Mang Lin

Characterization and sources of aerosol particles over the southeastern Tibetan Plateau during the Southeast Asia biomass-burning season

The Tibetan Plateau is one of the highest regions in theworld, exerting profound influence on the large-scale atmospheric circulation of Asia and the global climate. Here we report ambient concentrations of black carbon (BC), aerosol mass (PM2.5 and PM10) and associated carbonaceous species and water-soluble inorganic ions from a remote mountain site in the southeastern part of the Tibetan Plateau during spring, in order to characterize the major sources contributing to the ambient aerosol in the background atmosphere of Southeast Asia. Significant build-up of aerosol and BC concentrations was observed during a dry period, accompanied by the occurrence of fires and transport of pollution from the nearby regions of Southeast Asia and the northern part of the Indian Peninsula. The concentrations of BC, PM2.5 and PM10 mass reached maximum hourly values of 1470 ng m-3, 107 and 117 μg m-3, respectively. Organic carbon (OC), elemental carbon (EC) and sulfate were the predominant aerosol components. OC showed strong correlations with EC (R2 = 0.93 for PM2.5 and 0.74 for PM10) and non-sea-salt potassium, especially in fine aerosol (R2 = 0.95). In addition, the relative change rates of K+ against OC reached characteristically high values, highlighting the important contributions of biomass-burning smoke.

Contribution of fungal spores to particulate matter in a tropical rainforest

The polyols arabitol and mannitol, recently proposed as source tracers for fungal spores, were used in this study to estimate fungal contributions to atmospheric aerosol. Airborne particulate matter (PM2.5 and PM10) was collected at Jianfengling Mountain, a tropical rainforest on Hainan Island situated off the south China coast, during spring and analyzed for arabitol and mannitol by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The average concentrations of arabitol and mannitol exhibited high values with averages of 7.0 and 16.0xa0 ngxa0m − 3 respectively in PM2.5 and 44.0 and 71.0xa0ngxa0m − 3 in PM10. The two tracers correlated well with each other, especially in the coarse mode aerosol (PM2.5 − 10), indicating they were mainly associated with coarse aerosol particles and had common sources. Arabitol and mannitol in PM10 showed significant positive correlations with relative humidity, as well as positive correlations with average temperature, suggesting a wet emissions mechanism of biogenic aerosol in the form of fungal spores. We made estimations of the contribution of fungal spores to ambient PM mass and to organic carbon, based on the observed ambient concentrations of these two tracers. The relative contributions of fungal spores to the PM10 mass were estimated to range from 1.6 to 18.2%, with a rather high mean value of 7.9%, and the contribution of fungal spores to organic carbon in PM10 ranged from 4.64 to 26.1%, with a mean value of 12.1%, implying that biological processes are important sources of atmospheric aerosol.

Observation of elevated fungal tracers due to biomass burning in the Sichuan Basin at Chengdu City, China

Fungal material (i.e., spores and fragments) is an important component of atmospheric aerosols. In order to examine the variability of fungal abundance in fine particles (PM(2.5)) during a biomass burning season, an intensive measurement campaign was conducted in the Sichuan Basin at Chengdu, a megacity in southwest China, in spring 2009. The aerosol samples were analyzed for carbonaceous species, including molecular tracers for biomass burning and fungal material, and water soluble ions. The results were interpreted with the help of principle component analysis, fire count maps, and the WRF model. Elevated concentrations of arabitol and mannitol were found with average concentrations of 21.5±16.6 ng m(-3) and 43.9±19.3 ng m(-3), respectively, which were unexpectedly higher than those measured in fine particles in any other study reported previously. Even higher concentrations were observed in cases with simultaneous enhancements in the biomass burning tracers levoglucosan and K(+). In the case of influence by pollution plumes from biomass burning regions, the fungal tracer concentrations reached maximum values of 79.6 ng m(-3) and 121.8 ng m(-3), coinciding with peak levels of levoglucosan and K(+). Statistically significant correlations were found between the simultaneously observed fungal tracers (arabitol and mannitol) and biomass burning tracers (levoglucosan and K(+)), suggesting that these species were emitted by co-located sources, and hence the elevated fungal tracers were likely associated with biomass burning activities.

Change of air quality and its impact on atmospheric visibility in central-western Pearl River Delta.

