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The dew condensation frequency is high, and the dew amount is heavy in urban ecosystems. During the condensation process, particulate matter acts as a condensation core, playing an important role in purifying the air. At night, dew mainly condenses on plant leaf surfaces, the plant leaves settle the particles in the dew, and some of the particles are resuspended into the atmosphere in the process of dew evaporation after sunrise. This paper monitored the condensation and evaporation processes of dew on four common plants in Changchun city from June to September 2020. By analyzing the mass and size of particles on different leaves after dew condensation and evaporation, the ability of different plants to retain particles in dew was analyzed. The results showed that there was no significant difference in the TSP capture ability during dew condensation between Buxus sinica (Rehd. et Wils.) Cheng subsp. sinica var. parvifolia M. Cheng, Syringa oblata Lindl., Hemiptelea davidii (Hance) Planch., and Pinus tabuliformis Carrière, with a TSP content of 0.21 ± 0.06 μg/cm2. Coarse particulate matter is the main type of deposit in the dew condensation stage. Particulate deposition varied according to species, leaf shape, and microstructure. The proportion of TSP remaining on leaves after dew evaporation from Pinus tabuliformis Carrière, Hemiptelea davidii (Hance) Planch., Buxus sinica (Rehd. et Wils.) Cheng subsp. sinica var. parvifolia M. Cheng, and Syringa oblata Lindl. tree was 89.7 ± 3.9%, 80.6 ± 3.6%, 75.9 ± 4.5%, and 71.4 ± 3.7%, respectively. The ability of the leaves to trap fine particles was significantly higher than that for coarse particles (P < 0.05) after dew evaporation. The highest amount of particle captured by Syringa oblata Lindl. individual was 15.17 g/y during dew condensation, and the amount of remaining particles after dew evaporation was 10.83 g/y. This paper provides a theoretical basis for the selection of tree species for urban greening. [ABSTRACT FROM AUTHOR]

Scientists have effectively proved that vegetative environment buffers (VEBs) can be used for reducing dust emissions from livestock buildings, but they have seen fewer tests in poultry farms. A field research was conducted to assess the effectiveness of VEBs on reducing downwind transport of particulate matter (PM) from a ventilated poultry house in Changchun. Five plant species transferred from local area were used to establish five diverse VEBs and separately installed outside of the ventilation fans in summer 2017. The five plant species were Winged Euonymus (WE), Malus Spectabilis (MS), Padus Maackii (PAA), Acer Saccharum Marsh (ASM), and Padus Virginiana "Red Select Shrub" (PV_RSS). The mass concentrations of PM2.5 and PM10 (particulate matter with an aerodynamic diameter of 2.5 μm and 10 μm or less, respectively) were monitored at downwind and upwind sampling locations around the VEB. The results showed that with the presenting of VEBs, the particle concentrations at the downwind sampling point were significantly reduced compared with that at the upwind sampling point (p < 0.05). Specifically, compared to the control test without VEB, the VEB with PV_RSS had the best PM concentration reduction rate (CRR) of 47.24%±4.33% and 41.13%±5.83% for PM2.5 and PM10, respectively. The rough surface of plant leaves may help intercept more PM, though it was also affected by other factors (such as the blade angle, the interaction with wind) needed to be further investigated. The VEB with PV_RSS, which presented the best capacity of CRR, selectively intercepted PM, mainly related to the elements of N, Na, Mg, P, S, and Cl. Implications: Five plant species, including WE, PAA, MS, ASM, and PV_RSS, were evaluated as VEBs to mitigate particulate emissions from outside of a ventilated poultry house in Changchun. They all significantly reduced particulate matter emissions. However, the PV_RSS presented the best capability of trapping fine and coarse particles: PM2.5 and PM10, respectively, while the PAA was the worst one. The microstructure of leaves affected particle deposition and remaining on the leaves, and PV_RSS selectively intercepted particulate matter mainly related to certain elements. [ABSTRACT FROM AUTHOR]

Plant leaf surface moisture is a frequent meteorological phenomenon that has complicated sources. As such, the determination of whether surface moisture is the input water or only the redistribution of water in the soil–plant–atmosphere ecosystem is of great importance. In this study, δ18O and δD characteristic values of dew, guttation, and soil waters in Buxus sinica var. parvifolia M. Cheng were monitored during the frost-free period (June–September 2017) in Changchun, China, to differentiate the hydraulic relationship among atmospheric vapor, rainwater, soil, dew, and guttation waters and quantitatively distinguish the leaf surface moisture on the canopy and bottom of plants. The water vapor sources of the leaf surface moisture on plants' canopy and bottom were quantitatively verified in accordance with isotope fractionation and mass conservation principles. Results demonstrated that leaf surface moisture, atmospheric vapor, soil water, and dew were closely related. Leaf surface moisture was mainly the condensation of dew. The sources of canopy and bottom leaf surface moisture were basically the same. The proportions of canopy moisture from plant guttation, atmospheric vapor, and soil water were 2.4%–2.5%, 79.8%–92.4%, and 5.1%–17.8%, respectively. By comparison, the proportions of bottom leaf surface moisture were 0.6%–1.4%, 80.0%–93.0%, and 6.4%–18.6%, respectively. Leaf surface moisture is an important water input in urban systems. Moreover, the characteristic values of stable hydrogen and oxygen isotopes of urban dew are supplemented, and the transformation of atmospheric vapor, rainwater, and soil and dew waters is revealed. [ABSTRACT FROM AUTHOR]