Particulate matter transported from urban greening plants during precipitation events in Beijing, China

Mengfan Cai; Zhongbao Xin; Xinxiao Yu

doi:10.1016/j.envpol.2019.06.119

Particulate matter transported from urban greening plants during precipitation events in Beijing, China

Environ Pollut. 2019 Sep;252(Pt B):1648-1658. doi: 10.1016/j.envpol.2019.06.119. Epub 2019 Jul 1.

Authors

Mengfan Cai¹, Zhongbao Xin², Xinxiao Yu³

Affiliations

¹ School of Soil and Water Conservation, Beijing Forestry University, 35 Tsinghua Road, Haidian District, Beijing 100083, PR China; Department of Building, Civil and Environmental Engineering, Faculty of Engineering and Computer Science, Concordia University, 1455 De Maisonneuve Blvd. W., Montreal, Quebec H3G 1M8, Canada.
² School of Soil and Water Conservation, Beijing Forestry University, 35 Tsinghua Road, Haidian District, Beijing 100083, PR China. Electronic address: bjxin@bjfu.edu.cn.
³ School of Soil and Water Conservation, Beijing Forestry University, 35 Tsinghua Road, Haidian District, Beijing 100083, PR China.

PMID: 31284207
DOI: 10.1016/j.envpol.2019.06.119

Abstract

Particulate matter (PM) deposited on canopy surfaces could be washed off and carried in throughfall to the ground. This would help plants recapture airborne PM on their canopy surfaces and then develop a PM purification capacity. Sixteen commonly greening plant species in north China (including 13 arbor species and 3 shrub species) were selected to investigate the washing process of plant-deposited PM during precipitation events. We measured the PM wash-off mass in throughfall under canopies of 16 plant species and in atmospheric precipitation during 14 precipitation events through field positioning experiments in 2015, compared the seasonal changes and species differences in PM wash-off mass, and discussed the predominant factors resulting in the variation. The results showed that plant-deposited PM was largely washed off by precipitation. The average wash-off mass of total suspended particulate (TSP) in throughfall was 1.3 times higher than that in precipitation, at 18.3 ± 0.7 kg hm^-2 and 7.9 ± 0.9 kg hm^-2, respectively. There were significant seasonal differences in TSP wash-off mass. The value was higher in summer at 22.3 ± 1.0 kg hm^-2, followed by that of winter (10.8 ± 0.6 kg hm^-2) and spring (8.9 ± 1.0 kg hm^-2). TSP wash-off mass in throughfall greatly varied among plant species (F = 9.542, n = 627, p < 0.001). Of the 16 selected species, Platanus acerifolia (38.0 ± 5.8 kg hm^-2) showed the largest difference from that of Liriodendron chinese (8.9 ± 0.6 kg hm^-2) (n = 80, p < 0.001). PM wash-off mass of different particle sizes in throughfall increased with the increase of event-based precipitation. This study enhanced the quantitative understanding of plant-deposited PM washed-off by natural precipitation among plant species and seasons. The results could provide significant guidelines for the selection and allocation of plant species to improve the PM retention capacity of urban greening plants.

Keywords: Greening plants; Natural precipitation; PM wash-off mass; Particulate matter; Throughfall.

MeSH terms

Air Pollutants / analysis*
Beijing
Environmental Monitoring / methods*
Particle Size
Particulate Matter / analysis*
Plants / chemistry*
Rain / chemistry*
Seasons
Species Specificity
Urbanization

Substances

Air Pollutants
Particulate Matter