Stereodivergent Synthesis of All Stereoisomers of 2,3-Disubstituted δ-Lactam Derivatives via Organocatalytic Cascade Reactions and Base-Induced Epimerization.

A protocol was developed to achieve stereodivergent synthesis of stereoisomers of δ-lactam bearing vicinal chiral centers. Organocatalytic cascade reactions were employed to produce the target products as the kinetic products, which exhibited remarkable enantioselectivities. In the presence of DBU, the kinetic product underwent epimerization to form a thermodynamically more stable diastereomer without loss in enantioselectivity. By simply switching the chiral organocatalyst and its enantiomer, we can efficiently obtain four stereoisomers with high enantioselectivities.

Organocatalytic inverse-electron-demand Diels-Alder reaction between 5-alkenyl thiazolones and ß,γ-unsaturated carbonyl compounds.

An inverse-electron-demand oxa-Diels-Alder reaction of 5-alkenyl thiazolones with ß,γ-unsaturated carbonyl compounds enabled by quinine thiourea was studied, which allows the enantioselective synthesis of a broad range of highly functionalized pyranthiazoles bearing three continuous stereocenters. This protocol is adaptable to a wide scope of substrates and has great potential for scale-up synthesis and facile transformation.

Solvent directed chemically divergent synthesis of ß-lactams and α-amino acid derivatives with chiral isothiourea.

A protocol for the chemically divergent synthesis of ß-lactams and α-amino acid derivatives with isothiourea (ITU) catalysis by switching solvents was developed. The stereospecific Mannich reaction occurring between imine and C(1)-ammonium enolate generated zwitterionic intermediates, which underwent intramolecular lactamization and afforded ß-lactam derivatives when DCM and CH3CN were used as solvents. However, when EtOH was used as the solvent, the intermediates underwent an intermolecular esterification reaction, and α-amino acid derivatives were produced. Detailed mechanistic experiments were conducted to prove that these two kinds of products came from the same intermediates. Furthermore, chemically diversified transformations of ß-lactam and α-amino acid derivatives were achieved.

Metal-free, visible-light induced enantioselective three-component dicarbofunctionalization and oxytrifluoromethylation of enamines via chiral phosphoric acid catalysis.

Using diverse carbon-centered radical precursors and electron-rich (hetero)aromatics and alcohols as nucleophiles, a visible-light driven chiral phosphoric acid (CPA) catalyzed asymmetric intermolecular, three-component radical-initiated dicarbofunctionalization and oxytrifluoromethylation of enamines was developed, which provides a straightforward access to chiral arylmethylamines, aza-hemiacetals and γ-amino acid derivatives with excellent enantioselectivity. As far as we know, this is the first example of constructing a chiral C-O bond using simple alcohols via visible-light photocatalysis. Chiral phosphoric acid played multiple roles in the reaction, including controlling the reaction stereoselectivity and promoting the generation of radical intermediates by activating Togni's reagent. Mechanistic studies also suggested the importance of the N-H bond of the enamine and indole for the reactions.

Enantioselective Synthesis of Spirorhodanine-Pyran Derivatives via Organocatalytic [3 + 3] Annulation Reactions between Pyrazolones and Rhodanine-Derived Ketoesters.

A series of novel biselectrophilic ß,γ-unsaturated α-ketoesters were designed and synthesized from rhodanine. Under the catalysis of chiral squaramides, the enantioselective [3 + 3] annulation reaction of these novel ketoesters with pyrazolones was developed. This reaction offers an efficient method for the synthesis of chiral 2'-thioxo-5,6-dihydrospiro[pyrano[2,3-c]pyrazole-4,5'-thiazolidin]-4'-ones.

[Mass Concentrations and Size Distributions of Water-soluble Inorganic Ions in Atmospheric Aerosols in Beibei District, Chongqing].

