Wetlands with greater degree of urbanization improve PM2.5 removal efficiency. (September 2018)

• Record Type: Journal Article
• Authors: Liu, Jiakai; Yan, Guoxin; Wu, Yanan; Wang, Yu; Zhang, Zhenming; Zhang, Mingxiang
• Is Part Of: Chemosphere. Volume 207(2018)
• Page Start: 601
• Page End: 611
• Publication Date: 2018-09
• Subjects: Urbanization -- PM2.5 -- Wetlands -- Dry deposition -- Leaf accumulation; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.05.131
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In recent decades, China has experienced both rapid urbanization and heavy air pollution and the rapid urbanization trend would be continue in the next decade. Wetlands have been shown to be efficient in particle removal, primarily through dry deposition and leaf accumulation. Thus, a more comprehensive understanding of PM2.5 removal by wetlands during urbanization processes could inform urban planning. In the current study, three wetland plots, Cuihu Lake Park (CL), Summer Palace (SP), and Olympic Park (OP), were selected as low, medium, and highly degrees of urbanization site respectively based on the proportions of building and traffic district areas to compare the removal efficiencies. Results show the average dry deposition velocity in OP was significantly higher than CL and SP. Dry deposition is mainly influenced by meteorological conditions. Buildings and other infrastructure make the meteorological conditions conducive to deposition, resulting in higher wind velocity, higher temperature, and more intense turbulence between buildings. Variation in leaf accumulation was not statistically significant between the three plots, and plant species was the major factor affecting the amount of accumulation. The dry deposition contribution to particle removal increases with degree of urbanization. The average dry deposition accounted for 39.74%, 52.55%, and 62.75% at low, middle and high level respectively. Therefore, Wetlands with greater degree of urbanization improve PM2.5 removal efficiency primarily by accelerating the dry deposition process. The result emphasizes the importance of wetlands in particle removal in highly urbanized areas and thus more wetlands should be preserved and/or created during urban expansion. Highlights: Dry deposition and leaf accumulation are the two main processes of PM2.5 removal by wetlands. Urbanization improves wetland PM2.5 removal mainly by increasing dry deposition fluxes. Meteorological factors changed by urbanization is the main reason of higher deposition. The contribution of dry deposition to PM2.5 removal increases with urbanization and PM2.5 concentration.