Observational Insights into Isoprene Secondary Organic Aerosol Formation through the Epoxide Pathway at Three Urban Sites from Northern to Southern China.

Isoprene is the most abundant precursor of global secondary organic aerosol (SOA). The epoxide pathway plays a critical role in isoprene SOA (iSOA) formation, in which isoprene epoxydiols (IEPOX) and/or hydroxymethyl-methyl-α-lactone (HMML) can react with nucleophilic sulfate and water producing isoprene-derived organosulfates (iOSs) and oxygen-containing tracers (iOTs), respectively. This process is complicated and highly influenced by anthropogenic emissions, especially in the polluted urban atmospheres. In this study, we took a 1-year measurement of the paired iOSs and iOTs formed through the IEPOX and HMML pathways at the three urban sites from northern to southern China. The annual average concentrations of iSOA products at the three sites ranged from 14.6 to 36.5 ng m-3. We found that the nucleophilic-addition reaction of isoprene epoxides with water dominated over that with sulfate in the polluted urban air. A simple set of reaction rate constant could not fully describe iOS and iOT formation everywhere. We also found that the IEPOX pathway was dominant over the HMML pathway over urban regions. Using the kinetic data of IEPOX to estimate the reaction parameters of HMML will cause significant underestimation in the importance of HMML pathway. All these findings provide insights into iSOA formation over polluted areas.

Polycyclic aromatic hydrocarbons induce endothelial injury through miR-155 to promote atherosclerosis.

Polycyclic aromatic hydrocarbons (PAHs) are considered as an external factor that induces atherosclerotic cardiovascular disease. Although miR-155 is known to be involved in cardiovascular disease, whether it is involved in PAH-induced arteriosclerosis remains unclear. We evaluated the effects of PAHs on vascularization, permeability, and miR-155 expression in HUVECs. We found that PAHs-induced sclerosis of HUVECs was characterized by increasing permeability, decreasing proliferation, and vascular lumen number. The expression of miR-155 was upregulated by PAHs treatment, and transfection with miR-155 inhibitor could reverse above effect of PAHs-induced sclerosis. Meanwhile, transcriptome sequencing revealed that 63 genes were downregulated in the group of PAHs treatment alone, and were then upregulated in the miR-155 inhibitor group. These genes were mainly involved in complement and coagulation cascades, cytokine-cytokine receptor interaction, TNF signaling pathway, and NF-kappa B signaling pathway. Among these 63 genes, SERPIND1 was directly targeted and regulated by miR-155. Further in vivo experiments in ApoE-/- mice confirmed that PAH accelerates the development of arteriosclerosis by promoting the expression of miR-155 to downregulate the SERPIND1. Therefore, PAH exaggerates atherosclerosis by activating miR-155-dependent endothelial injury. This study provides a fundamental insight on the miR-155 mechanism for PAHs enhancing atherosclerosis and miR-155 potentially serving as a novel drug target.

[Characterization and Size Distribution of Carbonaceous Aerosols at Mountain Dinghu].

To understand the characterization and sources of carbonaceous aerosols at Mountain Dinghu, organic carbon (OC) and elemental carbon (EC) in size-resolved aerosol samples were measured at a regional background site in South China using a DRI Model 2001A analyzer. The average mass concentrations of organic carbon (OC) are (5.6±2.0) µg ·m-3 in PM1.1, (7.3±2.4) µg ·m-3 in PM2.1, and (12.8±4.0) µg ·m-3 in PM9.0; the average mass concentrations of elemental carbon (EC) are (2.3±1.4) µg ·m-3in PM1.1, (2.7±1.6) µg ·m-3 in PM2.1, and (3.4±1.7) µg ·m-3 in PM9.0. OC concentrations in PM1.1 and PM2.1 account for 43.8% and 57.0% of OC in PM9.0, and EC concentrations in PM1.1 and PM2.1 account for 67.6% and 79.4%, respectively. OC and EC are enriched with fine particles. In PM1.1 and PM2.1, the highest concentrations of OC and EC are measured in autumn, and the lowest concentration of OC is measured in winter and EC in summer. In PM9.0, the highest OC concentration is measured in summer. Carbonaceous aerosols are mainly composed of OC2, EC1, OC3, and OC4. In summer, the concentration of OC3 is higher than that of EC1, suggesting that biogenic sources are dominant during summer. The concentration of EC1 in winter is the highest, indicating that the impacts of motor vehicle emissions are prominent in the local area during winter. OC and EC both show bimodal distributions in four seasons, with peaks in the size ranges of 0.43-0.65 µm for fine particles and 3.3-5.8 µm for coarse particles. In PM1.1 and PM2.1, the sources of OC are mainly primary emissions. In PM2.1, the highest concentration of SOC is measured in spring at (3.0±1.4) µg ·m-3 and the lowest in winter at (1.3±1.4) µg ·m-3, indicating that the secondary aerosol formation is significant in spring. At the Mountain Dinghu background site, OC is mainly from coal combustion and motor vehicle emissions for fine particles and from biogenic sources for coarse particles. EC is mainly from coal combustion, motor vehicle emissions, and dust.

