1种钝化剂对3种水稻生长影响及降镉效果的研究

Effect of a kind of passivator on growth of 3 rice varieties and cadmium reduction

为了考察钝化剂对不同程度污染土壤及不同水稻品种的适应性,采用盆栽试验研究了2种程度镉污染农田土壤(轻度污染土壤和重度污染土壤)中钝化剂的修复效果以及3个品种水稻对镉的吸收。结果表明:添加钝化剂后,2种污染程度土壤的pH值在不同时期均显著提高(轻度污染土壤pH值提高了0. 18～0. 73,重度污染土壤pH值提高了0. 42～0. 71),土壤中pH值与土壤有效态Cd呈负相关性(轻度污染土壤的pH值与土壤有效态Cd相关系数为0. 77;重度污染土壤的pH值与土壤有效态Cd的相关系数为0. 91)。2种程度镉污染土壤分蘖期和成熟期的有效态Cd在施加钝化剂后明显降低(轻度污染土壤有效态Cd在分蘖期的最大降幅为30. 69%,在成熟期的最大降幅为25. 69%;重度污染土壤有效态Cd在分蘖期的最大降幅为6%,在成熟期的最大降幅为7. 5%)。糙米总Cd在施加钝化剂后也明显降低(轻度污染土壤的糙米总Cd降低幅度为59. 46%～66. 67%,重度污染土壤的糙米总Cd降低幅度为18. 71%～57. 60%)。施加钝化剂对水稻株高、叶绿素、有效穗、生物量及产量无显著性差异。此外,3个水稻品种的糙米Cd富集系数有一定的差异,2种污染程度土壤中水稻生长有差异。因此,钝化剂对3种水稻品种均具有降镉效果,且对3种水稻生长无负面影响。钝化剂对水稻生长轻度镉污染土壤的修复效果优于重度污染土壤的修复效果,施用钝化剂能使轻度污染土壤中糙米总Cd达标,不能使重度污染土壤中糙米总Cd达标;轻度污染土壤中水稻生长效果明显优于重度污染土壤中水稻生长。

A pot experiment has been conducted in this paper to investigate the effects of a passivator on the remediation and absorption of Cd in the different varieties of rice crops.The results demonstrate that when the passivator is added to the paddy soil,it would be possible to increase significantly the pH value in different levels of the polluted soil.For instance,the pH value can be raised by a rate of 0.18-0.73 units in the slightly polluted soil and 0.42-0.71 units in the severely polluted soil.The pH value of the soil nature has been found negatively correlated with the bioavailable Cd in such a degree that the correlation coefficient between the pH value and the bioavailable Cd tends to be 0.77 in the slightly polluted soil and 0.91 in the severely polluted soil.What is more,the bioavailable Cd concentration tends to be lowered when the passivator is added for the different stages.Literally speaking,in the slightly polluted soil,the most severe decline can be as high as to 30.69%at the tillering stage whereas 25.69%of decline during the mature stage.More exactly speaking,for the severely polluted soil,the greatest decline can be as high as to 6%at the tillering stage and 7.5%at the mature stage.The Cd concentration for the brown rice has also been found obviously decreased when the passivator is added:for example,with the slightly polluted soil,the decline can be made by as much as to 59.46%-66.67%,whereas in the case of the severely polluted soil,the decline has been declined by as much as to 18.71%-57.60%.Nevertheless,no obvious change can be found in the plant-growing height,the chlorophyll,the effective panicle,the biomass and the harvested yield between the CK and the treatments consequence by the passivator addition.And,in spite of what is said above,there has also been found a certain difference in the concentration coefficient of the Cd content rate with the brown rice among the different rice varieties,an obvious difference is in the rice growth at the different levels of the soil pollution.Hence,it can be concluded that the passivator should be in a position not only to reduce the bioavailable Cd concentration,but can also bring about no negative effects on the rice growth in the 3 rice varieties at the different levels of the polluted soil.From the results of the above mentioned experimental tests,the remediation effects of the passivator in the slightly polluted soil prove to be better than those with that of the severely polluted soil.The Cd concentration of the brown rice in the slightly polluted soil tends to reach the GB 2762-2012 food safety national standard contamination limit when the passivator has been added than in not severely polluted soil.Thus,the effects of rice growth in the slightly polluted soil turn out to be better than those of the severely polluted one.