叶面滞尘对火电厂周边绿化树种叶片反射光谱及光合作用的影响

以宁东能源化工基地典型火电厂周边5种常见绿化树种白蜡、臭椿、火炬树、山槐、榆树的叶片为对象,并在雨后第1天和第15天分别采用洗脱法分析其滞尘能力,地物光谱仪测定滞尘对叶面反射光谱的影响,Li-6400便携式光合仪测定滞尘对光合特征参数(净光合速率、气孔导度和蒸腾速率)的影响。结果表明,5种绿化树种的滞尘能力由大到小表现为:火炬树、臭椿、榆树、山槐、白蜡。光谱反射曲线总体特征是洁净叶片反射率大于滞尘叶片反射率,主要表现在740~1300 nm波段,而在350~680、1500~2500 nm波段,则无一致性规律,存在波动。叶面滞尘量与叶片光谱反射率相关性研究表明对叶面滞尘敏感的波段主要集中在可见光波(700~750 nm)和近红外波段(1390~1500 nm)。滞尘不改变叶面特有的反射特征,但存在增强或削弱效果,且这种增强或者削弱效果存在种间差异。滞尘对叶片反射光谱曲线一阶导数的三边位置没有明显影响,说明三边位置对滞尘的干扰不敏感;三边幅值和三边面积对滞尘有明显的响应,5种绿化树种均表现为洁净叶片大于滞尘叶片。在相同的污染环境下,滞尘会对绿化树种的光合生理特征产生抑制作用,但并非滞尘量越大、光合特征损失率越大,而损失的幅度因植物种类的不同而异,存在种间差异。综合各树种受滞尘影响的光合特征参数变化,发现榆树和山槐对当地大气降尘污染的抗性较强。

Influence of Leaf Dust Retention on Leaf Surface Reflectance Spectroscopy and Photosynthesis of Greening Tree Species Around Thermal Power Plant

Taking 5 kinds of greening tree species(Fraxinus chinensis,Ailanthus altissima,Rhus typhina,Maackia amurensis,Ulmus pumila)around typical thermal power plant in Ningdong Energy Industrial Base as the research objects,leaves of these tree species were collected on the 1^st day and 15^th day after raining and to study their dust retention capabilities by using the method of washing and filtering.The associated influences of dust retention on leaf surface reflectance spectroscopy were studied by using FieldSpec4 Hi-Res NG spectroradiometer,and the photosyntheses of the trees tested were measured by portable photosynthesizer Li-6400.The results indicated that there were significant differences in dust retention capabilities among 5 tree species.The amount of dust retention capability ranked as R.typhina,A.altissima,U.pumila,M.amurensis,F.chinensis.The basic characteristics of spectral reflection curves showed that the reflectance of dust free leaves was higher than that of dust detained leaves,mainly manifested in 740-1300 nm band.Whereas,there were no uniform rule and existing fluctuation in 350-680 and 1500-2500 nm bands.The correlation between leaf dust retention capability and leaf surface reflectance spectroscopy indicated that the bands sensitive to the dust retention mainly focused in the visible(700-750 nm)and the near-infrared spectra(1390-1500 nm).And dust retention didn't alter the inherent reflectance characteristics,but could strengthen or weaken them.These kinds of strengthening and weakening were inter-specific differences among 5 kinds of greening tree species.Dust retention had no obvious influence on three edge position changes of leaf spectral reflectance curve first derivative,which meant three edge positions were not sensitive to the disturbance of dust retention.And dust retention had significant influence on three edge amplitudes and areas,to all the 5 kinds of greening tree species,the three edge amplitudes and areas of dust free leaves were higher than those of dust detained leaves.Under the same contaminative circumstance,dust retention had inhibition effect on the photosynthesis characteristic parameters(P_n,G_s,E)of greening tree species,but not as the more dust detained,the more photosynthesis losses obtained.The photosynthesis characteristics loss rates varied among the tree species.It was found M.amurensis and U.pumila had stronger resistance to local atmospheric dust pollution based on the comprehensive consideration of the influence of dust retention on photosynthesis characteristics parameter changes.