Tobacco - The Heavy Metal Cadmium In The Soil System Migration And Transformation Of Its Biological Effects

Study on the tobacco cultivated in the pot shows that if cadmium is added to the yellow-soil at the concentrations of 0.5mg/kg and 1.0mg/kg ,the maximal leaf area and the speed of the new leaf appearance decrease, the roots elongate, the quantity of the unstable root also increases, the dry-material accumulation of the leaf and the roots is inhibited by cadmium added, the dry-material accumulation of the stem is restrained largely by the high-concentration of cadmium compared with the low-concentration of cadmium. The capacity of cadmium in the tobacco is: leaf＞root＞stem, in the same tobacco plant, the low leaf＞the middle leaf and the high leaf. With the growth of the tobacco, the capacity of cadmium will decrease in all the organs. The cadmium capacity of the leaf, root and stem will be enhanced as the pollutant concentration of cadmium is enhanced. Cadmium is easy to be transferred in tobacco, and the transferring coefficient＞1. The result of the potted tobacco also shows that, the vertical mobility ability of cadmium is small, if cadmium is added into the yellow soil at different concentration, the quantity of the exchange-cadmium, the combination-cadmium and the remnant-cadmium increases according to the added concentration; the proportion of the exchange-cadmium will increase, but the proportion of the combination-cadmium and the remnant-cadmium will decrease. It is easy for the cadmium to accumulate in the leaf of the tobacco, and the accumulation coefficient＞1, as the increase of the cadmium concentration in the soil, the concentration in the leaf increases too, so does the accumulation coefficient, respectively 5.05 and 6.25.