Yangjun Wang

The impact of the “Air Pollution Prevention and Control Action Plan” on PM2.5 concentrations in Jing-Jin-Ji region during 2012–2020

In order to cope with heavy haze pollution in China, the Air Pollution Prevention and Control Action Plan including phased goals of the fine particulate matter (PM2.5) was issued in 2013. In this study, Chinas emission inventories in the baseline 2012 and the future scenarios of 2017 and 2020 have been developed based on this Action Plan. Beijing-Tianjin-Hebei (Jing-Jin-Ji) region, one of the most polluted regions in China, was taken as a case to assess the impact of phased emission control measures on PM2.5 concentration reduction using WRF-CMAQ model system. With the implementation of the Action Plan, the emissions of sulfur dioxide (SO2), nitrogen oxides (NOX), PM2.5, non-methane volatile organic compound (NMVOC), and ammonia (NH3) in 2017 will decrease by36%, 31%, 30%,12%, and -10% from the 2012 levels in Jing-Jin-Ji, respectively. In 2020, the emissions of SO2, NOX, PM2.5, NMVOC, and NH3 will decrease by 40%, 44%, 40%, 22%, and -3% from the 2012 levels in Jing-Jin-Ji, respectively. Consequently, the ambient annual PM2.5 concentration under the scenarios of 2017 and 2020 will be 28.3% and 37.8% lower than those in 2012, respectively. The Action Plan provided an effective approach to alleviate PM2.5 pollution level in Jing-Jin-Ji region. However, emission control of NMVOC and NH3 should be paid more attention and be strengthened in future. Meanwhile, emission control of NOx, SO2, NH3 and NMVOC synergistically are highly needed in the future because multiple pollutants impact on PM2.5 and O3 concentrations nonlinearly.

The cytotoxic effects of synthetic 6-hydroxylated and 6-methoxylated polybrominated diphenyl ether 47 (BDE47).

Polybrominated diphenyl ethers (PBDE) have been widely applied as flame retardants in plastics, polyurethane foam, paints, and synthetic fabrics. The rising PBDE level in human tissues and environment has led to concern about the health impact of exposure to PBDE. The 2,2′,4,4′‐tetrabromodiphenyl ether (BDE47), the dominant PBDE congener found in the environment and human tissues, has been shown to be an endocrine disruptor. It has also been reported to cause liver and neurodevelopmental toxicity. BDE47 can be metabolized to 6‐OH‐BDE47 and 6‐MeO‐BDE47. So far little has been reported on the cytotoxicity of the metabolites. In the present study, the cytotoxicity of the two metabolites was investigated by exposing human hepatoma cell line HepG2 to different doses of 6‐OH‐BDE47 and 6‐MeO‐BDE47. The cell viability, cell cycle, apoptosis, DNA damage, micronucleus levels, and oxidative stress response were studied. The results indicated that both metabolites could markedly inhibit the proliferation of HepG2 cells with 6‐OH‐BDE47 showing a stronger effect, and significantly increase the micronucleus level and apoptosis rate in a dose‐dependant manner. Moreover, treatment with 6‐OH‐BDE47 (≥0.5 μM) resulted in a marked cell cycle block. The SCGE experiments revealed that both metabolites could cause DNA damage in a dose‐dependant manner. Analysis of the oxidative stress response showed that 6‐OH‐BDE47 treatment (≥2.0 μM) significantly increased intracellular ROS levels as indicated by GSH depletion and elevation of SOD level, whereas 6‐MeO‐BDE47 showed a weaker effect, suggesting that oxidative stress might play a role in the cytotoxic effects. We concluded that 6‐OH‐BDE47 or 6‐MeO‐BDE47 exposure was able to induce inhibition of cell viability, increase of apoptosis rate, cell cycle block, and DNA damages, which might involve the alterated oxidative stress response due to the elevated free radicals and impaired antioxidative system.

Ozone sensitivity analysis with the MM5-CMAQ modeling system for Shanghai.

Ozone has become one of the most important air pollution issues around the world. This article applied both O3/(NO(y)-NO(x)) and H2O2/HNO3 indicators to analyze the ozone sensitivity in urban and rural areas of Shanghai, with implementation of the MM5-CMAQ modeling system in July, 2007. The meteorological parameters were obtained by using the MM5 model. A regional emission inventory with spatial and temporal allocation based on the statistical data has been developed to provide input emission data to the MM5-CMAQ modeling system. Results showed that the ozone concentrations in Shanghai show clear regional differences. The ozone concentration in rural areas was much higher than that in the urban area. Two indicators showed that ozone was more sensitive to VOCs in urban areas, while it tended to be NO(x) sensitive in rural areas of Shanghai.

