Study On Purification Ability Of Six Aquatic Plants To Heavy Metals In Water

With the continuous development of economy and industry,the pollution of heavy metals in water has become increasingly serious.Aquatic phytoremediation technology of heavy metal polluted water has attracted people’s attention because of its economic,high efficiency,and environmental protection advantages.This article was to explore the purification effect of common aquatic plants on heavy metals in water bodies.Six aquatic plants including Pistia stratiotes,Eichhomia crassipes,Canna indica,Iris pseudacorus,Ceratophyllum demersum and Myriophyllum spicatum were chosen to operate a hydroponic experiment.This experiment was expect to test the removal rate,transfer enrichment coefficient and physiological indicators in water by 6 aquatic plants and their combinations.The optimal aquatic plants and combinations were selected,and a model for simulating the absorption of heavy metals by aquatic plants per unit was established.The main research results are as follows:(1)After 70 days of purification test of aquatic plants,different single aquatic plants showed different removal abilities to 4 kinds of heavy metals.As time went by,the removal rate increased continuously.Myriophyllum spicatum had the best removal effect on Hg,with a removal rate of 94.77%;Eichhornia crassipes had the best removal effect on Co,with a removal rate of 94.86%;Eichhornia crassipes had the best removal effect on Cu,which is removed at different concentrations.The rate could reach 100%.Myriophyllum spicatum,Pistia stratiotes,Iris pseudacorus,Canna indica also had good removal effects;Eichhornia crassipes had the best removal effect on Mn,with a removal rate of 99.53%.(2)In the aquatic plant combination group,B5 had the best removal effect on Hg,with a removal rate of 93.56%;B4 had the best removal effect on Co,with a removal rate of 94.59%,and various aquatic plant combinations had good removal effects.;B4 had the best removal effect on Cu,with a removal rate of 100%,and various aquatic plant combinations had extremely strong removal effects;B4 had the best removal effect on Mn,with a removal rate of 99.47%,and various combinations of aquatic plants had good removal effects.(3)The concentration of heavy metals in water had a certain effect on the purification ability of aquatic plants.At low concentrations of Co,Cu,and Mn,combined aquatic plants had the best purification ability,and were significantly different from medium and high concentrations;at low concentrations of Co and Mn,A single aquatic plant had the best purification ability,and it was significantly different from medium and high concentrations.(4)Six kinds of aquatic plants showed different enrichment abilities for different heavy metals.The submerged plant Ceratophyllum demersum had the strongest enrichment capacity for these four heavy metals,and the comprehensive enrichment coefficients for Hg,Co,Cu,and Mn are 436.42,1178.05,1527.51,and 1814.65,respectively.(5)The six aquatic plants showed different transfer abilities to different heavy metals.The 4 kinds of emergent and floating water plants had weak transfer ability to Hg,and most of them were less than 1.Eichhornia crassipes has the strongest transfer ability to Co,followed by water lotus,and Iris pseudacorus had the worst transfer ability and cannot transfer Co to the ground;The 4 kinds of emergent and floating water plants had weaker transfer ability to Cu;Pistia stratiotes had the strongest transfer ability to Mn,followed by Canna indica,and Eichhornia crassipes had the worst transfer ability.(6)As the concentration of heavy metals increases,the contents of K and P in aquatic plants showed a continuous downward trend.At the same time,there was a negative correlation between the heavy metals in aquatic plants and the nutrient elements K and P.As the concentration of heavy metals increases,The biomass growth of each group of aquatic plants was continuously decreasing.Heavy metals had a stress effect on the growth of aquatic plants.