In order to study the concentration and distribution characteristics of water-soluble inorganic ions in aerosol particles of the Beibei district of Chongqing, aerosol samples were collected with an Andersen cascade impactor between March 2014 and February 2015. Water-soluble inorganic ions, including Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, NO3-, and SO42- were determined for different particle sizes (9.00, 5.80, 4.70, 3.30, 2.10, 1.10, 0.65, and 0.43 µm) using the ion chromatography method. Results showed that SO42-, NH4+, NO3-, Cl-, Na+, and K+ were mainly distributed in fine particles, while Mg2+, Ca2+, and F- were mainly present in coarse particles. SNA (SO42-, NH4+, and NO3-) exhibited clear unimodal distribution, with peaks in the droplet mode of 0.65-1.10 µm, mainly present in the form of (NH4)2SO4 and NH4NO3 in fine particles. The formation of SO42- is mainly attributed to in-cloud processes and partly to oxidation of SO2. Na+, Cl-, and Mg2+ exhibited bimodal distribution in coarse and fine particles; K+ was a single peak distribution in the range of 0.43-1.10 µm, while peaks of F- and Ca2+ concentrations were in coarse particles. Average annual concentrations of total water-soluble ions in PM2.1 and PM9.0 were (32.68±15.28) µg·m-3and (48.01±19.66) µg·m-3 over the observation period. Seasonal variations of PM2.1 and PM9.0concentrations decreased in the order of winter > spring > summer > autumn. This was the same for most ions, but a small number of ions (F-, Mg2+ and Ca2+) had a different pattern in the spring, summer, and winter. The SNA were the major components of water-soluble ions in PM2.1, and Ca2+ was the major component of water-soluble ions in PM9.0 besides SNA. The concentration of cations was significantly higher than that of anions' in PM2.1 and PM9.0, with a certain correlation between different ions. Emissions from motor vehicle exhaust, combustion processes, soil sources, and fugitive dust were the major sources of water-soluble ions in this area. The effect of air temperature on secondary ions is significant (P<0.05), but relative humidity and wind speed have no significant effect (P>0.05).

[Pollution Characteristics of Organic Carbon and Elemental Carbon in Atmospheric Aerosols in Beibei District, Chongqing].

To study the pollution characteristics of atmospheric carbon aerosols, aerosol samples were collected via a cascade impactor (Andersen) from March 2014 to February 2015 in Beibei District, Chongqing. Organic carbon (OC) and element carbon (EC) were detected using a DRI 2001A carbon analyzer. The results showed that the annual average concentrations of OC and EC in PM2.1 were (16.3±7.6) and (1.8±0.7), respectively, and (25.0±9.6), and (3.2±1.3) µg·m-3, respectively, in PM9.0. The concentrations of both OC and EC were higher in winter and spring than in summer and autumn for PM2.1, whereas, for PM9.0, the concentration of OC was higher in summer and spring than in winter and autumn and that of EC was higher in winter and spring than in summer and autumn. The particle size distributions of OC and EC for the study year were analyzed, and it was found that those of OC were bimodal, with peaks in the size ranges of 0.43-0.65 µm for fine particles and 4.7-5.8 µm for coarse particles, and those of EC were trimodal, with peaks in the size ranges of 0.43-0.65 µm for fine particles and 4.7-5.8 µm for coarse particles and a concurrent significant peak in the particle size range of 2.1-3.3 µm. In addition, the correlations between OC and EC were analyzed and the SOC in PM2.1 was estimated. It was found that the average concentration of SOC was (6.3±5.9) µg·m-3, which accounted for 33.5%±22.6% of the OC concentration in Beibei District. Furthermore, OC and EC were significantly correlated. Finally, the pollution sources of atmospheric aerosols in Beibei were analyzed, and it was found that the pollution in Beibei mainly came from the exhaust gas of gasoline vehicles, biomass combustion, and coal combustion.

Temporal and spatial variation in major ion chemistry and source identification of secondary inorganic aerosols in Northern Zhejiang Province, China.

