Halophyte Halogeton glomeratus, a promising candidate for phytoremediation of heavy metal-contaminated saline soils

Abstract

Phytoremediation by halophytes has been widely advocated as an alternative approach to remediate salt-affected and heavy metal-contaminated soils. The present study was the first to evaluate the phytoremediation potential of halophyte H. glomeratus in heavy metal-contaminated saline soils using a field trial. H. glomeratus seeds were sown in heavy metal-contaminated saline soil plots and plots without plants were used as the control. The effects of phytoremediation on heavy metal-contaminated saline soils were measured in the following parameters: the plant performance in heavy metal-contaminated saline soil, the exchangeable cation and heavy metal composition of salt samples, the selected chemical properties in soil after planting H. glomeratus, and the oil composition and content in seeds. After one growth season, the survival of plants, dry biomass, seed, and total salt yields of plants were 92.36%, 9806.30 kg ha−1, 619.81 kg ha−1, and 2105.35 kg ha−1, respectively. A large amount of salts and heavy metals accumulated in H.glomeratus plants growing on the heavy metal-contaminated saline soil plots. The salt samples extracted from H. glomeratus plants showed high Na levels (83.33%) and heavy metal concentrations, including Cr, Ni, Cu, Zn, As, Cd, and Hg. After sowing H. glomeratus seeds in heavy metal-contaminated saline soil plots, the levels of salt, Na, and heavy metals in test soils were significantly decreased compared with unsown plots. In addition, the oil content of seeds harvested from H. glomeratus was 19.2% and contained 91.8% unsaturated fatty acids. Our pilot results showed H. glomeratus can potentially hyperaccumulate not only salts but also heavy metals, and the seed oil contained a favorable ratio of fatty acids. Therefore, H. glomeratus is a promising candidate for phytoremediation of salt-affected and heavy metal-contaminated soils.