Abstract:

With the increasing level of cadmium pollution in soils, the safety of crops produced in cadmium polluted or slightly polluted fields has attracted much attention. Therefore, more and more researches focus on remediation of cadmium polluted soils and the reduction of the pollution risks of agricultural products. Field experiments were conducted to study the effects of various passivators on soil cadmium and cadmium absorption in wheat and rice grain, including sepiolite, straw biochar, lime, lime coupled with humic acid, lime coupled with sepiolite, lime coupled with sodium metasilicate and magnesium sulfate. Meanwhile, the potential effects of reducing pollution risk for wheat and rice were evaluated. The results showed that combined application of lime and humic acid increased the soil pH of wheat field by 16.8%. Sole application of lime increased the soil pH of paddy field by 3.7%. Combined application of lime, sodium metasilicate and magnesium sulfate reduced the cadmium concentration in wheat grain by 25.8%. Sole application of straw biochar reduced the cadmium concentration in wheat straw by 18.3%. Combined application of lime and sepiolite reduced the cadmium concentration in rice grain and straw by 72.8% and 28.0%, respectively. Furthermore, combined application of lime and humic acid reduced the cadmium transfer coefficient of wheat and rice by 39.7% and 28.0%, respectively. The correlation analysis showed that the relationship between cadmium concentration in wheat grain and straw was a power function, and the cadmium concentration in grain increased slowly with the increase of cadmium concentration in straw. There was a positive linear correlation between the cadmium concentration in rice grain and straw. These results indicate that lime coupled with humic acid is the best passivator treatment for reducing cadmium pollution risks of wheat and rice. In this case, the cadmium concentration in wheat and rice grains were effectively reduced and the physicochemical properties of soil were improved as well.

Key words: soil cadmium pollution, wheat, rice, passivator, pollution remediation

摘要：

在土壤镉污染日趋加重的背景下,镉污染农田生产安全性备受关注,进行土壤镉污染修复和降低农产品镉污染风险成为相关领域的研究重点。该研究通过田间试验揭示不同钝化剂处理（海泡石、秸秆生物炭、石灰、石灰+腐殖酸、石灰+海泡石、石灰+偏硅酸钠+硫酸镁）对土壤镉及小麦和水稻吸收镉的影响,并比较钝化剂对降低小麦和水稻镉污染风险效果的差异。结果表明,石灰+腐殖酸（施用质量比为2:1）能使小麦田土壤pH提升16.8%,单施石灰使水稻田土壤pH提升3.7%;石灰+偏硅酸钠+硫酸镁（施用质量比为20:4:1）使小麦籽粒镉含量降低25.8%;单施秸秆生物炭能够使小麦秸秆镉含量降低18.3%;石灰+海泡石（施用质量比为2:15）能使水稻籽粒镉含量降低72.8%,水稻秸秆镉含量降低28.0%。从不同钝化材料对小麦和水稻镉转移系数的影响来看,石灰+腐殖酸（施用质量比为2:1）能够同时降低小麦和水稻对镉的转移系数,降幅分别为39.7%和28.0%,对两种作物而言是降低镉转移系数的最佳钝化材料。经过对小麦、水稻籽粒和秸秆镉含量的相关性分析可知,小麦籽粒镉含量与秸秆镉含量呈幂函数关系,籽粒镉含量随秸秆镉含量的升高而缓慢增加;水稻籽粒镉含量与秸秆镉含量呈线性正相关关系。选用适当的钝化材料并进行适当处理能够有效降低小麦与水稻籽粒中的镉含量,降低污染风险,同时还可以改善土壤理化性状,起到修复受污染土壤的作用。

关键词: 土壤镉污染, 小麦, 水稻, 钝化剂, 污染修复