Study On Phytoremediation Technology Of Cd Pollution And Cd And Pb, Zn Combined Pollution Of Alumina

There is serious soil pollution of Cd and Pb,Zn in China,the same result also appears in Shaanxi Province,as the main mining area.Among several remediation methods about heavy metal pollution,phytoremediation has obvious advantages such as less secondary pollution and lower economic cost,and is often chosen as the main method of heavy metal contaminated soil.Brassica juncea,Bidens pilosa,alfalfa,Artemisia lavandulaefolia respectively have some kinds of characteristics to repair heavy metals in soil.In strengthening measures of phytoremediation,the chelating agents can change the form of heavy metals and different nitrogen forms can change the pH of soil,which can strenthen the ability for plants to uptake more heavy metals.In this paper,we mainly studied the effects of four plants on the remediation of Cdand their contaminated soils with Pb and Zn,as well as the promoting effects in different chelating agents.Based on the above experimental processes,the following conclusions are mainly obtained in this work:(1)There is no significant relationship between seed germination rate of Brassica juncea,Bidens pilosa and concentration of heavy metals in soil,but high concentration of heavy metal pollution has negative relationship with the germination rate of Artemisia lavandulaefolia and Alfalfa.The more growth of concentration,the more serious impacts will be.(2)Brassica juncea,alfalfa,Bidens pilosa,Artemisia lavandulaefolia can maintain normal growth in Cd,Cd-Pb,Cd-Zn or Cd-Pb-Zn polluted soil.With the increase of heavy metal concentration,it shows that a positive effect on Brassica juncea,alfalfa,Artemisia lavandulaefolia,while there are some negative effects on the growth of Bidens pilosa.The addition of different kinds of nitrogen fertilizers doesn’t promote the growth of Artemisia lavandulaefolia,and ammonium nitrate in the soil can inhibit the growth of Brassica juncea.The addition of EDTA and citric acid at the later stage of plants growth does not affect the plant height,but it has an effect on plant fresh weight.(3)In this experiment,the plants show the following regularity for the enrichment of Cd.,for Cd,Cd-Pb and Cd-Zn,Cd-Pb-Zn pollution soil,the repair effect is Bidens pilosa>Brassica juncea>Artemisia lavandulaefolia>alfalfa;Bidens pilosa>Artemisia lavandulaefolia>Brassica juncea>alfulfa;Brassica juncea>Bidens pilosa>Artemisia lavandulaefolia>alfalfa,especially.(4)The remediation of Pb in the soil of the Cd-Pb and Cd-Pb-Zn combined pollution is as follows:Bidens pilosa>Artemisia lavandulaefolia>Brassica juncea>alfalfa.In Cd-Zn and Cd-Pb-Zn contaminated soil,the remediation of Zn is Brassica juncea>Artemisia lavandulaefolia>Bidens pilosa>alfalfa.(5)The absorption of different elements in the same plant is also different.The enrichment coefficient shows that Cd is most easy to be enriched while Pb is the most difficult one.(6)For Cd-Pb-Zn polluted soil,the addition of urea and ammonium nitrate can promote the absorption of Cd and Zn in Brassica juncea,but it has no significant effect on Artemisia lavandulaefolia.EDTA and citric acid can significantly increase the absorption of Pb and Zn in Artemisia lavandulaefolia and Brassica juncea.(7)For Cd-Pb-Zn polluted soil,with "urea plus citric-acid" treatment,Brassica juncea has the best absorption effect on Cd,but Pb and Zn are under "urea plus EDTA"treatment.Artemisia lavandulaefolia has the most enrichment of Cd and Pb in the treatment of "urea plus EDTA",while the highest concentration of Zn is in the treatment of "urea plus citric-acid".Consequently,considering the factors such as biomass,Artemisia lavandulaefolia and Brassica juncea have the best potential in phytoremediation.For Cd-Pb-Zn pollution,the treatment of "urea plus EDTA" has the best effect on promoting the absorption of heavy metals in Artemisia lavandulaefolia and Brassica juncea.