杭州校园中不同植被对PM_(2.5)的吸附能力

PM_(2.5) Absorption Capacity of Different Vegetation on the Campus of Hangzhou City

为合理安排绿地配置,极大发挥植物改善生态环境的功能,为城市系统绿化的功能化规范化经济化提供更加合理的理论支持,通过获取杭州电子科技大学校园内现有的4种植被的不同时间段和不同离地高度的ρ(PM_(2.5)),用统计学的t检验方法研究了ρ(PM_(2.5))的变化规律.以一天当中不同时间空地的ρ(PM_(2.5))作为参照,分别对相同时间、不同植被区域、不同高度和不同时间、相同植被区域、相同高度的ρ(PM_(2.5))作对比.结果表明:(1)早晨水杉林、松树林、混合林的PM_(2.5)吸附能力相似,与空地的平均差值分别为14.36、12.00和12.79μg/m3;草地的PM_(2.5)吸附能力较差,与空地的平均差值仅为4.75μg/m3.中午时,水杉林的PM_(2.5)吸附能力最强,与空地ρ(PM_(2.5))平均差值为10.87μg/m3,其次为混合林(8.18μg/m3),草地ρ(PM_(2.5))反而比空地高14.90μg/m3.下午水杉林与混合林的PM_(2.5)吸附能力与中午相比略微减弱.晚上,除混合林外,其他3种绿地均与空地无显著差异.(2)对比距地面0.1与1.5 m高的空气中ρ(PM_(2.5))的差异发现,一般情况下树林中0.1 m处ρ(PM_(2.5))大于1.5 m处,空地0.1 m处ρ(PM_(2.5))小于1.5 m处.研究显示,大部分植被在早晨吸附能力最强、晚上最弱,不同植被对于PM_(2.5)的吸附能力也有所不同.由此,在所统计的植被中,水杉林对空气中PM_(2.5)的吸附能力最强,在以后的绿地规划中,可考虑多增加水杉林的种植面积;但在增加城市林地面积减少空气中PM_(2.5)的同时,还应考虑到植物自身生理能否带来一些城市负面影响,从面得出最优种植方案.

To rationally arrange the allocation of the green land,fully improve the ecological environment and provide more reasonable theoretical supports for the functionalization,standardization and economicalization of urban greening,we collected PM2.5 samples from four plantings on the campus of Hangzhou Dianzi University. The PM_（2.5） concentrations of different time periods and different heights from the ground were analyzed by t-test to study the variation of PM_（2.5） values. Here,we used the PM_（2.5） concentrations at ground as a reference to compare with different vegetation areas at different heights/times and in the same vegetation area/height. Results showed that：（ 1） In the morning,the situations of metasequoia forest,pine forest and mixed forest＇s ability of the PM_（2.5） adsorption were similar,with average difference of 14. 36,12. 00 and 12. 79 μg/m3,respectively. However,the grass ability of PM_（2.5） adsorption was poor; the average difference of the area was 4. 75 μg/m3. At noon,the metasequoia forest＇s ability of the PM_（2.5） adsorption was the best with the difference of the area at 10. 87 μg/m3. Tthe mixed forest was followed by the metasequoia forest which was 8. 18 μg/m3,the grass was 14. 90 μg/m3 larger than the average of ground. In the afternoon,the metasequoia forest and the mixed forest＇s ability of the PM_（2.5） was 14. 90 μg/m3 larger than the average of ground. In the afternoon,the metasequoia forest and the mixed forest＇s ability of the PM_（2.5） adsorption was less than that in the noon. At the night,except the mixed forest,the others didn＇t show significant different to the ground.（ 2） Compared the difference of PM_（2.5） concentrations in the height of 0. 1 and 1. 5 m,the PM_（2.5） concentrations in lower level was more than the higher levelin the forest,but the ground was opposite. It can be concluded that most of the vegetation had the strongest adsorption capacity in the morning,and the weakest in the night,the sorption capacity of different vegetation to PM_（2.5） was also different. Among the vegetations,the metasequoia forest adsorbs PM_（2.5） best,it can be considered to increase the planting area of metasequoia forest in future. However,while increasing urban forest area to reduce PM_（2.5） in the air,it should also take into account whether the plant＇s own physiological ability can bring about some negative effects of the city,so as to draw an optimal planting plan.