Absorption and Accumulation of As and Cd in Tea

Through field investigations and pot trials,it was found that As and Cd was low in mobility in tea plant.Most of the As and Cd absorbed by the plant is fixed in feeder roots and only a small amount is transported to above ground parts.Distribution of As and Cd,based on their concentrations per unit dry matter,in tea plants growing on un-contaminated soil,is in the order as feeder roots>stems or main roots>old leaves>young leaves.When tea plants were growing on polluted soils,simulated by addition of salts of these two metals,feeder roots possibly acted as both buffer and defense,inhibiting As and Cd from moving up to above ground parts.The concentration of Cd from 6 to 20 mg·kg^-1 in soil was significantly and negatively correlated with chlorophyll content,photosynthetic rate,transpiration rate and biomass production rate of tea plants,whereas the concentration of As from 50 to 200 mg·kg^-1 was first negatively,but late little correlated.