To investigate the seasonal and spatial variations of ion chemistry of fine particles in Northern Zhejiang Province (NZP), China, one year-long field sampling was conducted at four representative sites (two urban, one suburb, and one rural sites) in both cities of Hangzhou and Ningbo from December 2014 to November 2015. Twelve water soluble inorganic ions (WSII) were characterized in this comprehensive study. The annual average of PM2.5 concentration in NZP as overall was 66.2 ± 37.7 µg m-3, and urban sites in NZP were observed with more severe PM2.5 pollution than the suburban and rural sites. The annual average concentration of total WSII at four sampling sites in NZP was 29.1 ± 19.9 µg m-3, dominated by SO42- (10.3 µg m-3), and followed by NO3- (8.9 µg m-3), NH4+ (6.6 µg m-3), Cl- (1.3 µg m-3) and K+ (0.7 µg m-3). Among all cations, NH4+ was the predominant neutralizing ion with the highest neutralization factor (NF), while the remaining cations showed limited neutralization capacity. The highest and lowest sulfur oxidation ratio (SOR) values in this region were found in summer and winter, respectively; while the seasonal patterns for nitrogen oxidation ratio (NOR) were opposite to that of SOR. Principal component analysis (PCA) showed that the significant sources of WSII in NZP were industrial emissions, biomass burning, and formation of secondary inorganic aerosols. In addition, contribution from transboundary transport of polluted aerosols was also confirmed from the assessment through air mass backward trajectory analysis.

[Comparison of Monitoring Methods of Organic Carbon and Element Carbon in Atmospheric Fine Particles].

Accurate measurement of organic carbon (OC) and elemental carbon (EC) in atmospheric fine particulate is an important scientific basis for studying the formation and source apportionment of carbonaceous aerosol. The selection of different analysis programs will lead to difference in the OC and EC concentrations, and further result in the misjudgment of the results. The OC and EC concentrations observed using three temperature protocols including RT-Quartz ( R) , NIOSH 5040 (N) and Fast-TC (F) were compared and analyzed in combination with the degree of air pollution in Beijing. The results showed that there was no significant difference in the TC (TC = OC + EC), OC and EC concentrations observed using R, N and F protocols and certain deviation was found among the TC (TC = OC + EC) , OC and EC concentrations. For TC, the results observed using R protocol were 5% lower than those using N protocol; hut 1% higher than those using F protocol. For OC, the results obtained using R were 9% lower than those using N protocol and 1% higher than those using F protocol. For EC, the results obtained using R were 20% higher than those using N protocol and 11% lower than those using F protocol. The variation coefficients for TC, OC and EC obtained based on R protocol were less than the other two temperature protocols under different air quality degrees. The slopes of regression curves of TC, OC and EC between on-line analysis using R protocol and off-line analysis were 1.21,1. 14 and 1.35, respectively. The correlation coefficients of TC, OC and EC were 0.99, 0.99 and 0.98, respectively. In contrast with the Black carbon ( BC) concentrations monitored by multi-angle absorption spectrophotometer (MAAP), the EC concentrations measured by on-line OC/EC analyzer using R protocol were obviously lower. When the BC concentrations were less than or equal to 8 gg*m3, the EC/BC ratio was 0.39. While the EC/BC ratio was 0.88, when the BC concentrations were greater than 8 ggm3. The variation trends of EC and BC concentrations were similar, while systematic error existed between the results obtained using those two instruments.

[Composition characteristics of atmospheric volatile organic compounds in the urban area of Beibei District, Chongqing].

