Season impacts on estimating plant's particulate retention: Field experiments and meta-analysis

Plants can effectively remove atmospheric particles, which contribute to air pollution. However, few studies have focused on seasonal variability of plant dust retention, an essential factor to estimate annual dust removal from the atmosphere. This study conducted a field experiment to explore the seasonal variability of particulate retention on evergreen leaved urban greening shrub plants. We performed a meta-analysis to synthesize the available literature on the subject to discuss our findings further. Results showed that particulate matter deposited on leaf surfaces (sPM) in autumn and winter was significantly higher than in spring and summer. In comparison, the particulate matter trapped in epicuticular waxes (wPM) in summer was significantly higher than in the other three seasons. The seasonal differences also existed in both sPM and wPM among particle sizes. The total dust retention of Rhododendron × pulchrum Sweet, Osmanthus fragrans Lour, and Photinia × fraseri Dress were estimated as 360.89 t, 586.66 t, and 448.84 t per year, respectively. They were significantly different from model estimates if only one season was chosen as an estimator. Furthermore, the meta-analysis revealed significant differences among seasons, particle sizes, and different leaf habits (evergreen or deciduous). In contrast, no significant differences were observed between life forms or between growth forms. Our findings both from field experiment and met-analysis highlights that seasonal variation can significantly affect the dust retention capacity of plants, which should be taken into account into particle matter retention capacity evaluations.