171 results on '"Wanyun, Xu"'
Search Results
2. Low Hygroscopicity of Newly Formed Particles on the North China Plain and Its Implications for Nanoparticle Growth
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Juan Hong, Jiamin Ma, Nan Ma, Jingnan Shi, Wanyun Xu, Gen Zhang, Shaowen Zhu, Shaobin Zhang, Min Tang, Xihao Pan, Linhong Xie, Guo Li, Uwe Kuhn, Chao Yan, Ximeng Qi, Qiaozhi Zha, Wei Nie, Jiangchuan Tao, Yao He, Yaqing Zhou, Yele Sun, Hanbing Xu, Li Liu, Runlong Cai, Guangsheng Zhou, Ye Kuang, Bin Yuan, Qiaoqiao Wang, Tuukka Petäjä, Veli‐Matti Kerminen, Markku Kulmala, Yafang Cheng, and Hang Su
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hygroscopicity ,NPF ,nanoparticle growth ,Geophysics. Cosmic physics ,QC801-809 - Abstract
Abstract The growth of newly formed particles through new particle formation (NPF) contributes a significant fraction to the cloud condensation nuclei, yet the driving mechanisms remain unclear, especially for polluted environments. To investigate the potential species contributing for nanoparticle growth in environments with significant anthropogenic influences, we measured the hygroscopicity of newly formed particles at 20–40 nm at a rural observational site in the North China Plain during winter 2018. Our results demonstrate that these particles were not very hygroscopic, with the mean hygroscopicity parameter κ of 0.13 ± 0.09. Clear differences in the inferred κ of the growing material responsible for the growth were observed among different events, indicating that even at the same region, the compounds driving particle growth may not be identical. This may be synergistically influenced by the NPF precursors, oxidants and meteorological conditions, suggesting complex mechanisms might co‐exist behind nanoparticle growth in polluted environments.
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- 2024
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3. Community perspectives of flagship species: can conservation motivators mitigate human-wildlife conflict?
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Wanyun Xu, Lingxia Xu, Yuqi Cao, Jiaoyang Zheng, Yaling Wang, Kun Cheng, Chun-Hung Lee, Huxuan Dai, Sonamtso Mei, and Cheng Zong
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community-based conservation ,national parks ,conservancy motivations ,flagship species ,human-wildlife conflicts ,choice experiment ,Evolution ,QH359-425 ,Ecology ,QH540-549.5 - Abstract
Public perception of endangered species is crucial for successful management of community-based conservation and sustainability of national parks. By the method of choice experiment, our study evaluated conservation preferences and willingness to donate money for flagship and non-flagship species using a choice experiment with 409 residents living near the Lanstang river source of Sanjiangyuan National Park, China. We found that flagship species such as the Snow leopard (Pristine plateau) and White-lipped deer (Przewalskium albirostris) generated more conservation funds than non-flagship species. However, not all flagship species were accepted. Respondents disliked Tibetan brown bears (Ursus arctos pruinosus) due to direct human-wildlife conflicts such as bodily injury and property damage. Heterogeneity of preference was influenced by household income, religious beliefs, ethnicity, culture, and conservation awareness. Results can be used to establish a local community-participative framework by combining conservation motivations that alleviate human-wildlife conflict.
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- 2024
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4. Divergent Impacts of Biomass Burning and Fossil Fuel Combustion Aerosols on Fog‐Cloud Microphysics and Chemistry: Novel Insights From Advanced Aerosol‐Fog Sampling
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Ye Kuang, Weiqi Xu, Jiangchuan Tao, Biao Luo, Li Liu, Hanbin Xu, Wanyun Xu, Biao Xue, Miaomiao Zhai, Pengfei Liu, and Yele Sun
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fogs ,clouds ,activation ,biomass burning ,fossil fuel combustion ,Geophysics. Cosmic physics ,QC801-809 - Abstract
Abstract Activation of biomass burning aerosols (BBA) and fossil fuel combustion aerosols (FFA) in fogs and clouds significantly impact regional air quality through aqueous chemistry and climate by affecting cloud microphysics. However, we lack direct observations of how these aerosols behave in fogs and clouds. Using a newly developed aerosol‐cloud sampling system, we conducted observations during fog events and found that BBA, despite their high organic content, effectively contributed to super‐micron interstitial aerosols and fog droplets in low supersaturation fogs. In contrast, FFA, predominantly externally mixed organic, did not grow beyond the super‐micron size in fogs due to their near‐hydrophobic nature. Measurements conducted under supersaturations relevant for cloud formation revealed that portions of FFA could serve as cloud condensation nuclei, but only when supersaturation exceeded ∼0.14%. These findings have broad implications for future investigations into the influence of BBA and FFA on fog and cloud chemistry and their interactions with clouds.
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- 2024
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5. Editorial: Machine learning in studies of atmospheric environment and climate change
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Ying Chen, Wanyun Xu, Jianjun He, and Yu Wang
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atmospheric science ,climate change ,machine learning ,data science ,air pollution ,Environmental sciences ,GE1-350 - Published
- 2023
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6. The Impact of Agroecosystems on Nitrous Acid (HONO) Emissions during Spring and Autumn in the North China Plain
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Jianhui Zeng, Wanyun Xu, Ye Kuang, Weiqi Xu, Chang Liu, Gen Zhang, Huarong Zhao, Sanxue Ren, Guangsheng Zhou, and Xiaobin Xu
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HONO ,NH3 ,dew ,guttation ,soil emission ,atmospheric oxidation capacity ,Chemical technology ,TP1-1185 - Abstract
Solar radiation triggers atmospheric nitrous acid (HONO) photolysis, producing OH radicals, thereby accelerating photochemical reactions, leading to severe secondary pollution formation. Missing daytime sources were detected in the extensive HONO budget studies carried out in the past. In the rural North China Plain, some studies attributed those to soil emissions and more recent studies to dew evaporation. To investigate the contributions of these two processes to HONO temporal variations and unknown production rates in rural areas, HONO and related field observations obtained at the Gucheng Agricultural and Ecological Meteorological Station during spring and autumn were thoroughly analyzed. Morning peaks in HONO frequently occurred simultaneously with those of ammonia (NH3) and water vapor both during spring and autumn, which were mostly caused by dew and guttation water evaporation. In spring, the unknown HONO production rate revealed pronounced afternoon peaks exceeding those in the morning. In autumn, however, the afternoon peak was barely detectable compared to the morning peak. The unknown afternoon HONO production rates were attributed to soil emissions due to their good relationship to soil temperatures, while NH3 soil emissions were not as distinctive as dew emissions. Overall, the relative daytime contribution of dew emissions was higher during autumn, while soil emissions dominated during spring. Nevertheless, dew emission remained the most dominant contributor to morning time HONO emissions in both seasons, thus being responsible for the initiation of daytime OH radical formation and activation of photochemical reactions, while soil emissions further maintained HONO and associated OH radial formation rates at a high level, especially during spring. Future studies need to thoroughly investigate the influencing factors of dew and soil emissions and establish their relationship to HONO emission rates, form reasonable parameterizations for regional and global models, and improve current underestimations in modeled atmospheric oxidation capacity.
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- 2024
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7. Kinetic Limitations Affect Cloud Condensation Nuclei Activity Measurements Under Low Supersaturation
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Jiangchuan Tao, Ye Kuang, Biao Luo, Li Liu, Hanbin Xu, Nan Ma, Pengfei Liu, Biao Xue, Miaomiao Zhai, Wanyun Xu, Weiqi Xu, and Yele Sun
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cloud condensation nuclei ,kinetic limitation ,hygroscopicity ,hygroscopic growth ,activation ,Geophysics. Cosmic physics ,QC801-809 - Abstract
Abstract The commercial continuous‐flow streamwise thermal‐gradient cloud condensation nuclei (CCN) counter is widely used in aerosol CCN activity measurements which are critical for investigating aerosol‐cloud interactions. In CCN measurements, a critical threshold is needed for distinguishing interstitial aerosols and activated droplets, and a default threshold of 0.75 μm was set in CCN counter. Theoretically, interstitial aerosols could also grow larger than 0.75 μm in CCN counter at low supersaturations, thus theoretical thresholds derived from the Köhler theory were suggested. Here, we report that droplet growth in the CCN counter is kinetically limited and CCN‐active droplets does not reach their theoretical diameters under low supersaturations. Neglecting the kinetic growth limitation in CCN identification would count less CCN and underestimate the aerosol hygroscopicity parameter κ by up to 50% for supersaturations lower than 0.1%. We recommend that thresholds considering kinetic limitations should be used as new criteria for CCN identification under low supersaturations.