In order to study the composition and distribution of VOCs (Volatile Organic Compounds) in the atmosphere in the urban area of Beibei district, Chongqing, atmospheric samples were collected from March 2012 to February 2013 with special stainless steel cylinders, and analyzed with a three-stage preconcentration method coupled with GC-MS. 78 species of VOCs were detected in this study, of which there were 25 species of alkanes, 15 species of olefins, 28 species of aromatic hydrocarbons and 10 species of halogenated hydrocarbons. The results showed that the top seven species of VOCs according to the order of annual average concentration in the atmosphere of Beibei were: Dichloromethane (3. 08 x 10(-9) ) , Benzene (2. 09 x 10-9) , Isopentane (1. 85 x 10 -9) , Toluene (1. 51 x 10(-9)) , Propane (1. 51 x 10(-9)), m/p-xylene (1.43 x 10(-9)) and Styrene (1. 39 x 10-9). The concentration of TVOCs (Total Volatile Organic Compounds) in the atmosphere of Beibei was 33. 89 x 10 -9 during the measuring period, and the seasonal variation was obvious with the order of spring (42. 57 x 10 -9) > autumn (33.89 x 10-9) > winter (31.91 x 10 -9) > summer (27.04 x 10(-9)). In the composition of TVOCs, alkanes and aromatic hydrocarbons provided the largest contribution to TVOCs (31.5% and 30.7% ) , followed by halogenated hydrocarbon, accounting for 27.4% , and the last one was olefins, with only 10.4%. By means of ozone formation potential, the analysis results showed that olefins and aromatic hydrocarbon compounds were the two important materials which made the biggest contribution to the formation of ozone in the atmosphere of Beibei. We further analyzed the sources of VOCs in atmosphere of Beibei by the method of Principal Component Analysis (PCA). Vehicle exhaust was the biggest source and its contribution to VOCs was 50. 41%. The calculated results with T/B value also confirmed that traffic was the biggest source contributing to the VOCs in atmosphere of Beibei.

[Observation of atmospheric pollutants in the urban area of Beibei District, Chongqing].

To study the characteristics of atmospheric pollutants in the urban area of Beibei district of Chongqing, the concentrations of the atmospheric pollutants were measured by automatic on-line continuous monitoring equipments from Jan. 2012 to Feb. 2013. The results showed that the concentrations of the pollutants often exceeded the corresponding values of the new National Ambient Air Quality Standards (GB 3095-2012) except SO2. Of these pollutants, PM2.5 was the most serious in this area. The concentrations of the atmospheric pollutants had significant seasonal variation. The concentrations of O3 and O(x) were both the highest in summer and the lowest in winter. The average concentrations of O3 were (36.1 +/- 19.2), (48.8 +/- 32.6), (29.8 +/- 28.6) and (18.2 +/- 15.8) microg x m(-3), and the average O(x) concentrations were (77.6 +/- 20.6), (91.3 +/- 37.6), (77.5 +/- 30.6) and (69.4 +/- 18.2) microg x m(-3) in spring, summer, autumn and winter in 2012, respectively. The concentrations of NO(x) appeared higher in winter and lower in summer, the average concentrations of NO, NO2 and NO(x) were (11.8 +/- 9.4), (42.3 +/- 13.1) and (54.1 +/- 20.8) microg x m(-3) in spring, (8.2 +/- 4.9), (40.5 +/- 9.9) and (48.7 +/- 12.6) microg x m(-3) in summer, (20.7 +/-17.1), (47.2 +/- 14.1) and (67.9 +/- 25.5) microg x m(-3) in autumn, and (30.4 +/- 25.1), (51.2 +/- 15.9), (81.6 +/- 37.9) microg x m(-3) in winter. The concentrations of SO2 appeared higher in spring and winter, and lower in summer and autumn. The concentrations of SO2 were (50.5 +/- 23.3), (26.3 +/- 16.7), (38.8 +/- 18.4) and (53.7 +/- 23.4) microg x m(-3) in spring, summer, autumn and winter, respectively. The concentrations of PM2.5 appeared higher in winter and changed smoothly in other seasons, with the average concentration of (61.4 +/- 28.5), (68.1 +/- 32.5), (61.9 +/- 27.1) and (89.6 +/- 44.2) microg x m(-3) in spring, summer, autumn and winter, respectively. The curves of diurnal variations of O3, O(x), NO, NO(x) and SO2 all showed single peak. However, the time of the peak values varied for different pollutants, 16:00 for O3 and O(x), and 8:00-11:00 for NO, NO(x) and SO2. The diurnal variations of NO2 and PM2.5 were similar to the two peaks that appeared in the morning and at night, respectively. Moreover, the diurnal ranges of O3 and O(x) concentrations were much wider in summer, while the wider ranges were observed in winter for NO, NO2, NO(x), SO2 and PM2.5. There was no difference in the diurnal pattern of NO between weekends and weekdays, the concentrations of N2O in weekdays were much higher than those on weekends, but with O3 the situation was the opposite. Correlation analysis indicated that the O3 concentration was positively correlated with temperature and wind speed, while negatively correlated with relative humidity. However, the situation of NO(x) was the opposite. PM2.5 concentration was negatively correlated with temperature and wind speed, while positively correlated with relative humidity. SO2 concentration had different correlations with the meteorological parameters in different seasons. In addition, wind direction was an important factor affecting the concentrations of the atmospheric pollutants.

