Chelator complexes enhanced Amaranthus hypochondriacus L. phytoremediation efficiency in Cd-contaminated soils. (December 2019)

• Record Type: Journal Article
• Authors: Wang, Kai; Liu, Yonghong; Song, Zhengguo; Wang, Di; Qiu, Weiwen
• Is Part Of: Chemosphere. Volume 237(2019)
• Publication Date: 2019-12
• Subjects: Degradable chelator -- Phytoextraction -- Amaranthus hypochondriacus L. -- Bioavailable Cd -- Soil enzyme activity; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.124480
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The use of degradable chelating agent to enhance phytoextraction is a promising and low-cost method for remediation of heavy metals-polluted soil. However, very limited information is available regarding the effect of chelating agent combinations on plant growth and its capacity to extract metals. In this study, a pot experiment was conducted to evaluate the applicability of [N, N]-bis glutamic acid (GLDA), nitrilotriacetic acid (NTA), [S, S]- ethylenediamine disuccinic acid (EDDS), and citric acid (CA) alone and in combination to enhance the phytoextraction efficiency of amaranth ( Amaranthus hypochondriacus L.) in two Cd-contaminated agricultural soils (S1 soil 2.12 mg/kg and S2 soil 2.89 mg/kg; the environmental standard value of Cd in agricultural soils in China is lower than 0.8 mg/kg). The results showed that, except for EDDS, other treatments had no obvious effect on plant biomass, and even promoted biomass increase to reach 1.06 (S1), 2.07 (S2) g/pot. The increase in total Cd extraction amount by 5 mM of single chelators GLDA and NTA reached 3.87 and 2.81 (S1), and 3.28 and 2.50 (S2) times that of the control group, respectively. For complexed chelating agents, G-N (GLDA + NTA) combinations (GLDA = 3 mM, NTA = 2 mM) extracted the highest amount of Cd compared with other treatments, reaching 0.36 and 0.52 mg/pot (4.50 and 3.71 times that of the control group), respectively. The order of extraction amount was G-N > GLDA > NTA > G-E (GLDA + EDDS) > G-C (GLDA + CA) > CA (5 mM total Cd concentration). Moreover, soil enzyme activity of G-N treatment increased significantly compared to that of the control group, indicating the great application potential of a composite chelating agent relative to a single chelating agent. Therefore, degradable chelators, especially the G-N combination, can effectively increase the available Cd content and greatly enhance the ability of plants to absorb and transport Cd in soils. Highlights: GLDA and NTA combination can enhance the phytoextraction efficiency of Amaranthus hypochondriacus L. The addition of chelating agent can effectively promote Cd bioavailability in soil. Most chelating agents can increase Cd accumulation by Amaranthus hypochondriacus L. 3 mM GLDA +2 mM NTA combination has the highest amount of extracted Cd in all treatments. GLDA and NTA combined treatment significantly boost soil enzyme activity.