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- 2023
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8. Influence of meteorological factors on open biomass burning at a background site in Northeast China
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Yulong Wang, Linlin Liang, Wanyun Xu, Chang Liu, Hongbing Cheng, Yusi Liu, Gen Zhang, Xiaobin Xu, Dajiang Yu, Peng Wang, Qingli Song, Jiumeng Liu, and Yuan Cheng
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Environmental Engineering ,Environmental Chemistry ,General Medicine ,General Environmental Science - Published
- 2024
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9. Exploring HONO formation and its role in driving secondary pollutants formation during winter in the North China Plain
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Shaobin Zhang, Guo Li, Nan Ma, Yao He, Shaowen Zhu, Xihao Pan, Wenlin Dong, Yanyan Zhang, Qingwei Luo, Jeannine Ditas, Uwe Kuhn, Yuxuan Zhang, Bin Yuan, Zelong Wang, Peng Cheng, Juan Hong, Jiangchuan Tao, Wanyun Xu, Ye Kuang, Qiaoqiao Wang, Yele Sun, Guangsheng Zhou, Yafang Cheng, and Hang Su
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Environmental Engineering ,Environmental Chemistry ,General Medicine ,General Environmental Science - Published
- 2023
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10. Measurement Report: Wintertime new particle formation in the rural area of the North China Plain – influencing factors and possible formation mechanism
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Juan Hong, Min Tang, Qiaoqiao Wang, Nan Ma, Shaowen Zhu, Shaobin Zhang, Xihao Pan, Linhong Xie, Guo Li, Uwe Kuhn, Chao Yan, Jiangchuan Tao, Ye Kuang, Yao He, Wanyun Xu, Runlong Cai, Yaqing Zhou, Zhibin Wang, Guangsheng Zhou, Bin Yuan, Yafang Cheng, and Hang Su
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Atmospheric Science - Abstract
The high concentration of fine particles and gaseous pollutants makes polluted areas, such as the urban setting of North China Plain (NCP) of China, a different environment for new particle formation (NPF) compared to many clean regions. Such conditions also hold for other polluted environments in this region (for instance, the rural area of NCP), yet the underlying mechanisms for NPF remain less understood, owing to the limited observations of particles in the sub−3 nm range. Comprehensive measurements, particularly covering the particle number size distribution down to 1.3 nm, were conducted at a rural background site of Gucheng (GC) in the North China Plain (NCP) from 12 November to 24 December 2018. In total, five NPF events during the 39 effective days of measurements for the campaign were identified, with the mean particle nucleation rate (J1.3) and growth rate (GR1.3–2.4) being 22.0 cm−3 s−1 and 3.9 nm h−1, respectively. During these 5 d, NPF concurrently occurred at an urban site in Beijing. Sharing similar sources and transport paths of air masses arriving at our site to that of urban Beijing, we hypothesize that NPF events during these days in this region might be a regional phenomenon. The simultaneous occurrence of NPF in both places implies that H2SO4-amine nucleation, concluded for urban Beijing there, could probably be the dominating mechanism for NPF at our rural site. The higher concentration of sulfuric acid during many non-event days compared to that of event days indicates that the content of sulfuric acid may not necessarily lead to NPF events under current atmosphere. Only when the condensation sink or coagulation sink was significantly lowered, atmospheric NPF occurred, implying that condensation sinks (CSs) and coagulation sinks (CoagSs) are the dominating factors controlling the occurrence of NPF for the present rural environment of the NCP, which is quite similar to the feature seen in urban Beijing.
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- 2023
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11. Validating HONO as an Intermediate Tracer of the External Cycling of Reactive Nitrogen in the Background Atmosphere
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Jianshu Wang, Yingjie Zhang, Chong Zhang, Yaru Wang, Jiacheng Zhou, Lisa K. Whalley, Eloise J. Slater, Joanna E. Dyson, Wanyun Xu, Peng Cheng, Baobin Han, Lifan Wang, Xuena Yu, Youfeng Wang, Robert Woodward-Massey, Weili Lin, Weixiong Zhao, Limin Zeng, Zhiqiang Ma, Dwayne E. Heard, and Chunxiang Ye
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Environmental Chemistry ,General Chemistry - Published
- 2023
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12. Long-term changes of regional ozone in China: implications for human health and ecosystem impacts
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Xiaobin Xu, Weili Lin, Wanyun Xu, Junli Jin, Ying Wang, Gen Zhang, Xiaochun Zhang, Zhiqiang Ma, Yuanzhen Dong, Qianli Ma, Dajiang Yu, Zou Li, Dingding Wang, and Huarong Zhao
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surface ozone ,china ,exposure metrics ,human health ,vegetation ,long-term trends ,Environmental sciences ,GE1-350 - Abstract
The first Tropospheric Ozone Assessment Report (TOAR) provides information on present-day distributions and long-term trends of ozone metrics relevant for climate change, human health, and vegetation. However, only few results are available in TOAR for China due to limited long-term ozone observations. Here, we present an integrated analysis of long-term measurements of surface ozone from eight sites distributed in the North China Plain (NCP) and Yangtze River Delta (YRD), the relatively underdeveloped region Northeast China, and the remote regions in Northwest and Southwest China. Trends and present-day values for seven annual and five seasonal ozone metrics were calculated following the TOAR methodologies. We compare the seasonal and diurnal cycles of ozone concentrations as well as the present-day values of ozone among sites and discuss the long-term trends in the ozone metrics. Large and significant increases of ozone are detected at the background site in the NCP, moderate increases at the global baseline site in western China, significant decreases at the northwestern edge of China, and nearly no trend at other sites. Extremely high values of ozone occurred in the NCP and YRD, particularly in warmer seasons. The present-day levels of summer ozone metrics in the NCP are much higher than the thresholds set in TOAR for the highest value groups of ozone metrics. The summer ozone metrics at the Shangdianzi background site in the NCP indicate increases at rates of more than 2%/yr during 2004–2016. In contrast, ozone at the Lin’an background site in the YRD was constant over the period 2006–2016. Our results fill some knowledge gaps in spatiotemporal changes of ozone in China and may be of useful in the assessment of ozone impacts on human health and vegetation.
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- 2020
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13. Evaluating Communities’ Willingness to Participate in Ecosystem Conservation in Southeast Tibetan Nature Reserves, China
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Lingxia Xu, Wanyun Xu, Chao Jiang, Huxuan Dai, Qiaoqi Sun, Kun Cheng, Chun-Hung Lee, Cheng Zong, and Jianzhang Ma
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community participation ,ecosystem conservation ,economic evaluation ,types of nature reserves ,southeast Tibet ,Agriculture - Abstract
Southeast Tibet is significant in maintaining key ecological functions and providing irreplaceable ecosystem services but is also extremely vulnerable and susceptible to the impacts of human activities. Understanding the attitudes of local residents toward ecosystem conservation is considered essential for nature resource management. We therefore aimed to conduct an evaluation framework under hypothetical scenarios to measure communities’ willingness to participate in ecosystem conservation using the contingent valuation method (CVM). Second, this study determined the underlying factors that might affect local’s willingness to participate and then compared the willingness to pay (WTP) and willingness to work (WTW) for different types of nature reserves. We found that income, education, community attachment, and acceptance of a payment scheme are significant factors determining the average amount that residents are willing to pay for ecosystem conservation, while their income, acceptance of a work scheme, and education are significant factors influencing the average service time that residents are willing to devote to work. Our results revealed that community residents have considerable willingness to participate in ecosystem conservation, which points not only to the great value attached to the ecosystem service function of Southeast Tibet nature but also suggests that people’s willingness to participate is influenced by a conglomeration of socio-economic characteristics and their previous experience. The information herein can be used to implement conservation planning that involves community co-management and policymaking for sustainable development and will be beneficial to the dynamic conservation and adaptive management of Tibetan nature reserves.
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- 2022
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14. Hygroscopic Growth and Activation Changed Submicron Aerosol Composition and Properties in North China Plain.
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Weiqi Xu, Ye Kuang, Wanyun Xu, Zhiqiang Zhang, Biao Luo, Xiaoyi Zhang, Jiangchuang Tao, Hongqin Qiao, Li Liu, and Yele Sun
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Aerosol hygroscopic growth and activation under high relative humidity (RH) conditions significantly influence the physicochemical properties of submicron aerosols (PM
1 ). However, this process remains poorly characterized due to limited measurements. To address this gap, we deployed an advanced aerosol-fog sampling system that automatically switched between PM1 , PM2.5 , and TSP inlets at a rural site in the North China Plain in cold season. The results revealed that aerosol swelling due to water vapor uptake influenced aerosol sampling under high RH conditions by shifting the cut-off size of impactors. Under subsaturated high RH (> 90%), over 25% of aerosol mass with dry diameters below 1 µm resided in supermicron ranges, while in supersaturated foggy conditions, more than 70% submicron aerosol migrated to supermicron ranges. Hygroscopic growth and activation particularly affected highly hydrophilic inorganic salts shifting a significant mass submicron sulfate and nitrate particles to supermicron ranges, with 27 - 33% under 95% = RH = 99%, and 65.5% in supersaturated foggy conditions. Moreover, more than 10% of submicron biomass burning organic aerosols grew beyond 2.5 µm during fog events, while fossil fuel-related OA (FFOA) remained dominantly in submicron ranges, suggesting inefficient aqueous conversion of FFOA. The two SOA factors (OOA1 and OOA2) behaved differently under supersaturated conditions, with OOA2 exhibiting a higher activated fraction despite a lower oxygen-to-carbon ratio. A substantial increase in organic nitrate and organosulfur mass concentrations in activated droplets during fog events suggested aqueous conversions and formations of brown carbon with potential radiative impacts. Overall, our study highlights remarkably different aqueous processing of primary and secondary PM1 aerosol components under distinct ambient RH conditions. [ABSTRACT FROM AUTHOR]- Published
- 2024
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15. Insights into characteristics and formation mechanisms of secondary organic aerosols in the Guangzhou urban area
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Miaomiao Zhai, Ye Kuang, Li Liu, Yao He, Biao Luo, Wanyun Xu, Jiangchuan Tao, Yu Zou, Fei Li, Changqin Yin, Chunhui Li, Hanbing Xu, and Xuejiao Deng
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Atmospheric Science - Abstract
Emission controls have substantially brought down aerosol pollution in China; however, aerosol mass reductions have slowed down in recent years in the Pearl River Delta (PRD) region, where secondary organic aerosol (SOA) formation poses a major challenge for air quality improvement. In this study, we characterized the roles of SOA in haze formation in urban Guangzhou in the PRD using year-long aerosol mass spectrometer measurements for the first time and discussed possible pathways of SOA formations. On average, organic aerosols (OA) contribute dominantly (50 %) to nonrefractory submicron aerosol mass (NR-PM1). The average mass concentration of SOA (including by less- and more-oxidized OA, LOOA and MOOA) contributed most to NR-PM1, reaching about 1.7 times that of primary organic aerosols (POA, including hydrocarbon-like and cooking-related OA) and accounting for 32 % of NR-PM1, even more than sulfate (22 %) and nitrate (16 %). Seasonal variations of NR-PM1 revealed that haze-formation mechanisms differed much among distinct seasons. Sulfate mattered more than nitrate in fall, while nitrate was more important than sulfate in spring and winter, with SOA contributing significantly to haze formations in all the seasons. Daytime SOA formation was weak in winter under low oxidant levels and air relative humidity, whereas prominent daytime SOA formation was observed in fall, spring and summer almost on a daily basis, suggesting important roles of photochemistry in SOA formations. Further analysis showed that the coordination of gas-phase photochemistry and subsequent aqueous-phase reactions likely played significant roles in quick daytime SOA formations. Obvious nighttime SOA formations were also frequently observed in spring, fall and winter, and it was found that daytime and nighttime SOA formations together had resulted in the highest SOA concentrations in these seasons and contributed substantially to severe haze formations. Simultaneous increases in nitrate with SOA after sunset suggested the important roles of NO3 radical chemistry in nighttime SOA formations, and this was further confirmed by a continuous increase in the NO+ / NO2+ fragment ratio that related to measured particulate nitrate after sunset. The findings of this study have promoted our understanding of haze pollution characteristics of the PRD and laid down future directions for investigations of SOA-formation mechanisms in urban areas of southern China that share similar emission sources and meteorological conditions.
