Study On Phytoremediation Technology Of Flower Cdmium Hyperaccumulator

Among the many heavy metal contaminated soil remediation technologies,phytoremediation has attracted the attention of researchers for its advantages of low investment,no damage to soil structure and no pollution caused by two times.Among them,it is a hot spot in recent years to use flower type hyperaccumulator for phytoremediation,which has advantages of mature cultivation technology,beautifying environment and not entering food chain.Because of the high p H,the bioavailability of heavy metals in alkaline contaminated soil is low,which greatly limits the development of phytoremediation.In this paper,the effects of plant density on Phytoremediation efficiency were studied by using Cd hyperaccumulator Mirabilis jalapa and Tagetes patula as experimental plants.At the same time,citric acid and tartaric acid were used to improve the bioavailability of Cd in soil and to improve the efficiency of phytoremediation,which provided the basis for phytoremediation of alkaline Cd contaminated soil.Our previous survey results show that heavy metal pollution exists opened the eastern outskirts of the Huafei River sewage irrigation area,the soil p H value of =7.5-8.5 in this experiment,the area selected plots,carry out intensive research work of phytoremediation,the results are as follows:(1)The effect of planting density on the restoration of flower plant PeacockIn the unit area,the biomass of the upper and root of peacock grassland increased first and then decreased with the increase of planting density,reasonable planting density can increase plant biomass.With the increase of planting density,the stems of cadmium content in plant decreased the peacock,however,except for T4 processing,There were no significant differences in cadmium content in other treatments(p>0.05,LSD,test).With the increase of planting density,in the unit area,the amount of cadmium extracted from the upper and the roots of the peacock grassland increased first and then decreased,under the condition of T2(50 strain /m2),the extraction amount of cadmium from peacock grass in the per unit area was the biggest,the amount of cadmium extracted from the upper and the roots increased by 32.93% and 55.77%,respectively.The transfer coefficient of Cd has no obvious change with the increase of planting density,the enrichment coefficient and root enrichment coefficient both increased first and then decreased.Under the condition of T2(50 strain /m2),the accumulation ability of aerial part of Tagetes was strongest,under the condition of T4(80 strain /m2),the accumulation ability of Malachite grass was the worst.(2)The effect of citric acid on the phytoremediation of flower plantsWith the increase of citric acid concentration,the biomass of the overground part and roots showed an increasing trend,the biomass of Mirabilis was the largest at 15mmol/kg;With the increase of citric acid concentration,the cd content in each part of Mirabilis jalapa increased first and then decreased;The amount of cadmium extracted from the overground part and roots increased with the increase of citric acid concentration.Under the 2mmol/kg treatment conditions,the amount of cadmium extracted by mirabilis was the highest;As the concentration of citric acid increased,the enrichment coefficient of aboveground and root increased first and then decreased,and the enrichment coefficients of the shoots and roots were greater than 1 under citric acid intensification.With the increase of citric acid concentration gradient,the biomass of the shoot and root increased first and then decreased,and the biomass of 5mmol/kg treatment was highest;The cadmium content in each site decreased first and then increased with the increase of citric acid concentration;With the increase of citric acid concentration,the cadmium extraction from the upper part and root of the peacock decreased first and then increased,and the citric acid concentration was 15mmol/kg.The amount of cadmium extracted was the largest;With the concentration of citric acid,the enrichment coefficient of cadmium and root decreased first and then increased with the increase of concentration of citric acid in contaminated soil,In the process of transfer of cadmium from soil to ground,malachite grass has super enrichment ability.(3)The effect of tartaric acid on the phytoremediation of flowers and plantsWith the increase of tartaric acid concentration gradient,the biomass of the shoots and roots showed the trend of increasing first and then decreasing,when treated with 0.5mmol/kg,the biomass of Mirabilis was the largest;Under different concentrations of tartaric acid treatment,the content of cadmium in leaves of Mirabilis mirabilis was significantly higher than that of other parts(p<0.05,LSD,text);The amount of cadmium extracted from the upper and the roots of Mirabilis increased first and then decreased with the increase of tartaric acid concentration,the amount of cadmium extracted from 0.5mmol/kg was the highest;The transfer coefficient increases with the increase of tartaric acid concentration,and then decreases with the increase of tartaric acid concentration,the enrichment coefficient of Cd increased with the increase of tartaric acid concentration,under the condition of 5mmol/kg treatment,the accumulation ability of Mirabilis was the strongest.With the increase of tartaric acid concentration,the biomass of the upper and root of the peacock grassland increased first and then decreased,2mmol/kg treatment had the largest biomass of tagetes;The content of cadmium in each part of the peacock grass increased first and then decreased with the increase of tartaric acid,the content of cadmium in leaf was higher than that in other parts,the peacock grass mainland shoot and root of Cd increased with the concentration of tartaric acid showed a downward trend after the first increase,When 2mmol/kg,the amount of cadmium extracted from the peacock grass was the largest;With the increase of tartaric acid concentration,the concentration coefficient of the upper part of peacock grassland increased firstly and then decreased,under the condition of 2mmol/kg treatment,the accumulation ability of peacock grass was the strongest.