Determination of Cu, Pb, Fe, and Zn in Plant Component Polymers of a Hyperaccumulating Plant

Abstract

Soil contaminated with harmful metals has caused the metal contamination of natural water and drinking water, resulting in negative effects on human society. [1][2][3][4] The treatment of harmful metal-contaminated soil is a major concern of the environmental community.5 Phytoremediation, the use of green plants to clean up metal-contaminated environments, has attracted attention as an environmentally friendly useful metal-extraction technique for treating toxic contaminated soil. [6][7][8][9] This technology has utilized hyperaccumulating plants that absorb harmful metals (Cd, Pb, As, etc.) from contaminated soil, and accumulate in the harvestable above-ground biomass. 10,11 Moreover, the recovery of valuable metals and the production of energy resources, i.e. methane or ethanol, and functional resin from a hyperaccumulating plant are necessary for cost-effective phytoremediation. 12 On the background, techniques for estimation of the metal concentration in hyperaccumulating plants are required for evaluating the degree of metal accumulation of plants. A steam explosion degrading and removing lignin that covered holocellulose (cellulose and hemicellulose) has been reported as an useful pretreatment for the effective utilization of plant biomass, i.e. wood, potato, and bamboo. [13][14][15][16] Furthermore, the steam-exploded product was easily converted into sugars and ethanol by using enzymes and yeast. The steam explosion technique reasonably allows the plant body to be liquefied and separated into plant component polymers.This work improved the determination technique of the metals (Cu, Pb, Fe, and Zn) in plant component polymers of a hyperaccumulating plant, Athyrium yokoscense, by using various methods, i.e. Wayman's extraction method, and the analytical method with ICP emission spectrometry. The Wayman's extraction method liquefied and separated the A. yokoscense fern into four plant component polymers, i.e. the water-soluble material fraction, the holocellulose fraction, the methanol-soluble lignin fraction (low-molecular-weight lignin), and the residual lignin fraction (high-molecular-weight lignin). The metal concentrations in plant component polymers were measured using ICP emission spectrometry for clarifying the distribution of metals in A. yokoscense fern. Experimental Hyperaccumulating plant sampleA fern plant, Athyrium yokoscense, was collected from Ogoya abandoned mine area (Komatsu City, Ishikawa, Japan). The dry plants were separated into the aboveground part (leaves, leaf blade, petiol, and rhizome) and the underground part (roots). Pretreatment methodThe plant samples were hydrolyzed using a steam explosion method. The apparatus for the steam explosion (Japan Chemical Engineering and Machinery, Osaka, Japan) consisting of a steam generator, a high-pressure reactor, a receiver, and a condenser with a silencing action. [12][13][14][15][16] The solid and liquid products of the exploded fern were recovered in a cyclone at the bottom of the receiver, and the gaseous products were passed from the t...

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

“…[21] Techniques for heavy metal quantitative and qualitative analysis vary in the amount of sample preparation required from bulk to surface measurements. [22,23] For bulk and quantitative measurement of metals which require separation of plant parts, drying, and acid digestion [1,9,19] ; atomic absorption spectroscopy [24][25][26][27][28][29] allows single element analysis at low concentrations, [22,30] while the inductively coupled plasma (ICP) [1,6,9,19,[31][32][33] allows analysis of up to 70 elements at low concentrations. [22,30] In general, acid digestion and considerable sample treatment are the disadvantages of these methods.…”