[Characteristics of Aerosol Optical Depth in the Urban Area of Beibei and Its Correlation with Particle Concentration].

To understand the atmospheric quality of the Beibei District of Chongqing, using the simultaneous observation data of aerosol optical depth and particulate matter concentration in 2014, we analyzed the characteristics of aerosol optical depth (AOD) in the urban area of Beibei and its correlation with particle concentration. The results showed that the annual average of AOD500nm in Beibei District is 1.46±0.69, which varies significantly by month. The highest value in November was 2.90±1.85, and the lowest in September was 0.54±0.05. There is particulate matter pollution in Beibei District. The annual average values of PM2.5 and PM10 are (62±40)µg·m-3 and (94±51)µg·m-3, respectively, which exceed the secondary standard of GB 3095-2012 Ambient Air Quality Standard. The limit values, the daily average over-standard rates of PM2.5 and PM10, are 26% and 15%, respectively. There was significant correlation between fine particle PM2.5 and PM10 concentration of respirable particulate matter. The annual coefficient of determination R2 could reach 0.95 (P<0.01). The correlation between AOD and PM2.5 and PM10 was positive throughout the year. The coefficient of determination R2 was 0.48 and 0.46, respectively, and the coefficient of determination and correlation function were different in different seasons, among which the correlation in winter was the best and the correlation in summer was the worst. AOD and air quality index showed positive correlation characteristics throughout the year, and the coefficient of determination R2 was 0.15 (P<0.05). The AOD value was affected by the comprehensive effects of weather elements. The temperature, humidity, water vapor, and other factor data should also be collected synchronously during the observation period.

Spatial and seasonal variations of isoprene secondary organic aerosol in China: Significant impact of biomass burning during winter.

Isoprene is a substantial contributor to global secondary organic aerosol (SOA). The formation of isoprene SOA (SOAI) is highly influenced by anthropogenic emissions. Currently, there is rare information regarding SOAI in polluted regions. In this study, one-year concurrent observation of SOAI tracers was undertaken at 12 sites across China for the first time. The tracers formed from the HO2-channel exhibited higher concentrations at rural sites, while the tracer formed from the NO/NO2-channel showed higher levels at urban sites. 3-Methyltetrahydrofuran-3,4-diols exhibited linear correlations with their ring-opening products, C5-alkenetriols. And the slopes were steeper in the southern China than the northern China, indicating stronger ring-opening reactions there. The correlation analysis of SOAI tracers with the factor determining biogenic emission and the tracer of biomass burning (levoglucosan) implied that the high level of SOAI during summer was controlled by biogenic emission, while the unexpected increase of SOAI during winter was largely due to the elevated biomass burning emission. The estimated secondary organic carbon from isoprene (SOCI) exhibited the highest levels in Southwest China. The significant correlations of SOCI between paired sites implied the regional impact of SOAI in China. Our findings implicate that isoprene origins and SOAI formation are distinctive in polluted regions.

[Observation of size distribution of atmospheric OC/EC in Tangshan, China].

Atmospheric particulate matter pollution is serious in Tangshan, a heavy industrial city of North China. The annual average concentrations of PM1.1, PM2.1, PM9.0 and TSP were (75 +/- 43), (106 +/- 63), (221 +/- 100) and (272 +/- 113) microg x m(-3), respectively, from 2009 to 2011. Carbonaceous aerosols were the key components in various size particles. Elemental carbon (EC) accounted for 9%, 9%, 6% and 4% of PM1.1, PM2.1, PM9.0 and TSP, respectively, meanwhile, organic carbon (OC) accounted for 25%, 24%, 16% and 14% of PM1.1, PM2.1, PM9.0 and TSP, respectively. The concentration spectrum distribution of particulate matter and the enrichment amount of the carbonaceous aerosols showed seasonal variations. In autumn and winter, the EC and OC concentration in the fine particulate matter reached up to (9 +/- 4), (11 +/- 5) and (19 +/- 7), (28 +/- 10) microg x m(-3), respectively, accounting for 11%, 10% and 26%, 25% of fine particles; EC and OC in spring and summer were (5 +/- 2), (5 +/- 1) and (15 +/- 3), (15 +/- 1) microg x m(-3), respectively, accounting for about 7%, 6% and 26%, 18% of TSP, respectively.

