Dissertation > Environmental science, safety science > Environmental Quality Assessment and Environmental Monitoring > Environmental monitoring > Soil monitoring

Study on the distribution characteristics of rare earth elements in soil of Gannan navel orange orchard

Author ZhongLinSheng
Tutor LiXun
School Gannan Teachers' College
Course Organic Chemistry
Keywords ICP-AES Microwave digestion Soil Rare earth element
CLC X833
Type Master's thesis
Year 2012
Downloads 118
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Rare earth elements (REEs) are important nutrient for plant growth and development, andrare earth elements can promote plant growth and development, increase fruit production, improvefruit quality and enhance plant disease resistance. Application of rare earth elements in agriculturehas been more and more wide after development of decades. Gannan area of Jiangxi provinceriches in leaching type of rare earth ore, and the state of rare earth elements are easily absorbed byplants. Gannan is also an important production base of navel orange, which is famous for highquality due to the unique soil conditions, navel orange fruit is orange-red, large, peel thin, and thejuice rich, sweet and fragrant. Therefore, the study of soil REE contents in Gannan navel orangeorchard is important for the Gannan navel orange production. To solve this problem, the methodsto determine rare earth elements are particularly important. In this paper, La, Ce, Nd, Sm, Eu, Gd,Tb, Yb, Lu and Y in soil were determined by inductively coupled plasma emission spectrometrywith microwave digestion and precipitation twice. The method has been successfully applied todetermine the concentrations of ten rare earth elements in soils of navel orange orchards inSouthern Jiangxi province. The distributions of the rare earth elements in orchard soils wereinvestigated based on the concentrations of REEs, and the relationships between the content of therare earth elements and the types of soil, pH values and organism contents were discussed. Detailsare as follows:Chapter I: Review. The properties, measurement methods and applications of the rare earthelements were reviewed, and the significance of this work was introduced.Chapter II: The pretreatments of the soil samples. Microwave digestion system was used forthe preparation of soil sample solution with a mixture acid of HF, HNO3and HCl, and twiceprecipitations were performed to remove most of the matrix elements in soil sample solution.Chapter III: The optimization of ICP-AES conditions for the determination of REEs. Spectralinterferences of La, Ce, Nd, Sm, Eu, Gd, Tb, Yb, Lu and Y existed in the method of inductivelycoupled plasma-atomic emission spectroscopy were investigate in detail for the selection ofspectral lines. The results to detect the soil standard reference materials (GSS-4, GSS-5) showedthat measured values were all in range the standard value allowed and consistent with the standardvalue, indicating that the method was accurate and reliable. The detection limit of each elementrang from0.2to38.2μg L-1, and the relative standard deviations were in the range of0.8%-3.2%.Chapter IV: Study on the distribution characteristic of the rare earth elements in soil samplesfrom orchards in Ganzhou. The established method has been successfully applied to determine thecontent of rare earth elements in soil samples from orchards in Ganzhou, and the distribution ofrare earth elements in the different types soil were explored. The results showed that the total concentration and a single type of REE in orchard soil both conform following rule: redsoil>purple soil>paddy soil>yellow soil. The REE contents in different types of soil are different.In addition, the contents of some rare earth elements in the soil had obvious relationships with thepH value and organism contents.

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