覆膜种植下重金属在土壤-莴苣的迁移特征

Migration characteristics of heavy metals in the soil and lettuce system under mulching

通过田间种植莴苣试验,研究地膜覆盖对农田土壤中重金属迁移转化的规律。结果表明,地膜覆盖能有效降低重金属向地上部分转移,在同等种植方式下,通过地膜覆盖,Cu、Fe、Zn、Pb和Cd以残余态的方式被吸附在土壤中,其在土壤中的含量分别增加了1.5、4.6、3.8、0.2、0.1 mg/kg;而在莴苣植株中的Cu、Fe、Zn、Pb和Cd以游离态转移到土壤中,茎内的Cu、Fe、Zn、Pb和Cd分别减少0.6、16.8、10.8、0.03、0.01 mg/kg,叶内的分别减少0.09、5.5、2.3、0.16、0.03 mg/kg。结果表明覆膜使重金属以残余态的方式被大量吸附在土壤中,可以提高莴苣的产量,且食用安全性显著提高。

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