Hydroponic phytoremediation of antimony by Tamarix smyrnensis and Nerium oleander

Background: Antimony (Sb) is considered a priority pollutant and its removal from the environment is of great importance. Among the various treatments, phytoremediation is considered an efficient method when the accumulation of this metalloid in plant tissues is sufficiently high. This work focused on removal of Sb(III) from aqueous solution at two Sb concentrations (5 and 10 ppm) and using salt as stressor (100 mmol L-1) only at the lowest Sb concentration (5 ppm). The response of two salt-tolerant plant species - Tamarix smyrnensis and Nerium oleander - was monitored when subjected to Sb-contaminated hydroponic solutions. Results: Plant growth and water content remained unaltered within the 15-day experimental period, while the chlorophyll content declined significantly at the higher Sb level (10 ppm) only for N. oleander. The antioxidant enzymatic activity in T. smyrnensis with respect to guaiacol peroxidase (GPOD) and catalase (CAT) was significantly increased in the treatment under Sb and salt stress. In N. oleander there was a strong increase in GPOD activity by the exposure to Sb, whereas the CAT activity was increased considerably with the presence of salinity. Sb concentration was detected on the surface of the leaves, indicating that excretion occurred in both plants. Increased accumulation was observed in N. oleander in the absence of salinity whereas, under salt stress, Sb accumulation was considerably higher (60%) in T. smyrnensis. Notably, both plants could accumulate a high amount of Sb, preferentially in the roots, with the concentrations in the leaves being significantly lower. Conclusion: The experimental results from this study demonstrate that both plants are suitable for phytoremediation due to substantial Sb accumulation without visible Sb toxicity. (c) 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Automated summary

This study found that Tamarix smyrnensis and Nerium oleander, two salt-tolerant plants, have a strong ability to accumulate Sb(III), thus they can effectively remove Sb from aqueous solutions. Although the higher concentration of Sb (10 ppm) significantly affected the chlorophyll content in Nerium oleander, it didn't have a significant impact on plant growth and water content during the experimental period. Additionally, the study also found that the roots of both plants are more prone to accumulating Sb.