[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.

[Comparison of atmospheric particulate matter and aerosol optical depth in Beijing City].

The pollution of particulate matter was serious in Beijing City from the synchronous observation of particulate matter mass concentration and aerosol optical characteristics in 2009. The annual mean concentrations of PM2.5 and PM10 were (65 +/- 14) microg x m(-3) and (117 +/- 31) microg x m(-3), respectively, which exceeded the national ambient air quality annual standards to be implemented in 2016. There were 35% and 26% days of 2009 that the daily standards were exceeded. There was a significant correlation between fine particulate (PM2.5) and inhalable particle (PM10), with a correlation coefficient (R) of approximately 0.90 (P < 0.001). PM10 contained a large percentage of PM2.5, with an annual percentage of about 61%. The percentage became much higher from spring to winter, while the correlation between PM2.5 and PM10 became much stronger. The annual mean of AOD (500 nm) and Angstrom exponent were (0.55 +/- 0.1) and (1.12 +/- 0.08), respectively. There were significant correlations between PM2.5, PM10 and AOD in the four seasons and the whole year, and the correlation coefficients were greater than or equal to 0.50. Furthermore, the correlation functions and coefficients had seasonal variations. The correlations were more significant in summer and autumn than in spring and winter. The annual correlation could cover up the seasonal systematic differences. The correlations between AOD revised by Mixed Layer Height and PM2.5 PM10 revised by Relative Humidity became stronger, and the exponential correlations were superior to the linear correlations.

[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 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.

[Change and analysis of background concentration of air pollutants in north China during 2008 Olympic Games].

To understand the atmospheric background in North China and evaluate the effect of pollutant emission control as well as the influence of contaminant transportation in the regional pollution, during the 2008 Olympic Games, concentrations of four main air pollutants were observed from June to November at Xinglong station which is the regional background station of North China. We compared the concentrations and diurnal variations in different periods, analyzed the pollution transportation using the ground meteorological data and the backward trajectory model and compared the concentrations between different observation stations in Northern China. The results indicated that the concentrations of NOx, SO2, O3 and PM2.5 in summer were 8.4, 10.5, 126.0 and 59.8 microg x m(-3) respectively and in autumn were 11.7, 17.2, 97.5 and 30.7 microg x m(-3) respectively. During the period of Olympic (2008-08-08-2008-08-24), the concentrations of NOx, SO2, O3 and PM2.5 were 6.6, 6.8, 100.5 and 33.3 microg x m(-3) and reduced 29.0%, 46.9%, 18.6% and 36.5% respectively compared to the average concentrations of the period before and after Olympic Games. The concentration of NOx has reduced 62.5% and the PM2.5 has reduced 29.0% compared to the same term of Olympic in 2007. The air quality has obvious improvement in North China during the Olympic Games. Before the emission control, the concentrations of pollutants were lower in the night and became higher gradually in the daytime and reached the peak values in 17:00-20:00 which can indicate the accumulation of regional pollution transportation in Xinlong. In the emission control period, the accumulation of pollutants in afternoon was obviously weakened and the transportation of pollutants was lower which can reveal the obvious effect of the emission control in Beijing and peripheral areas. The atmosphere in Xinglong was mainly influenced by the monsoon from south direction in summer and autumn and the pollution of Xinglong was seriously influenced by the regional pollution in the south direction. Compared the concentrations between different stations, we can conclude that in summer and autumn the pollutions of NOx and SO2 are relatively lower, the pollution of O3 is not allowed to be optimism and the pollution of PM2.5 is very serious which should be paid enough attentions to.

[Observation and analysis of air pollution in Tangshan during summer and autumn time].

