基于光谱参数和Cu^(2+)吸收机理的玉米叶片铜污染预测研究

Study on Copper Pollution Prediction of Corn Leaves Based on the Spectral Parameters and the Cu^(2+) Absorption Mechanism

依据多个浓度梯度下Cu^(2+)胁迫的玉米盆栽实验,通过采用多种光谱特征参数、红边位置(REP)、红边一阶微分包围面积(FAR)和归一化植被指数(NDVI)等光谱参量;以及另五种植被指数(红边归一化植被指数NDVI_(705),改进红边比值植被指数mSR_(705),改进红边归一化植被指数mNDVI_(705),光化学植被指数PRI和结构不敏感色素指数SIPI);并结合Cu^(2+)的光谱吸收机理,同时基于玉米叶片的反射光谱和Cu^(2+)含量实验室实测数据,开展了玉米叶片光谱参数及植被指数与铜污染程度预测的相关性分析研究。实验结果表明:本文提到的大部分光谱参数及植被指数与叶片中Cu^(2+)含量具有一定的相关性;随着Cu^(2+)浓度增加,盆栽玉米在低于200μg/g浓度时仍可正常生长;而在高于浓度为200μg/g后生长受到抑制。玉米受Cu^(2+)污染时,在Cu^(2+)特征吸收峰810 nm处反射率有下降趋势,与无Cu^(2+)污染时反射率上升的趋势相反,说明Cu^(2+)光谱吸收机理可以用来区分和预测玉米是否受到Cu^(2+)污染。

According to the poted corn experiments stressed by multi Cu2+concentration gradient tests,many correlation analyses were carried out between leaf spectral parameters,vegetation indexes and the predicted copper pollution degrees based on the com leaves’reflectance spectra and Cu2t contents measured in the laboratory by using a variety of spectral curve characteristic parameters,some spectral parameters such as red edge position(REP),first-derivative area of red-edge(FAR)and normalized difference vegetation index(NDVI),as well as other five vegetation indexes that were the red edge NDVI(NDVI705),modified red edge simple ratio index(mSR7〇5),modified red edge NDVI(mNDVI705),photochemical reflectance index(PRI)and structure insensitiveindex(SIPI),at the same time combing with the spectral absorption mechanismof Cu2t.Experimental results show that,most of the spectral parameters mentioned have a certain correlation with the leaves’Cu2t contents;the growth of potted corn could still be normal at less than200"g/g but was inhibited at higher than200"g/g along with the increase of the Cu2t concentration;and the Cu2t absorption mechanism can be used to distinguish andpredict whether the corn is polluted by Cu2t or not in terms of the reason that the corn leaf’s reflectance located inthe Cu2t absorption peak at the wavelength of810nm was decreased when contaminated by Cu2t but the reflectance could have increasing trend when no pollution of the heavy metal.