[Exploring the Severe Haze in Beijing During December, 2015: Pollution Process and Emissions Variation].

Severe haze episodes shrouded Beijing and its surrounding regions again during December, 2015, causing major environmental and health problems. Beijing authorities had launched two red alerts for atmospheric heavy pollution in this period, adopted a series of emergency control measures to reduce the emissions from major pollution sources. To better understand the pollution process and emissions variation during these extreme pollution events, we performed a model-assisted analysis of the hourly observation data of PM2.5, and meteorological parameters combined with the emissions variation of pollution sources. The synthetic analysis indicated that: (1) Compared with the same period of last year, the emissions of atmospheric pollution sources decreased in December 2015. However, the emission levels of primary pollutants were still rather high, which were the main intrinsic causes for haze episodes, and the unfavorable diffusion conditions represented the important external factor. High source emissions and meteorological factors together led to this heavy air pollution process. (2) Emergency control measures taken by the red alert for heavy air pollution could decrease the pollutants emission by about 36% and the PM2.5 concentrations by 11% to 21%. Though the implementation of red alert could not reverse the evolution trend of heavier pollution, it indeed played an active role in mitigation of PM2.5 pollution aggravating. (3) Under the heavy pollution weather conditions, air pollutants continued to accumulate in the atmosphere, and the maximum effect by taking emergency measures occurred 48-72 hours after starting the implementation; therefore, the best time for executing emergency measures should be 36-48 hours before the rapid rise of PM2.5 concentration, which requires a more powerful demand on the accuracy of air quality forecast.

[Characteristic of Particulate Emissions from Concrete Batching in Beijing].

With the economic development and population growth in Beijing, there is a strong need for construction and housing, which leads to the increase of the construction areas. Meanwhile, as a local provided material, the production of concrete has been raised. In the process of concrete production by concrete batching, there are numerous particulates emitted, which have large effect on the atmospheric environment, however, systematic study about the tempo-spatial characteristics of pollutant emission from concrete batching is still rare. In this study, we estimated the emission of particulates from concrete batching from 1991 to 2012 using emission factor method, analyzed the tempo-spatial characteristics of pollutant emission, established the uncertainty range by adopting Monte-Carlo method, and predicted the future emission in 2020 based on the relative environmental and economical policies. The results showed that: (1) the emissions of particulates from concrete batching showed a trend of "first increase and then decrease", reaching the maximum in 2005, and then decreased due to stricter emission standard and enhanced environmental management. (2) according to spatial distribution, the emission of particulates from concrete batch mainly concentrated in the urban area with more human activities, and the area between the fifth ring and the sixth ring contributed the most. (3) through scenarios analysis, for further reducing the emission from concrete batching in 2020, more stricter standard for green production as well as powerful supervision is needed.

[Situation and Characteristics of Air Pollutants Emission from Crematories in Beijing, China].

Hazardous Air Pollutants (HAPs) such as exhaust particulate matter (PM), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxide (NOx), mercury (Hg) and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-furans ( PCDD/Fs) are emitted by the process of cremation and the burning of oblation. Risks to health posed by emissions of hazardous air pollutants from crematories are emerging concerns. Through field investigation and data collection, we obtained the related activity levels and monitored the concentrations of air pollutants from typical cremators, so as to better understand the current pollutants emission levels for crematory. Using the emission factor method, we calculated the emission inventory of HAPs for crematory of Beijing in 2012 and quantified the range of uncertainty. Using atmospheric diffusion model ADMS, we evaluated the influence of crematories on the surrounding environment, and identified the characteristics of air pollution. The results showed that: for the cremators installed with flue gas purification system, the emission concentration of exhaust PM was rather low, and the CO emission concentration fluctuated greatly. However, relative high emission concentrations of PCDD/Fs were detected mainly due to insufficient combustion. Exhaust PM, CO, SO2, NOx, Hg and PCDD/Fs emitted by crematory of Beijing in 2012 were estimated at about 11. 5 tons, 41.25 tons, 2.34 tons, 7.65 tons, 13.76 kg and 0.88 g, respectively; According to the results of dispersion model simulation, the concentration contributions of exhaust PM, CO, SO2, NOx, Hg, PCDD/Fs from crematories were 0.05947 microg x m(-3), 0.2009 microg x m(-3) and 0.0126 microg x m(-3), 0.03667 microg x m(-3) and 0.06247 microg x m(-3), 0.004213 microg x m(-3), respectively.

[Correlation between acidic materials and acid deposition in Beijing during 1997-2011].