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- 2023
16. Strong light scattering of highly oxygenated organic aerosols impacts significantly on visibility degradation
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Li Liu, Ye Kuang, Miaomiao Zhai, Biao Xue, Yao He, Jun Tao, Biao Luo, Wanyun Xu, Jiangchuan Tao, Changqin Yin, Fei Li, Hanbing Xu, Tao Deng, Xuejiao Deng, Haobo Tan, and Min Shao
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Atmospheric Science - Abstract
Secondary organic aerosols (SOAs) account for a large fraction of atmospheric aerosol mass and play significant roles in visibility impairment by scattering solar radiation. However, comprehensive evaluations of SOA scattering abilities under ambient relative humidity (RH) conditions on the basis of field measurements are still lacking due to the difficulty of simultaneously direct quantifications of SOA scattering efficiency in dry state and SOA water uptake abilities. In this study, field measurements of aerosol chemical and physical properties were conducted in winter in Guangzhou (lasting about 3 months) using a humidified nephelometer system and aerosol chemical speciation monitor. A modified multilinear regression model was proposed to retrieve dry-state mass scattering efficiencies (MSEs, defined as scattering coefficient per unit aerosol mass) of aerosol components. The more oxidized oxygenated organic aerosol (MOOA) with an O/C ratio of 1.17 was identified as the most efficient light scattering aerosol component. On average, 34 % mass contribution of MOOA to total submicron organic aerosol mass contributed 51 % of dry-state organic aerosol scattering. The overall organic aerosol hygroscopicity parameter κOA was quantified directly through hygroscopicity closure, and hygroscopicity parameters of SOA components were further retrieved using a multilinear regression model by assuming hydrophobic properties of primary organic aerosols. The highest water uptake ability of MOOA among organic aerosol factors was revealed with κMOOA reaching 0.23, thus further enhancing the fractional contribution of MOOA in ambient organic aerosol scattering. In particular, the scattering abilities of MOOA were found to be even higher than those of ammonium nitrate under RH of %, which was identified as the most efficient inorganic scattering aerosol component, demonstrating that MOOA had the strongest scattering abilities in ambient air (average RH of 57 %) during winter in Guangzhou. During the observation period, secondary aerosols contributed dominantly to visibility degradation (∼70 %), with substantial contributions from MOOA (16 % on average), demonstrating significant impacts of MOOA on visibility degradation. The findings of this study demonstrate that more attention needs to be paid to SOA property changes in future visibility improvement investigations. Also, more comprehensive studies on MOOA physical properties and chemical formation are needed to better parameterize its radiative effects in models and implement targeted control strategies on MOOA precursors for visibility improvement.
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- 2022
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17. High frequency of new particle formation events driven by summer monsoon in the central Tibetan Plateau, China
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Lizi Tang, Min Hu, Dongjie Shang, Xin Fang, Jianjiong Mao, Wanyun Xu, Jiacheng Zhou, Weixiong Zhao, Yaru Wang, Chong Zhang, Yingjie Zhang, Jianlin Hu, Limin Zeng, Chunxiang Ye, Song Guo, and Zhijun Wu
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Atmospheric Science - Abstract
New particle formation (NPF) is an important source of cloud condensation nuclei (CCN), which affects Earth's radiative balance and global climate. The mechanism and CCN contribution of NPF at the high-altitude mountains, especially in the Tibetan Plateau (TP), was unclear due to lack of measurements. In this study, intensive measurements were conducted at the Nam Co station (4730 m a.s.l.) in the central TP during both the pre-monsoon and summer monsoon seasons. The frequencies of NPF events exhibited evident seasonal differences with 15 % in the pre-monsoon season and 80 % in the monsoon season. The comprehensive analysis of the measured condensation sink (CS), gaseous precursors and meteorological conditions, supplemented by the model simulations of SO2 and volatile organic compound (VOC), points to the organic involved nucleation as the dominant mechanism. Condensation sink and gaseous sulfuric acid could have no significant effect on the occurrence of NPF events. The frequent NPF events in the summer monsoon season may result from the higher frequency of southerly and southwesterly air masses, which brought the organic precursors to participate in the NPF process. It had increased the aerosol number concentrations and CCN at supersaturation of 1.2 % by more than 2 and 0.6 times compared with those in the pre-monsoon season, respectively. Considering that the smaller particles formed by NPF may further grow and reach CCN size during the following days due to the low-level coagulation sink, the amount of potential CCN in the monsoon season could be much larger than our local measurement results. Our results emphasized the importance of considering the seasonal effect of NPF when simulating the amounts of aerosols and CCN in the high-altitude atmosphere. Long-term investigations with a full set of instrumentation are required for deeper scientific understanding of NPF process and its role in the global budget in the TP.
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- 2023
18. O3 and PAN in southern Tibetan Plateau determined by distinct physical and chemical processes
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Wanyun Xu, Yuxuan Bian, Weili Lin, Yingjie Zhang, Yaru Wang, Gen Zhang, Chunxiang Ye, and Xiaobin Xu
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Tropospheric ozone (O3) and peroxyacetyl nitrate (PAN) are both photochemical pollutants harmful to the ecological environment and human health. In this study, measurements of O3 and PAN as well as their precursors were conducted from May to July 2019 at Nam Co station (NMC), a highly pristine high-altitude site in the southern Tibetan Plateau (TP), to investigate how distinct transport processes and photochemistry contributed to their variations. Results revealed that, despite highly similar diurnal variations with steep morning rises and flat daytime plateaus that were caused by boundary layer development and downmixing of free-tropospheric air, day-to-day variations in O3 and PAN were in fact controlled by distinct physicochemical processes. During the dry spring season, air masses rich in O3 were associated with high-altitude westerly air masses that entered the TP from the west or the south, which frequently carried high loadings of stratospheric O3 to NMC. During the summer monsoon season, a northward shift of the subtropical jet stream shifted the stratospheric downward entrainment pathway also to the north, leading to direct stratospheric O3 entrainment into the troposphere of the northern TP, which traveled southwards to NMC within low altitudes via northerly winds in front of ridges or closed high pressures over the TP. Westerly and southerly air masses, however, revealed low O3 levels due to the overall less stratospheric O3 within the troposphere of low-latitude regions. PAN, however, was only rich in westerly or southerly air masses that crossed over polluted regions such as northern India, Nepal or Bangladesh before entering the TP and arriving at NMC from the south during both spring and summer. Overall, the O3 level at NMC was mostly determined by stratosphere–troposphere exchange (STE), which explained 77 % and 88 % of the observed O3 concentration in spring and summer, respectively. However, only 0.1 % of the springtime day-to-day O3 variability could be explained by STE processes, while 22 % was explained during summertime. Positive net photochemical formation was estimated for both O3 and PAN based on observation-constrained box modeling. Near-surface photochemical formation was unable to account for the high O3 level observed at NMC, nor was it the determining factor for the day-to-day variability of O3. However, it was able to capture events with elevated PAN concentrations and explain its day-to-day variations. O3 and PAN formation were both highly sensitive to NOx levels, with PAN being also quite sensitive to volatile organic compound (VOC) concentrations. The rapid development of transportation networks and urbanization within the TP may lead to increased emissions and loadings in NOx and VOCs, resulting in strongly enhanced O3 and PAN formation in downwind pristine regions, which should be given greater attention in future studies.
