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Li M.,Nanjing University | Wang T.,Nanjing University | Xie M.,Nanjing University | Zhuang B.,Nanjing University | And 4 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2017

Land surface parameters play an important role in the land-atmosphere coupling and thus are critical to the weather and dispersion of pollutants in the atmosphere. This work aims at improving the meteorology and air quality simulations for a high-ozone (O3) event in the Yangtze River Delta urban cluster of China, through incorporation of satellite-derived land surface parameters. Using Moderate Resolution Imaging Spectroradiometer (MODIS) input to specify the land cover type, green vegetation fraction, leaf area index, albedo, emissivity, and deep soil temperature provides a more realistic representation of surface characteristics. Preliminary evaluations reveal clearly improved meteorological simulation with MODIS input compared with that using default parameters, particularly for temperature (from −2.5 to −1.7°C for mean bias) and humidity (from 9.7% to 4.3% for mean bias). The improved meteorology propagates through the air quality system, which results in better estimates for surface NO2 (from 11.5 to 8.0 ppb for mean bias) and nocturnal O3 low-end concentration values (from −18.8 to −13.6 ppb for mean bias). Modifications of the urban land surface parameters are the main reason for model improvement. The deeper urban boundary layer and intense updraft induced by the urban heat island are favorable for pollutant dilution, thus contributing to lower NO2 and elevated nocturnal O3. Furthermore, the intensified sea-land breeze circulation may exacerbate O3 pollution at coastal cities through pollutant recirculation. Improvement of mesoscale meteorology and air quality simulations with satellite-derived land surface parameters will be useful for air pollution monitoring and forecasting in urban areas. ©2017. American Geophysical Union. All Rights Reserved.

Wang M.,Peking University | Shao M.,Peking University | Chen W.,Peking University | Yuan B.,Peking University | And 6 more authors.
Atmospheric Chemistry and Physics | Year: 2014

Understanding the sources of volatile organic compounds (VOCs) is essential for ground-level ozone and secondary organic aerosol (SOA) abatement measures. We made VOC measurements at 27 sites and online observations at an urban site in Beijing from July 2009 to January 2012. Based on these measurement data, we determined the spatial and temporal distribution of VOCs, estimated their annual emission strengths based on their emission ratios relative to carbon monoxide (CO), and quantified the relative contributions of various sources using the chemical mass balance (CMB) model. These results from ambient measurements were compared with existing emission inventories to evaluate the spatial distribution, species-specific emissions, and source structure of VOCs in Beijing. The measured VOC distributions revealed a hotspot in the southern suburban area of Beijing, whereas current emission inventories suggested that VOC emissions were concentrated in downtown areas. Compared with results derived from ambient measurements, the annual inventoried emissions of oxygenated VOC (OVOC) species and C2-C4 alkanes may be underestimated, while the emissions of styrene and 1,3-butadiene may be overestimated by current inventories. Source apportionment using the CMB model identified vehicular exhaust as the most important VOC source, with the relative contribution of 49%, in good agreement with the 40-51% estimated by emission inventories. The relative contribution of paint and solvent utilization obtained from the CMB model was 14%, significantly lower than the value of 32% reported by one existing inventory. Meanwhile, the relative contribution of liquefied petroleum gas (LPG) usage calculated using the CMB model was 6%, whereas LPG usage contribution was not reported by current emission inventories. These results suggested that VOC emission strengths in southern suburban area of Beijing, annual emissions of C2-C4 alkanes, OVOCs and some alkenes, and the contributions of solvent and paint utilization and LPG usage in current inventories all require significant revisions. © 2014 Author(s).

