重金属在土壤-水稻体系中的分布、变化及迁移规律分析

以佛山市南海区小塘镇和高明区杨梅镇的标准农田为研究对象,分析重金属在土壤和水稻植株不同部位的分布及其随时间变化、迁移规律。结果表明:重金属被水稻吸收以后,多数仍滞留在土壤里,只有少量向地上部分迁移。重金属在水稻植株不同部位的质量分数分布由大到小的次序为:根→茎→籽→叶。水稻地上部分中4种重金属元素分布由大到小的次序是:Zn→Cu→Pb→Cd。水稻分蘖期重金属在根、茎和叶的积累量达到最大,随着时间的延续,在根部积累的重金属就越来越少,茎和叶积累的重金属在拔节期降至最小,随后又慢慢上升。4种重金属在水稻植株中的迁移能力由大到小依次为:Cd→Zn→Cu→Pb,但也有个别情况是Cu的迁移能力大于Zn。

The Regularity of distribution, change and migration of heavy metals in soil-rice plant system

Taking the standard farmlands in Xiaotang town of Nanhai area and Yangmei town of Gaoming area in Guangdong as research object, the authors analyzed the regularity of distribution, change and migration of heavy metals in soil and rice plant. The results indicated that after the heavy metals (Zn, Cu, Pb and Cd) were absorbed by the rice plant, the most was still detained in the underground part, only a little moved to an upper part of rice. The concentration order of heavy metals in the different part of rice was: root> stem > grain > leaf.The distribution sequence of four heavy metals in an upper part of rice plant was: Zn> Cu> Pb> Cd. The concentration of heavy metals in root, stem and leaf reached the highest levels at the time of rice tillering. As time went on, the concentration of heavy metals decreased in root, and it reached the lowest levels in stem and leaf at the jointing growth period, and then increased slowly. The transportation sequence of four heavy metals in rice was:Cd > Zn > Cu > Pb, but also there was indi- vidual Cu> Zn phenomenon.