【作者】 王文斌；

【导师】 黄建国；

【作者基本信息】 西南农业大学 ， 植物营养学， 2002， 硕士

【摘要】 根据成土母质、土壤类型、人为耕作等因素在云南主要产烟区采集土壤样品，并同步采集烟叶样品和烟叶主产区主要使用的复合肥、钾肥、磷肥等肥料。样品消解后用LS-6500液体闪烁计数仪测量样品中的总α和总β放射性。用低本底γ能谱仪测量样品中的⁶⁰Co、¹³⁷Cs、⁴⁰K、²³⁸U、²³²Th、²²⁶Ra的放射性比活度。同时进行了磷肥用量对烟叶放射性影响的田间试验。 研究结果如下： 1．土壤中放射性核素含量的高低顺序为⁴⁰K＞²³⁸U＞²³²Th＞²²⁶Ra＞¹³⁷Cs，其含量平均值和变化范围分别为⁴⁰K：549．14Bq／Kg，151～1170Bq／Kg；²³⁸U：77．77Bq/Kg，13．8～281Bq／Kg；²³²Th：56．43Bq／Kg，12．3～164Bq／Kg：²²⁰Ra：48．64Bq／Kg，10．2～159Bq／Kg；¹⁵⁷Cs：3．64Bq／Kg，0．488～8．72Bq／Kg。土壤中⁶⁰Co含量低于仪器探测限。各地土壤中的核素含量不一，其中大理的¹³⁷Cs，玉溪的⁴⁰K，红河的²²⁶Ra和²³⁸U，临沧的²³²Th含量最高。 2．土壤中的放射性核素含量变化较大，土壤母质和施肥等因素是土壤中放射性核素的重要来源。成土母质的多样性，地形地貌的复杂性、植物根系的富集性及肥料种类的差异性等因素是造成土壤中放射性核素含量变异较大的主要原因。 3．土壤中⁴⁰K和²³⁸U表现为积累型，²²⁶Ra和²³²Th表现为损耗型。放射性核素的积累与损耗与肥料中核素的含量、植物对核素的吸收能力、核素自身的化学性质以及土壤的理化性质如pH值等因素有关。 4．土壤中的总α放射性活度平均值为548．03Bq／Kg，变化于248．74～1047．74Bq／Kg之间；总β放射性活度的平均值为654．49Bq／Kg，变化于244．60～2082．70Bq／Kg之间。除玉溪地区外，土壤中的总α放射性小于总β放射性。 5．在云南烟区三类主要土壤中，红壤的¹³⁷Cs、²²⁶Ra、²³²Th、²³⁸U的含量最高，紫色土的⁴⁰K和总β最高，水稻土的总α最高。 6．与国内外文献相比较，云南烟区土壤中¹³⁷Cs的含量低于四川省，总α低于上海市，总β低于四川省和上海市。除⁴⁰K外，其它天然放射性核素²²⁶Ra、²³²Th、²³⁸U的含量均高于全国平均值，其中²³⁸U最为显著，高于其它任何地区。⁴⁰K、²³²Th、²³⁸U的含量均高于世界典型值。 7．供试肥料中，宁夏生产的稀十有机复合肥含¹³⁷Cs的含量最高，复肥和磷肥其次，钾肥中¹³⁷Cs的含量最低。几种肥料中¹³⁷Cs的含量差异不大。 钾肥中⁴⁰K含量远高于其它肥料。复肥和稀土有机肥中的⁴⁰K含量低于钾肥，远高于磷肥。磷肥中的⁴⁰K含量最低。钾肥对土壤中的⁴⁰K的积累影响最大。 磷肥中²²⁶Ra和²³⁸U的含量最高，钾肥中²²⁶Ra和²³⁸U的含量最低，稀土有机复合肥和复肥处于中等水平。虽然磷肥中²²⁶Ra的含量低于国家标准规定的限制浓度，但其中的²²⁶Ra和²³⁸U的含量仍远高于土壤，施用磷肥是农业土壤中²²⁶Ra和²³⁸U的重要来源。 肥料中²³²Th的含量在几种天然放射性核素中最低，以稀土有机复合肥中²³²Th的含量最高。供试肥料中²³²Th的含量均低于土壤含量，对土壤中²³²Th的积累影响较小。 磷肥总α放射性最高，钾肥总β放射性最高，复肥总α和总β放射性处于中等水平，稀土有机复合肥在几种肥料中最低。 8．烟叶中各核素的含量平均值为¹³⁷Cs：1．02Bq／Kg，⁴⁰K：820．4Bq／Kg，²²⁶Ra：3．18Bq／Kg，²³²2Th：5．74Bq／Kg，²³⁸U：30．05Bq／Kg。烟叶中⁶⁰Co的含量低于仪器探测限。各核素含量高低顺序为 仰》欢业人＃枷／＞＆IE卫。。K＞二。。U＞。。。Th＞二ZoR。＞’1一Cs＠ 厄。卜壤中各核索含一高低顺序一致口烟n中习‘K含挝远高｝卜壤，其它核素含量低｝”十琐。 烟叶中‘OK含量的变异柠度较小，”’C。、”‘Ra、”’TI。、j’U的变异程度较人。各地烟IZ的核素含量不同，其中昆明的‘厂Cs；楚硼的川K，临沧的H‘Ra、刀‘TI。以及人lpn‘U含这最高。 烟叶中总。放射性活度“卜均值为29！S4Bq／他，约为十壤的10，总p放射性活度平均伯为793刀68丫他，烟叶总。小干总p。各地烟【中总。和总p的变异性不大，前者变异系数为15．78％，后者变异系数为9．8％。9．烟叶对士壤中放射性核素的转移系数大＊p序为“K＞”‘U＞”’CS＞”’Tll＞2’‘RI，转移系数5厂别为1．49、0．39、0二8。010、0刀7。烟叶对‘’K的富集能力最强，对‘’‘卜a的富集能力最弱－烟叶对十壤总。和总p的转移系数分别为O臼、1二1。烟叶对土壤总。和总日的转移系数小同主要是因为烟叶吸收以Off变为主的”‘RO、’”“U、’”’Tll和以p衰变为主的“K的能力有所差异。10．烟则和士壤中刀二！。含量的习关性最在，总。的相关性次之，”’＊s‘’K’＊＊a”‘U 一e的相关性较差。根据相X系数推测，烟川中’刀、h和总。放射性主要来源于士壤；驯K和总p主要来自于施肥：”‘Rs部分来源于十壤，部分来源于肥料；烟草更多还原

