Visualization of copper(II) in velvet mesquite (Prosopis Juliflora-Velutina) and soybeans (Glycine max) by earth field magnetic resonance imaging

Abstract

The goal of this research was to visualize the uptake of copper by plants to promote phytoremediation. The hypothesis was that regions of the plant that contain more copper have enhanced nuclear magnetic resonance using copper as a paramagnetic contrast agent. Earth field magnetic resonance imaging (EFMRI) spectrometry uses a magnetic field 300,000 times weaker than a 600 MHz nuclear magnetic resonance spectrometer. As in conventional human MRI, this portable instrument is capable of recording one, two, and three dimensional images, although the sample size is reduced. The enhancement of signal was first demonstrated recording the two dimensional images of different concentrations of aqueous copper sulfate. The study also focused on growing mesquite and soybean plants in hydroponic media containing 0.25 mM copper nitrate for four and three weeks, respectively, and recording their EFMRI images with plants grown without copper nitrate. The results showed that EFMRI allows the probing the plant absorption of copper without having to dissect the specimen and therefore requires less sample preparation and time than current techniques. This technique may be beneficial to phytoremediation by imaging plants to evaluate their copper accumulation.