| Experiments was concluded in the field with lettuce to study effect of plastic film mulching on translocation characteristics of heavy metals. Results showed that mulching can effectively reduce the transfer of heavy metals to the aerial part. In greengrocery systems, compared with un-mulched growth, the relative content of high activity Cu, Fe, Zn, Pb, Cd in roots and high activity in stems increased. It indicated that they were easy to translocate from roots and stems into leaves. The activity of Cu in leaves of greengroceries used mulched growth decreased, showing accumulation in leaves. In the same planted way, the concentration of Cu, Fe, Zn, Pb and Cd in the soil increased 1.5, 4.6, 3.8, 0.2, 0.1 mg/kg, while in lettuce stems reduced 0.6, 16.8, 10.8, 0.03, 0.01 mg/kg, and 0.09, 5.5, 2.3, 0.16, 0.03 mg/kg in leaf. Heavy metal are adsorbed on the soil with residual state in the film. It it could be sure that plastic mulching changed form distribution and translocation mechanism of heavy metals, even brought heavy metals accumulate in vegetables, and directly affected the safety quality of vegetable |
