Abstract: Heavy metal is a typical pollutant in aquatic ecosystem. The ions of heavy metals enter food chain resulting in healthy risks. Phytoremediation is emerging as the most potential technique of removing heavy metals due to its low expense and high efficiency. Toxic metals can inhibit plants growth, destroy the cell structure of plants , reduce enzyme activity and affect respiration and photosynthesis of plants. But the aquatic plants also suffer from heavy metal pollution to some degrees. The mechanism of removing heavy metals by aquatic plants is simply summarized from four aspects in this paper: phyto uptake, bioaccumulation and activities of rhizosphere microorganisms and removal by root system. Furthermore, factors affecting the removal efficiency are analysed, including pH, temperature, and soil characteristics. The study provides an overall theoretical basis for alleviating metal pollutions by using aquatic plants. Meanwhile, the prospects and several problems of the removal mechanism and the response of plants are presented.

Key words: aquatic plants, heavy metal, removal mechanism, ecological environment, physiological response