ANALYSIS ON ENRICHMENT OF AQUATIC PLANTS RESPONSE TO DIFFERENT HEAVY METAL IONS IN POLLUTED WATERTAKING DUCKWEED AS AN EXAMPLE

In order to improve the quality of water, the enrichment of different heavy metal ions by aquatic plants is studied-taking duckweed as an example.The site of the experiment is in Sichuan University of China, mainly from the following aspects of research: the heavy metal content in water, the heavy metal content in duckweed, chlorophyll content, adsorption capacity of Cadmium ions in different concentrations of nitric acid solution, enrichment capacity of Cadmium ion and the relationship between heavy metal content in duckweed and that of water.The study shows that the aquatic plants such as duckweed have a strong enrichment to Cu, Pb and Zn in the complex water body of heavy metals Cu, Pb and Zn, and their enrichment ability is higher than that of the water plants.With the increase of Cd 2+ concentration, the content of chlorophyll a and b in duckweed decreased significantly, and the decline is increased with the increase of Cd 2+ concentration.In 3 mg/L Cadmium nitrate solution, duckweed has a maximum absorption rate of Cd 2+ reaching 87%, the adsorption of duckweed decreased with increasing concentration and the enrichment of Cd 2+ in duckweed showed a nonmonotonic curve with the increase of treatment time.The concentration of Cd 2+ in the duckweed of 8d reached the maximum value (1.6 mg/g), and the concentration of Cd 2+ is reduced in the 9-12d duckweed, the concentration of heavy metals in water is significantly correlated with the concentration of Cu, Pb, Zn and Mn in aquatic plants duckweed.The method can effectively analyze the supposed enrichment.The sensitivity of duckweed can be used to detect changes of heavy metals in water, which can be used as an bioindicator of environmental pollution.At the same time, the accuracy of heavy metal determination by this method is high.