常见绿化植物角质层对PAHs的吸附作用

为准确预测萘(Naphthalene,Nap)菲(Phenanthrene,Phe)、芴(Fluorene,Fl)和芘(Pyrene,Pyr)在植物叶面的吸附行为,用化学分离法分离得到马尾松(Pinus massoniana)、海桐(Pittosporum.tobira)、桂花(Osmanthus fragrans)叶面角质层,研究了角质层对Nap、Phe、Fl和Pyr的吸附特征及影响因素。结果表明:3种植物角质层吸收Nap、Phe、Fl和Pyr的作用机理是分配作用。根据线性等温吸附曲线斜率K_d值表明,3种植物角质层对Nap的吸附性能非常强,表现为桂花强于海桐和马尾松;马尾松和桂花对Phe的吸附性能相似,略强于海桐;马尾松对的Fl吸附性能强于桂花和海桐,桂花对Pyr的吸附性能强于马尾松和海桐。通过扫描电镜观测发现,马尾松角质层具有丰富的微观形貌,两侧气孔器排列紧密。桂花角质层表面粗糙呈褶皱状,海桐角质层表面平滑,但两者都未观察到气孔器。植物角质层微观结构的不同是导致植物吸附多环芳烃(polycyclic aromatic hydrocarbons, PAHs)存在种间差异的重要原因。通过傅里叶红外光谱观测显示:海桐、桂花和马尾松在C=O(～1 734 cm~(-1))均有信号,表明其表皮都有明显的酯键吸收峰;3种植物表皮角质层的C-O-C峰(～1 057 cm~(-1))也最为突出,这与其叶片中糖类含量有关。

Sorption of PAHs to Plant Cuticle with Common Greening Plant

For accurately predicting foliar uptake of the Naphthalene (Nap), Phenanthrene (Phe), Fluorene (Fl) and Pyrene (Pyr), leaf cuticle of Pinus massoniana，Pittosporum. Tobira and Osmanthus fragrans were isolated by chemical methods. Adsorption behavior of PAHs onto leaf cuticle was investigated and the their influence factors. The three tree species cuticle were obtained by means of the chemical separation. The results showed that the distribution of PAHs was mainly responsive for the absorption of Nap, Phe, Fl and Pyr. According to the value of Kd, which was the by the rate of linear isothermal adsorption curve, three tree species had a strong sorption capacity of Nap. P. tobira had a stronger sorption capacity than O. fragrans and P. tobira. P. massoniana had an similar adsorption capacity of Phe compared with O. fragrans, but stronger than that of P. tobira. P. massoniana had a stronger sorption capacity of Fl than O. fragrans and P. tobira. O. fragrans had a stronger sorption capacity of Pyr than P. massoniana and P. tobira. An scanning electron microscope (SEM) observation revealed that the P. sylvestris cuticle has a rich microstructure, with stoma distributed densely on both sides. The surface of O. fragrans cuticle had rough folds, whereas P. tobira cuticle was smooth. However, we did not observe an obvious stoma in both P. tobira and O. fragrans cuticle. The differences in the leaf microstructure of plant cuticle were major causes of the interspecies difference of PAHs (polycyclic aromatic hydrocarbons, PAHs) adsorption. A Fourier transform infrared (FTIR) analysis revealed that P. massoniana contained fatty components, with the highest lipid content among the three trees. We also observed signals of three plant cuticle in C=O (~1 734 cm^-1), indicating an obvious absorption peak of ester bond. Moreover, C-O-C peak (~1 057 cm^-1) is most prominent, which related to sugar content.