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- 2023
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19. Supplementary material to 'O3 and PAN in southern Tibetan Plateau determined by distinct physical and chemical processes'
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Wanyun Xu, Yuxuan Bian, Weili Lin, Yingjie Zhang, Yaru Wang, Gen Zhang, Chunxiang Ye, and Xiaobin Xu
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- 2023
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20. Markedly different impacts of primary emissions and secondary aerosol formations on aerosol mixing states revealed by simultaneous measurements of CCNC, V/HTDMA and SP2
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Jiangchuan Tao, Biao Luo, Weiqi Xu, Gang Zhao, Hanbin Xu, Biao Xue, Miaomiao Zhai, Wanyun Xu, Huarong Zhao, Sanxue Ren, Guangsheng Zhou, Li Liu, Ye Kuang, and Yele Sun
- Abstract
The aerosol mixing state is a crucial physical-chemical property that affects their optical properties and cloud condensation nuclei (CCN) activity. Multiple techniques are commonly employed to determine aerosol mixing states for various applications, and comparisons between these techniques provide insights of the variations in aerosol chemical and physical properties. These techniques include size-resolved CCN activity measurements using a system with CCN counter (CCNC) coupled with a differential mobility analyzer (DMA), a Humidified/Volatility Tandem differential mobility analyzer (H/V-TDMA) which measures aerosol hygroscopicity/volatility distributions, and a single particle soot photometer (SP2) which directly quantifies black carbon (BC) mixing states. This study provides a first time intercomparisons of aerosol mixing state parameters obtained through simultaneous measurements of a DMA-CCNC, a H/VTDMA and a DMA-SP2. The impact of primary aerosols emissions and secondary aerosol formations on the aerosol mixing states and intercomparison results were analyzed. The results showed that differences in mixing state parameters measured by different techniques varied greatly under different conditions. The V-TDMA and DMA-SP2 measurements showed that the non-volatile population identified by the V-TDMA was mainly contributed by BC-containing aerosols. The HTDMA and DMA-SP2 measurements indicated that a substantial proportion of nearly hydrophobic aerosols were not contributed from BC-containing aerosols, but likely originated from fossil fuel combustion and biomass burning emissions. Synthesized comparison results between DMA-CCNC, HTDMA and DMA-SP2 measurements revealed that some of the nearly hydrophobic BC-free particles were CCN-inactive under supersaturated conditions, likely from fossil combustion emissions, while others were CCN-active under supersaturated conditions linked to biomass burning emissions. Fossil fuel combustion-emitted BC-containing aerosols tended to be more externally mixed with other aerosol compositions compared to those emitted from biomass burning activities. These results highlight significant disparities in the mixing states as well as physiochemical properties between aerosol originated from fossil fuel combustion and biomass burning. The formation of secondary nitrate and organic aerosols exerted significant impacts on variations in aerosol mixing states, generally enhancing aerosol hygroscopicity and volatility, while reducing differences in mixing state parameters derived from different techniques, resulting in a reduction in aerosol heterogeneity. The variations in BC-free particle number fractions showed that secondary aerosols tended to form more quickly on BC-free particles than on BC-containing particles. Further comparison of mixing state parameters revealed that the two resolved SOA factors in this study exhibited remarkably different physical properties, indicating that they were likely formed through different pathways. These findings suggest that intercomparisons among aerosol mixing states derived from different techniques can provide deeper insight into aerosol physical properties and how they are impacted by secondary aerosol formation, aiding the investigation of secondary aerosol formation pathways.
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- 2023
21. Supplementary material to 'Markedly different impacts of primary emissions and secondary aerosol formations on aerosol mixing states revealed by simultaneous measurements of CCNC, V/HTDMA and SP2'
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Jiangchuan Tao, Biao Luo, Weiqi Xu, Gang Zhao, Hanbin Xu, Biao Xue, Miaomiao Zhai, Wanyun Xu, Huarong Zhao, Sanxue Ren, Guangsheng Zhou, Li Liu, Ye Kuang, and Yele Sun
- Published
- 2023
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22. Wet Inorganic Nitrogen Deposition at the Daheitin Reservoir in North China: Temporal Variation, Sources, and Biomass Burning Influences
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Leixiang Wu, Xiaobo Liu, Kun Li, Wanyun Xu, Wei Huang, Panwei Zhang, Xiaohui Zhao, Chang Liu, Gen Zhang, and Linlin Liang
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precipitation ,nitrogen deposition ,potassium ,biomass burning ,air pollution ,Meteorology. Climatology ,QC851-999 - Abstract
Atmospheric nitrogen deposition is of great concern to both air quality and the ecosystem, particularly in northern China, which covers one-quarter of China’s cultivated land and has many heavily air polluted cities. To understand the characteristics of wet N deposition at rural sites in northern China, one-year wet deposition samples were collected in the Daheitin reservoir region. Due to the intense emissions of gaseous nitrogen compounds from heating activities during cold seasons and distinct dilution effects under different rainfall intensities and frequencies, the volume weighted mean concentrations of wet N deposition showed higher levels in dry seasons but lower levels in wet seasons. In contrast, the wet N deposition rates varied consistently with precipitation, i.e., high during the wet season and lower during the dry season. The annual wet deposition rate of total inorganic ions (the sum of NO3−–N and NH4+–N) at the rural site in North China from July 2019 to June 2020 was observed at 18.9 kg N ha−1 yr−1, still remained at a relatively high level. In addition, biomass burning activities are ubiquitous in China, especially in northern China; however, studies on its impact on wet N deposition are limited. Non-sea salt potassium ion (nss-K+) was employed as a molecular tracer to investigate the characteristics of biomass burning activities as well as their impact on the chemical properties of wet N deposition. Three precipitation events with high nss-K+ levels were captured during the harvest season (June to July). The variations in the patterns of nss-K+, deposited N species, and ratios of nss-K+ to nitrogen species as well as their relationships all indicated that biomass burning emissions contributed remarkably to NO3−–N but had a minor influence on NH4+–N.
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- 2020
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23. Supplementary material to 'Characterization of dust-related new particle formation events based on long-term measurement in North China Plain'
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Xiaojing Shen, Junying Sun, Yangmei Zhang, Chunhong Zhou, Ke Gui, Wanyun Xu, Quan Liu, Junting Zhong, Can Xia, Xinyao Hu, Sinan Zhang, Jialing Wang, Shuo Liu, Jiayuan Lu, and Xiaoye Zhang
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- 2023
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24. Characterization of dust-related new particle formation events based on long-term measurement in North China Plain
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Xiaojing Shen, Junying Sun, Yangmei Zhang, Chunhong Zhou, Ke Gui, Wanyun Xu, Quan Liu, Junting Zhong, Can Xia, Xinyao Hu, Sinan Zhang, Jialing Wang, Shuo Liu, Jiayuan Lu, and Xiaoye Zhang
- Abstract
Mineral dust is a major natural atmospheric aerosol that impacts the Earth's radiation balance. The significant scavenging process of fine particles by the strong wind during the dust provided a relatively pristine environment in which the occurrence of new particle formation (NPF) was less influenced by anthropogenic emissions. In this study, the NPF events occurring after the dust event (dust-related NPF) and other normal days (other NPF events) were classified based on the long-term particle number size distribution (PNSD) in urban Beijing in spring from 2017 to 2021. By comparing the two types of NPF events, we estimated that anthropogenic emissions could contribute approximately 50 % to the observed formation rate and 30 % to the growth rate. Anthropogenic emissions played a more important role when nucleated particles grew into the sizes above 10 nm. We also assessed a severe dust storm that originated from Mongolia and swept over northern China on March 15–16, 2021. The maximum hourly mean PM10 mass concentration reached 8000 μg m-3 during the dust storm. A downward trend of particle hygroscopicity was found during dust storms as compared with the polluted episode, resulting in an increasing trend of the critical diameter at different supersaturations (ss) where aerosols are activated as cloud condensation nuclei (CCN), although NPF occurred at approximately noon time when dust faded. The critical diameter was elevated by approximately 6 %–10 % (ss = 0.2 % and 0.7 %) during the dust storm, resulting in a lower CCN activation ratio, especially at low supersaturation. Modifications of the nucleation and growth process, as well as the particle-size distribution and hygroscopicity by the dust, provide valuable information that reveals the underlying climate and air quality effects of Asian mineral dust.
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- 2023
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25. Supplementary material to 'Insights into characteristics and formation mechanisms of secondary organic aerosols in Guangzhou urban area'
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Miaomiao Zhai, Ye Kuang, Li Liu, Yao He, Biao Luo, Wanyun Xu, Jiangchuan Tao, Yu Zou, Fei Li, Changqin Yin, Chunhui Li, Hanbing Xu, and Xuejiao Deng
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- 2022
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26. Supplementary material to 'Measurement Report: Wintertime new particle formation in the rural area of North China Plain: influencing factors and possible formation mechanism'
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Juan Hong, Min Tang, Qiaoqiao Wang, Nan Ma, Shaowen Zhu, Shaobin Zhang, Xihao Pan, Linhong Xie, Guo Li, Uwe Kuhn, Chao Yan, Jiangchuan Tao, Ye Kuang, Yao He, Wanyun Xu, Runlong Cai, Yaqing Zhou, Zhibin Wang, Guangsheng Zhou, Bin Yuan, Yafang Cheng, and Hang Su
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- 2022
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27. Measurement Report: Wintertime new particle formation in the rural area of North China Plain: influencing factors and possible formation mechanism
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Juan Hong, Min Tang, Qiaoqiao Wang, Nan Ma, Shaowen Zhu, Shaobin Zhang, Xihao Pan, Linhong Xie, Guo Li, Uwe Kuhn, Chao Yan, Jiangchuan Tao, Ye Kuang, Yao He, Wanyun Xu, Runlong Cai, Yaqing Zhou, Zhibin Wang, Guangsheng Zhou, Bin Yuan, Yafang Cheng, and Hang Su
- Abstract
The high concentration of fine particles as well as gaseous pollutants makes polluted areas, such as the urban setting of North China Plain (NCP) of China, a different environment for NPF compared to many clean regions. Such conditions also hold for other polluted environments in this region, for instance, the rural area of NCP, yet the underlying mechanisms for NPF remain less understood owing to the limited observations of particles in the sub-3nm range. Comprehensive measurements, particularly covering the particle number size distribution down to 1.34 nm, were conducted at a rural background site of Gucheng (GC) in the North China Plain (NCP) from 12 November to 24 December in 2018. Five NPF events during the 39 effective days of measurements for the campaign were identified, with the mean particle nucleation rate (J1.34) and growth rate (GR1.34-2.4) were 29.1 cm-3·s-1 and 0.54 nm·h-1, respectively. During these five days, NPF concurrently occurred in an urban site in Beijing, indicating that NPF events during these days in this region might be a regional phenomena. This implies that H2SO4-amine nucleation, concluded for urban Beijing there, could also be the dominating mechanism for NPF at our rural site. The condensation sink or coagulation sink for the survival of newly-formed and small clusters are the dominating factor controlling the occurrence of NPF under current atmosphere, whereas the contribution from the available H2SO4 cannot be neglected, either. This feature is slightly different from that of urban Beijing, where CS mainly determines whether NPF takes place or not.
