A Study on Changes of Vegeta tion and Tolerance of Alive Plantto Pb Pollution in the Area around a Lead Smeltery

Because of Pb pollution , the vegetation changed greatly and a large number of p lants died excep t a fewspecies that showed higher tolerance to Pb around a lead smeltery located in Lian-Hua County of J iangxi Province ,China. With investigation and analysis of these changes , some results were obtained as follows: (1) The specieswith higher Pb toleration was in the order of N erium indicum > Clerodend rum cy rtophyllum > Phy tolacca acinosa;(2) Experiments of p lant tolerance to Pb indicated that the stem phloem ofwoody p lantwas the highest one to accumulate Pb from soil , followed by the stalk of herb p lant. In addition, various organs and tissues of p lant showeddifferences in accumulation of Pb. In this paper it was described that the order of up take of Pb was stem phloem >root > leaf > stem xylem in Clerodendrum cyrtophy llum , and N erium ind icum had another order of up take of Pbwhich was stem phloem > root > stem xylem > leaf . These two species had differences of accumulation of Pb between their stem xylems and between their roots. The rate of up take of Pb of N erium ind icum was the highest at thefirst fourmonths during its growing. (3) Because Pb wasmainly distributed within the dep th of 0210 cm of soil andthe way to lead extensiveness of Pb pollution was that Pb followed water to enter streams , rivers and so on , therefore it is necessary to take the measures of construction engineering for revegetation in the district of heavy Pb pollution and at the same time , seedings of fibrous root and seedings of cuttage and seedings of herb p lant are very im2portant to make more effective revegetation and control of Pb pollution.