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

Abstract

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 (Hg0). The plants were exposed for 30days to 5, 10, 20, 40, and 80mg of Hg0 in a 1-L Hoagland medium with the Hg0 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 80mg Hg0 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 Hg0 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 40mg of Hg0in 1 L. Regarding the carbonyl index in root proteins, significant differences compared to control were foundat the highest Hg treatment. Based on these results, it was shown that E. crassipes is able to take up elementalHg from Hoagland medium. However, the Hg0 treatments did not show a strong stress-response activation mechanism in the evaluatedplant tissues.