Compound Pollution of Cd, Pb, Cu, Zn and As on Lowland Rice.
Wu Yanyu et al.(Institute of Applied Ecology, Academia Sinica, Shenyang 110015)
The ecological effects of Cd, Pb, Cu, Zn and As on lowland rice were studied in brown earth in the pot and field experiments. When the dosages of the heavy metals added to the soils were close to the Soil Environmetal Standards, lowland rice grew normally in appearence and its yield decreased by 10%. The causes of decrease in yield were that the soil criteria values of Cd and Pb reduced and the uptake of Cd, Pb and Zn by rice seed increased. The concentrations of Cd and Pb in rice exceeded the Food Health Standards, which posed latent danger to human health. There was a synergistic effect in these five elements. The coexistance of Pb, Cu, Zn and As enhanced the activity and desorption of Cd. So, the concentrations of Cd in seed in low dosage treatment exceeded the standard by 37.5%, while these of Cd in high dosage treatment exceeded by 100%.