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| 有机氧同位素测试方法及植物生长过程中的同位素分馏效应 | |
| 其他题名 | The method of measuring oxygen isotope ratios for organic material and its application in isotopic fractionation during growing plants |
| 张庆乐 | |
| 出版年 | 2004 |
| 学位类型 | 硕士 |
| 导师 | 刘卫国 |
| 学位授予单位 | 中国科学院地球环境研究所 |
| 中文摘要 | 植物有机质的氧同位素组成在生态学、古气候学和植物生理学等领域有着潜在而广泛的应用。本文建立了一种快速、准确的在线测试有机氧同位素的实验方法，并通过对一些样品的测试结果与生长环境条件的分析，讨论了影响有机氧同位素组成的主要因素，试图对干早半干旱环境条件下植物有机质氧同位素的分馏机制有进一步的了解。本文主要包括以下内容：一采用Finnigan-MAT公司最新的TC-EA-MS技术，通过大量的条件实验，建立了高效、准确的在线测试有机氧同位素组成的实验方法。标准物质的测量精度＜0.4%。二通过对生长过程中不同部位玉米叶片氧同位素的对比研究，认为影响植物叶片有机质氧同位素组成的主要因素随采样时间和采样部位的不同而变化，在考虑环境因素的同时，非气候因素（生化分馏效应）的影响不可忽视。在利用植物有机氧同位素组成来解释环境信息时，应考虑非气候因素产生的影响，使其指示的气候意义更加明确。三通过对单一玉米叶片内有机质氧同位素的变化分析，认为植物叶片有机质氧同位素组成受植物生理因素和环境因素（湿度）的双重影响，在植物生长过程中，湿度越低，则单一汗卜片有机质氧同位素组成差异越大。四通过对贺兰山地区树轮纤维素氧同位素组成与气候要素的对比分析，认为在干早半干旱区树轮的氧同位素组成与降水量变化和夏季风强弱存在较好的正相关关系。这一结论与该地区现代降水氧同位素组成与降水量的关系是一致的。五通过对贺兰山地区树轮碳、氧同位素与环境要素的对比分析，发现二者都与生长季节降水量存在较好的相关性。我们可以通过对某地区树轮进行多种同位素指标（c和。）的综合分析，来更好的区分其指示的气候意义。 |
| 英文摘要 | Stable oxygen isotope in plant material has a potential and widely application in the study of paleoclimate, ecology, physiology and other fields. In this study, we finished a quick and precise method of measuring oxygen isotopic composition for organic matter by using TC/EA-MS technology. Moreover, by using oxygen isotope ratios of some plant samples, we discuss the relationship between oxygen isotope ratios in plant and major environmental factors. The aim of this work is to understand machenism of isotopic fractionation during growing plants. The main goals of this study are as follows: 1.\tEstablishing an on-line method of measuring oxygen isotope ratios for organic material by TC/EA-MS. The overall analytical uncertainty is 0.4%o for standard material. 2.\tBy analyzing the oxygen isotope ratios of different leaves in growing maize, we find that the major environmental factor affecting oxygen isotopic composition of plant material varies with different sampling time and parts. Moreover, nonclimatic factors (biochemical fractionation) have to pay attention when reconstruct paleoclimate by using oxygen isotope ratios in plant material. By analyzing the oxygen isotope ratios of organic material in a single maize leave, we find oxygen isotopic composition of leave material is controlled by physiological and environmental factors. The difference of organic oxygen isotopic composition decreases with relative humidity during growing plant. In this work, our results show a postive relationship between oxygen isotope ratios of tree ring cellulose and precipitation amount for the Helan Mountain located in arid northwest China. This relationship is supported by oxygen isotopic distribution of rainfall today. Although exact mechanism of oxygen isotope fractionation of tree ring with precipitation amount is unclear, our results indicate that oxygen isotopic composition of tree ring is a potential effective proxy of monsoon precipitation for arid nowthwest China. 5. By comparing the correlation between the carbon and oxygen isotope ratios of tree ring cellulose and environmental parameters (precipitation and temperature) in the Helan Mountain, We find a good correlation in both stable isotopes and the amount of growing precipitation (May through September). Though knowledge of the factors controlling isotopic signals in plant remains incomplete, there is negative correlation between carbon and oxygen isotope ratios in tree ring cellulose. It suggests that we can further infer environmental parameters from the combination of carbon and oxygen isotope ratios of tree ring cellulose in one region. |
| 中文关键词 | 植物 ; 氧同位素 ; 分馏效应 ; 夏季风 ; 降水 |
| 英文关键词 | TC／EA-MS TC/EA-MS oxygen isotope plant isotope fractionation monsoon precipitation |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源机构 | 中国科学院地球环境研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286349 |
| 推荐引用方式 GB/T 7714 | 张庆乐. 有机氧同位素测试方法及植物生长过程中的同位素分馏效应[D]. 中国科学院地球环境研究所,2004. |
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