Xu X.-B.,CAS Research Center for Eco Environmental Sciences | Xu X.-B.,University of Chinese Academy of Sciences | Xu X.-B.,Beijing Municipal Environmental Monitoring Center | Shi Y.-J.,CAS Research Center for Eco Environmental Sciences | And 5 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2015

The toxic effects of the ubiquitous pollutant 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) on the earthworm Eisenia fetida were assessed by determining growth-inhibition and gene transcript levels of superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST), and transcriptional changes of the stress-response gene (heat-shock protein 70 [Hsp70]). Somatic growth and growth-inhibition rates in all BDE-47-treated groups were significantly different from those of the controls. The SOD gene transcripts were upregulated at all exposure doses and reached the maximum at the concentration of 400 mg/kg dry weight (dw) (3.84-fold, P < 0.01), which protected earthworms from oxidative stresses. However, downregulation of CAT and Hsp70 was present in all exposure doses and reached to the minimum at concentrations of 400 mg/kg dw (0.07-fold, P < 0.01 and 0.06-fold, P < 0.01, respectively). Upregulation of GST gene transcript level presented significant changes at concentrations of 10 (2.69-fold, P < 0.05) and 100 mg/kg dw (2.55-fold, P < 0.05). SOD maintained a dynamic balance to upregulate SOD expression to eliminate superoxide radicals in all dosage treatments, but downregulation of CAT decreased the ability to eliminate hydrogen peroxide. These changes could result in biochemical and physiological disturbances in earthworms. © 2015 Springer Science+Business Media New York

Wang Z.-S.,Beijing Municipal Environmental Monitoring Center | Pan L.-B.,Chinese Research Academy of Environmental Sciences
Huanjing Kexue/Environmental Science | Year: 2014

The emission inventory of air pollutants from the thermal power plants in the year of 2010 was set up. Based on the inventory, the air quality of the prediction scenarios by implementation of both 2003-version emission standard and the new emission standard were simulated using Models-3/CMAQ. The concentrations of NO2, SO2, and PM2.5, and the deposition of nitrogen and sulfur in the year of 2015 and 2020 were predicted to investigate the regional air quality improvement by the new emission standard. The results showed that the new emission standard could effectively improve the air quality in China. Compared with the implementation results of the 2003-version emission standard, by 2015 and 2020, the area with NO2 concentration higher than the emission standard would be reduced by 53.9% and 55.2%, the area with SO2 concentration higher than the emission standard would be reduced by 40.0%, the area with nitrogen deposition higher than 1.0 t·km-2 would be reduced by 75.4% and 77.9%, and the area with sulfur deposition higher than 1.6 t·km-2 would be reduced by 37.1% and 34.3%, respectively.

News Article | December 19, 2015
Site: www.reuters.com

A electric screen showing Shanghai Pudong financial area in a clear day is seen amid heavy smog in Zhengzhou, Henan province, China, December 9, 2015. A woman wearing a face mask stands on a bridge in front of the financial district of Pudong amid heavy smog in Shanghai, China, December 15, 2015. A man sets up a warning sign next to a vehicle after an accident amid heavy smog after the city issued its first ever 'red alert' for air pollution, in Beijing, China, December 8, 2015. A woman wearing a protective mask rides a bicycle as China warned residents across a large part of northern China to prepare for a wave of choking smog arriving over the weekend, in Beijing, China, December 18, 2015. A man and woman wearing protective masks ride a scooter as China warned residents across a large part of northern China to prepare for a wave of choking smog arriving over the weekend, in Beijing, China, December 18, 2015. A woman wearing a protective mask makes her way as China warned residents across a large part of northern China to prepare for a wave of choking smog arriving over the weekend, in Beijing, China, December 18, 2015. A man wears a protective mask makes her way as China warned residents across a large part of northern China to prepare for a wave of choking smog arriving over the weekend, in Beijing, China, December 18, 2015. Beijing's skyline and a power plant are seen from a high-rise building as China warned residents across a large part of northern China to prepare for a wave of choking smog arriving over the weekend, in Beijing, China, December 18, 2015. The Forbidden City is seen amid heavy smog under a red alert for air pollution, in Beijing, China, December 19, 2015. Buildings inside the Forbidden City are seen amid heavy smog under a red alert for air pollution, in Beijing, China, December 19, 2015. China had warned residents across a large part of its north on Friday to prepare for severe smog arriving over the weekend, the worst of which would hit Beijing, prompting the capital to issue its second ever "red alert". A red alert is triggered when the government believes air quality will surpass a level of 200 on an index that measures various pollutants for at least three days. The U.S. government deems a level of more than 200 to be "very unhealthy". On Saturday morning the Beijing Municipal Environmental Monitoring Center was showing an air quality reading of 104. "Today I have to work. And where is the smog?" posted one Beijing resident on Weibo, China's Twitter equivalent. "The smog is not so bad. Why do they have driving restrictions?" said another Weibo user in the capital. The Beijing city government issued its first "red alert" last week following criticism that previous bouts of smog had failed to trigger the highest warning level. In Beijing, a red alert means around half the vehicles are removed from the roads, with an odd-even licence plate system enforced. Schools are recommended to close and outdoor construction is banned. Wang Bin, head of the emergency response division of the Beijing Municipal Environmental Protection Bureau, said that measures were taken in advance to reduce the impact of the pollution and help people to prepare, the official Xinhua news agency reported. The red alert issued earlier this month prevented further deterioration of air quality, the report added, citing the authorities. Beijing's latest red alert is due to last until midnight on Tuesday. The National Meteorological Center said Thursday that parts of north China will see the worst smog so far this year, starting Saturday. But it only issued a yellow alert for the city and many surrounding areas on Saturday. Yellow is the second level on China's four-tier colour-coded pollution alert system. The weather observatory said that areas including southern Beijing, central Hebei, north Henan and west Shandong would be affected by heavy smog, which would start to dissipate from Wednesday. It advised the public to take protective measures and those who suffer from respiratory diseases were urged to stay indoors or to wear face masks if they need to go out.

