关键词: 绿化树种, 大气颗粒物, 叶表面滞尘, 微结构

Abstract: The dust retention capacity of greening tree species is closely related to leaf surface micro-structure. We measured the dust retention quantities of the leaves from five broad-leaved greening tree species around a thermal power plant in Ningdong Energy Industrial Base, using the method of washing and filtering. The leaf surface microstructure was observed by scanning electron microscopy. The relationship between leaf surface micro-structure and dust retention capability was analyzed. Results showed that there were significant differences in dust retention capability of leaves among the five species, with a rank of Rhus typhina>Ailanthus altissima>Ulmus pumila>Maackia amurensis>Fraxinus chinensis. Rhus typhina and Ailanthus altissima, with combined characteristics of epidermis trichome, stomata, gap and roughness, had higher dust retention capability. According to the analysis of particle size and composition of dust detained on the leaves, some tree species showed selective retention and adsorption. For example, Fraxinus chinensis as a stomatal adsorption type tree species had stronger capability of PM_2.5 adsorption, while Rhus typhina and Ailanthus altissima, due to the combined characteristics of epidermis tomentum, stomata, gap and roughness, had a wider particle size adsorption range. Based on the results of energy dispersive spectrometer analysis, dust derived from soil was identified on leaves broadly, while organic pollutants derived from anthropogenic sources were also found on the tree species with epidermis tomentum. Therefore, according to the local air pollution type, tree species with leaf surface micro-structures being beneficial to dust retention should be chosen for greening in the energy industrial zone.

Key words: greening tree species, atmospheric particulate matter, leaf surface dust retention, micro-structure.