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- 2022
28. Rapid hydrolysis of NO2 at high ionic strengths of deliquesced aerosol particles
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Masao Gen, Haotian Zheng, Yele Sun, Wanyun Xu, Nan Ma, Hang Su, Yafang Cheng, Shuxiao Wang, Jia Xing, Shuping Zhang, Likun Xue, Chaoyang Xue, Yujing Mu, Xiao Tian, Atsushi Matsuki, and Shaojie Song
- Abstract
Nitrogen dioxide (NO2) hydrolysis in deliquesced aerosol particles forms nitrous acid and nitrate and thus impacts air quality, climate, and nitrogen cycle. Traditionally, it is considered to proceed far too slowly in the atmosphere. However, the significance of this process is highly uncertain because kinetic studies have only been made in dilute aqueous solutions, and not under high ionic strength conditions of the aerosol particles. Here, we use laboratory experiments, air quality models, and field measurements to examine the effect of ionic strength on the reaction kinetics of NO2 hydrolysis. We find that high ionic strengths (I) enhance the reaction rate constants (kI) by more than two orders of magnitude compared to that at infinite dilution (kI=0), yielding log10(kI/kI=0) = 0.058I. A state-of-the-art air quality model shows that the enhanced NO2 hydrolysis reduces the negative bias in the simulated concentrations of nitrous acid by 27% on average when compared to field observations over the North China Plain. Rapid NO2 hydrolysis also enhances the levels of nitrous acid in other polluted regions such as North India and further promotes atmospheric oxidation capacity. This study highlights the need to evaluate various reaction kinetics of atmospheric aerosols with high ionic strengths.
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- 2022
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29. Identifying the O3 chemical regime inferred from the weekly pattern of atmospheric O3, CO, NOx, and PM10: Five-year observations at a center urban site in Shanghai, China
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Gen Zhang, Yifeng Sun, Wanyun Xu, Lingyan Wu, Yuseng Duan, Linlin Liang, and Yuan Li
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Environmental Engineering ,Environmental Chemistry ,Pollution ,Waste Management and Disposal - Published
- 2023
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30. Supplementary material to 'High frequency of new particle formation events driven by summer monsoon in the central Tibetan Plateau, China'
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Lizi Tang, Min Hu, Dongjie Shang, Xin Fang, Janjiong Mao, Wanyun Xu, Jiacheng Zhou, Weixiong Zhao, Yaru Wang, Chong Zhang, Yingjie Zhang, Jianlin Hu, Limin Zeng, Chunxiang Ye, Song Guo, and Zhijun Wu
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- 2022
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31. Unexpected high NOX emissions from lakes on Tibetan Plateau under rapid warming
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Hao Kong, Jintai Lin, Yuhang Zhang, Chunjin Li, Chenghao Xu, Lu Shen, Xuejun Liu, Kun Yang, Hang Su, and Wanyun Xu
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Nitrogen oxides affect health and climate. Their emissions from inland waters such as lakes are generally considered negligible and are absent in air quality and climate models. Here we find unexpected high emissions from remote lakes on the Tibetan Plateau based on satellite observations and emission inversion. The total emissions from 135 lakes larger than 50 km2 reach 1.9 Ton N h− 1, comparable to individual megacities worldwide. The emissions per unit area exceed those from crop fields. This is the first report of strong natural emissions from inland waters. The emissions are likely from anammox-dominated microbial processes under low-oxygen, low-organic, alkaline and saline conditions. They are associated with substantial warming and glacial and permafrost melting on the plateau, constituting a previously unknown feedback between climate, lake ecology and nitrogen emissions. Veröffentlicht in Nature Geoscience u.d.T.: High natural nitric oxide emissions from lakes on Tibetan Plateau under rapid warming
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- 2022
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32. Measurement report: Chemical characteristics of PM2.5 during typical biomass burning season at an agricultural site of the North China Plain
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Gen Zhang, Xuyan Liu, Linlin Liang, Wanyun Xu, Xiaoye Zhang, Chang Liu, Guenter Engling, Zhen-yu Du, Yuan Cheng, and Junying Sun
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Pollution ,Atmospheric Science ,Daytime ,010504 meteorology & atmospheric sciences ,Levoglucosan ,media_common.quotation_subject ,Agricultural site ,Potassium ,chemistry.chemical_element ,010501 environmental sciences ,Particulates ,Inorganic ions ,01 natural sciences ,chemistry.chemical_compound ,chemistry ,Environmental chemistry ,Environmental science ,Biomass burning ,0105 earth and related environmental sciences ,media_common - Abstract
Biomass burning activities are ubiquitous in China, especially in northern China, where there is a large rural population and winter heating custom. Biomass burning tracers (i.e., levoglucosan, mannosan and potassium (K + )), as well as other chemical components, were quantified at a rural site (Gucheng, GC) in northern China from 15 October to 30 November, during a transition heating season, when the field burning of agricultural residue was becoming intense. The measured daily average concentrations of levoglucosan, mannosan and K + in PM 2.5 (particulate matter with aerodynamic diameters less than 2.5 µ m) during this study were 0.79 ± 0.75, 0.03 ± 0.03 and 1.52 ± 0.62 µ g m −3 , respectively. Carbonaceous components and biomass burning tracers showed higher levels during nighttime than daytime, while secondary inorganic ions were enhanced during daytime. An episode with high levels of biomass burning tracers was encountered at the end of October 2016, with high levoglucosan at 4.37 µ g m −3 . Based on the comparison of chemical components during different biomass burning pollution periods, it appeared that biomass combustion can obviously elevate carbonaceous component levels, whereas there was essentially no effect on secondary inorganic aerosols in the ambient air. Moreover, the levoglucosan / mannosan ratios during different biomass burning pollution periods remained at high values (in the range of 18.3–24.9); however, the levoglucosan / K + ratio was significantly elevated during the intensive biomass burning pollution period (1.67) when air temperatures were decreasing, which was substantially higher than in other biomass burning periods (averaged at 0.47).
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- 2021
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33. Aerosol Promotes Peroxyacetyl Nitrate Formation During Winter in the North China Plain
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W. Zhang, Liyuan Yin, Gen Zhang, Shengrui Tong, Ying Wang, Zhiqiang Ma, Wanyun Xu, Ye Kuang, Weili Lin, and Xiaobin Xu
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Aerosols ,Peroxyacetyl nitrate ,Air Pollutants ,China ,Ozone ,Ozonolysis ,Photodissociation ,General Chemistry ,010501 environmental sciences ,Particulates ,01 natural sciences ,Trace gas ,Aerosol ,Box modeling ,chemistry.chemical_compound ,chemistry ,Environmental chemistry ,Environmental Chemistry ,Environmental science ,Peracetic Acid ,Environmental Monitoring ,0105 earth and related environmental sciences - Abstract
Peroxyacetyl nitrate (PAN) is an important indicator for photochemical pollution, formed similar to ozone in the photochemistry of certain volatile organic compounds (VOCs) in the presence of nitrogen oxides, and has displayed surprisingly high concentrations during wintertime that were better correlated to particulate rather than ozone concentrations, for which the reasons remained unknown. In this study, wintertime observations of PAN, VOCs, PM2.5, HONO, and various trace gases were investigated to find the relationship between aerosols and wintertime PAN formation. Wintertime photochemical pollution was affirmed by the high PAN concentrations (average: 1.2 ± 1.1 ppb, maximum: 7.1 ppb), despite low ozone concentrations. PAN concentrations were determined by its oxygenated VOC (OVOC) precursor concentrations and the NO/NO2 ratios and can be well parameterized based on the understanding of their chemical relationship. Data analysis and box modeling results suggest that PAN formation was mostly contributed by VOC aging processes involving OH oxidation or photolysis rather than ozonolysis pathways. Heterogeneous reactions on aerosols have supplied key photochemical oxidants such as HONO, which produced OH radicals upon photolysis, promoting OVOC formation and thereby enhancing PAN production, explaining the observed PM2.5-OVOC-PAN intercorrelation. In turn, parts of these OVOCs might participate in the formation of secondary organic aerosol, further aggravating haze pollution as a feedback. Low wintertime temperatures enable the long-range transport of PAN to downwind regions, and how that will impact their oxidation capacity and photochemical pollution requires further assessment in future studies.
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- 2021
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34. The chemical composition and mixing state of BC-containing particles and the implications on light absorption enhancement
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Jiaxing Sun, Yele Sun, Conghui Xie, Weiqi Xu, Chun Chen, Zhe Wang, Lei Li, Xubing Du, Fugui Huang, Yan Li, Zhijie Li, Xiaole Pan, Nan Ma, Wanyun Xu, Pingqing Fu, and Zifa Wang
- Subjects
Atmospheric Science - Abstract
The radiative forcing of black carbon (BC) depends strongly on its mixing state in different chemical environments. Here we analyzed the chemical composition and mixing state of BC-containing particles by using a single-particle aerosol mass spectrometer and investigated their impact on light absorption enhancement (Eabs) at an urban (Beijing) and a rural site (Gucheng) in the North China Plain. While the BC was dominantly mixed with organic carbon (OC), nitrate, and sulfate at both the urban and rural sites, the rural site showed a much higher fraction of BC coated with OC and nitrate (36 % vs. 15 %–20 %). Moreover, the BC mixing state evolved significantly as a function of relative humidity (RH), with largely increased coatings of OC–nitrate and nitrate at high RH levels. By linking with an organic aerosol (OA) composition, we found that the OC coated on BC comprised dominantly secondary OA in Beijing, while primary and secondary OA were similarly important in Gucheng. Furthermore, Eabs was highly dependent on secondary inorganic aerosol coated on BC at both sites, while the coated primary OC also resulted in an Eabs of ∼ 1.2 for relatively fresh BC particles at the rural site. A positive matrix factorization analysis was performed to quantify the impact of different mixing states on Eabs. Our results showed a small Eabs (1.06–1.11) for BC particles from fresh primary emissions, while the Eabs increased significantly above 1.3 when BC was aged rapidly with increased coatings of OC–nitrate or nitrate; it can reach above 1.4 as sulfate was involved in BC aging.
