Elemental mercury accumulation in Eichhornia crassipes (Mart.) Solms-Laubach

The aquatic macrophyte Eichhornia crassipes has great potential for the control of Hg pollution in the environment. The aim of this study was to investigate the capability of E. crassipes to accumulate elemental mercury (Hg-0). The plants were exposed for 30 days to 5, 10, 20, 40, and 80 mg of Hg-0 in a 1-L Hoagland medium with the Hg-0 settled at the bottom of the flask. The roots of the plants did not touch the mercury during the treatment. After exposure, the total Hg (T-Hg) concentrations in the roots, leaves, and stems were measured using a direct mercury (Hg) analyzer. The highest concentrations were found at 80 mg Hg-0 treatment in the roots, leaves, and stems, in that order. The translocation factor indicated a poor capability of Hg to translocate from the roots to the shoots. The relative growth and the root-length inhibition measurements showed that the differences between Hg-0 treatments were not significant. In addition, the treatments negatively affected the chlorophyll concentration. The carotenoid content was found to be significantly different at 20 and 40 mg of Hg-0 in 1 L. Regarding the carbonyl index in root proteins, significant differences compared to control were found at the highest Hg treatment. Based on these results, it was shown that E. crassipes is able to take up elemental Hg from Hoagland medium. However, the Hg-0 treatments did not show a strong stress-response activation mechanism in the evaluated plant tissues.

Automated summary

This study found that the aquatic macrophyte Eichhornia crassipes can accumulate elemental mercury (Hg-0) from the Hoagland medium, with the highest concentrations observed at 80 mg Hg-0 treatment. The translocation of Hg from roots to shoots was found to be poor. The treatments negatively affected the relative growth, chlorophyll concentration, and carotenoid content, but did not activate a strong stress-response mechanism in the evaluated plant tissues.