[PM2.5 Pollution Characterization and Cause Analysis of a Winter Heavy Pollution Event, Liaocheng City].

Heavy pollution events frequently occur during fall and winter seasons in northern areas. In order to understand the characteristics and chemical composition of PM2.5 during heavy pollution in winter in Liaocheng City, ambient PM2.5 samples were collected between January 7-11,2016. Mass concentration, water-soluble ions, carbonaceous species, and elements were analyzed, as well as the causes of pollution. Results showed that PM2.5 mass concentration was 238.3 µg·m-3 with the trend clearly that of an inverted V; this concentration represents exceedance of the National Ambient Air Quality Standard (GB 3095-2012) by more than 2.2 times. NO3-, SO42-, and NH4+(SNA)were the main water-soluble ions. As pollution increased or decreased, NH4+, SO42-, NO3-, and Cl- exhibited the same trend, which contrasted with that of Ca2+. During the peak of pollution, NH4+, NO3-, and SO42- concentrations were 48.96, 68.45, and 80.55 µg·m-3, with these representing levels 6.29, 7.31, and 7.84 times those of the initial stage, respectively. During the pollution event, OC and EC concentration variation ranges were 20.8-60.2 µg·m-3, and 3.0-7.5 µg·m-3, respectively. The concentration of OC was significantly higher than that of EC and the variation amplitude was significantly larger. During the event, the mass concentrations of 27 inorganic elements on each day were 10.2, 22.4, 16.0, 19.6, and 8.2 µg·m-3, respectively. Enrichment factors (EF) of all elements were less than 10, indicating lack of enrichment and showing that sources were mainly natural. PM2.5 mass concentration reconstruction results showed that organic matter (OM), SO42-, and NO3- were major components, followed by NH4+, crustal material, and other ions. EC and trace element content was relatively low. As PM2.5 pollution worsened, secondary inorganic salt (NH4+, SO42-, NO3-) concentrations and proportions increased, OM concentration increased but its proportion decreased, while crustal material concentration and proportion both decreased, showing that secondary inorganic conversion was the main cause of this pollution event, mainly driven by coal and motor vehicle emissions.

[Characteristics and Sources of Elements in Atmospheric Dust Fall in Zhuzhou City, Central China].

To study the concentration characteristics as well as sources of elements and heavy metal pollution in atmospheric dust fall in Zhuzhou City, 144 samples from 12 sites in the Zhuzhou urban area were collected from January to December in 2012 and 28 kinds of elements in the samples were analyzed. The results showed that the dust fall quantities of the industrial areas and mixed commercial and residential (MCR) areas were, respectively, 89.46 g·m-2 and 33.20 g·m-2 and the range of all sample points was 23.14-114.67 g·m-2. There were 10 elements (Na, Mg, Al, K, Ca, Ti, Mn, Fe, Zn, Pb) in the industrial areas as well as 8 elements in the MCR areas, for which the contents greatly exceeded 1000 mg·m-1 in the atmospheric dust fall. The Zn and Pb contents exceeded 10000 mg·kg-1 in the dust fall of the industrial areas, which were far higher than those in the Earth's crust. The main sources of dust fall in Zhuzhou City were metal smelting, shallow ground dust, vehicle emissions, construction dust, and industrial production with specific elements (Mo, Ba). Correlation analysis, principal component analysis (PCA), and analysis of transportation characteristics showed that 13 elements (Mn, Fe, Co, Cu, Zn, As, Se, Ag, Cd, Sn, Sb, Tl, Pb) in dust fall mainly came from waste gas emissions of industrial areas in Zhuzhou, in which 7 heavy metal elements (Cu, Zn, As, Ag, Cd, Sb, Pb) caused serious pollution. The contents of heavy metals in the industrial areas were 7.4 to 4079.4 times the contents defined in China soil elements background values, whereas those in the MCR areas were 3.6 to 1413.4 times the soil background values. Cd was the highest background ratio element. The degree of contamination was clearly higher in the industrial areas than in the MCR areas.

[Spatial Distribution Characteristics of NMHCs in Spring in Cangzhou City].

