Two hyperspectral indices for detecting cadmium and lead contamination from arice canopy spectrum

Abstract

Neither Cadmium (Cd) nor lead (Pb) is necessary for crop growth, and they both cause severe soil pollution in many countries. A cross-stress experiment was designed to investigate the feasibility of diagnosing the type and the level of Cd-Pb cross-stress by observing rice canopy hyperspectral images. Two-way analysis of variance and random forest algorithm were employed to select the sensitive indices for Cd-Pb cross-stress diagnosing. Following the exploration of bandwidth expansion from 1 to 20 nm, the final sensitive indices were proposed. We proposed two indices for distinguishing the two heavy metals named: the cadmium stress vegetation index (CSVI) and the lead stress vegetation index (LSVI). The diagnostic accuracies of CSVI distinguishing the four different Cd-stressed levels (0, 2, 5, 8 mg L −1 ) reached 0.85, 0.92, 0.96, and 0.92, respectively, while the precision for four Pb-stressed levels (0, 50,