Morphologies and elemental compositions of local biomass burning particles at urban and glacier sites in southeastern Tibetan Plateau: Results from an expedition in 2010

Many studies indicate that the atmospheric environment over the southern part of the Tibetan Plateau is influenced by aged biomass burning particles that are transported over long distances from South Asia. However, our knowledge of the particles emitted locally (within the plateau region) is poor. We collected aerosol particles at four urban sites and one remote glacier site during a scientific expedition to the southeastern Tibetan Plateau in spring 2010. Weather and backward trajectory analyses indicated that the particles we collected were more likely dominated by particles emitted within the plateau. The particles were examined using an electron microscope and identified according to their sizes, shapes and elemental compositions. At three urban sites where the anthropogenic particles were produced mainly by the burning of firewood, soot aggregates were in the majority and made up >40% of the particles by number. At Lhasa, the largest city on the Tibetan Plateau, tar balls and mineral particles were also frequently observed because of the use of coal and natural gas, in addition to biofuel. In contrast, at the glacier site, large numbers of chain-like soot aggregates (similar to 25% by number) were noted. The morphologies of these aggregates were similar to those of freshly emitted ones at the urban sites: moreover, physically or chemically processed ageing was rarely confirmed. These limited observations suggest that the biomass burning particles age slowly in the cold, dry plateau air. Anthropogenic particles emitted locally within the elevated plateau region may thus affect the environment within glaciated areas in Tibet differently than anthropogenic particles transported from South Asia. (C) 2018 Elsevier B.V. All rights reserved

Persistent sulfate formation from London Fog to Chinese haze

Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world

Air quality changes during the COVID-19 lockdown in an industrial city in North China: post-pandemic proposals for air quality improvement

To better understand the changes in air pollutants in an industrial city, Handan, North China, during the COVID-19 lockdown period, the air quality and meteorological conditions were recorded from 1 January to 3 March 2020 and the corresponding period in 2019. Compared to the corresponding period in 2019, the largest reduction in PM2.5–10, PM2.5, NO2 and CO occurred during the COVID-19 lockdown period. PM2.5–10 displayed the highest reduction (66.6%), followed by NO2 (58.4%) and PM2.5 (50.1%), while O3 increased by 13.9%. Similarly, compared with the pre-COVID-19 period, NO2 significantly decreased by 66.1% during the COVID-19 lockdown, followed by PM2.5–10 (45.9%) and PM2.5 (42.4%), while O3 increased significantly (126%). Among the different functional areas, PM2.5 and PM2.5–10 dropped the most in the commercial area during the COVID-19 lockdown. NO2 and SO2 decreased the most in the traffic and residential areas, respectively, while NO2 increased only in the township and SO2 increased the most in the industrial area. O3 increased in all functional areas to different extents. Potential source contribution function analysis indicated that not only the local air pollution lessened, but also long-distance or inter-regional transport contributed much less to heavy pollution during the lockdown period. These results indicate that the COVID-19 lockdown measures led to significantly reduced PM and NO2 but increased O3 , highlighting the importance of the synergetic control of PM2.5 and O3 , as well as regional joint prevention and the control of air pollution. Moreover, it is necessary to formulate air pollution control measures according to functional areas on a city scale

Evaluation of Policy Influence on Long-Term Indoor Air Quality in Emperor Qin’s Terra-Cotta Museum, China

Long-term measurement results of indoor air quality (IAQ) from 1989 to 2013 inside Pit No. 1, the largest display hall in Emperor Qin’s Terra-cotta Museum (QTM), were used to evaluate the effectiveness of measures for conservation environment improvement of antiques. By comparing the results of sampling campaigns in 2013 with databases in 1989, 2004–2005, 2006–2007 and 2011, seasonal and inter-annual variation in microclimate, aerosol chemical compositions and gaseous pollutant concentrations were incorporated in estimating the probable influences of the management of the surroundings, tourist flow, excavation and restoration tasks and renovation and/or new construction work on IAQ in the QTM. After the implementation of the environmental policies in 1990s, a significant decrease of indoor particulate matter mass for the QTM was quantified. The mass concentrations of summer TSP decreased from 540.0 μg∙m−3 in 1994 to 172.4 μg∙m−3 in 2004, as well as the winter TSP decreased from 380.0 μg∙m−3 in 1994 to 312.5 μg∙m−3 in 2005. The mass concentrations of summer PM2.5 decreased from 108.4 μg∙m−3 in 2004 to 65.7 μg∙m−3 in 2013, as well as the winter PM2.5 decreased from 242.3 μg∙m−3 in 2005 to 98.6 μg∙m−3 in 2013. However, it is noted that potential hazards due to the fluctuant microclimate conditions, gaseous and secondary particulate acidic species in indoor air should still be considered to ensure the long-term preservation and conservation of the museum’s artifact collection

