter range of 10-200 nm got their peak values at noontime,well correlated with the mixing ratio of SO_2 and the intensity of solar radiation in summer.While in winter,those in the same diameter range showed the main peaks during the traffic hours happened in the morning and evening.    

10.  Levels, sources and health risks of carbonyls and BTEX in the ambient air of Beijing, China  被引次数:8
   Yujie Zhang  Yujing Mu  Junfeng Liu  Abdelwahid Mellouki《环境科学学报(英文版)》,2012年第24卷第1期
   The atmospheric concentrations of carbonyls and BTEX (benzene, toluene, ethylbenzene, m,p-xylene and o-xylene) were measured simultaneously at a same sampling site in Beijing from September 2008 to August 2010. The average concentrations of the total measured carbonyls during autumn, winter, spring, and summer were 37.7, 31.3, 39.7, 50.5 μg/m3, respectively, and maximal values for their diurnal variations usually happened at noontime. In contrast to carbonyls, the average concentrations of the total measured BTEX during the four seasons were 27.2, 31.9, 23.2, 19.1 μg/m3, respectively, and minimal values for their diurnal variations always occurred in the early afternoon. The average concentration for carbonyls increased about 24% from September 2008-August 2009 to September 2009-August 2010, for BTEX, increased about 15%. Integrated life time cancer risks for three carcinogens (benzene, formaldehyde and acetaldehyde) in Beijing exceeded the value of 1E-06, and the hazard quotient (HQ) of non-cancer risk of exposure to formaldehyde exceeded unity.    

11.  Characteristics of ozone vertical profile observed in the boundary layer aroundBeijing in autumn  
   Zhiqiang M  Xiaoling Zhang  Jing Xu  Xiujuan Zhao  Wei Meng《环境科学学报(英文版)》,2011年第23卷第8期
   In the autumn of 2008, the vertical profiles of ozone and meteorological parameters in the low troposphere (0–1000 m) were observedat two sites around Beijing, specifically urban Nanjiao and rural Shangdianzi. At night and early morning, the lower troposphere dividedinto two stratified layers due to temperature inversion. Ozone in the lower layer showed a large gradient due to the titration of NO. Airflow from the southwest brought ozone-rich air to Beijing, and the ozone profiles were marked by a continuous increase in the residuallayer at night. The accumulated ozone in the upper layer played an important role in the next day’s surface peak ozone concentration,and caused a rapid increase in surface ozone in the morning. Wind direction shear and wind speed shear exhibited different influenceson ozone profiles and resulted in different surface ozone concentrations in Beijing.    

12.  Gaseous elemental mercury concentration in atmosphere at urban and remote sites in China  被引次数:7
   WANG Zhang-wei  CHEN Zuo-shuai  DUAN Ning  ZHANG Xiao-shan《环境科学学报(英文版)》,2007年第19卷第2期
   An investigation of gaseous elemental mercury concentration in atmosphere was conducted at Beijing and Guangzhou urban, Yangtze Delta regional sites and China Global Atmosphere Watch Baseline Observatory (CGAWBO) in Mt. Waliguan of remote continental area of China. High temporal resolved data were obtained using automated mercury analyzer RA-915 . Results showed that the overall hourly mean Hg0 concentrations in Mt. Waliguan were 1.7± 1.1 ng/m3 in summer and 0.6±0.08 ng/m3 in winter. The concentration in Yangtze Delta regional site was 5.4±4.1 ng/m3, which was much higher than those in Waliguan continental background area and also higher than that found in North America and Europe rural areas. In Beijing urban area the overall hourly mean Hg0 concentrations were 8.3±3.6 ng/m3 in winter, 6.5±5.2 ng/m3 in spring, 4.9±3.3 ng/m3 in summer, and 6.7±3.5 ng/m3 in autumn, respectively, and the concentration was 13.5±7.1 ng/m3 in Guangzhou site. The mean concentration reached the lowest value at 14:00 and the highest at 02:00 or 20:00 in all monitoring campaigns in Beijing and Guangzhou urban areas, which contrasted with the results measured in Yangtze Delta regional site and Mt. Waliguan. The features of concentration and diurnal variation of Hg0 in Beijing and Guangzhou implied the importance of local anthropogenic sources in contributing to the high Hg0 concentration in urban areas of China. Contrary seasonal variation patterns of Hg0 concentration were found between urban and remote sites. In Beijing the highest Hg0concentration was in winter and the lowest in summer, while in Mt. Waliguan the Hg0 concentration in summer was higher than that in winter. These indicated that different processes and factors controlled Hg0 concentration in urban, regional and remote areas.    

