Spectrographic method for estimation of the heavy metal salts influence on the plants growth

Abstract

The paper is devoted to the problem of the heavy metal salts influence on the plants spectral characteristics. Also in the article is described the procedure of remote passive sensing of vegetation state that can be used for developing environmental pollution detection algorithm. The investigation was consisted from two independent experiments: the first was aimed to study how various heavy metal salts are affecting the spectral characteristics of the Kalanchoe; the second – to study how different concentrations of harmful agents influence on the spectral properties of the dark green Ceratophyllum demersum. For mixes creation was used the following chemical agents: 1) FeSO_4 (2.7 mol); 2) CsCl (4 mol); 3) ZnSO_4 (3 mol); 4) MnCl_2 (4 mol); 5) K_2Cr_2O_7 (3 mol); 6) control sample. The spectral measurements were carried out with experimental box that consists of the led lamp and the portable spectral system based on the ASP-100 spectrometer. The leaves reflectance spectra after exposure to different heavy metals salts demonstrated sufficient changes in the form of a spectral curve after 24 hours. This effect allows to use reflectance spectra as identifier by remote methods. Also, the similar reactions occurred at different concentrations. To simplify the measurement procedure of harmful agents affects as physiological stress a contrast ratio was used. More informative and reliable indicator of the different concentrations and salts effect was found in the near infrared range (from 500 nm to 750 nm). This happens as the plants are not uniformly located in test tubes. Contrast ratio analysis showed that the most sensitive spectral bounds that maximally sense the harmful agent presence at environment are the ranges in 530 nm and 670 nm. A linear statistical relationship was observed between the plants physiological stress expressed by the pigment content and spectral parameters, that characterizing the leaves ability of light transmission and reflection. From the results of experimental observations followed that changes in the biological and spectral characteristics of a plant depend from a stress duration, a harmful agent concentration and the type of the agent.

Keywords

• remote sensing
• estimation
• vegetation state
• harmful agents