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- 2022
35. Characteristics of bacterial and fungal communities and their associations with sugar compounds in atmospheric aerosols at a rural site in North China.
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Mutong Niu, Shu Huang, Wei Hu, Yajie Wang, Wanyun Xu, Wan Wei, Qiang Zhang, Zihan Wang, Donghuan Zhang, Rui Jin, Libin Wu, Junjun Deng, Fangxia Shen, and Pingqing Fu
- Subjects
ATMOSPHERIC aerosols ,FUNGAL communities ,BACTERIAL communities ,MICROBIOLOGICAL aerosols ,TREHALOSE ,GAS chromatography/Mass spectrometry (GC-MS) ,SUGARS ,MICROBIAL metabolites - Abstract
Bioaerosols play significant roles in causing health and climate effects. Sugar compounds in air have been widely used to trace the source of bioaerosols. However, knowledge about the association of sugar molecules and the microbial community at taxonomic levels in atmospheric aerosols remains limited. Here, microbial community compositions and sugar molecules in total suspended particles collected from a typical rural site, Gucheng, in the North China Plain were investigated by gas chromatography-mass spectrometry and high-throughput gene sequencing, respectively. Results show that fungal community structure exhibited distinct diurnal variation with largely enhanced contribution of Basidiomycota at night, while bacterial community structure showed no obvious difference between daytime and night. SourceTracker analysis revealed that bacteria and fungi were mainly from plant leaves and unresolved sources (presumably human-related emission and/or longdistance transport), respectively. All the detected anhyrosugars and sugar alcohols, and trehalose showed diurnal variations with lower concentrations in the daytime and higher concentrations at night, which may be affected by enhanced fungal emissions at night, while primary sugars (except trehalose) showed an opposite trend. The Mantel test resulted that more sugar compounds exhibited significant associations with fungal community structure than bacterial community structure. Cooccurrence analysis revealed the strong associations between sugar compounds and a few saprophytic fungal genera with low relative abundances, e.g., Hannaella, Lectera, Peniophora, Hydnophlebia, Sporobolomyces and Cyphellophora. This study suggested that the entire fungal community likely greatly contributed to sugar compounds in rural aerosols, rather than specific fungal taxa, while the contribution of bacteria was limited. [ABSTRACT FROM AUTHOR]
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- 2023
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36. Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain (McFAN): integrated analysis and intensive winter campaign 2018
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Chunsheng Zhao, Yafang Cheng, Peng Cheng, Qiaoqiao Wang, Nan Lu, Yang Gao, Hang Su, Nan Ma, Bin Yuan, Aijun Ding, Qiang Zhang, Guangjie Zheng, Jiangchuan Tao, Juan Hong, Min Shao, Uwe Kuhn, Yuxuan Zhang, Ulrich Pöschl, Guo Li, Min Tang, Shaobin Zhang, Ye Kuang, Wanyun Xu, Zhibin Wang, Guangsheng Zhou, Pingqing Fu, Yele Sun, and Xihao Pan
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Pollution ,Haze ,010504 meteorology & atmospheric sciences ,Single-scattering albedo ,media_common.quotation_subject ,Humidity ,010501 environmental sciences ,Atmospheric sciences ,complex mixtures ,01 natural sciences ,Aerosol ,Fog ,chemistry.chemical_compound ,chemistry ,Relative humidity ,Physical and Theoretical Chemistry ,Sulfate ,0105 earth and related environmental sciences ,media_common - Abstract
Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. The Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain (McFAN) investigated the physicochemical mechanisms leading to haze formation with a focus on the contributions of multiphase processes in aerosols and fogs. We integrated observations on multiple platforms with regional and box model simulations to identify and characterize the key oxidation processes producing sulfate, nitrate and secondary organic aerosols. An outdoor twin-chamber system was deployed to conduct kinetic experiments under real atmospheric conditions in comparison to literature kinetic data from laboratory studies. The experiments were spanning multiple years since 2017 and an intensive field campaign was performed in the winter of 2018. The location of the site minimizes fast transition between clean and polluted air masses, and regimes representative for the North China Plain were observed at the measurement location in Gucheng near Beijing. The consecutive multi-year experiments document recent trends of PM2.5 pollution and corresponding changes of aerosol physical and chemical properties, enabling in-depth investigations of established and newly proposed chemical mechanisms of haze formation. This study is mainly focusing on the data obtained from the winter campaign 2018. To investigate multiphase chemistry, the results are presented and discussed by means of three characteristic cases: low humidity, high humidity and fog. We find a strong relative humidity dependence of aerosol chemical compositions, suggesting an important role of multiphase chemistry. Compared with the low humidity period, both PM1 and PM2.5 show higher mass fraction of secondary inorganic aerosols (SIA, mainly as nitrate, sulfate and ammonium) and secondary organic aerosols (SOA) during high humidity and fog episodes. The changes in aerosol composition further influence aerosol physical properties, e.g., with higher aerosol hygroscopicity parameter κ and single scattering albedo SSA under high humidity and fog cases. The campaign-averaged aerosol pH is 5.1 ± 0.9, of which the variation is mainly driven by the aerosol water content (AWC) concentrations. Overall, the McFAN experiment provides new evidence of the key role of multiphase reactions in regulating aerosol chemical composition and physical properties in polluted regions.
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- 2021
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37. Size-resolved characterization of organic aerosol in the North China Plain: new insights from high resolution spectral analysis
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Weiqi Xu, Chun Chen, Conghui Xie, Wanyun Xu, Yele Sun, Yanmei Qiu, Nga L. Ng, Zifa Wang, Nan Ma, Pingqing Fu, Xiaole Pan, Yunle Chen, and Jiang Zhu
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North china ,High resolution ,Radiative forcing ,Atmospheric sciences ,Pollution ,Analytical Chemistry ,Aerosol ,Chemistry (miscellaneous) ,Mass spectrum ,Environmental Chemistry ,Environmental science ,Cloud condensation nuclei ,Spectral analysis ,Particle size - Abstract
Organic aerosol (OA), a large fraction of fine particles, has a large impact on climate radiative forcing and human health, and the impact depends strongly on size distributions. Here we conducted size-resolved OA measurements using a high-resolution aerosol mass spectrometer at urban and rural sites in the North China Plain (NCP) in summer and winter. Our results showed substantially different size distributions of OA with the diameters peaking at ∼550 nm in summer, and 420 nm and 350 nm at urban and rural sites, respectively, during wintertime. Positive matrix factorization (PMF) of size-resolved high-resolution mass spectra of OA resolved various OA factors at urban and rural sites. In particular, we found that the mass spectra of the same type of secondary OA (SOA) from bulk PMF analysis can be largely different across different sizes. Biomass burning OA (BBOA) and fossil-fuel-related OA (FFOA) showed broad size distributions peaking at 350 nm in winter at the rural site, where primary OA (POA = BBOA + FFOA) dominated OA across different sizes. Comparatively, secondary OA (SOA) in the NCP peaked at ∼400–500 nm during wintertime, and ∼500–650 nm in summer. SOA played an enhanced role during more severely polluted days with peak diameters shifting to larger sizes, while the changes in POA size distributions were small. The size-resolved oxygen-to-carbon (O/C) ratios were also determined and linked with the hygroscopicity parameter of OA (κOA). The results showed that κOA increased substantially with particle size, with higher values in summer in Beijing (0.28 ± 0.021) than those during wintertime (0.17 ± 0.019 and 0.12 ± 0.018). The size-resolved κOA would benefit a better prediction of cloud condensation nuclei than bulk κOA in future studies.
- Published
- 2021
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38. Measurements of higher alkanes using NO+ chemical ionization in PTR-ToF-MS: important contributions of higher alkanes to secondary organic aerosols in China
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Shan Huang, Chaomin Wang, Hang Su, Wei Chen, Yafang Cheng, Wanyun Xu, Bin Yuan, Xuemei Wang, Yele Sun, Chenshuo Ye, Sihang Wang, Jipeng Qi, Xinming Wang, Weiwei Hu, Zelong Wang, Zhanyi Zhang, Nan Ma, Min Shao, Baolin Wang, Bin Jiang, Shenyang Zhang, Suxia Yang, Wei Song, Chen Wang, Wenjie Wang, and Caihong Wu
- Subjects
Atmospheric Science ,Chemical ionization ,Pearl river delta ,010504 meteorology & atmospheric sciences ,Chemistry ,Secondary organic aerosols ,North china ,010501 environmental sciences ,Mass spectrometry ,behavioral disciplines and activities ,01 natural sciences ,Atmosphere ,Ptr tof ms ,chemistry.chemical_compound ,Higher alkanes ,Environmental chemistry ,0105 earth and related environmental sciences - Abstract
Higher alkanes are a major class of intermediate-volatility organic compounds (IVOCs), which have been proposed to be important precursors of secondary organic aerosols (SOA) in the atmosphere. Accurate estimation of SOA from higher alkanes and their oxidation processes in the atmosphere is limited, partially due to the difficulty of their measurement. High-time-resolution (10 s) measurements of higher alkanes were performed using NO+ chemical ionization in proton transfer reaction time-of-flight mass spectrometry (NO+ PTR-ToF-MS) at an urban site in Guangzhou in the Pearl River Delta (PRD) and at a rural site in the North China Plain (NCP). High concentrations were observed in both environments, with significant diurnal variations. At both sites, SOA production from higher alkanes is estimated from their photochemical losses and SOA yields. Higher alkanes account for significant fractions of SOA formation at the two sites, with average contributions of 7.0 % ± 8.0 % in Guangzhou and 9.4 % ± 9.1 % in NCP, which are comparable to or even higher than both single-ring aromatics and naphthalenes. The significant contributions of higher alkanes to SOA formation suggests that they should be explicitly included in current models for SOA formation. Our work also highlights the importance of NO+ PTR-ToF-MS in measuring higher alkanes and quantifying their contributions to SOA formation.