13.  Diurnal variations of polycyclic aromatic hydrocarbons associatedwith PM2:5 in Shanghai, China  
   Zeping Gu  Jialiang Feng  Wenliang Han  Li Li  Minghong Wu  Jiamo Fu  Guoying Sheng《环境科学学报(英文版)》,2010年第22卷第3期
   Forty-eight daily time interval PM2:5 samples were collected from December 2006 to January 2008 in an urban site in Shanghai,China. Concentrations and compositions of polycyclic aromatic hydrocarbons (PAHs) were analyzed with GC-MS to study the diurnaland seasonal variations and to identify the main emitting sources. The diurnal variation of the PAHs concentrations was greater inthe late autumn and winter sampling days, and was greatly influenced by meteorological conditions such as wind speed and ambienttemperature. The concentration of PAHs in the mornings (6:30–10:00) increased distinctly, and was high in the late autumn and wintersampling days, indicating the contribution from vehicle emissions during rush hours. The diurnal variation of the high molecular weightPAHs did not seem to be controlled by the shift of gas-particle partitioning due to temperature variation, instead, it could be indicative ofthe variation in the source. Statistical analyses showed that the concentrations of PAHs were negatively correlated with temperature andwind speed, and positively correlated with relative humidity. Diagnostic ratios of PAHs suggested mixed emission sources of petroleumand coal/biomass combustion for PAHs in the PM2:5 in Shanghai.    

14.  Characterisation and seasonal variations of particles in the atmosphere of rural, urban and industrial areas: Organic compounds  
   Fabrice Cazier  Paul Genevray  Dorothée Dewaele  Habiba Nouali  Anthony Verdin  Frédéric Ledoux  Adam Hachimi  Lucie Courcot  Sylvain Billet  Saâd Bouhsin  Pirouz Shirali  Guillaume Garçon  Dominique Courcot《环境科学学报(英文版)》,2016年第28卷第6期
   Atmospheric aerosol samples (PM2.5–0.3, i.e., atmospheric particles ranging from 0.3 to 2.5 μm) were collected during two periods: spring–summer 2008 and autumn–winter 2008–2009, using high volume samplers equipped with cascade impactors. Two sites located in the Northern France were compared in this study: a highly industrialised city (Dunkirk) and a rural site (Rubrouck). Physicochemical analysis of particulate matter (PM) was undertaken to propose parameters that could be used to distinguish the various sources and to exhibit seasonal variations but also to provide knowledge of chemical element composition for the interpretation of future toxicological studies. The study showed that PM2.5–0.3 concentration in the atmosphere of the rural area remains stable along the year and was significantly lower than in the urban or industrial ones, for which concentrations increase during winter. High concentrations of polycyclic aromatic hydrocarbons (PAHs), dioxins, furans and dioxin like polychlorinated biphenyls (DL-PCBs), generated by industrial activities, traffic and municipal wastes incineration were detected in the samples. Specific criteria like Carbon Preference Index (CPI) and Combustion PAHs/Total PAHs ratio (CPAHs/TPAHs) were used to identify the possible sources of atmospheric pollution. They revealed that paraffins are mainly emitted by biogenic sources in spring–summer whereas as in the case of PAHs, they have numerous anthropogenic emission sources in autumn-winter (mainly from traffic and domestic heating).    