Local and regional contributions to fine particulate matter in Beijing during heavy haze episodes

In order to alleviate extreme haze pollution, understanding the origin of fine particulate matter (PM2.5) is crucial. In this study, we applied Particulate Matter Source Apportionment Technology (PSAT) in CAMx (Comprehensive Air Quality Model with Extensions) to quantify the impacts of emissions from different regions on PM2.5 concentrations in Beijing for haze episodes during January 6-23, 2013. Emission inventory was developed by Tsinghua University. Evolution of local and Regional contributions during local and non-local dominated haze episodes were discussed, separately. In the meanwhile, average contribution of other every city in Jing-Jin-Ji region to PM2.5 concentrations larger than 75μgm-3 in Beijing urban for each range of local contribution percent was analyzed. The results indicate that local emissions contributed 83.6% of PM2.5 at the urban center of Beijing, while regional transport from surrounding cities and parts of Shandong, Henan and Anhui provinces contributed 9.4%; long-range transport contributed the remaining 7.0% mainly from areas >750km away to the south of Beijing during this study period. Compared to non-local-dominated haze episodes, local-dominated heavy haze episodes in Beijing were easily resulted from unfavorable meteorological conditions with much lower PBL and wind velocity. Furthermore, local contribution is more easily to cause a sharp increase or sharp reduction of PM2.5 concentration in central Beijing, reflecting that Beijing local has much stronger potential to form extremely heavy haze episodes. The results indicated that controlling local emissions is a much more important measure to alleviate the extreme haze episodes in Beijing, like that on the night of Jan 12, 2013. Furthermore, emission control in Jing-Jin-Ji region, especially in Tangshan, Tianjin, Baoding, Langfang, Shijiazhuang and Cangzhou, as well as Henan and Shandong province, are important to reduce the PM2.5 concentrations and the occurrence of haze episodes in Beijing.

Degradation of halogenated benzenes in solution by electron beam irradiation method.

In this work, the dehalogenation and degradation of halogenated benzenes (chlorobenzenes, bromobenzene) under electron beam radiation were investigated. Several factors affected the degradation of halogenated benzenes by the electron beam radiation method, such as the dose of the electron beam, the initial pH value of the solutions and the kind of halogen. The rule of dehalogenation and degradation followed the order: bromobenzene > 1,2,4‐trichlorobenzene > p‐dichlorobenzene > chlorobenzene. The final products were found to be benzene and diphenyl. Dehalogenation of halogenated benzenes occurred in the presence of NaOH. Based on the results, a general reaction pathway for the degradation of halogenated benzenes is proposed.

The Particle-Phase Polycyclic Aromatic Hydrocarbons Exhausted from Diesel Engines Fuelled with Emulsified Diesel

Emulsified diesel is an alternative fuel for internal combustion engines. It can reduce the emitted pollutants. In this work, the effect of water-oil emulsions on the particulate matter (PM) and particle-phase polycyclic aromatic hydrocarbons (PAH) composition exhausted by diesel engine was studied. Three different water-oil blends emulsions with volume fractions of water ranging from 0% to 15% were investigated. The experimental results indicated that the mean reductions of PM mass concentration of E10, E15 are 19.31% and 17.99%, respectively, compared with E0.The mean increases of total PAH content of E10, E15 are 5.08% and 20.19%, respectively, compared with E0. The BaPeq (benzo [a] pyrene equivalent toxicity) of E0, E10 and E15 are 4.75, 6.53 and 8.86 respectively. Therefore, the blending fraction is a significant factor for the particle-phase total PAH content. Besides, researches on health effects of emulsified diesel are needed as well.

An Integrated Source Apportionment Methodology and Its Application over the Yangtze River Delta Region, China

An integrated source apportionment methodology is developed by amalgamating the receptor-oriented model (ROM) and source-oriented numerical simulations (SOM) together to eliminate the weaknesses of individual SA methods. This approach attempts to apportion and dissect the PM2.5 sources in the Yangtze River Delta region during winter. First, three ROM models (CMB, PMF, ME2) are applied and compared for the preliminary SA results, with information from PM2.5 sampling and lab analysis during the winter seasons. The detailed source category contribution of SOM to PM2.5 is further simulated using the WRF-CAMx model. The two pieces of information from both ROM and SOM are then stitched together to give a comprehensive information on the PM2.5 sources over the region. With the integrated approach, the detailed contributing sources of the ambient PM2.5 at different receptors including rural and urban, coastal and in-land, northern and southern receptors are analyzed. The results are compared with previous data and shows good agreement. This integrative approach is more comprehensive and is able to produce a more profound and detailed understanding between the sources and receptors, compared with single models.