[Variation characteristics of surface ozone and its precursors during summertime in Nanjing northern suburb].

It is not optimistic about current air quality in Nanjing northern suburb, an area with the agglomeration of heavy industry such as steel-making and petrochemical industry. Measurement of ozone and its precursors conducted from May 18th to August 31st, with the Meteorological data recorded simultaneously, were analyzed to characterize the local photochemical pollution in summertime. The results showed that the average volume fraction of ozone (O3), nitrogen oxide (NO(x)) and volatile organic compounds (VOCs) in Nanjing northern suburb was about (32.01 ± 15.20) x 10(-9), (21.50 ± 14.02) x 10(-9) and (33.16 ± 25.20) x 10(-9), respectively, and carbon monoxide (CO) was (0.66 ± 0.44) x 10(-6). For O3, the maximum value reached 146.42 x 10(-9), exceeding the National Ambient Air Quality Standard II by a rate of 14.1%. The background level of O3, NO(x), VOCs and CO were estimated to be (5.71 ± 2.51) x 10(-9), (12.20 ± 0.36) x 10(-9), (22.44 ± 0.38) x 10(-9) and (0.28 ± 0.01) x 10(-6), respectively, from the frequency distribution of their hourly averaged volume fraction. Pollutants were significantly affected by local emission sources near the site. When affected by the southwest wind with the speed of 2-3 m x s(-1), active species of VOCs were easy to reach high level, accompanied by an increased concentration of O3; Under the influence of easterly winds, NO(x), CO and VOCs, mainly emitted from industrial sources and traffic sources, were prone to reach high level. The regulation and control measures were taken on industrial production and some vehicles during the Nanjing Asian Youth Games, but the concentration of O3 was not significantly reduced, and there were 4 days exceeding the National Ambient Air Quality Standard II.

[Variation of atmospheric pollutants in Qinhuangdao City].

To illuminate the air pollution situation of the tourist city of Qinhuangdao, the atmospheric pollutants were measured from autumn 2009 to summer 2010. The results showed that the mean average concentration of NO, NO2, SO2, O3 and PM10 during the observation period reached (18 +/- 18), (45 +/- 18), (42 +/- 46), (44 +/- 25) and (128 +/- 77) microg x m(-3), respectively. The particulate matter pollution was serious, and the rate of the annual mean value exceeded the National Ambient Air Quality Standard II by 28%. The average daily concentration and average max hourly O3 concentration were (64 +/- 21)microg x m(-3) and (126 +/- 42) microg x m(-3) in summer, and the air masses from the southern ocean aggravated the O3 pollution. The concentrations of NO(x) SO2 and PM10 in the heating period were 1.5, 4.9 and 1.5 times more than those in the period without heating and the daily average concentration of SO2 and PM10 exceeded the National Ambient Air Quality Standard II by 53% and 11% in the heating period, respectively. The superimposition effect of regional transport in the Beijing-Tianjin-Hebei region and industrial area surrounding the Bohai Bay and local harbor emission led to an increase of 17% (NO(x)), 27% (SO2) and 12% (PM10), resulting in average concentrations of up to (100 +/- 49), (110 +/- 84) and (215 +/- 108) microg x m(-3) in winter. The winds from northern inland and southern ocean can effectively remove the air pollutants.

[Variation analysis of background atmospheric pollutants in North China during the summer of 2008 to 2011].