Li L.,Beijing Municipal Environmental Monitoring Center | Liu Y.,Emory University
Atmospheric Environment | Year: 2011

Both the long-term and short-term variability of carbon monoxide (CO) pollution in Beijing metropolitan area, China are studied with 11 years of MOPITT observations and 10 years of ground measurements. The impact of the 2008 Beijing Olympic Games on regional air quality is also examined. MOPITT CO columns exhibit different temporal patterns from ground CO concentration measurements. MOPITT CO column in August has gradually increased from 2000 to 2007, even though ground level CO concentrations have significantly decreased due to continued local air pollution control effort. Both CO columns and ground CO concentrations were reduced due to strict albeit temporary emissions control measures from July to September 2008 to support the Beijing Olympic Games. However, the reduction of total CO columns (∼13%) was less pronounced than ground CO concentration (∼44%), indicating that local emission control effort was partially offset by the continuously deteriorating regional air quality. In addition, MOPITT CO mixing ratio profiles indicate a significant regional pattern at higher altitudes. CO total columns after 2008 show an overall increasing trend, in contrast to the decreasing trend observed in ground measurements. © 2011 Elsevier Ltd.

Li L.,Beijing Municipal Environmental Monitoring Center | Wang Y.,Minzu University of China
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2011

NO 2 mass concentration during 1999-2010 and vertical column density data during 2004-2010 in Beijing were studied using satellite monitoring data (OMI and GOME-2) and conventional observation data. The results showed that there was an increase of NO 2 mass concentration in Beijing from 1999 to 2007. Air cleaning measures taken during 2008 Beijing Olympic Games reduced NO 2 mass concentration and column density greatly, which again increased in 2009 but with a level lower than before 2008. This is possibly resulted from the source control efforts associated with the Olympics, economic downturn and the adjustment of industrial structure. In 2010, NO 2 mass concentration at Nongzhanguan station and Dingling station continued to increase, but at Gucheng station reduced to the minimum, thanks to the off production of smelting and hot-rolled steel in Shijingshan District. NO 2 columns were season-dependent. There were shorter chemical lifetimes and smaller NO 2 columns in summer than in winter in Beijing. At Waliguan where natural emissions dominated, NO 2 columns showed reversed phenomenon compared to Beijing. At Longfengshan both affected by anthropogenic and natural emissions, NO 2 columns had two peaks and two troughs. Diurnal variation of NO 2 was also obvious. GOME2 generally observed higher NO 2 amounts at 9:30 than OMI at 13:45 in Beijing, and there was reverse result at Waliguan. NO 2 daily change displayed characteristics at Longfengshan. NO 2 columns in Beijing had a good correlation with NO 2 mass concentration at Dingling Station.