【Abstract】 Soils and tobacco were sampled together according to soil parent materials, soil types and cultivation practices. The a and p radioactivities in the samples were determined by LS-6500 liquid scintillation counter following digestion. And the actives of 60Co, 137Cs, 40K, 238U, 232Th, and 226Ra in soil samples were detected by low background y spectrometer. The measurements of radionuclides and activities were performed similarly in phosphorus, potassium and complex fertilizers. Moreover, the effects of phosphorus fertilizers on radionuclides and activities in tobacco were studied in a field experiment.Following are the results obtained:1. The concentrations of radionuclides in soils followed the role of 40K> 238U> 232Th> 226Ra>’37Cs. The means of 40K, 238U, 232Th, 226Ra and l37Cs are .549.14Bq/Kg, 77.77Bq/Kg, 56.43Bq/Kg, 48.64Bq/Kg and 3.64Bq/Kg, respectively. They fluctuated from 151Bq/Kg to 1170Bq/Kg (*%.), 13.8Bq/Kg to 281Bq/Kg (238U), 12.3Bq/Kg to 164Bq/Kg (232Th), 10.2Bq/Kg to 159Bq/Kg (226Ra) and 0.488Bq/Kg to 8.72Bq/Kg (I37Cs). The contents of ^Co were lower than the limit of detector. Furthermore, radionoclides varied in soils and highest concentrations of l37Cs, 40K, 226Ra and 238U and 232Th were found in the soils in Dali, Yuxi, Honghe and Lincang regions, respectively.2. Great changes of radionuclides were detected in soils and most of them came from, parent materials and fertilizers. The main reason for the variations could be explained by different parent materials, complicate landform, radionuclides absorption by plants, fertilization and cultivation practices.3. 40K and 238U accumulated, while 226Ra and 232Th depleted in soils. The accumulation and depletion were related to the nuclides in fertilizers, abilities of nuclides absorption by plants, physical and chemical properties of nuclides and soils such as pH and so on.4. The averages of a and P radioactivities were 548.03Bq/Kg and 654.49Bq/Kgrespectively, which varied from 248.74Bq/Kg to 1047.74Bq/Kg (a) and from 244.60Bq/Kg to 2082.70Bq/Kg (p). It is noticed a radioactivities were less than P radioactivities in soils except those in Yuxi area.5. The concentrations of 137Cs,226Ra, B2Th and238U were highest in red soils, while highest 40K and |3-radioactivity were observed in purplish ones and a in paddy soils.6. The conctents of I37Cs and a-radioactivities in tobacco growing soils were lower than Sichuan and Shanghai, respectively, in contrast to p-radioactivities, which was lower than both Sichuan and Shanghai. Moreover the average concentrations of 226Ra, 2j2Th and 238U were higher than those of our country, China, except K, which was relatively low. It is noticed that 238U was higher than those in any other areas in China. These contents of radionuclides in Yunnan were also higher than the volumes in typical areas.7. In regards to the concentrations of 137Cs in measured fertilizers, they followed the order of rare - organic fertilizer>composite fertilizers>phosphorus fertilizers> potassium fertilizers, but no remarkable differences of 137Cs were detected among these fertilizrs.The concentration of 40K were in order of potassium fertilizers?composite fertilizers and phosphorus fertilizers?rare - organic fertilizer, indicating the greate influences of 40K in potassium fertilizers on soil 40K.The measurement showed the higher contents of 226Ra and 2;>8U in phosphrous fertilizers than those in rare - organic fertilizer and in composite fertilizers and than those in potassium fertilizers once more. The concentrations of 226Ra in phosphate fertilizers were much higher than those in soils, enve though they were lower than the national regulation standards, showing that the two radionuclides in soils mainly could come from phophrous fertilizers in the case of large amount of phosphate supplied in tobacco production.The concentrations of Th were lowest in fertilizers compared to any other radionuclides. 232Th in rare - organic fertilizer was the highest in the fertilizers detected.更多还原