类水滑石化合物（LDH）对土壤磷素行为影响的实验研究

【作者】 张晓伟；

【导师】 李剑超；

【作者基本信息】 陕西师范大学 ， 水土保持与荒漠化防治， 2010， 硕士

【摘要】 土壤中的磷素在农业生产中占据着重要的地位,它的含量和形态不仅会影响土壤的性质,而且还会影响到植物的生长状态。由于人为乱砍滥伐、扩大建设用地和大量使用化学肥料等行为,造成了土壤质量的下降和土壤中磷素的流失。并且在雨水等流水作用下部分磷素会被带入水体,增加水体中的磷含量,加剧河流湖泊的富营养化和地下水的污染。为了缓解此类问题,出现了包膜肥料和各种土壤改良剂,但是这些方法都有各自的不足。为了提供更多解决思路,本试验拟从施加磷肥的源头入手,通过在实验室制备类水滑石化合物(LDH),利用它的阴离子可交换性,对施加到土壤中的磷进行吸附和解吸的调节作用,从而减少被土壤永久固定而成为无效磷的含量和被雨水溶解而带走的磷肥含量。同时LDH缓慢释放磷,调节土壤中磷含量在时间上的分布,以提高磷素对植物的有效性。试验首先在Mg/Al摩尔比为3：1,溶液温度为75℃和溶液pH为10.5的条件下完成Mg/Al-CO3-LDH样品的制备。然后将制成的样品通过XRD和SEM测试并对其进行特征分析,样品表现出明显的水滑石特征峰和较好的层状晶体结构,说明样品已经具备LDH结构；然后在实验室中,将LDH样品与磷分别加入到土壤中,在饱和含水条件下观察在不同阶段土壤中易解吸磷含量的变化,并与未添加LDH的土壤进行对比；其次将Ca2+、Cl-、CO32-、NO3-、SO42-、腐植酸和pH等作为影响因子,按不同含量分别将各因子添加到水溶液和土壤中。研究在这些因子的影响下,LDH和磷在溶液中和在土壤中的关系,以及影响作用的大小；最后进行野外实验田试验,在两块试验田中分别添加相同含量的磷,其中一块添加定量的LDH。长时间观察LDH在实际土壤环境中对磷素的影响情况,并对比两块试验田的含磷量。因为LDH具有阴离子可交换性,即LDH具有吸附阴离子的能力,而活性较强的其他阴离子又可将其中的阴离子替换出的性能。LDH对于PO43-、HPO42-和H2PO4-等具有吸附作用,在较强活性CO32-的作用下会使磷酸根等阴离子产生脱附。在这种作用下实验结果表明：在饱和含水土壤中,Mg/Al-CO3-LDH最高时可将土壤中易解吸磷的含量提高2倍。通过向土壤中施加各种影响因子后发现,Ca2+、CO32-、pH和腐植酸的含量对LDH和磷的关系影响比较大,而Cl-、NO3-和SO42-影响比较小。将Mg/Al-CO3-LDH施加到试验田后发现,在含LDH的试验田中,易解吸磷含量始终比未添加LDH的试验田中多,最高时是其的1.3倍,使得易解吸磷在土壤中含量增加和停留时间延长,提高了磷的有效性和利用率。由于LDH具有上述特性,使其在土壤中对施入的磷肥起到了缓释的作用。对磷肥的节省、延长磷对作物的供应时间、土壤的保护和对水体富营养化的缓解都起到一定的积极作用。更多还原

【Abstract】 The phosphorus in soil Occupies an important position in the agricultural production. The quantity and conformation of phosphorus may affect not only the quality of the soil but the growth of plants. Some wrong actions, such as deforestation, expansion of building and overfertilization, lead to soil degradation and erosion of phosphorus in the soil. At the same time, the phosphorus in soil may flow into the waters with rainwater. Therefore, the increase of phosphorus intensifies the pollution of the rivers, lakes and the underground water. In order to solve those problems, coated fertilizer and all kinds of Soil conditioner were invented and used. But there are some shortcomings on those inventions. In order to provide more solutions solve those problems, LDH that has exchangeable property of anion was synthesized in the lab and was mixed in the soil. Phosphate was adsorbed and desorbed by LDH. As a result, some phosphorus that were fixed in soil and taken by the rainwater are reduced. At the same time, LDH can release phosphorus to soil, regulate the content of phosphorus at the different period, and improve the validity of the phosphorus for the growth of the plant.Test procedures follow like this. First, Mg/Al-CO3-LDH was synthesized on conditions that moore ratio of Mg/Al was 3:1, that solution temperature was 75℃and solution pH was 11. Second, the sample was proved and analysised by XRD and SEM. The results of analysis showed that the sample with better lameller structure and characteristic peak of hydrotalcite is LDH. Third, LDH and phosphorus were fixed into soil. Then readily desorbable phosphorus (RDP) in the soil was determined under conditions of water saturated soil and At the different time. And the result was compared with the soil withou LDH. Forth, some anions were taken as effective factors, Ca2+、Cl-、CO32-、NO3-、SO42-、pH and Humic Acid, and were mixed separately with solution and soil in the lab. So as to research the relationship and effect between LDH and phosphate in solution and soil. Finally, LDH was mixed in experimental fields and was researched the relationship with phosphorus for a long time. And the result was compared with soil without LDH.LDH has the abilities of adsorption and desorption according to the exchangeable property of anion in the LDH. For example, PO43-,HPO42- and H2PO4- may be adsorbed by LDH and were displaced by other active anions such as CO32-. According to the property, It was found that Mg/Al-CO3-LDH can raise the content of the RDP to three times. After put LDH into soil, the results showed that Ca2+、CO32-、pH and Humic Acid have a stronger influence on the adsorption and desorption of LDH than other effect factors in the lab. In fields, the soil had more. RDP in the experimental fields with LDH (L-soil) than the experimental fields without LDH (Soil). The large discrepancy of RDP is about 1.5 times. And RDP was kept for longer time in the L-soil and availability of RDP was improved.The propertiesof LDH in the soil make positive contribution that phorphosus are slow-released and saved, that plants may get more phorphosus which can preserve the soil and reduce eutrophication to water.更多还原