15.  Trend and seasonal variations of atmospheric CH4 in Beijing  被引次数:1
   WANG Yue-si  WANG Ming-xing  LUO Dong-mei  ZHENG Xun-hu  ZHOU Li《环境科学学报(英文版)》,2000年第12卷第3期
   The atmospheric CH4 in Beijing is still increasing, even though its increasing rate has significantly decreased from 1.76 %/a during 1985-1989 to 0.50 %/a during 1990-1997. The seasonal variation of CH4 concentration showed a double-peak pattern, one peak appearing in winter and the other in summer. It is evident that the annually seasonal variations of atmospheric CH4 in Beijing are different. From 1986 to 1997, the atmospheric CH4 increased by 185 ppbv, 37% and 21% of which were due to the increase in winter and in summer, respectively. After 1993, the annually seasonal increasing rate of CH4 concentration in summer (due to emission from biogenic sources) is negative while the increasing rate in winter (due to emission from non-biogenic sources) is positive about 25 ppbv/a. As a result, the increase of CH4 emission from non-biogenic sources in winter is the major reason that caused theannually seasonal increasing rate from 1993 to 1997. The biogenic sources in Beijing are shrinking while the non-biogenic ones (such as fossil fuel combustion) are enlarging.    

16.  Comparison of temporal and Spatial Characteristics of Ozone Pollution at Ground Level in the Eastern China  
   Liu Houfeng《中国人口.资源与环境(英文版)》,2006年第4卷第3期
   Monitoring data from ozone(O3) automatic stations in three typical cities with different climatic areas in the southern and northern parts of eastern China are used to analyze temporal and spatial characteristics of ozone pollution at ground level. The results show that ozone pollution level has distinct regional differences and the concentration in the suburbs is higher than that in the urban areas. The seasonal variation of ozone concentration in different climatic areas is greatly affected by the variation of precipitation. Ozone concentration in Shenyang and Beijing , in the temperate zone, has one perennial peak concentration, occurring in early summer, May or June. Ozone concentration in Guangzhou, in sub-tropical zone, has two peak values year round. The highest values occur in October and the secondary high value in June. The ozone season in the south is longer than that in the north. The annual average daily peak value of ozone concentrations in different climates usually occur around 3 pm. The diurnal variation range of ozone concentration declines with the increase of latitude. Ozone concentration does not elevate with the increase of traffic flow. Ozone concentration in Guangzhou has a distinct reverse relation to CO and NOx. This complicated non-linearity indicates that the equilibrium of ozone photochemical reaction has regional differences. Exceeding the rate of Beijing's lh ozone concentration is higher than that of Guangzhou, whereas the average 8h ozone level is lower than that of Guangzhou, indicating that areas in low latitude are more easily affected by moderate ozone concentrations and longer exposure. Thus, China should work out standards for 8h ozone concentration.    

17.  Comparison of temporal and Spatial Characteristics of Ozone Pollution at Ground Level in the Eastern China  
   Liu Houfeng《中国人口.资源与环境(英文版)》,2006年第4卷第3期
   Monitoring data from ozone(O3) automatic stations in three typical cities with different climatic areas in the southern and northern parts of eastern China are used to analyze temporal and spatial characteristics of ozone pollution at ground level. The results show that ozone pollution level has distinct regional differences and the concentration in the suburbs is higher than that in the urban areas. The seasonal variation of ozone concentration in different climatic areas is greatly affected by the variation of precipitation. Ozone concentration in Shenyang and Beijing , in the temperate zone, has one perennial peak concentration, occurring in early summer, May or June. Ozone concentration in Guangzhou, in sub-tropical zone, has two peak values year round. The highest values occur in October and the secondary high value in June. The ozone season in the south is longer than that in the north. The annual average daily peak value of ozone concentrations in different climates usually occur around 3 pm. The diurnal variation range of ozone concentration declines with the increase of latitude. Ozone concentration does not elevate with the increase of traffic flow. Ozone concentration in Guangzhou has a distinct reverse relation to CO and NOx. This complicated non-linearity indicates that the equilibrium of ozone photochemical reaction has regional differences. Exceeding the rate of Beijing's lh ozone concentration is higher than that of Guangzhou, whereas the average 8h ozone level is lower than that of Guangzhou, indicating that areas in low latitude are more easily affected by moderate ozone concentrations and longer exposure. Thus, China should work out standards for 8h ozone concentration.    