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- 2020
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39. A Review on Laboratory Studies and Field Measurements of Atmospheric Organic Aerosol Hygroscopicity and Its Parameterization Based on Oxidation Levels
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Jiangchuan Tao, Min Shao, Wanyun Xu, Chunsheng Zhao, Ye Kuang, and Nan Ma
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Carbon chain ,Secondary organic aerosols ,Management, Monitoring, Policy and Law ,Laboratory results ,Atmospheric sciences ,complex mixtures ,Pollution ,Aerosol ,chemistry.chemical_compound ,chemistry ,Cloud droplet ,Cloud condensation nuclei ,Environmental science ,Waste Management and Disposal ,Water Science and Technology - Abstract
The study of organic aerosol hygroscopic growth and cloud droplet activation is crucial for accurately quantifying their climate and environmental impacts. However, the physical mechanisms behind organic aerosol hygroscopicity variations are not well understood. In this review, we summarized laboratory and field measurements of the organic aerosol hygroscopicity parameter κOA, discussed the physical understanding of why κOA was generally positively correlated with organic aerosol oxidation level, summarized proposed κOA parameterization schemes, and examined possible explanations for the marked differences among these parameterization schemes. Recent findings challenged the general cognition that cloud condensation nuclei (CCN) activity of secondary organic aerosol depended largely on solubility, showing it to be mainly controlled by molecular weight, yet the universality of this finding needs to be further examined. It was found that carbon chain length and functional groups had significant impacts on κOA and additional parameters other than O/C ratio need to be included when parameterizing κOA of multifunctional compounds, which is typically the case for ambient atmospheric aerosols. Additionally, laboratory results of secondary organic aerosol suggest that κOA might be highly RH-dependent under sub-saturated conditions, especially for biogenic secondary organic aerosols. This review summarized laboratory and field measurements of atmospheric organic aerosol hygroscopicity parameter κOA and its parameterization schemes. The results demonstrate that representing κOA with a single oxidation level parameter still bears large uncertainty, and physical mechanisms associated with hygroscopic growth and cloud activation processes of organic aerosol still remain unresolved and need further investigation.
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- 2020
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40. Efficient Conversion of NO to NO2 on SO2-Aged MgO under Atmospheric Conditions
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Tao Wang, Gen Zhang, Wanyun Xu, Zhe Wang, Qingxin Ma, Chang Liu, Jinzhu Ma, Xiaoye Zhang, Linlin Liang, Hong He, and Honghong Wang
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Troposphere ,Chemistry ,Environmental chemistry ,Oxidizing agent ,Environmental Chemistry ,General Chemistry ,010501 environmental sciences ,01 natural sciences ,0105 earth and related environmental sciences - Abstract
The NO–NO2 cycle determines the formation of O3 and hence plays a critical role in the oxidizing capacity of troposphere. Traditional view concluded that the heterogeneous oxidation of NO to NO2 wa...
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- 2020
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41. Current Challenges in Visibility Improvement in Southern China
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Ye Kuang, Pusheng Zhao, Fei Li, Biao Luo, Min Shao, Yaqiang Wang, Biao Xue, Li Liu, Wanyun Xu, Yuxuan Bian, Bin Yuan, and Shan Huang
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Pearl river delta ,010504 meteorology & atmospheric sciences ,Ecology ,Health, Toxicology and Mutagenesis ,Visibility (geometry) ,North china ,010501 environmental sciences ,Particulates ,01 natural sciences ,Pollution ,Current (stream) ,Southern china ,Environmental Chemistry ,Environmental science ,Physical geography ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
Stringent emission controls effectively brought down particulate mass concentrations by >30% in the North China Plain (NCP) and Pearl River Delta (PRD) regions. However, the low-visibility (
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- 2020
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42. Photochemical Aqueous-Phase Reactions Induce Rapid Daytime Formation of Oxygenated Organic Aerosol on the North China Plain
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Chaomin Wang, Min Shao, Gen Zhang, Yele Sun, Yao He, Sihang Wang, Hang Su, Caihong Wu, Nan Ma, Zhiqiang Ma, Jiangchuan Tao, Yafang Cheng, Ye Kuang, Shenyang Zhang, Wanyun Xu, and Bin Yuan
- Subjects
Aerosols ,Air Pollutants ,China ,Daytime ,Ultraviolet Rays ,Xylene ,Air pollution ,Hydrogen Peroxide ,General Chemistry ,010501 environmental sciences ,medicine.disease_cause ,Photochemistry ,01 natural sciences ,Ethylbenzene ,Aerosol ,chemistry.chemical_compound ,chemistry ,medicine ,Environmental Chemistry ,Relative humidity ,Hydrogen peroxide ,Scavenging ,0105 earth and related environmental sciences - Abstract
Secondary organic aerosol (SOA) constitutes a large fraction of organic aerosol worldwide, however, the formation mechanisms in polluted environments remain poorly understood. Here we observed fast daytime growth of oxygenated organic aerosol (OOA) (with formation rates up to 10 μg m-3 h-1) during low relative humidity (RH, daytime average 38 ± 19%), high RH (53 ± 19%), and fog periods (77 ± 13%, fog occurring during nighttime with RH reaching 100%). Evidence showed that photochemical aqueous-phase SOA (aqSOA) formation dominantly contributed to daytime OOA formation during the periods with nighttime fog, while both photochemical aqSOA and gas-phase SOA (gasSOA) formation were important during other periods with the former contributing more under high RH and the latter under low RH conditions, respectively. Compared to daytime photochemical aqSOA production, dark aqSOA formation was only observed during the fog period and contributed negligibly to the increase in OOA concentrations due to fog scavenging processes. The rapid daytime aging, as indicated by the rapid decrease in m,p-xylene/ethylbenzene ratios, promoted the daytime formation of precursors for aqSOA formation, e.g., carbonyls such as methylglyoxal. Photooxidants related to aqSOA formation such as OH radical and H2O2 also bear fast daytime growth features even under low solar radiative conditions. The simultaneous increases in ultraviolet radiation, photooxidant, and aqSOA precursor levels worked together to promote the daytime photochemical aqSOA formation. We also found that biomass burning emissions can promote photochemical aqSOA formation by adding to the levels of aqueous-phase photooxidants and aqSOA precursors. Therefore, future mitigation of air pollution in a polluted environment would benefit from stricter control on biomass burning especially under high RH conditions.
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- 2020
- Full Text
- View/download PDF
43. Supplementary material to 'Strong light scattering of highly oxygenated organic aerosols impacts significantly on visibility degradation'
- Author
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Li Liu, Ye Kuang, Miaomiao Zhai, Biao Xue, Yao He, Jun Tao, Biao Luo, Wanyun Xu, Jiangchuan Tao, Changqin Yin, Fei Li, Hanbing Xu, Tao Deng, Xuejiao Deng, Haobo Tan, and Min Shao
- Published
- 2022
- Full Text
- View/download PDF
44. Measurement report: On the difference in aerosol hygroscopicity between high and low relative humidity conditions in the North China Plain
- Author
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Jingnan Shi, Juan Hong, Nan Ma, Qingwei Luo, Yao He, Hanbing Xu, Haobo Tan, Qiaoqiao Wang, Jiangchuan Tao, Yaqing Zhou, Shuang Han, Long Peng, Linhong Xie, Guangsheng Zhou, Wanyun Xu, Yele Sun, Yafang Cheng, and Hang Su
- Subjects
Atmospheric Science - Abstract
Atmospheric processes, including both primary emissions and secondary formation, may exert complex effects on aerosol hygroscopicity, which is of significant importance in understanding and quantifying the effect of aerosols on climate and human health. In order to explore the influence of local emissions and secondary formation processes on aerosol hygroscopicity, we investigated the hygroscopic properties of submicron aerosol particles at a rural site in the North China Plain (NCP) in winter 2018. This was conducted by simultaneous measurements of aerosol hygroscopicity and chemical composition, using a custom-built hygroscopic tandem differential mobility analyzer (HTDMA) and a capture-vaporizer time-of-flight aerosol chemical speciation monitor (CV-ToF-ACSM). The hygroscopicity results showed that the particles during the entire campaign were mainly externally mixed, with a more hygroscopic (MH) mode and a less hygroscopic (LH) mode. The mean hygroscopicity parameter (κmean) values derived from hygroscopicity measurements for particles at 60, 100, 150, and 200 nm were 0.16, 0.18, 0.16, and 0.15, respectively. During this study, we classified two distinct episodes with different relative humidity (RH) and temperature (T) conditions, indicative of different primary emissions and secondary formation processes. It was observed that aerosols at all measured sizes were more hygroscopic under the high-RH (HRH) episode than those under the low-RH (LRH) episode. During the LRH, κ decreased with increasing particle size, which may be explained by the enhanced domestic heating at low temperature, causing large emissions of non-hygroscopic or less hygroscopic primary aerosols. This is particularly obvious for 200 nm particles, with a dominant number fraction (>50 %) of LH mode particles. Using O:C-dependent hygroscopic parameters of secondary organic compounds (κSOA), closure analysis between the HTDMA-measured κ and the ACSM-derived κ was carried out. The results showed that κSOA under the LRH episode was less sensitive to the changes in organic oxidation level, while κSOA under HRH had a relatively stronger dependency on the organic O:C ratio. This feature suggests that the different sources and aerosol evolution processes, partly resulting from the variation in atmospheric RH and T conditions, may lead to significant changes in aerosol chemical composition, which will further influence their corresponding physical properties.