To study the air pollution in Tangshan City and its effects on Beijing and the surrounding areas during the Beijing Olympics, the on-line monitoring of atmospheric pollutant was performed at the summer and autumn time in 2007 and 2008 in Tangshan. The results show that the average PM2.5 concentrations are 105.1 microg x m(-3) +/- 46.5 microg x m(-3) in summer and 108.1 microg x m(-3) +/- 61.8 microg x m(-3) in autumn. The average max hourly O3 concentrations are 153.9 microg x m(-3) +/- 50.9 microg x m(-3) in summer and 114.6 microg x m(-3) +/- 56.5 microg x m(-3) in autumn. The average NO2 concentrations are 39.2 microg x m(-3) +/- 10.0 microg x m(-3) in summer and 42.7 microg x m(-3) +/- 11.6 microg x m(-3) in autumn, and the average SO2 concentrations are 44.8 microg x m(-3) +/- 31.1 microg x m(-3) in summer and 52.2 microg x m(-3) +/- 25.2 microg x m(-3) in autumn. The average oxidant (NO2 + O3) concentrations are 111.9 microg x m(-3) +/- 27.0 microg x m(-3) in summer and 87.2 microg x m(-3) +/- 27.8 microg x m(-3) in autumn. As one of the fine particles sources in areas of Beijing, Tianjin and Hebei, Tangshan is severely polluted by fine particles; Concentrations of SO2 and NO2 are higher than that of surrounding areas, but still attain the national standard for Grade II. Long-term NO2 concentration which mainly comes from automobile exhaust changes little. The O3 concentration is relatively low compared to nearby areas, however, it remains unknown how high local emission of O3 precursor (NOx) would affect the regional O3 production. During the Beijing Olympics, affected by industrial emission reduction, all air pollutant concentrations were reduced especially SO2 and PM2.5, so reducing industrial emission should be useful for improving air quality in Tangshan.

[Determination of trace metals in atmospheric dry deposition with a heavy matrix of PUF by inductively coupled plasma mass spectroscopy after microwave digestion].

Interest in atmospheric dry deposition results mostly from concerns about the effects of the deposited trace elements entering waterbody, soil and vegetation as well as their subsequent health effects. A microwave assisted digestion method followed by inductively coupled plasma mass spectrometric (MAD-ICP/MS) analysis was developed to determine the concentrations of a large number of trace metals in atmospheric dry deposition samples with a heavy matrix of polyurethane foam (PUF). A combination of HNO3-H2O2-HF was used for digestion. The experimental protocol for the microwave assisted digestion was established using two different SRMs (GBW 07401, Soil and GBW 08401, Coal fly ash). Subsequently, blanks and limits of detection for total trace metal concentrations were determined for PUF filter which was used for dry deposition sampling. Finally, the optimized digestion method was applied to real world atmospheric dry deposition samples collected at 10 sites in Jingjinji area in winter from Dec. 2007 to Feb. 2008. The results showed that the area-averaged total mass fluxes ranged between 85 and 912 mg x (m2 x d)(-1), and fluxes of most elements were highest at Baoding and lowest at Xinglong. In addition, the elemental fluxes in urban areas of Beijing, Tianjin and Tangshan were measured to be higher than that in suburb and rural sites. The average fluxes of crust elements (A1, Fe, Mn, K, Na, Ca and Mg) were one to three orders of magnitude higher than anthropogenic elements (Cu, Pb, Cr, Ni, V, Zn and Ba), varying from 151 to 16034 microg x (m2 x d)(-1) versus 14 to 243 microg x (m2 x d)(-1). Zinc was the most abundant heavy metal and calcium the highest of the crust elements while the elements Mo, Co, Cd, As and Be deposited less or even could not be detected. The anthropogenic and crustal contributions were estimated by employing enrichment factors (EF) calculated relative to the average crustal composition. The EF values of all elements except Pb and Zn were below 10, suggesting that local soil and/or dust generally dominate in the dry deposition flux.

[Effects of synoptic type on surface ozone pollution in Beijing].

Ozone (O), influenced by meteorological factors, is a primary gaseous photochemical pollutant during summer to fall in Beijing' s urban ambient. Continuous monitoring during July to September in 2008 was carried out at four sites in Beijing. Analyzed with synoptic type, the results show that the ratios of pre-low cylonic (mainly Mongolia cyclone) and pre-high anticylonic to total weather conditions are about 42% and 20%, illustrating the high-and low-ozone episodes, respectively. At the pre-low cylonic conditions, high temperature, low humidity, mountain and valley winds caused by local circulation induce average hourly maximum ozone concentration (volume fraction) up to 102.2 x 10(-9), negative correlated with atmospheric pressure with a slope of -3.4 x 10(-9) Pa(-1). The time of mountain wind changed to valley wind dominates the diurnal time of maximum ozone, generally around 14:00. At the pre-high anticylonic conditions, low temperature, high humidity and systematic north wind induce average hourly maximum ozone concentration (volume fraction) only 49.3 x 10(-9), the diurnal time of maximum ozone is deferred by continuous north wind till about 16:00. The consistency of photochemical pollution in Beijing region shows that good correlation exists between synoptic type and ozone concentration. Therefore, getting an eye on the structure and evolution of synoptic type is of great significances for forecasting the photochemical pollution.

[Application of passive sampler to monitor and study atmospheric trace gases in Beijing-Tianjin-Hebei area].