18.  Peroxyacetyl nitrate observed in Beijing in August from 2005 to 2009  
   Tianyu Gao  Li Han  Bin Wang  Guang Yang  Zhenqiang Xu  Limin Zeng  Jianbo Zhang《环境科学学报(英文版)》,2014年第26卷第10期
   Measurements of peroxyacetyl nitrate(PAN) were made at a Beijing urban site each August from2005 to 2009. Over this 5-year period, the average PAN concentration for August in each year increased from 3(2005) to 11.7 μg/m3(2007); however, it decreased rapidly in 2008(4.1 μg/m3).Generally, the variation over the 5 years showed a rise in the first part of the study period,followed by a decline. We considered two categories of local and regional air masses in this study, which revealed that the PAN concentration in Beijing was affected mainly by southeastern air masses. The August PAN variation was influenced predominantly by local air masses in 2005,but by 2009 regional air masses had become more important. This study showed the level and variation of PAN in the month of August in 5 consecutive years for the first time, and proved that control measures are useful in decreasing photochemical pollution; hence, these measures are probably feasible for other megacities too. Furthermore, this method of analyzing regional and local impacts might be useful for other studies as well.    

19.  Chemical characteristics of precipitation and wet deposition of major ions in Liaozhong County of Liaoning Province,Northeast China  
   Houfeng Liu  Yizhen Chen  Shanzhong Qi  Chunnan Zhang《中国人口.资源与环境(英文版)》,2013年第3期
   The chemical characteristics of precipitation were analyzed based on the chemical composition of principal ionic within acid rain(from February 2007 to January 2008)of Liaozhong Meteorological Station located in Malong Village in Liaozhong County of Northeast China,meteorological conditions on the corresponding period ground,and variation of several air pollutants concentration.The results indicated that:(1)The precipitation average pH value of all samples was4.76;the frequency of acid rain during the observation period was 70.7%;the frequency was 82.8%in summer and autumn.(2)In the chemical composition of precipitation,the primary anions were SO42-and NO3-;the primary cations were NH4+and Ca2+.(3)All concentration of anions was higher in summer and winter,but relatively low in spring and autumn.This showed that the relationship between regional rainfall acidification and pollution was not significant.(4)Rainwater acidity and nearly floor gaseous pollution concentration were different from each other,and pH and NOx,CO,NO2 and O3concentrations showed significant negative correlation,but was not obvious with SO2 concentration.However,the pH and alkaline pollutants,such as particulate,was positively correlative.    

20.  Understanding unusually high levels of peroxyacetyl nitrate (PAN) in winter in Urban Jinan, China  
   Lu Liu  Xinfeng Wang  Jianmin Chen  Likun Xue  Wenxing Wang  Liang Wen  Dandan Li  Tianshu Chen《环境科学学报(英文版)》,2018年第71卷第9期
   Peroxyacetyl nitrate(PAN), as a major secondary pollutant, has gained increasing worldwide attentions, but relevant studies in China are still quite limited. During winter of 2015 to summer of 2016, the ambient levels of PAN were measured continuously by an automatic gas chromatograph equipped with an electron capture detector(GC–ECD) analyzer at an urban site in Jinan(China), with related parameters including concentrations of O3, NO, NO_2, PM_(2.5), HONO,the photolysis rate constant of NO_2 and meteorological factors observed concurrently. The mean and maximum values of PAN concentration were(1.89 ± 1.42) and 9.61 ppbv respectively in winter, and(2.54 ± 1.44) and 13.47 ppbv respectively in summer. Unusually high levels of PAN were observed during severe haze episodes in winter, and the formation mechanisms of them were emphatically discussed. Study showed that high levels of PAN in winter were mainly caused by local accumulation and strong photochemical reactions during haze episodes, while mass transport played only a minor role. Accelerated photochemical reactions(compared to winter days without haze) during haze episodes were deduced by the higher concentrations but shorter lifetimes of PAN, which was further supported by the sufficient solar radiation in the photolysis band along with the high concentrations of precursors(NO_2, VOCs) and HONO during haze episodes. In addition, significant PAN accumulation during calm weather of haze episodes was verified by meteorological data.    

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