Simultaneous collections of non-methane hydrocarbons (NMHCs) were carried out at 15 sampling sites including urban, suburb and potential pollution areas in Cangzhou City in spring 2015. The results showed that NMHCs were generally higher in urban areas than those in suburb and rural areas; the highest concentration of NMHCs was observed at Cangzhou High-tech zone (urban area); the concentrations of NMHCs were significantly lower at rural sites than in most urban sites except Hejian site; vehicular emissions were the main sources of NMHCs in Cangzhou; Cangzhou chemical fertilizer plant and Cangzhou oil refinery had no significant influence on urban NMHCs during their shutdown period; Dagang Oilfield, with better oil and gas recovery systems, did not have a significant impact on urban NMHCs. In general, alkanes, alkenes and aromatics accounted for 65%, 16% and 19% of NMHCs in Cangzhou City, respectively; xylene (19%), ethylene (14%), toluene(11%), propylene (5%), isopentane (5%) and isopentene (5%) were the most dominant contributors to ozone formation potential; aerosol formation potential was mainly derived from toluene (28%), pinene (28%), xylene(16%), ethylbenzene (9%) and benzene (9%).

[Characterization of chemical compositions in PM2.5 and its impact on hazy weather during 16th Asian Games in Guangzhou].

Aerosol samples for PM2.5 were collected days and nights from 4 to 30 November 2010 in Guangzhou. The concentrations of organic carbon, element carbon, and water-solubility ions of all particle samples were determined by thermal/optical carbon analyzer and ion chromatography, respectively. In-situ online PM,, mass concentrations, light extinction coefficients (bext), and selected meteorological parameters for this period were also measured. Temporal variation of PM,, mass concentrations and its relationship with bext were discussed, and bext was reconstructed by revised IMPROVE formula. The results showed that the average mass concentration ol PM2.5 was (77.0 +/- 24.4) microg.m-3 during the Asian Games period, which was 27.8% lower than that of the period before Asian Games. PM2.5 and relative humidity were the dominant factors contributing to hazy weather. The average value of bx, was 418 Mm-1 during the Asian Games period, which was 28.3% lower than that of the period before Asian Games. The major contributors to bext included (NH4) 2SO4, POM, and LAC, which accounted for 87.0% of bext during the Asian Games period. A series of stringent air quality control measures were implemented by the Guangzhou Municipal Government and other cooperative cities, which greatly alleviated the hazy weathers in Guangzhou urban area during the Asian Games period.

[Spatial distribution characteristics of NMHCs during winter haze in Beijing].

NMHCs and NOx samples were simultaneously collected and analyzed in six urban and suburban representative sampling sites (Sihuan, Tian'anmen, Pinguoyuan, Fatou, Beijing Airport and Miyun) during a typical haze period in winter 2005, Beijing. The concentrations of NMHCs during the sampling period in descending order were: Sihuan (1101.29 microg x m(-3)) > Fatou (692.40 microg x m(-3)) >Tian'anmen (653.28 microg x m(-3)) >Pinguoyuan (370.27 microg x m(-3)) > Beijing Airport (350.36 microg x m(-3)) > Miyun (199.97 microg x m(-3)). Atmospheric benzene pollution in Beijing was rather serious. The ratio of NMHCs/NOx ranged from 2.1 to 6.3, indicating that the peak ozone concentrations in urban Beijing were controlled by VOCs during the sampling period. Analysis of propylene equivalent concentration and ozone formation potential showed that the NMHCs reactivity descended in the order of Sihuan > Fatou > Tian'anmen > Pinguoyuan > Beijing Airport > Miyun. B/T values (0.52 to 0.76) indicated that besides motor vehicle emission, coal combustion and other emission sources were also the sources of NHMCs in Beijing in winter. The spatial variations of isoprene in Beijing indicated that the contribution of anthropogenic sources to isoprene increased and the emissions by biogenic sources decreased in winter. The spatial variations of propane and butane indicated that LPG emissions existed in the urban region of Beijing.