Applying of passive sampler which is a cheap and simple method, the concentrations of SO2, NO2, O3 and NH3 were monitored in ten stations as network in Beijing-Tianjin-Hebei area from Dec. 2007 to investigate the concentration level and change of contaminants as well as the compound pollution in this region. Passive sampler method was fully evaluated to check the applicability in the area and the concentration and spatial distribution of pollutants were studied in this paper. The evaluation results indicate that passive sampler method can be used for long-term sampling and the frequency was settled as one month. The coefficients of variation of parallel samplers of SO2, NO2, O3 and NH3 were 6.4%, 7.1%, 4.2% and 3.9% respectively which can represent the good stability of this method. The concentrations monitored by passive sampler had good consistency with the monthly average concentrations calculated from active monitoring. The correlation coefficients of SO2, NO2 and O3 were 0.91, 0.88 and 0.93, slopes of fitted curve were 1.25, 0.98 and 0.93 and average relative standard deviation were 23.3%, 14.9% and 8.5% respectively which indicated that passive sampler can basically meet the atmospheric sampling requirement. Short-term monitoring of NH3 also indicated that results of passive sampler and active monitoring were comparable. Passive sampler is proven to be a reliable atmospheric monitoring method and can be used in regional pollution investigation. In the summer of 2008, average concentrations which were monitored by passive sampler calculated from 10 observation stations of SO2, NO2, O3 and NH3 were (12.3 +/- 6. 3) x 10(-9), (13.2 +/- 7.0) x 10(-9), (40.5 +/- 9.5) x 10(-9) and (24.0 +/- 13.7) x 10(-9) respectively in Beijing-Tianjin-Hebei area. The concentrations of SO2 and NO2 were relatively higher in city sites and concentrations of NH3 were higher in agricultural sites. The pollution of SO2, NO, and NH3, are obviously influenced by local emission. The concentrations of O3 were about 40 x 10(-9) in most area around Beijing and Tianjin except background station Xinglong and showed regional pollution characteristic.

[Introduction and calibration of the Chinese sun hazemeter network].

Much of the current uncertainty in the quantitative assessment of the climate and environment change is due to our lack of knowledge of the aerosol, for which the large-scale sun hazemeter ground-based network directly provides basic data. The data also can revise the results of the satellite remote sensing. Depending on the stations of CERN, the standard network was first built in China. The accurate and reliable hazemeter (LEDs) was uniformly used in the network. The hazemeters were calibrated by Langley plot method and transfer calibration and were uniformly checked. The AODs, which were synchronously retrieved from hazemeters (RSD < 3%) and CEMIL (RSD < 5%), were coherent and comparable. The stability and reliability of the hazemeters and the network was approved.

[AOD and angstrom parameters of aerosols observed by the Chinese sun hazemeter network from August to December 2004].

Atmospheric aerosol optical depth (AOD(lamda=500 nm)), Angstrom turbidity coefficient (beta) and Angstrom wavelength exponent (alpha) are obtained using the CERN sun hazemeter network from Aug to Dec, 2004. The results are as follows: At the Tibetan Plateau, Haibei and Lhasa, the mean of AOD is 0.09, 0.12; the mean of beta is 0.05, 0.13; the mean of a is 1.09, 0.06, respectively. At the Northeast of China, Hailun and Sanjiang, the mean of AOD is 0.14, 0.15; the mean of beta is 0.04, 0.06; the mean of a is 2.32, 1.58, respectively. At the desert region of North China, e.g., Fukang, Shapotou and Eerduosi, the range of averaged AOD is from 0.17 to 0.32; the range of averaged beta is from 0.09 to 0.19; the range of averaged a is from 0.68.to 1.28. At the forest areas, e.g. Changbai Mountain, Beijing forest and Xishuangbanna, the range of averaged AOD is from 0.19 to 0.42; the range of averaged beta is from 0.12 to 0.19; the range of averaged a is from 1.11 to 1.25. At agriculture areas, e.g. Shenyang, Fengqiu, Taoyuan and Yanting, the range of averaged AOD is from 0.34 to 0.68; the range of averaged beta is from 0.18 to 0.38; the range of averaged a is from 0.97 to 1.39. At the littoral areas and the lake of East China, e.g. Jiaozhou Bay, Shanghai City and Tai Lake, the range of averaged AOD is from 0.49 to 0.68; the range of averaged beta is from 0.21 to 0.29; the range of averaged a is from 1.24 to 1.37. At the inland cities, Beijing City and Lanzhou City, the mean of AOD is 0.47, 0.81; the mean of beta is 0.20, 0.45; the mean of a is 1.66, 0.89, respectively. The variations of aerosol properties at nineteen stations are explained in the paper.