The Study On Particulate Matter Retaining Capability Of Common Plants In Harbin And Variation Characteristics Of Particulate Matter Concentration In Urban Green Land

Currently urban air particulate matter pollution has become the most serious environmental pollution problem in city.It has a harmful effect on plant, animal and human health. Urban green space plays a very significant role in purification of atmospheric pollution which is closely related to characteristics of individual plants and structures of green spaces.In this research, dust-retention capability and leaves’ micro-structure of major afforested plants in Harbin were studied to determine the main factors influencing the dust retention. Different types and different canopy density of urban green land are selected to study the relationship between urban green land and particulate matters and the relationship between environmental factors and particulate matters, which can provide a reference for the construction of urban green space for Harbin. The main results are as follows:1.The results of Study on major afforested plants in Harbin showed significant differences among different trees. The order of particulate matter removal effect of major afforested abort plants in Harbin are as follows:Morus alba>Catalpa ovata>Padus maackii>Fraxinus mandschurica>Salix matsudana>Syringa reticulata var. amurensis>Armeniaca vulgaris> Euonymus maackii>Betula platyphylla; the order of particulate matter removal effect of major afforested shrub plants in Harbin are as follows:Spiraea bunmalba ’Goldmound’>S. thunbergii>Amygdalus triloba>Weigela florida>S. bunmalba ’Goldflame’> S. pubescens subsp.microphylla> Hydrangea paniculata> Acer ginnala> Swida alba> Forsythia mandschurica> W. florida ’Red Prince’> Viburnum opulus var. calvescens>S. villosa> Sambucus williamsii>S. oblata Lindl.>Ligustrum obtusifolium.Selecting afforested plants which have high particulate matter removal capability can improve dust-blocking effect, and making beautiful environment.2.The results of microscopic scanning showed that leaves with irregular cells, chamber or groove and cell outline are beneficial to retain particulate matter. Those plants whose leaf surfaces had deep cuticle ornamentation or epicuticular wax can retain particulate matter effectively, while those whose leaf surfaces are smooth and cuticle ornamentation were lighter had poor effects of particulate matter removal abiliy. The particulate matter retention increased with the increase of the amount of stomata and hair. It is advisable to choose tree species whose surface morphology enhance dust retaining capability to improve urban atmospheric environment.3.The results of different type and different canopy density urban green-lands showed that: urban green-lands have obvious function of particulate matter removal capability. The particulate mass concentration decreased with the increase of canopy density of urban green- lands。The particulate mass reduction ability of urban green-lands tends to be stable when canopy density greater than 0.8.4.The order of particulate matter removal effect of different type of urban green-land are as follows:shrub-lawn>lawn>arbor-lawn> arbor- shrub-lawn, coniferous forest> broad leaved forest. The particulate matter concentration in the morning was significantly higher than that in the afternoon.5.PM1.0 concentration was significantly correlated with PM2.5. Particulate matter concentrations in urban green-land were significantly and positively correlated with LAI and canopy density. The relationship between particulate matter and meteorological factor is complex. Temperature is negatively correlated with particulate matter and the particulate matter concentration decreased with the increasing of temperature when temperature was higher than 25℃or 27℃. Relative humidity is positively correlated with particulate matter,while the particulate matter concentration decreased with the increasing of Relative humidity when Relative humidity was higher than 85%. Wind speed is negatively correlated with particulate matter,while the particulate matter concentration increased with the increasing of Wind speed when Wind speed was higher than 1.1 m/s.