土壤中铅的植物可利用性化学调控研究

针对重庆市蔬菜重金属污染现状，选取Pb为研究对象，通过盆栽试验，探讨石灰、腐殖酸、硫化钠对污染土壤中Pb活性的影响及Pb在植物体内的积累效应。研究结果表明，石灰、腐殖酸、硫化钠均能降低Pb的植物可利用性。不同石灰用量均能明显抑制Pb向植物迁移；在石灰的各种加入量中，10．0g／kg的加入量对Pb的抑制效果最明显，莴笋中Pb质量分数下降了35．7％；在腐殖酸的各种加入量中，2．67g/kg的加入量对Pb的抑制效果最明显，植物中Pb质量分数下降了23．0％；在硫化钠的各种加入量中，0．47g/kg的加入量对Pb的抑制效果最明显，植物体内Pb质量分数降低了23．8％。各种添加剂均能使植物根部Pb的分配系数下降，而茎、叶Pb的分配系数上升。

Regulation of phyto-availability of soil lead by chemical additives

According to the heavy metal pollution of vegetables in Chongqing area, pot experiments were carried out to study the effect of limestone, humic acid, and sodium sulfide on amelioration of Pb polluted soil and on Pb accumulation in plants. The results showed that the three soil additives reduced the phyto-availability of Pb in polluted soils. With the increase in limestone application rates, the content of Pb in plants decreased, and it implied that the movement of Pb to plants was obviously restrained by all the application rates. The contents of Pb in plants was reduced by 35.7%, 23.0% and 23.8% at the application rates of 10.0 g/kg of limestone, 2.67 g/kg of humic acid and 0.47 g/kg of sodium sulfide, respectively. The application of all the chemical additives in this experiment reduced the distribution of lead in root, while increased the distribution in leaves and stems.