Research Of Risk Control Technology On Heavy Metal Contaminated Farmland

As the situation of heavy metal pollution has become more serious,how to efficiently control contaminated Farmland and realize the safe utilization of farmland is of great significance.This test takes the heavy metal Contaminated Farmland as the research object to realize the risk control of the heavily contaminated farmland by adjusting plant structure.Two groups of compound passivators(silkworm excrement compounded with reduced iron powder(SiFe2),silkworm compounded with illite soil and reduced iron powder(SiYiFe2))which had good passivation effect on various heavy metals were selected through the previous experiments.Meanwhile,four kinds of plants(Helianthus annuus Linn,Tagetes patula L,Cymbopogon citratus and Morus alba Linn.Sp)with larger biomass,faster growth and strong tolerance to heavy metals was selected.The pot experiment was carried out to investigate the effects of the compound passivators with different plants on the basic properties of the soil,the contents of available heavy metals,the plant growth and the accumulation of heavy metals.The purpose was to explore a risk control technology suitable for the heavy metal polluted farmland and realize the safe utilization of farmland.The main research results are as follows.(1)The application of compound passivators significantly increased the soil pH and catalase activity.Compared with CK treatment,the soil pH increased by 0.40 to 1.03 units while the activity of catalase increased by 13.49%to 31.94%.The contents of organic matter in soil with Cymbopogon citratus increased by 3.49%to 4.08%,while the content of organic matter in soil with Tagetes patula L increased by 8.15%when added with SiFe2.The soil organic matter of other two plants did not change significantly.(2)The application of compound passivators reduced the available heavy metals in soil.Compared with CK treatment,the contents of available Cd,Cu,Zn and As in the soil with Helianthus annuus Linn,Tagetes patula L and Cymbopogon citratus decreased significantly after the application of compound passivators,and the contents of available Cu,Zn and As in the soil with Morus alba Linn.Sp were significantly reduced.(3)The application of composite passivators promoted the growth of Helianthus annuus Linn,Tagetes patula L,Cymbopogon citratus and Morus alba Linn.Sp.Compared with CK treatment,the plant height and the biomass of Helianthus annuus Linn,Tagetes patula L,Cymbopogon citratus increased significantly,and the plant height,leaf area and leaf biomass of Morus alba Linn.Sp were significantly higher than that of the CK treatment.(4)Compared with CK treatment,the application of compound passivators improved the stress effect of heavy metals on plants.The addition of S1Fe2 had obviously reduced the heavy metals in the Helianthus annuus Linn.The contents of Cd,Cu,Zn and As in the root,stem and leaf part of the ground were reduced in varying degrees.The contents of Cd?Pb?Cu?As in the root of Tagetes patula L added with S1Fe2 is higher than that in treatment added with S1Y1Fe2.while the contents of Cd?Cu?Zn and As in the stem and leaf of Tagetes patula L had no significance between two treatments.The contents of Cd?Pb?Cu?As in the root,stem and leaf part of Cymbopogon citratus increased significantly,while the content of Cd,Pb,Cu,Zn,As in the leaves of Morus alba Linn.Sp decreased in varying degrees.In conclusion,two kinds of planting models(SiFe2 with Tagetes patula L and S1Y1Fe2 with Morus alba Linn.Sp)suitable for heavy metal polluted farmland were selected in this study to realize the risk control of heavy metal polluted farmland by adjusting the planting structure.