In order to understand the change of background concentration of air pollutants with the development of economy in the region of North China, the concentrations of NO(x), O3 and PM2.5 were monitored during the summer of 2008 to 2011 at Xinglong station, which is the regional background station of North China. The results indicated that the average concentration of NO(x) in the summer of the four years was (9.1 +/- 5.1), (5.9 +/- 2.6), (12.2 +/- 4.6) and (14.1 +/- 5.0) microg x m(-3), respectively, the daily maximum hourly concentration of O3 was (163.3 +/- 42.7), (175.2 +/- 48.8), (199.6 +/- 52.6) and (207.2 +/- 62.1) microg x m(-3), respectively, and the average concentration of PM2.5 was (59.8 +/- 44.6), (44.4 +/- 28.0), (58.1 +/- 34.2) and (52.5 +/- 36.7) microg x m(-3), respectively; in which, the concentrations of atmospheric pollutants had increased most significantly in 2010, especially the concentration of NO(x). The average concentrations of NO(x), O3 and PM2.5 increased by 106%, 14% and 31%, respectively, compared to those in the summer of 2009. Because of the increase in the number of motor vehicle and the fast development of industry in the region of North China in 2010, the background concentrations of atmospheric pollutants were increasing obviously. The atmospheric oxidizer has also increased, the concentration of O(x) reached (155.3 +/- 40.2) microg x m(-3) and has increased by 20% compared to the average concentration of the period during the summer of 2009, the compound pollution of high concentration of ozone and fine particles becomes more and more serious in North China.

[Characteristics of atmospheric pollutants in Beijing, Zhuozhou, Baoding and Shijiazhuang during the period of summer and autumn].

In order to evaluate the potential impact of the atmospheric pollution in Beijing by those cities which located southwest of it, the observations of PM10, NO(x) and O3 were conducted during the period of summer-autumn (Jul. 16-Oct. 15, 2009) in Beijing, Zhuozhou, Baoding and Shijiazhuang online, with the automated instruments which conform to international standards. The results showed that the principal pollutant was PM10, and the average concentration was (99 +/- 88), (121 +/- 74), (141 +/- 92) and (180 +/- 107) microg/m3, respectively. The concentration of NO(x) was (66 +/- 48), (23 +/- 14), (47 +/- 35) and (52 +/- 32) microg/m3, respectively. Ozone, the photochemical pollutant, the daily maximum concentration hourly was (107 +/- 60), (128 +/- 55), (164 +/- 61) and (120 +/- 54) microg/m3, respectively. Owing to the emission of local sources, the atmospheric PM10 pollution of Shijiazhuang was the most serious in 4 cities, in order was Baoding, Zhuozhou and Beijing. However, the average concentration of O3 in Baoding was the highest for the dual influence of Beijing and Shijiazhuang. Two episodes of heavy regional atmospheric pollution in July 2009 were analyzed with the surface meteorological data and backward trajectory model. The results suggested that the air quality in Beijing and the surrounding areas was significant influenced by the three cities of Hebei province in summer-autumn.

[Variation of air pollution in new Tangshan industrial area during winter heating period].

To illuminate the air pollution situation of the new Tangshan industrial area in the heating period, the observation of atmospheric pollutants was conducted in Tangshan City, Qianan City and Caofeidian Town from Oct. 2009 to Apr. 2010. The result showed that air pollution was serious in the area in winter. The regional mean concentration of NO, NO2, SO2, CO, PM2.5 and PM10 reached (26 +/- 28), (52 +/- 27), (72 +/- 53), (3 500 +/- 3 600), (82 +/- 65), (164 +/- 121) microg x m(-3) in the heating period, respectively. The concentration of NO and SO2 was 2.5 times in the heating period more than in the non-heating period. The concentration of NO2 and PM10 increased by -30%. The rates that CO and PM10 exceeded the National Ambient Air Quality Standard II were 27% and 40%; and the rate that PM2.5 exceeded the WHO IT1 Standard was 38%. The typical diurnal variations of NO, NO2, SO2, PM2.5 and PM10 were similar with peaking at 08:00 and 18:00, but the diurnal variation of CO was single peak at 08:00 with accumulating in evening. The peaks of NO, CO and SO2 were very high in morning because of the rush hours and the heating, which were 50, 90, and 5100 microg x m(-3), respectively. The peaks of NO2, PM2.5 and PM10 were relatively gentle, which were 56, 105, and 202 microg x m(-3), respectively. The cluster analysis of backward trajectories showed only the northerwinds, the cold airs can wash away the air pollution, while the southerwinds and easternwinds can easily accumulate the pollutants or transport the pollutants to the Beijing-Tianjin region.

