Study On The Relationship Between Heavy Metal Dose Polluted In Soil And Toxicity In Vegetables And Its Control Technology

Three classical soils,paddy soil, brown soil and red soil are adopted to study the root elongation of pakchoi and cabbage, radish and onion, tomato and cucumber in different concentration of Cu, Zn, Pb ,and to demonstrate the toxicity and inhibition of vegetable root in different dose of heavy metal .As the study shows, tomato is the most sensitive to Cu, Zn, Pb in paddy soil, and pakchoi was insensible. Tomato and pakchoi are both the most sensitive to Cu, Zn, Pb, to the contrary, cucumber and radish are the least sensitive in red soil.. Onion is is the most sensitive to Cu, Zn, Pb, while cucumber is not sensitive in brown soil .Different heavy metal inhibits vegetable growth differently , Cu is the most sensitive, Zn,Pb are infer. A significantly negative relationship was found between root elongation and available concentration of heavy metal in the involved soil, which shows the heavy metal concentration is important factor as for inhibiting vegetable elongation. After being compared among three soils at the same concentration level, the sequence of inhibition ratio of heavy metal to tomato and pakchoi elongation is as fellows: red soil is the most sensitive, paddy soil the next, brown soil the last.Heavy metal affects vegetable differently due to different heavy metal's aging time, with time prolonging, vegetable's elongation tends to increase, while heavy metal inhibits vegetable less and less. The account of heavy metal in the soil planting vegetable increaseswhen adding more into the soil, which means when the aging time for heavy metal in soil prolongs, the efficiency of heavy metal will descend. The heavy metal aging tendency is different at different concentration level. The bigger the concentration is, the quicker its aging velocity becomes within 30 days, and the time it reaches steady aging time becomes longer. Different aging time shows distinct toxic effect, it is the most toxiferous on the second day ,and the least toxiferous on the 180th day, which displays when the aging time for the heavy metal in soil becomes longer, its toxicity will descend.A most significantly relationship was found between available metal in the involved soil and heavy metal absorbed by plan(trCu=0.952**, rZn=0.998** ). I t can cut down concentration of heavy metal and improve vegetable biomass, lower the absorption of heavy metal when appendding lime in soil which had polluted by heavy metal(the total content of Cu descend 61.1%,55% at Cu100 ,Cu400 mg?kg-1; when the concentration of Zn in soil at 250,500 mg?kg-1,the total content of Zn descend 82.4%,87.6% ).Especially,it can make the content of heavy metal accord with the sanitation standard of vegetables when we add lime into soil polluted by heavy metal under the two level.So we adds lime into soil polluted by heavy metal in order to better the polluted soil, reduce its poison and ensure vegetable safety.The paper gets sensitive indicating plant for different soil by elongation experiment, and gets EC10,EC50 and EC90 to Cu,Zn,Pb for every vegetable. EC10 can be treated as physeal critical value for vegetable normal growth, if the index is inferior to EC10, the vegetable basically keeps normal growth. Meanwhile, EC90 is the critical value for vegetable′s being poisoned to death, if the index is above EC90 , the vegetable nearly can't vegetate.,which supply us foundation for vegetable safety production.