[A case-crossover study on the association between heat waves and daily deaths caused by acute myocardial infarction].

OBJECTIVE: To explore the effects of heat wave on daily deaths caused by acute myocardial infarction (AMI) in Beijing. METHODS: A case-crossover design was used to study the impact of 5 heat waves on the daily number of AMI deaths from Jan. 1, 1999 to Jun. 30, 2000. The effect of heat wave on death in different gender or age groups was also compared. The 7th day before and after death occurred was chosen as its own bi-directional self-control. The OR value and its corresponding risk period was used to reflect the impact of heat wave on daily number of AMI deaths, lag days and duration. RESULTS: There were five heat waves during the study period. The first heat wave sustained 9 days and the maximum temperature was 38.8°C with average humidity as 46.7%. The OR value for the AMI death was 1.437 (95%CI: 1.066 - 1.937). The second heat wave lasted 3 days, with the maximum temperature of 36.8°C and average humidity of 61.0%. The OR value for the AMI death was 1.846 (95%CI: 0.671 - 5.076). The third heat wave continued 7 days, with the maximum temperature of 41.5°C with average humidity of 58.5%. The OR value for the daily death counts caused by AMI was 2.427 (95%CI: 1.825 - 3.229). The fourth lasted for 3 days, with the maximum temperature of 39.6°C and average humidity as 31.9%. The OR value for the AMI deaths was 2.857 (95%CI: 1.088 - 7.506). The fifth heat wave lasted for 4 days, with the maximum temperature as 37.4°C, and average humidity as 42.0% during this period. The OR value for daily death counts caused by AMI was 1.500 (95%CI: 0.632 - 3.560). The OR value of the first heat wave for daily death counts of men and women caused by AMI were 1.153 (95%CI: 0.756 - 1.758) and 1.818 (95%CI: 1.185 - 2.790) respectively. The OR value for daily death counts of under 65 age was 1.200 (95%CI: 0.669 - 2.153), with the OR value for the older than 64 age group was 1.534 (95%CI: 1.083 - 2.173). The OR value for daily death counts of older than 64 age women was 1.818 (95%CI: 1.109 - 2.981). The OR values of the third heat wave for daily death counts of men and women caused by AMI were 2.392 (95%CI: 1.649 - 3.470) and 2.514 (95%CI: 1.613 - 3.919) respectively. The OR value for daily death counts of under 65 age group was 2.000 (95%CI: 1.149-3.482) and the OR value for the older than 64 age group was 2.623 (95%CI: 1.880 - 3.660). The OR value for daily death counts of older than 64 age group women was 2.800 (95%CI: 1.676 - 4.678). CONCLUSION: (1) Significant increase for daily death counts of AMI in Beijing was noticed during the heat wave and usually causing hysteretic effect. The lag phase was 0 - 2 days in general. (2) The increase of maximum temperature was greater at the beginning day when the heat wave occurred in the previous day, with shorter lag time and greater risk of AMI death. (3) The risk of AMI death in women was greater than in men during the heat wave period. (4) The risk of AMI death among those older than 64 age group was greater than the under 65 year olds. (5) The impact of heat wave to the elderly female was greater.

[Transport characteristics of air pollutants over the Yangtze Delta].

Meteorological field of January, April, July and October in 2004 was obtained by running MM5 with NCEP datasets. Then we used HYSPLIT 4.8 model to calculate the backward and forward trajectories of representative cities. Distributions of trajectories and the affected areas vary with seasons. Transport current affecting Yangtze River Delta is mainly from Mongolia, North China or Northeast region, via Yellow Sea area, Shandong, Jiangsu province or Shanghai. Another important transport path is current from southwest because of the Southwest monsoon. A movement of East Asia monsoon plays an important part in the mesoscale transport of pollutants in Yangtze Delta. Winter monsoon is a main mechanism which moves the air pollutants in Yangtze Delta to South China and West Pacific ocean. Another important transport system is the subtropical anticyclone over the western Pacific Ocean which controls the east coast of our country in spring and summer. This circulation system mainly affects the inland area of our country.