阿克苏市5种常见绿化树种滞尘规律

Patterns of dust retention by five common tree species for urban greening in Aksu City, Northwest China

绿化树种在截留沙尘、降低大气颗粒污染物浓度、改善城市生态环境等方面发挥着不可替代的作用。该文选取新疆南部典型绿洲城市——阿克苏市不同功能区的绿化树种,用多重比较法对比分析了二球悬铃木(Platanus×acerifolia)、新疆杨(Populus alba var.pyramidalis)、圆冠榆(Ulmus densa)、天山梣(Fraxinus sogdiana)和垂柳(Salix babylonica)5个树种叶片平均滞尘量随时间变化及不同高度叶片的滞尘能力,探讨了阿克苏市主要绿化树种的滞尘规律,得出以下结论:不同绿化树种单位叶面积滞尘量差异显著,差距在1.15–2.17倍之间,绿化树种滞尘量随着时间延长而增加;同一树种在城市不同功能区的滞尘能力不同:工业区>交通枢纽区>居民区>清洁区;不同高度的叶片,其滞尘量在工业区和交通枢纽区差异显著:高度1 m的叶片滞尘量>高度2 m的叶片滞尘量>高度4 m的叶片滞尘量。

Aims Air pollution poses a long-term threat to human health and life quality of urban residents. In particular, dust pollution in oasis cities of arid regions has been associated with reduced life expectancy. Trees （especially their leaves） in cities can absorb airborne particulate matter and reduce the impacts of air pollution on people and urban environment. This study examined dust retention capacity of the leaves of Platanus ×acerifolia, Populus alba var. pyramidalis, Ulmus densa, Fraxinus sogdiana, and Salix babylonica in different functional areas in Aksu City, Northwest China. Our objectives were to determine that how much dust can be removed on unit leaf area basis by each of the tree species and that how the patterns of dust removal may vary with time, among different sites, and the height where leaves are positioned.Methods Dust samples were washed off the leaf surfaces and weighed by electronic scales with an accuracy of μg （PTX-FA-210, Polestar, Hartford, USA）. Individual leaf area was measured with a Laser Leaf Area Meter and the sediments on each leaf were analyzed by a Laser Particle Size Analyzer. Data were tested by multiple comparisons （ANOVA） using procedures in SPSS, with the level of significance set atp 〈 0.05.Important findings The amount of dust per unit leaf area differed among the five tree species and the four functional areas. The leaves of Platanus× acerifolia had the highest dust retention, and those of Salix babylonica had the lowest dust retention. Among different areas, the amount of dust retention ranked in the order of industrial area 〉 transportation hub area 〉 residential area 〉 clean area. Leaves at a height of 1 m retained the most dust as com- pared with leaves at 2 m and 4 m, with the pattern being consistent across sites and among species.