Chemical Behavior Of Lead Added In Soil And Its Biological Effect On Pakchoi

Lead is a kind of typical pollutant, which can be uptake from soil by plant and is harmful to human health. It's significant to protection of environment and human health that understand the distribution of Pb forms in soil and its avalablities to plant.The study fouses on pakchoi planted on yellow cinnamon soil with added lead, to research the distrbution of Pb forms under different added lead levels, and its effects to the pakchoi growth and quality. Meanwhile, we researched the influence of Pb to the pakchoi growth and quality under different fertilizer conditions, and the effects of Pb²⁺ concertration in nourishing liquid. The main research results as following:1.The Ex changeable Pb, Carbonate-bound Pb, Fe-Mnoxide-bound Pb, Organic-bound Pb and Residual Pb achieved comparatively balance after 60 days cultivating, and the contents of Pb forms increased according to Pb levels.2. The Pb content of 100mg/Kg can promote the growth of root, plant height, green weight, but the contract effect strengthened with the high Pb content in yellow cinnamon soil.The Exchangeable Pb(>10mg/Kg) can decrease the green weight,but Organic-bound Pb have the contract effect. The Exchangeable Pb (>10 mg/Kg ) can decrease the plant height, though the Residual Pb have the contract effect. The Exchangeable Pb and Carbonate-bound Pb can promote Pb contents in rape leaves, but Organic-bound Pb can decrease it.The Exchangeable Pb and Carbonate-bound Pb can decrease the absorption of N,P,K obviously, and the effect increased with the added lead levels.When the Pb content is below 100mg/Kg, it can promote the absorption of B,Cu,Ni, while the higher contents' effect are negative. As to Mn,Mo,Zn absorption,negative effect strengthened with higher concertration of Pb.3. Nitrogenous fertilizer, phosphate fertilizer and potassium can promote the growth of root,plant height,green weight when additived the same Pb contents in yellow cinnamon soil.Nitrogenous fertilizer can decrease the absorption of Pb,and the effect strengthened when the fertilizer content increased . The Pb content increased 0.1mg/Kg when under 0.06g Na(H₂PO₄)₂/Kg,and it decreased 0.1mg/Kg when under 0.12g Na(H₂PO₄)₂/Kg . Potassium can decrease the absorption of Pb.Nitrogenous fertilizer can promote the absorption of element B,Mn, Zn ,Mo ,Ni, ,and it has negative effect to Cu of pakchoi, and the trend is clearer when the nitrogenous fertilizer quality increased in the Pb added soil. Phosphate fertilizer and potassium can promote absorption of B,Mn,Zn ,Mo,Ni,Cu in pakchoi .And the stimulative effect is clearer when the fertilizer contents increased when Cu content declined.4. Concertration of 5mg/L Pb²⁺ can promote the growth of root,plant height,green weight,but the contract effect strengthened for the high concertration Pb²⁺ in nourishing liquid.There are obviously minus relativity between green weight,plant height,NPK contents of pakchoi and the Pb²⁺ concertration. There are obviously relativity betweenPb content of pakchoi and the Pb²⁺ concertration.Concertration of 5mg/L Pb²⁺ can promote absorption of B,Cu,and the contract effect strengthened for the high concertration Pb²⁺ in nourishing liquid. There are obviously relativity between Mn,Mo,Zn,Ni contents of pakchoi and the Pb²⁺ concertration.