煤炭型城市绿化树种叶片磁性及对PM_(2.5)的指示作用

Magnetic Properties of Greening Tree Species and Their Indicating Functions for PM_(2.5) in the Coral City

近年来,以PM_(2.5)为主的城市大气污染日益严重,城市绿化树种叶片磁性对PM_(2.5)具有指示作用。该研究通过对平顶山市不同功能区内常见的19种绿化树种叶片样品进行磁性测试,旨在比较不同树种叶片磁性的差异,探讨叶片磁性与PM_(2.5)的关系。结果表明:(1)同一城市功能区,不同树种的叶片质量磁化率存在显著差异(p<0.05)。在污染严重的矿区,不同绿化树种叶片磁性参数均高于其它区域。其中广玉兰叶片磁性参数最高,为67.30×10^(-9)m^3/kg,悬铃木叶片磁性最低,为6.41×10^(-9)m^3/kg。同一区域,广玉兰、构树、侧柏、栾树、油松叶片磁性参数均较大,对空气有较好的净化作用;(2)不同城市功能区,同一树种叶片质量磁化率差异显著(p<0.05);(3)在5个城市功能区均有大量分布的绿化树种(悬铃木、广玉兰和杨树)叶片磁性均与PM_(2.5)回归关系显著(p<0.05)。本研究表明在不同城市功能区,可以栽植叶片磁性较大的树种对PM_(2.5)进行净化,并可利用在不同城市功能区广泛分布的悬铃木、广玉兰和杨树的叶片磁性对该市PM_(2.5)污染程度及其分布的空间格局进行指示和监测。

In recent years, air pollution, especially caused by PM（2.5） has become more and more serious. Magnetic properties of greening tree species have indicating function of PM（2.5）. This study measured magnetic indexes of 78 leaf samples of 19 domain greening tree trees in the different urban functional areas of Pingdingshan City, compared variation of the leaf magnetic indexes with the different greening tree species, and studied the correlation between PM（2.5） concentrations and the leaf magnetic indexes. The results show that in the same urban function region, different tree species had significant variations in the leaf mass magnetization rate（LMMR）（p〈0.05）. In the coal mine region where air pollution was serious, the leaf mass magnetiza-tion rates for all tree species were greater than any other regions. The tree species with the greatest value of LMMR was Magnolia grandiflora（67.30×10^-9 m^3/kg）, and that with lowest value for LMMR was Platanus acerifolia（6.41×10^-9 m^3/kg）.At the same region, these tree species including Magnolia grandiflora, Broussonetia papyrifera, Platycladus orientalis, Koelreuteria paniculata, Pinus tabulaeformis has greater values of LMMR than any other species, and had higher ability for purification air pollution. In the different urban function region, the same tree species showed the significant variance in the values of LMMR（p〈0.05）. LMMRs of Platanus acerifolia, Magnolia grandiflora, and Populus, which were widely distributed in the five urban regions, were significantly regressed with the concentrations of PM（2.5）（p〈0.05）. This study suggested that the tree species with greater LMMR could be recommended to be planted for purification of air pollution. Moreover, LMMR of the widely distributed tree species in the five urban regions, such as Platanus acerifolia, Magnolia grandiflora, and Populus could be used to indicate and monitor the heterogeneity of the spatial distribution of PM（2.5） in Pingdingshan City.