石灰及其后效对玉米吸收重金属影响的田间实例研究

Effect of Lime on Heavy Metals Uptake by Zea mays and the Persistence of the Liming Effect

通过田间试验方法,研究了在铅锌矿废水污染的土壤上施用石灰1 a后,继续施用石灰和石灰后效处理对后续第1、2季低累积玉米(Zea mays)的产量以及重金属Cd、Pb、Zn和Cu含量的影响,并分析了土壤pH、土壤DTPA提取态重金属含量和土壤重金属全量的变化。结果表明,连续施用石灰和石灰后效均显著提高玉米产量,其中连续施用石灰处理效果最佳,第1季籽粒产量是对照(无石灰)的6倍,第2季是对照的3.8倍。与对照相比,连续施用石灰处理显著降低了2季玉米籽粒Cd、Pb、Zn和Cu含量,石灰后效只能降低第2季玉米茎叶Cd、Pb和Cu含量,而籽粒Cd、Pb含量与对照相比略有升高,说明石灰后效能维持一年半左右。对照处理土壤Cd和Zn全量显著低于石灰处理,可能是土壤中Cd和Zn随着雨水的淋洗向下层迁移造成的。施用石灰可防止Cd和Zn对地下水的污染。

Liming can generally decrease the phyto-availability of heavy metals to the immediately subsequent crop.How long it can maintain of this liming effect is still to be verified.A field experiment was carried out one year after the first liming,to study the continuous application of lime and the residual effects of lime on growth and heavy metals（Cd,Pb,Zn,Cu）concentration of a low-accumulating cultivar of Zea mays in a soil contaminated by waste water from a lead /zinc mine.Changes in soil pH,DTPA-extractable heavy metals contents and total heavy metals contents as affected by application of lime were also determined.Results showed that the yield of the plant increased significantly for both treatments of continuous application and residual effect of lime,but the better treatments was continuous application of lime,where the grain yield was 6 times as the control in the first crop and 3.8 times in the second crop.The treatments of continuous application of lime low-ered the heavy metals（Cd,Pb,Zn,Cu）content significantly in grains as compared with the control.Residual effect of lime did not decrease the heavy metals（Cd,Pb,Zn,Cu）contents in corn grains in the second crop as compared with the control.It showed that the persistence of liming effect was only one and a half years.The soil total Cd and Zn of the control without any lime addition were significant lower than limed treatments,indicating that Cd and Zn in the soil were leached to the deep layer of the soil with the rain water,and the application of lime can prevent the contamination of underground water by Cd and Zn.