Browsing by Subject "NORTHERN CHINA"

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  • Du, Wei; Dada, Lubna; Zhao, Jian; Chen, Xueshun; Dällenbach, Kaspar; Xie, Conghui; Wang, Weigang; He, Yao; Cai, Jing; Yao, Lei; Zhang, Yingjie; Wang, Qingqing; Xu, Weiqi; Wang, Yuying; Tang, Guiqian; Cheng, Xueling; Kokkonen, Tom V.; Zhou, Wei; Yan, Chao; Chu, Biwu; Zha, Qiaozhi; Hakala, Simo; Kurppa, Mona; Jarvi, Leena; Liu, Yongchun; Li, Zhanqing; Ge, Maofa; Fu, Pingqing; Nie, Wei; Bianchi, Federico; Petäjä, Tuukka; Paasonen, Pauli; Wang, Zifa; Worsnop, Douglas R.; Kerminen, Veli-Matti; Kulmala, Markku; Sun, Yele (2021)
    The role of new particle formation (NPF) events and their contribution to haze formation through subsequent growth in polluted megacities is still controversial. To improve the understanding of the sources, meteorological conditions, and chemistry behind air pollution, we performed simultaneous measurements of aerosol composition and particle number size distributions at ground level and at 260 m in central Beijing, China, during a total of 4 months in 2015-2017. Our measurements show a pronounced decoupling of gas-to-particle conversion between the two heights, leading to different haze processes in terms of particle size distributions and chemical compositions. The development of haze was initiated by the growth of freshly formed particles at both heights, whereas the more severe haze at ground level was connected directly to local primary particles and gaseous precursors leading to higher particle growth rates. The particle growth creates a feedback loop, in which a further development of haze increases the atmospheric stability, which in turn strengthens the persisting apparent decoupling between the two heights and increases the severity of haze at ground level. Moreover, we complemented our field observations with model analyses, which suggest that the growth of NPF-originated particles accounted up to similar to 60% of the accumulation mode particles in the Beijing-Tianjin-Hebei area during haze conditions. The results suggest that a reduction in anthropogenic gaseous precursors, suppressing particle growth, is a critical step for alleviating haze although the number concentration of freshly formed particles (3-40 nm) via NPF does not reduce after emission controls.
  • Shang, Yuan; Prins, Maarten A.; Beets, Christiaan J.; Kaakinen, Anu; Lahaye, Yann; Dijkstra, Noortje; Rits, Daniel S.; Wang, Bin; Zheng, Hongbo; van Balen, Ronald T. (2018)
    The thick loess-palaeosol sequences in the Mangshan Loess Plateau (MLP; central China) along the south bank of the lower reach of the Yellow River provide high-resolution records of Quaternary climate change. In addition, substantial increases in grain-size and accumulation rate have been inferred in the upper part of the loess sequence, above palaeosol layer S2. This study investigates the sources of the long-term dust supply to the MLP and explores the mechanism behind the sudden increase in sediment delivery and coarsening of the loess deposits since S2 (similar to 240 ka) by using end member modelling of the loess grain-size dataset and single-grain zircon U-Pb dating. Our results indicate that the lower Yellow River floodplain, directly north of the MLP, served as a major dust supply for the plateau at least since the deposition of loess unit L9 and indirectly suggest that the integration of the Yellow River and the disappearance of the Sanmen palaeolake took place before L9 (similar to 900 ka). The sudden change in sedi-mentology of the Mangshan sequence above palaeosol unit S2 may result from an increased fluvial sediment flux being transported to the lower reaches of the Yellow River because of tectonic movements (initiated) in the Weihe Basin around 240 ka. Furthermore, sediment coarsening can be explained by the gradual southward migration of the lower Yellow River floodplain towards the MLP since the deposition of palaeosol S2. The migration is evidenced by the formation of an impressive scarp, and is likely caused by tectonic tilting of the floodplain area. (C) 2018 Elsevier Ltd. All rights reserved.
  • Wang, K.; Liu, C.; Zheng, X.; Pihlatie, M.; Li, B.; Haapanala, S.; Vesala, T.; Liu, H.; Wang, Y.; Liu, G.; Hu, F. (2013)
  • Wang, Yonghong; Gao, Wenkang; Wang, Shuai; Song, Tao; Gong, Zhengyu; Ji, Dongsheng; Wang, Lili; Liu, Zirui; Tang, Guiqian; Huo, Yanfeng; Tian, Shili; Li, Jiayun; Li, Mingge; Yang, Yuan; Chu, Biwu; Petäjä, Tuukka; Kerminen, Veli-Matti; He, Hong; Hao, Jiming; Kulmala, Markku; Wang, Yuesi; Zhang, Yuanhang (2020)
    Although much attention has been paid to investigating and controlling air pollution in China, the trends of air-pollutant concentrations on a national scale have remained unclear. Here, we quantitatively investigated the variation of air pollutants in China using long-term comprehensive data sets from 2013 to 2017, during which Chinese government made major efforts to reduce anthropogenic emission in polluted regions. Our results show a significant decreasing trend in the PM2.5 concentration in heavily polluted regions of eastern China, with an annual decrease of similar to 7% compared with measurements in 2013. The measured decreased concentrations of SO2, NO2 and CO (a proxy for anthropogenic volatile organic compounds) could explain a large fraction of the decreased PM2.5 concentrations in different regions. As a consequence, the heavily polluted days decreased significantly in corresponding regions. Concentrations of organic aerosol, nitrate, sulfate, ammonium and chloride measured in urban Beijing revealed a remarkable reduction from 2013 to 2017, connecting the decreases in aerosol precursors with corresponding chemical components closely. However, surface-ozone concentrations showed increasing trends in most urban stations from 2013 to 2017, which indicates stronger photochemical pollution. The boundary-layer height in capital cities of eastern China showed no significant trends over the Beijing-Tianjin-Hebei, Yangtze River Delta and Pearl River Delta regions from 2013 to 2017, which confirmed the reduction in anthropogenic emissions. Our results demonstrated that the Chinese government was successful in the reduction of particulate matter in urban areas from 2013 to 2017, although the ozone concentration has increased significantly, suggesting a more complex mechanism of improving Chinese air quality in the future.
  • Yang, Liu; Rezitis, Anthony; Zhu, Yuchun; Ren, Yang (2018)
    Understanding the factors affecting irrigation management performance is crucial for sustainable resource use, especially with the decentralized management mode of irrigation systems being implemented in rural China. This paper contributes to the research field by incorporating different categories of social trust and perceived organization support (POS) into the analysis of irrigation management performance, by linking multiple elements that are based on the Institutional Analysis and Development (IAD) framework. We employed principal component analysis (PCA) and ordered probit regression to analyze a database covering 785 households in the upstream of the Yellow River basin. The results suggested that social trust and POS positively affected the irrigation management performance, and social trust strengthened the positive effect of POS on the performance. Furthermore, the results indicated that personal trust and institutional trust, as well as perceived emotional support and physical support, positively affected the performance. In addition, we also found that household characteristics, household cognition, group characteristics, physical conditions, and rules-in-use also had significant impact on the performance. This paper can be used to inform the government that social trust and POS need to be considered in the common-pool resources (CPRs) management.