三种含钙物质对南方酸性镉污染土壤调酸降镉效应

Effects of three calcium substances in regulating pH and reducing cadmium for acid cadmium-contaminated soil of southern China

  • 摘要: 为验证含钙(Ca)物质对农田土壤酸化改良和镉(Cd)污染的协同修复效果,采用大田试验,研究了3种含钙物质(生石灰、石灰石粉和牡蛎壳粉)对土壤Cd含量、化学性质(pH、阳离子交换量、交换性钙、有机质、速效氮磷钾养分)及其水稻不同部位中Cd含量的影响。结果表明:与对照(CK)相比,施用含钙物质土壤pH上升了1.17 ~ 1.69个单位,其增幅为17.1% ~ 17.8%(P<0.05),以石灰石粉处理的pH值最高;交换性钙含量增加了60.2% ~ 171%(P<0.05);阳离子交换量增加了16.2% ~ 20.0%(P<0.05);有效态Cd含量降低了15.8% ~21.1%(P<0.05);水稻根系、茎秆、叶片、谷壳和糙米中Cd含量分别显著降低了25.6% ~ 38.5%、61.7% ~78.5%、60.5% ~ 88.9%、61.5% ~ 76.9%和47.6% ~ 66.7%(P<0.05),以石灰石粉处理糙米Cd含量最低;且各处理糙米中Cd含量均低于限量标准(≤0.20 mg·kg−1),各处理还显著降低了水稻不同部位中Cd富集系数(P<0.05)。相关性分析表明:水稻各部位中Cd含量与土壤有效态Cd含量呈显著正相关关系(P<0.01),而与土壤pH和阳离子交换量呈显著负相关关系(P<0.05)。施用含钙物质能有效阻止土壤Cd进入水稻体内,显著降低可食部位-糙米中的Cd含量,并以石灰石粉处理“调酸降镉”效果最好。

     

    Abstract: In order to verify the synergistic remediation effect of calcium (Ca) containing substances on farmland soil acidification and cadmium (Cd) pollution, a field experiment was conducted to study the effects of three Ca-containing substances (quicklime, limestone powder and oyster shell powder) on soil Cd content, chemical properties (pH, cation exchange capacity, exchangeable calcium, organic matter, available NPK nutrients) and Cd content in different parts of rice. The results showed that, compared with the control (CK), the application of Ca-containing materials increases soil pH by 1.17 - 1.69 units with a range increase of 17.1% - 17.8% (P<0.05), and limestone powder treatment is with the highest pH value. The exchangeable calcium content and cation exchange quantity increase by 60.2% - 171% and 16.2% - 20.0% (P<0.05) respectively, while the available state Cd content decreases by 15.79% - 21.1% (P < 0.05). Cd content in roots, stems, leaves, husks and brown rice are significantly reduced by 25.6% - 38.5%, 61.7% - 78.5%, 60.5% - 88.9%, 61.5% - 76.9% and 47.6% - 66.7%, respectively (P<0.05). The Cd content of brown rice with all treatments is lower than the limit standard (≤0.20 mg·kg−1) with limestone powder the lowest value. The Cd enrichment coefficients in different parts of rice (P<0.05) are significantly reduced by all Ca treatments. Correlation analysis showed that Cd content in all parts of rice is positively correlated with soil available Cd content (P<0.01), and is negatively correlated with soil pH and cation exchange capacity (P<0.05).The application of Ca-containing substances effectively prevent soil Cd from entering the rice body and significantly reduce the Cd content in the edible part-brown rice. Limestone powder is with the best effect of Cd reduction by acid adjustment.

     

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