Ambient air quality data, including atmospheric visibility, of Foshan city, a highly polluted city in the Pearl River Delta (PRD), and data obtained by the On-line Air Pollutant Exhaust Monitoring Network (OAPEMN), recently established by the National Emission Monitoring and Control Network for major industrial enterprises, were analyzed and are reported here for the first time, revealing the change in air pollution patterns and its impact on visibility degradation in the last decade. Reduced visibility of less than 8xa0km (after elimination of rainy and foggy periods) was found 22% of the time from 1998 to 2008, accompanied by elevated levels of pollutants, especially SO2 and PM10, in comparison with that of other developed cities. However, PM10 showed a steady decreasing trend (0.004xa0mgxa0mu2009−u20093xa0yearu2009−u20091) during 2001–2008, in contrast to the noticeable increase in ambient NO2 concentrations from ~0.020xa0mgxa0mu2009−u20093 before 2005 to above 0.050xa0mgxa0mu2009−u20093 afterward. Multiple regression analysis revealed that the percentage of reduced visibility strongly correlated with PM10 concentration, suggesting that visibility degradation was directly proportional to the loading of particles. Moreover, the fairly significant correlation between reduced visibility and NO2 concentration also implied that the impact of primary emissions of NO2 and enhanced secondary pollutants, formed via photochemical processes in the atmosphere, could not be ignored. The decreased PM10 levels were obviously the predominant factor for the improvement in visibility (5.0% per 0.01xa0mgxa0mu2009−u20093) and were likely due to the implementation of stricter air pollution control measures for industrial exhaust, which also resulted in reduced SO2 pollution levels in the recent 2xa0years. In particular, the OAPEMN records showed an overall enhanced SO2 removal by 64% in major industrial sectors. The continuous increase in road traffic and lack of efficient NOx control strategies in the PRD region, however, caused an increase in ambient NO2 concentrations.

Characterization of fine particulate black carbon in Guangzhou, a megacity of South China

Abstract Continuous measurement of fine particulate black carbon (BC) was conducted at an urban site of Guangzhou in South China from December 2007 to December 2008. The daily average BC concentrations ranged from 0.6 to 20.5xa0μg m −3 , with an average value of 4.7xa0μg m −3 , which was substantially higher than those observed in the urban areas of other developed countries. Diurnal fluctuations of BC were marked with two peaks, one in the morning rush hour (08:00xa0LT) and the other in the late evening hour (21:00–22:00xa0LT), while the lowest BC concentrations were observed in the afternoon. Ambient BC concentrations displayed significant seasonal and diurnal variations with higher values in winter and spring, followed by lower concentrations during autumn and summer. Wind speed, wind direction and temperature were important meteorological factors that affected BC concentrations. A clearly negative correlation ( r xa0=xa0−0.50, p r xa0>xa00.92, p 2 xa0g −1 ) in Guangzhou than the one recommended for typical Aethalometer measurements.

Implications of regional surface ozone increases on visibility degradation in southeast China

Abstract Long-term visibility (1968–2010) and air pollutant (1984–2010) data records in Hong Kong reveal that the occurrence of reduced visibility (RV, defined as the percentage of hours per month with visibility below 8 km in the absence of rain, fog, mist or relative humidity above 95%) in southeast China has increased significantly in the last four decades. The most pronounced rate of increase was observed after 1990 (nine times higher than that before 1990), when notable increases in surface ozone (O3) levels were simultaneously observed (1.06 µg m−3 per yr). The greatest increases in RV, and in O3, NO2 and SO2 concentrations are coincident in the autumn (1.47, 0.20 and 0.45 µg m−3 per yr respectively), when southeast China is strongly influenced by regional O3 formation and accumulation due to continental outflow of pollution from the east China coast under favourable meteorological conditions. Multiple regression revealed that the RV percentage correlated well (p<0.05) with NO2 and NO x in the 1980s, and with NO2, SO2 and O3 after the 1990s, suggesting that there have been changes in the predominant factors causing visibility degradation. In order to elucidate the reasons for these changes, the results were integrated with data from previous research. Possible impacts of elevated O3 on secondary particle formation and their effects on visibility degradation and aerosol radiative forcing in an oxidant-enhanced southeast China are highlighted. Other factors potentially leading to visibility degradation, such as ship emissions and biomass burning, are also discussed.

Emerging Air Pollution Issues in Changing Pearl River Delta of South China

1.1 Background The Pearl River Delta (PRD) in Southern China is one of the most developed regions in China. Administratively, the delta region is constituted by nine cities in Guangdong Province, and the Special Administrative Regions of Hong Kong and Macao. The PRD has developed into a manufacturing center of the world since the onset of China’s economic reform in the late 1970‘s. The important role of this region in China is highlighted by the high percentage contribution of gross domestic product (GDP) of Guangdong Province, which is mostly contributed by the PRD cities in the mainland, to that of the nation (>10%, National Bureau of Statistics China, 2009). As an important manufacturing center and city cluster, the PRD region is inevitably affected by severe air pollution problems, which attract much public attention. In response to this situation, a regional air quality monitoring network compositing of 16 automatic stations has been established by the joint effort from Guangdong and Hong Kong governments since late 2005 with an aim to examine the air pollution problem of the region (GDEPMC & HKEPD, 2005). A series of large scale research programs including comprehensive aircraft and groundbase measurements and modeling exercises have been conducted by the scientific community to better characterize and analyse the problem and to find scientific evidence for formulating possible control strategies (e.g. the Program of Regional Integrated Experiments on Air Quality over the PRD of China-PRIDE-PRD in 2004 and 2006) (Zhang et al., 2008; Hua et al., 2008).