[Characteristics of atmospheric pollutants during the period of summer and autumn in Shijiazhuang].

Atmospheric pollutants and their concentration change characteristics during Beijing Olympics in Shijiazhuang were studied. Air quality was measured by automatic on-line continuous monitoring equipments in summer and autumn of 2007 and 2008. The objectives of this study were to identify the effect of pollutants decrease on atmospheric environment, and develop the potential influence to Beijing and surrounding areas. The results show that the pollutants concentration often exceeds state criterion except nitrogen oxides, O3 concentration in summer and autumn is higher, averaged hourly maximum concentration (O3-Max) is (177.2 +/- 63.0) and (105.8 +/- 61.7) microg x m(-3), the concentrations of NO and NO2 are (4.5 +/- 4.0), (32.7 +/- 12.4) microg x m(-3) and (21.5 +/- 16.9), (60.5 +/- 16.9) microg x m(-3) respectively, SO2 concentration is (72.0 +/- 27.5) and (92.0 +/- 44.4) microg x m(-3), PM2.5 and PM10 concentrations reach to (102.3 +/- 47.6), (153.3 +/- 58.3) microg x m(-3) and (95.8 +/- 50.0), (147.4 +/- 67.0) microg x m(-3). Generally, pollutants declined obviously in Olympics period, the concentrations of NOx, O3-Max, SO2, PM2.5 and PM10 are (43.8 +/- 15.0), (142.0 +/- 54.9), (52.4 +/- 18.8), (76.7 +/- 35.1) and (116.5 +/- 38.8) microg x m(-3), and the reduction ratio of SO2, PM2.5 and PM10 are 34.6%, 22.8% and 21.0% compared with the whole monitoring period in 2008. The actuality of atmospheric pollution in summer and autumn was analyzed systemically, and which provided scientific evidences for evaluating the control measures of pollutants emission.

[Observations and comparison analysis of air pollution in Beijing and nearly surrounding areas during Beijing 2008 Olympic Games].

In order to study regional air quality, evaluate the interaction of air quality among Beijing and four cities and assess the effects of regional collaborative emission abatement in Beijing and surrounding areas for the Olympic Games period on regional air quality, and seek an effective means of early warning of air pollution, a monitoring network on observation of atmospheric pollutants in Beijing and four nearby cities which were Zhuozhou, Langfang, Xianghe and Yanjiao, was established to measure concentrations of NO(x), O3 and particulate matter in June 2008. The results show that the primary pollutants in Beijing and nearly surrounding areas are particulates during the study periods. The average mass concentrations of PM10 were (114 +/- 66) microg/m3 and (128 +/- 59) microg/m3 in Beijing and nearby cities, respectively, while the average mass concentrations of PM2.5 were (77 +/- 47) microg/m3 and (81 +/- 51) microg/m3, respectively. The average maximum hourly mass concentrations of O3 were (164 +/- 52) microg/m3 and (165 +/- 55) microg/m3, as well as the average mass concentrations of NO(x) were (58 +/- 23) microg/m3 and (25 +/- 14) microg/m3 in Beijing and nearby cities, respectively. Compared to June, concentrations of PM10, PM2.5, O3, NO(x) decreased by 69%, 62%, 18% and 41% during the Olympic period (from August 8 to 24) and 56%, 49%, 17% and 16% during the Paralympic Games period (from September 6 to 17) in Beijing. The mass concentration of PM2.5 was affected by the surrounding areas of Beijing seriously. The relative high concentrations of NO(x) in Beijing implied NO(x) had the potential tendency to be transported to the surrounding areas. Ozone showed regional pollution characteristics in summer. It shows that the monitoring network on observation of atmospheric pollutants in Beijing and nearly surrounding areas is significant in early warning of air pollution, and could provide scientific support for interregional cooperation of air pollution control.