Characterization of chemical components and cytotoxicity effects of indoor and outdoor fine particulate matter (PM2.5) in Xi'an, China

The chemical and cytotoxicity properties of fine particulate matter (PM2.5) at indoor and outdoor environment were characterized in Xi'an, China. The mass concentrations of PM2.5 in urban areas (93.29 similar to 96.13 mu g m(-3) for indoor and 124.37 similar to 154.52 mu g m(-3) for outdoor) were higher than suburban (68.40 mu g m(-3) for indoor and 96.18 mu g m(-3) for outdoor). The PM2.5 concentrations from outdoor environment due to fossil fuel combustion were higher than indoor environment. An indoor environment without central heating demonstrated higher organic carbon-to-elemental carbon (OC / EC) ratios and n-alkanes values that potentially attributed to residential coal combustion activities. The cell viability of human epithelial lung cells showed dose-dependent decrease, while nitric oxide (NO) and oxidative potential showed dose-dependent increase under exposure to PM2.5. The variations of bioreactivities could be possibly related to different chemical components from different sources. Moderate (0.4 0.6) correlations were observed between bioreactivities and elemental carbon (EC)/secondary aerosols (NO3-, SO42-, and NH4+)/heavy metals (Ni, Cu, and Pb). The findings suggest PM2.5 is associated with particle induced oxidative potential, which are further responsible for respiratory diseases under chronic exposure

Black carbon aerosol characterization in a remote area of qinghai–tibetan plateau, western china

AbstractThe concentrations, size distributions, and mixing states of refractory black carbon (rBC) aerosols were measured with a ground-based Single Particle Soot Photometer (SP2), and aerosol absorption was measured with an Aethalometer at Qinghai Lake (QHL), a rural area in the Northeastern Tibetan Plateau of China in October 2011. The area was not pristine, with an average rBC mass concentration of 0.36μgSTP-m−3 during the two-week campaign period. The rBC concentration peaked at night and reached the minimal in the afternoon. This diurnal cycle of concentration is negatively correlated with the mixed layer depth and ventilation. When air masses from the west of QHL were sampled in late afternoon to early evening, the average rBC concentration of 0.21μgSTP-m−3 was observed, representing the rBC level in a larger Tibetan Plateau region because of the highest mixed layer depth. A lognormal primary mode with mass median diameter (MMD) of ~175nm, and a small secondary lognormal mode with MMD of 470–500nm of rBC were observed. Relative reduction in the secondary mode during a snow event supports recent work that suggested size dependent removal of rBC by precipitation. About 50% of the observed rBC cores were identified as thickly coated by non-BC material. A comparison of the Aethalometer and SP2 measurements suggests that non-BC species significantly affect the Aethalometer measurements in this region. A scaling factor for the Aethalometer data at a wavelength of 880nm is therefore calculated based on the measurements, which may be used to correct other Aethalometer datasets collected in this region for a more accurate estimate of the rBC loading. The results present here significantly improve our understanding of the characteristics of rBC aerosol in the less studied Tibetan Plateau region and further highlight the size dependent removal of BC via precipitation

Comparison of cytotoxicity induced by PM2.5-bound polycyclic aromatic compounds from different environments in Xi'an, China

The chemical and bioreactivity properties of fine particulate matter (PM2.5) in indoor and outdoor environments in Xi'an were characterized, and the lung function of various participants was investigated. The concentrations of polycyclic aromatic hydrocarbons (PAHs), oxygenated polycyclic aromatic hydrocarbons, and nitrated polycyclic aromatic hydrocarbons were higher in outdoor environments than in indoor environments; in addition, urban areas had higher concentrations of these compounds than did suburban areas, with fossil fuel combustion likely being the primary source. Moreover, PM2.5-induced inflammation was higher in urban areas than in suburban areas. Indoor environments with coal combustion emissions showed relatively higher oxidative potential and inflammation. Moderate (phenanthrene) to strong (acenaphthylene and benzo(a)pyrene) correlations were observed between selected PAHs against interleukin 6 (IL-6), 8-hydroxy-desoxyguanosine (8-OHdG), and necrosis factor-alpha (TNF-alpha). Moreover, 9-fluorenone, 9,10-anthraquinone, and 5,12-naphthacenequinone exhibited higher oxidative stress and inflammation than did their parent PAHs. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were negatively correlated with 8-OHdG, and FEV1/FVC was negatively correlated with TNF-alpha and IL-6. These findings-which integrates PM2.5 with lung function and bioreactivity analyses-suggest that coal burning, especially indoors, could elevate the cytotoxicity of PM2.5 to the occupants and that chronic exposure may lead to a decline in lung function