Effect of combined pollution of Cd, Pb and Cu on growth and element absorption of Barringtonia racemosa

Objective To explore the effects of Cd-Pb-Cu combined heavy metal pollution on the growth and element absorption of Barringtonia racemosa, and provide a theoretical basis for the application of B. racemosa in the remediation of heavy metal combined pollution wetland.

Method The effects of Cd-Pb-Cu compound pollution on the growth, nutrient uptake, and heavy metal uptake and distribution of B. racemosa were investigated by an indoor pot experiment which simulated wetland environment.

Result The plant height was significantly inhibited under 20 mg·L⁻¹ Cd + 200 mg·L⁻¹ Pb + 400 mg·L⁻¹ Cu, decreasing by 14.20% compared with CK (no pollution), while the growth of ground diameter was not affected under all pollution treatments. Comparing with CK, the total biomass of B. racemosa increased significantly under 5 mg·L⁻¹ Cd + 100 mg·L⁻¹ Cu + 50 mg·L⁻¹ Pb. The contents of N, P and K were not significantly different from CK under all pollution treatments, however, the accumulation of all three nutrient elements in whole plant were significantly higher than that of CK. The contents and accumulations of Cd, Pb, Cu in whole plant were improved under Cd-Pb-Cu compound pollution conditions. With the increase of pollution concentration, the contents and accumulations of Cd, Pb, Cu all showed a trend of increasing first and then decreasing. The correlation analysis showed that K and Cu had more pronounced effects on plant growth and environmental adaptability of B. racemosa than other elements. The integrated transfer coefficient and cluster analysis showed that B. racemosa demonstrated stronger enrichment and transfer ability for heavy metals under 10 mg·L⁻¹ Cd + 100 mg·L⁻¹ Pb + 200 mg·L⁻¹ Cu.

Conclusion B. racemosa has strong adaptability and restoration ability to Cd-Pb-Cu compound pollution water, which can be used for ecological restoration of Cd, Pb, Cu polluted wetlands.