亚热带常绿树种对不同粒径颗粒物的滞留能力

可吸入颗粒物和细颗粒物是大部分城市的首要污染物,对人体健康和环境都有重要影响;而城市植物能吸附大气颗粒物,进而有效降低大气颗粒物浓度。为了深入探究不同树种叶表面特征与自身滞尘效益之间的关系,该研究以浙江省三种常见城市绿化树种(青冈、冬青、红花檵木)为对象,采用重量法提取各样本在3个粒径上(8~100,2.5~8,0.45~2.5μm)的单位叶面积滞尘量(μg·cm~(-2)),并结合叶面积指数估测全株滞尘量。结果表明:三种供试植物叶片对颗粒物平均单位叶面积滞留量在30.4~63.7μg·cm~(-2)之间,而平均单木滞尘量每株在1.36-9.36 g之间。红花檵木因其叶表粗糙、具有绒毛等特征,对颗粒物(0.45~100μm)有最大的吸附能力(63.74±12.0μg·cm~(-2));对于大颗粒物(8~100μm)和细颗粒物(0.45~2.5μm),三种植物叶片均对其分别具有最大(40.9%~57.5%)、最小(15.6%~20.6%)的吸附能力;对于单木滞尘量,青冈因其具有较大叶面积指数等特征,对颗粒物总吸附效果更佳(每株9.36g)。该研究结果表明城市绿化树种对减缓大气颗粒物污染起到重要作用。

Different sizes of particulate matters deposited on leaf of typical subtropical evergreen species

Both inhalable particulate matter (PM10) and fine particulate matter (PM2.5) are the primary pollutants in most of the cities in China,which are known for the harmness to human health. Urban plants could be used as biological fil-ters,playing an important role in reducing the concentrations of particulate matters in the air as result of adsorbing and arresting particulate matters on their foliage. Three typical types of subtropical evergreen plants (Cyclobalanopsis glauca,Ilex chinensis and Loropetalum chinense var.rubrum),always used as urban greening species,were selected to study their capacities in capturing particulate matter. The rinse and weight method were used to characterize PM in dif-ferent particle size fractions (8-100,2.5-8,0.45-2.5μm). The results showed that the particulate matters on leaves ranged from 30.4 μg·cm-2to 63.7 μg·cm-2,while the particles deposited by the whole tree ranged from 1.36 g to 9.36 g. Loropetalum chinensevar.rubrumwas the most efficient species in capturing particulate matters (63.7±12.0 μg·cm-2) for its rough surfaces and large quantity of hairs on the foliage. All the tested species have the strongest (40.9%-57.5%) and the weakest (15.6%-20.6%) dust-capturing capability for the large size fraction (8-100 μm) and the fine size fraction (0.45-2.5 μm) respectively. As for the total amount of surface particulate matters accumulated by the whole tree, Cyclobalanopsis glauca is the most efficient species (9.36 g per tree) for its spacial characteristics. All the results showed that urban plants played important roles in mitigating urban airborn particulate matters.