| With the developing of industrialization,the problem of particulate matter pollution is more serious.And it resultes in loss of resources and damage of human body and mind.Preventing particulate matter pollution has become an urgent problem to be solved in current.Gardening plants have a significant effect on preventing atmospheric particulate matter and improving ambient air quality.In this study,29 kinds of shrubs widely used on the road in Fuzhou city were analyzed about their dust,particles with sizes less than 10 μm(Dp<10 μm)and 2.5 μm(Dp<2.5μm)retained,the relationship between capacity and structure of leaves.At the same time,we discussed the effect of particulate matters retained on their temporal-spatial variation characteristics.Besides,we artificially simulated experiment to evaluate the maximum retention.We expect to come to conclusions about influencing factors on particulate matters retained and temporal-spatial variation characteristics of shurbs so as to provide a reference for prevention of particulate matter pollution in Fuzhou city.The main findings were as follows:1.There were significant differences on ability of dust,Dp<10 μm and Dp<2.5 μm retained of 29 greening shrubs in Fuzhou city.The order of particles retained were basically identical.The shrubs such as Ficus microcarpa ’Golden Leaves’,Rhododendro pulchrum、Loropetalum chinense var.rubrum、Duranta repens ’Dwarf Yellow’ were stronger than others.Shrubs all had different potential to retain particles to saturation,and the ability to retain particles to saturation of different particle size were different because of their own leaf characteristics.Carmona microphylla,Loropetalum chinense var.rubrum and others with bristle had a strong potential to retain 2.5 μm<Dp<10 μm and Dp>10 μm to saturation;Schefflera octophylla,Ficus microcarpa ’Golden Leaves’,Excoecaria cochinchinensis,Rhododendron pulchrum and others with high-density stomata,deep ravines,reticular veins and tomentum had a strong potential to retain Dp<2.5 μm to saturation.2.The ability of dust,Dp<10 μm and Dp<2.5 μm retained of species were mainly determined by their own leaf characteristics such as villus,gully,luster,glandular point,leaves with whorled or clumped;leaves was complex and narrow;discolored leaves,leaf edge was rewind or wrinkled and surface microstructure such as fluff,stomata,waxy layer and small room.And the trees with special characteristics were often with special microstructure.Typical species included Rhododendron pulchrum,Loropetalum chinense var.rubrum,Ficus microcarpa ’Golden Leaves’,Buxus microphylla var.sinica,Gardenia augusta var.radicans and Duranta repens ’Dwarf Yellow’,Jatropa pandurifolia and so on.So we should select such shrubs in greening.3.The ability of dust retained of species was affected by seasonal variation,while the ability of Dp<10 μm and Dp<2.5 μm retained were less affected.The ability of particles retained in autumn was the least and in spring or winter was the most.As the ability of dust,Dp<10 μm and Dp<2.5 pm retained per unit leaf area,Loropetalum chinense var.rubrum was strongest in spring;Buxus microphylla var.sinica and Rhododendron pulchrum were strong in summer and autumn or winter,Gardenia augusta var.radicans and Duranta repens ’Dwarf Yellow’ were strong in all seasons except spring.As the ability of dust,Dp<10 μm and Dp<2.5μm retained per leaf,the Cordyline fruticosa had obvious advantages in four seasons,every index was the strongest,the dust,Dp<10 μm and Dp<2.5 μm retained up to 15.75 mg/leaf,13.675 mg/leaf,12.725 mg/leaf in spring.In greening,we should secelet shrubs according to their ability of particles retained as dominant landscape species so as to form a better ambient air quality in four seasons.4.The ability of dust retained of shrubs was affected by space enviroment,while the ability of Dp<10 μm and Dp<2.5 μm retained were less affected.On different roads,the ability of Dp<10 μm and Dp<2.5μm retained was positively related to traffic on four roads and the order was West Minjiang Avenue(between 2nd to 3rd Ring Rd)>North Baima Rd(2nd Ring Rd)>Minjiang Avenue(between 2nd to 3rd Ring Rd)>3rd Ring Rd.The amount of dust retained in 3rd Ring Rd was least.At different layers,the ability of dust,Dp<10 μm retained reduced with increasing of layers and the down layer retained most.At different leaf angles,the ability of leaves at angle of 60°～90 ° retained particles most.Plants could be used in the particulate matter retained,it also should be protected by reasonable watered,clipped to maintain a certain height and angle,inensive planted and other measures to promote its growth and the retention.Besides,we also needed to control the motor vehicle emissions in Fuzhou.5.There was a significant difference in ability of particles with all kinds of sizes of shrubs.Shrubs mainly retained Dp<2.5 μm,and it could be above 80%.The retention of 2.5 μm<Dp<10 μm and Dp>10 μm had little contribution to overall quality of dust,and the Dp>10 μm was slightly more.The mass ratio of particles with different particle size would change slightly with different seasons and roads. |
