Detection of Heavy Metal Based Stress of Olive Trees Using Hyperspectral Spectroscopy and Chlorophyll Fluorescence: A Case Study of Olive Groves Around the Abandoned Hammam Zriba Mine in Northern Tunisia

Abstract

In the abandoned Hammam Zriba mine site, mine tailings were caused a real desertification phenomenon under the prevailing wind action leading to the invasion of olive trees. Therefore, timely and accurate detection of stressed olive trees may be a critical problem for food safety. Thus, this study aims at detecting the stress of olive trees induced by heavy metal pollution around a particular abandoned mine site through the spectral feature investigation and the using of spectral indices. Results have shown a convergence between olive leaves spectra and the measured chlorophyll fluorescence, which reveals the stress of olive trees. Olive leaves spectra indicate progressive decrease in Near-IR reflectance and the FV/FM ratio (Variable Fluorescence/Maximal Fluorescence ratio) was about 0.773 and 0.3 for stressed olive trees compared to 0.8 for healthy olive tree. Moreover, the correlation between all used vegetation indices and chlorophyll fluorescence was calculated.