Based on the environment monitoring data and the ambient air quality data during the period of 1997-2011 from Beijing municipal environmental monitoring center, the correlations between primary pre-cursors of acid deposition, acidic materials and precipitation in Beijing area were analyzed in detail by taking economic development and energy mix into account. These results will be helpful for assessing the performance of environment quality improvement, as well as supplying scientific supporting information to make policies for national and local environment protection authorities. The main findings included as follows: there are significant correlations between the concentrations of NO2, NOx, and SO2 in the atmosphere, which indicated that both N and S in ambient air of Beijing came from fossil fuels combustion; acidic pollutants in the air are mainly discharged from local emission sources in Beijing, while there is no obvious correlation between S and N in wet deposition and concentrations of SO2, NO2 and NOx in the atmosphere, which demonstrated that concentrations of different ions in the acid deposition were influenced by both local sources as well as the inputs from other surrounding districts. Besides, the concentration of NO3- appeared to be correlative with the amount of motor vehicles, implying that the NOx from motor vehicles have contributed the increase of NO3- concentration of substantially.

[Inventories of atmospheric arsenic emissions from coal combustion in China, 2005].

Anthropogenic arsenic (As) emitted from coal combustion is one of key trace elements leading to negative air pollution and national economy loss. It is of great significance to estimate the atmospheric arsenic emission for proposing relevant laws or regulations and selecting proper pollution control technologies. The inventories of atmospheric arsenic emissions from coal combustion in China were evaluated by adopting the emission factor method based on fuel consumption. Arsenic emission sources were firstly classified into several categories by economic sectors, combustion types and pollution control technologies. Then, according to provincial coal consumption and averaged arsenic concentration in the feed fuel, the inventories of atmospheric arsenic emission from coal combustion in China in 2005 were established. Coal outputand consumption in China in 2005 were 2,119.8 and 2,099.8 Mt, respectively. The total emissions of arsenic released into the atmosphere in 2005 in China were estimated at about 1,564.4 t, and Shandong ranked the largest province with 144.4 t arsenic release, followed by Hunan (141.1 t), Hebei (108.5 t), Henan (77.7 t), and Jiangsu (77.0 t), which were mainly concentrated in the eastern and central provinces of China. The arsenic emissions were largely emitted by industry sector (818.8 t) and thermal power generation sector (303.4 t), contributing 52.3% and 19.4% of the totals, respectively. About 375.5 t arsenic was estimated to be released into the atmosphere in the form of gas phase in China in 2005, with a share of 24% of the totals. In general, arsenic pollution control from coal combustion should be highlighted for the power and industry sectors in the whole country. However, arsenic poisoning caused by residential coal burning should also be paid great attention in some areas such as Xinjiang, Gansu, Qinghai and Guishou.

[Development of mercury emission inventory from coal combustion in China].

Mercury emission inventory by province from coal combustion in China was developed by combining fuel consumption, mercury content in fuel and emission factors after combustion in this study. The study is intended to provide an understanding of mercury transformation, transportation and deposition in atmosphere, as well as propose measures to control mercury pollution in China. Mercury emission sources were classified into 65 categories by economic sectors, fuel types, boiler types and pollution control technologies. For two different data sets of mercury content in coal the total amounts of mercury released into atmosphere in 2000 in China were estimated at about 161.6 tons and 219.5 tons, respectively. The biggest three source sectors were industry, power plants, and residential use, contributing 46%, 35% and 14% of total mercury emissions, respectively. The shares of elemental mercury (Hg0), oxidized mercury (Hg2+ ) and particulate mercury (Hgp) were 16% , 61% and 23% , respectively. The spatial distribution of mercury emissions from coal combustion in China is not uniform. Henan, Shanxi, Hebei, Liaoning and Jiangsu contributed large amounts of mercury emissions, exceeding 10t x a(- 1).

[Particle trajectory model desulfurization spray tower used in numerical simulation of flue gas].

The commercial computational fluid dynamics (CFD) software FLUENT is used to predict the two-phase flow in a flue gas desulfurization (FGD) spray tower. The Euler-Lagrange method is used, in which the gas flow is described with standard k-epsilon turbulence model, and the motion of the liquid droplets is described with the particle trajectory model. The procedure of model definition, including force analysis of liquid particle, gas turbulent dispersion and the gas-liquid coupling method, is presented. The results show that the uniformity of axial gas velocity in the spray tower is satisfactory, and the hollow spray nozzle used in the tower can efficiently prevent short-circuiting of the flue gas. The concentration of liquid droplets in the central region is higher than near the wall, and this problem can be solved by optimizing the arrangement of the spray nozzles near the wall. Model predictions for particle trajectory are shown to be in good agreement with experimental results, and the particle trajectory model can predict the two-phase flow in the spray tower successfully.