title: Effects of Reductants on Phytoextraction of Chromium (VI) by Ipomoea aquatica.
abstract: Reductants are often used to reduce Cr(VI) in chemical treatments, yet the effects of the reductants on Cr(VI) phytoremediation are not fully understood. This study investigates the effects of different reductants on Cr(VI) phytoremediation by Ipomoea aquatica in simulated solution with 3 mg L(-1) of Cr(VI), pH0 of 6, and an incubation time of 5 days. Results indicate that the applications of S2O3(2-), Fe0, and Fe2+ at low doses notably increased root Cr concentrations, which were obviously higher than that those in the control (Cr6+ alone). However, high reductant concentrations decreased bioaccumulation of Cr in the roots and shoots of the plant. Statistical results indicate that Cr concentrations were significantly and negatively correlated with Fe concentrations in the roots and shoots of the plant (p<0.05). This suggest that Fe accumulation inhibited Cr accumulation in the plant. A Cr(VI) concentration of 3 mg L(-1) caused short, brown lateral roots with tip necrosis, leaf chlorosis, and noticeable shoot wilting. The leaf necrosis and shoot wilting is caused by oxidative damage of lateral roots by Cr(VI) rather than by the reactive oxygen species generated by the oxidative stress. Addition of the reductants effectively reduced these plant injuries.
authors.affiliation: a Department of Environmental Engineering and Science , Feng-Chia University , Taichung , Taiwan , ROC.
authors.forename: Shan-Shin
authors.initials: SS
authors.lastname: Ton
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Lee
authors.forename: Yin-Hsin
authors.initials: YH
authors.lastname: Yang
authors.forename: Soi-Keong
authors.initials: SK
authors.lastname: Hoi
authors.forename: Wen-Che
authors.initials: WC
authors.lastname: Cheng
authors.forename: Kai-Sung
authors.initials: KS
authors.lastname: Wang
authors.forename: Han-Hsin
authors.initials: HH
authors.lastname: Chang
authors.forename: Shih-Hsien
authors.initials: SH
authors.lastname: Chang
mesh_terms: D001673:Biodegradation, Environmental; D002857:Chromium / Q000737:chemistry / Q000378:metabolism*; D052918:Environmental Restoration and Remediation / Q000295:instrumentation / Q000379:methods*; D027741:Ipomoea / Q000737:chemistry / Q000378:metabolism*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism*
chemical_list: D016877:Oxidants; D012989:Soil Pollutants; D002857:Chromium
keywords: Cr(VI); Ipomoea aquatica; phytoremediation; reductants