Li L.-J.,Beijing Municipal Environmental Monitoring Center | Wang Y.,Central University of Costa Rica | Li J.-X.,Beijing Municipal Environmental Monitoring Center
Huanjing Kexue/Environmental Science | Year: 2011

Observational data in clean area provides important references for evaluating environmental impact both from natural and anthropogenic sources. Atmospheric particulate matter of different size were closely examined using dustfall data during 1980-2009, TSP data during 1991-2009 and PM10 data since 2000 at Dingling station (DL), which was located in the clean area of Beijing. It was shown that dustfall amount at DL was on decrease in the last 30 years, by reasons of anthropogenic emission control and ecological environment improvement; meanwhile there was a 5-6 years' cycle of variation in yearly dustfall amount partly caused by dust storms. Similarly TSP and PM10 concentrations changed greatly but had a decreasing trend since 2000. Furthermore, the ratios of Pb and BaP in TSP at DL, namely Pb/TSP and BaP/TSP, were analyzed for anthropogenic influence. It was proved that the ratios were increasing and there was stronger influence of regional pollutant transport from urban areas. Lastly, it was also found that the coarser atmospheric particles were, the stronger their seasonal fluctuations in mass were, which were mainly affected by local sources rather than regional, and vice verse.

Li H.,Beijing University of Civil Engineering and Architecture | Xu S.,Beijing University of Civil Engineering and Architecture | Huang Y.,Beijing Municipal Environmental Monitoring Center | Wei P.,Beijing University of Civil Engineering and Architecture
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2013

Based on the situations of combined sewer overflow (CSO) and consequent water quality deterioration of urban rivers in Beijing, three rain periods were chosen to study the characteristics and their potential pollution risks from different combined sewage systems. The statistics of rainfall in 2012 show that CSOs usually occur when the accumulated rainfall reaches to 10 mm. In the case of heavy rainstorm, the average concentration of the pollutants in overflow are higher than that of sewage drainage systems in the dry weather. The concentrations of typical pollutants in overflow are as follows: TN 5.11~16.36 mg·L-1, TP 4.34~10.52 mg·L-1, NH4 +-N 1.88~12.73 mg·L-1, COD 134~250 mg·L-1, and SS 120~155 mg·L-1. The contribution rates of the sediment pollution load to runoff outflow of TN, TP, COD, and SS are 20.9%~44.6%, 35.7%~47.3%, 46.2%~48.8%, and 35.7%~79.7%, respectively. In conclusion, it is important to control the depositon and erosion of sediments in combined sewage systems, which can maintain the normal operation of the drainage system and reduce the effluents' pollution loading in the rainy season.

Li H.,Beijing University of Civil Engineering and Architecture | Su H.,Beijing University of Civil Engineering and Architecture | Huang Y.,Beijing Municipal Environmental Monitoring Center
Advances in Science and Technology of Water Resources | Year: 2013

Pollutant from sediment in the combined drainage pipes has been a main source of the non-point source pollution for the receiving water. Hence, it is of great importance to study the action of the pollutant from the water-sediment interface. The composition of the water-sediment interface, the pollutant characteristics, and the simulation model of the interface of the water-sediment were reviewed. The water-sediment interface pollutant can be divided into the organic layer, the near-bed solid layer and the fluid sediment layer. Both the organic layer and the near-bead solid layer have relatively high organic content and high water content, while the fluid sediment layer has high concentration of volatile matter. It can be concluded that the erosion resistance of the water-sediment interface pollutant is weak, and the water content is the main factor which affects the shear stress of the water-sediment interface. Besides, the existing research on model simulation of the water-sediment interface mainly focuses on predicting the contribution of the near-bed solid on the initial flushing, the pollutant erosion of the organic layer, and the biological degradation of the near-bed solid layer. It is advised that the pollutant characteristics of the water-sediment interface needs further study, and the local water-sediment interface pollution contribution model needs to be established.

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