Phytoextraction of cadmium-contaminated soils: comparison of plant species and low molecular weight organic acids

Abstract

To select suitable plants for phytoextraction of Cd-contaminated soils, we evaluated the phytoextraction potential of five local Cd-accumulators: Amaranthus hypochondriacus L., Solanum nigrum L., Phytolacca acinosa Roxb., Celosia argentea L., and Sedum spectabile Boreau. The plants were grown in three naturally contaminated soils with different total Cd levels (1.57, 3.89, and 22.4 mg kg⁻¹). Throughout the experimental period, no plants showed any visible symptoms of metal toxicity. The Cd uptake of C. argentea was the greatest in the S-YS soil (105 μg plant⁻¹) and among the greatest in the S-HC soil and S-TJ soil. Besides, C. argentea exhibited the highest bioconcentration factor (12.3) in three soils. To improve the phytoextraction efficiency of C. argentea, we applied four low molecular weight organic acids (LMWOAs): tartaric acid, malic acid, oxalic acid, and citric acid. Malic acid was more effective in enhancing Cd uptake by C. argentea than the other LMWOAs. Therefore, C. argentea may be a potential choice in actual remediation projects. Moreover, application of malic acid is an effective way to increase the phytoextraction efficiency of C. argentea.

Keywords:

• Cadmium
• Celosia argentea L.
• low molecular weight organic acids
• malic acid
• phytoremediation

Additional information

Funding

This research was sponsored by the National Science Foundation of China (41867022; 51638006), the National Key Research and Development Project of China [2018YFD0800704], the Guangxi Science and Technology Major Project [GuiKe-AA 17204047 and GuiKe-AD 18126018], the Natural Science Foundation of Guangxi [2018GXNSFAA138202], the Special Foundation for “Ten, Hundred and Thousand Talents Project” of Guangxi Province of China [2016207], Program for High Level Innovation Team and Outstanding Scholar of Universities in Guangxi [GuiCaiJiaoHan[2018]319], and Basic Ability Improvement Project for Young and Middle-Aged Teachers in Guangxi [2019KY0295].