- Published
- 2022
45. Primary Emissions and Secondary Aerosol Processing During Wintertime in Rural Area of North China Plain
- Author
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Chun Chen, Yanmei Qiu, Weiqi Xu, Yao He, Zhijie Li, Jiaxing Sun, Nan Ma, Wanyun Xu, Xiaole Pan, Pingqing Fu, Zifa Wang, and Yele Sun
- Subjects
Atmospheric Science ,Geophysics ,Space and Planetary Science ,Earth and Planetary Sciences (miscellaneous) - Published
- 2022
- Full Text
- View/download PDF
46. The importance of hydroxymethanesulfonate (HMS) in winter haze episodes in North China Plain
- Author
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Chun Chen, Zhiqiang Zhang, Lianfang Wei, Yanmei Qiu, Weiqi Xu, Shaojie Song, Jiaxing Sun, Zhijie Li, Yunle Chen, Nan Ma, Wanyun Xu, Xiaole Pan, Pingqing Fu, and Yele Sun
- Subjects
Aerosols ,Air Pollutants ,China ,Sulfates ,Water ,Dust ,Particulate Matter ,Biochemistry ,Sulfur ,General Environmental Science ,Environmental Monitoring - Abstract
Hydroxymethanesulfonate (HMS), a key marker species of aqueous-phase processing, plays a significant role in sulfur budget in atmosphere. Here we have a comprehensive characterization of HMS at urban and rural sites in North China Plain (NCP) by using the real-time measurements from a high-resolution aerosol mass spectrometer (AMS) and a single-particle AMS together with offline filter analysis. Our results showed much higher winter concentration of HMS at the rural site (average±1σ: 2.58 ± 2.56 μg m
- Published
- 2022
47. First long-term surface ozone variations at an agricultural site in the North China Plain: Evolution under changing meteorology and emissions
- Author
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Xiaoyi, Zhang, Wanyun, Xu, Gen, Zhang, Weili, Lin, Huarong, Zhao, Sanxue, Ren, Guangsheng, Zhou, Jianmin, Chen, and Xiaobin, Xu
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Environmental Engineering ,Environmental Chemistry ,Pollution ,Waste Management and Disposal - Abstract
Significant upward trends in surface ozone (O
- Published
- 2023
- Full Text
- View/download PDF
48. Measurement report: On the difference of aerosol hygroscopicity between high and low RH conditions in the North China Plain
- Author
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Jingnan Shi, Juan Hong, Nan Ma, Qingwei Luo, Yao He, Hanbing Xu, Haobo Tan, Qiaoqiao Wang, Jiangchuan Tao, Yaqing Zhou, Shuang Han, Long Peng, Linhong Xie, Guangsheng Zhou, Wanyun Xu, Yele Sun, Yafang Cheng, and Hang Su
- Abstract
Atmospheric processes, including both primary emissions and secondary formation, may exert complex effects on aerosol hygroscopicity, which is of significant importance in understanding and quantifying the effect of aerosols on climate and human health. In order to explore the influence of local emissions and secondary formation processes on aerosol hygroscopicity, we investigated the hygroscopic properties of submicron aerosol particles at a rural site in the North China Plain (NCP) in winter 2018. This was conducted by simultaneous measurements of aerosol hygroscopicity and chemical composition, using a self-assembled hygroscopic tandem differential mobility analyzer (HTDMA) and a capture-vaporizer time-of-flight aerosol chemical speciation monitor (CV-ToF-ACSM). The hygroscopicity results showed that the particles during the entire campaign were mainly externally mixed, with a more hygroscopic (MH) mode and a less hygroscopic (LH) particles mode. The mean hygroscopicity parameter values (κmean) derived from hygroscopicity measurements for particles at 60, 100, 150, and 200 nm were 0.16, 0.18, 0.16, and 0.15, respectively. During this study, we classified two distinct episodes with different RH/T conditions, indicative of different primary emissions and secondary formation processes. It was observed that aerosols at all measured sizes were more hygroscopic under the high RH (HRH) episode than those under the low RH (LRH) episode. During the LRH, κ decreased with increasing particle size, which may be explained by the enhanced domestic heating at low temperature, causing large emissions of non- or less-hygroscopic primary aerosols. This is particularly obvious for 200 nm particles, with a dominant number fraction (> 50 %) of LH mode particles. Using O : C-dependent hygroscopic parameters of secondary organic compounds (κSOA), closure analysis between the HTDMA_measured κ and the ACSM_derived κ was carried out. The results showed that κSOA under the LRH episode was less sensitive to the changes in organic oxidation level, while κSOA under the HRH had a relatively stronger dependency on the organic O : C. This feature suggests that the different sources and aerosol evolution processes, partly resulting from the variation in atmospheric RH/T conditions, may lead to significant changes in aerosol chemical composition, which will further influence their corresponding physical properties.
- Published
- 2022
- Full Text
- View/download PDF
49. Discrepancies in ozone levels and temporal variations between urban and rural North China Plain
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Xiaoyi Zhang, Wanyun Xu, Gen Zhang, Weili Lin, Huarong Zhao, Sanxue Ren, Guangsheng Zhou, Jianmin Chen, and Xiaobin Xu
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Atmospheric Science ,Environmental Engineering ,Ecology ,Geology ,Geotechnical Engineering and Engineering Geology ,Oceanography - Abstract
Effective emission reductions of some primary pollutants have brought down aerosol loadings but led to increasing relative importance of secondary pollutants, as was indicated by the rising O3 levels during warm seasons within urban and suburban areas of China, which has received much attention in recent years, especially in the North China Plain (NCP). This has raised serious concerns on its agricultural impacts, which were mainly evaluated based upon O3 model simulations or urban/suburban measurements due to a lack in long-term rural observations. In this study, we present highly valuable continuous O3 observations at a rural NCP site during 2013–2019. Compared to nearby urban/suburban sites, which experienced increased O3 levels, rural observations exhibited decreasing O3 mole fractions. While O3 mole fractions and AOT40 widely increased at urban/suburban NCP sites from 2013 to 2019, O3 observations in the rural NCP site (GC) revealed decreases, especially during summer and autumn with greater rates for AOT40. A reassessment of O3 agricultural impacts in the NCP region was performed using rural observations, resulting in wheat, maize and soybean averaged relative yield losses of 37 ± 14, 8 ± 4 and 30 ± 13% yr–1, respectively. O3 impacts on crop yields and resulting economic losses did not increase as was suggested by previous estimations based on urban/suburban O3 data. Our analyses indicated high overestimations (i.e., average relative differences in estimated crop production loss reaching 53%, 112% and 75%, respectively, for wheat, maize, and soybean). Despite alleviated O3 agricultural impacts, the total economic cost loss in Hebei province still took up 0.89% of the gross domestic production (3.47 × 1012 USD) in Hebei province. Since the China National Environmental Monitoring Center mainly aims at monitoring O3 levels in populated areas, observation sites representative of agricultural regions are lacking across China. The current study highlights the urgent necessity for the establishment of rural O3 observation networks and encourages extensive field experiments on exposure–response relationships of different crops varieties to O3 for more accurate agricultural impact evaluations. Additionally, explorations into the underlying mechanisms behind the reversed O3 temporal variation between rural and urban areas should be conducted for future development of pollution control strategies.
- Published
- 2022
- Full Text
- View/download PDF
50. Chemical composition and mixing state of BC-containing particles and the implications on light absorption enhancement
- Author
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Zhe Wang, Weiqi Xu, Conghui Xie, Chun Chen, Yan Li, Xubing Du, Wanyun Xu, Fugui Huang, Lei Li, Zhijie Li, Nan Ma, Pingqing Fu, Zifa Wang, Yele Sun, Jiaxing Sun, and Xiaole Pan
- Subjects
Total organic carbon ,chemistry.chemical_compound ,Nitrate ,chemistry ,Environmental chemistry ,Particle ,Relative humidity ,Carbon black ,Sulfate ,Chemical composition ,Aerosol - Abstract
The radiative forcing of black carbon (BC) depends strongly on its mixing state in different chemical environments. Here, we analyzed the chemical composition and mixing state of BC-containing particles by using a single particle aerosol mass spectrometer and investigated their impacts on light absorption enhancement (Eabs) at an urban (Beijing) and a rural site (Gucheng) in North China Plain. While the BC was dominantly mixed with organic carbon (OC), nitrate and sulfate at both urban and rural sites, the rural site showed much higher fraction of BC coated with OC and nitrate (36 % vs. 15 – 20 %). Moreover, the BC mixing state evolved significantly as a function of relative humidity with largely increased coatings of OC-nitrate and nitrate at high RH levels. By linking with the bulk composition of organic aerosol (OA), we found that the OC coated on BC comprised dominantly secondary OA in Beijing, while primary and secondary OA were similarly important in Gucheng. Furthermore, Eabs was highly dependent on the secondary inorganic aerosol coated on BC at both sites, while the coated primary OC also resulted in an Eabs of ~1.2 for relatively fresh BC particles at the rural site. Positive matrix factorization analysis was performed to quantify the impact of different mixing state on Eabs. Our results showed the small Eabs (1.06 ~ 1.11) for BC particles from fresh primary emissions, while the Eabs increased significantly above 1.3 when BC was aged rapidly with increased coatings of OC-nitrate or nitrate, and it can reach above 1.4 as sulfate was involved in BC aging.
- Published
- 2021
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