| 泥炭纤维素碳同位素组成作为东亚季风代用指标的可行性 |
| 郭敏
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| 导师 | 陶发祥
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| 2013
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| 学位授予单位 | 中国科学院研究生院
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| 学位授予地点 | 北京
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| 学位名称 | 硕士
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| 学位专业 | 地球化学
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| 关键词 | 泥炭
纤维素
碳同位素
东亚季风
中国东北
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| 摘要 | 东亚季风系统是全球最大、最复杂的季风系统之一，涉及20余亿人口的生存和全球尺度的水循环。对这一系统动力学的理解高度依赖于各种自然档案高分辨率（年到百年尺度）的季风重建。中国大陆广布的泥炭档案可能提供10年级到100年级尺度的季风演变史。 泥炭纤维素碳同位素古气候古季风研究的传统观点通常是将泥炭纤维素碳同位素组成作为东亚季风强度变化的代用指标。产生这一观点的逻辑思路是：东亚季风区的降雨量通常与东亚季风强度成正比，而植物纤维素的碳同位素组成又与降雨量成反比。如果这一思路是正确的，那么由于季风影响的广泛性和区域性，临近发育的几个泥炭地泥炭纤维素的碳同位素序列应该是高度相关的。因此，本文从两个方面论述上述思路的可靠性：一是选取吉林省临近发育的三个泥炭地（鹿乡、金川、哈尼）作为研究对象，从泥炭植物残体中分离出苔草残体，用标准程序萃取纤维素，结合AMS 14C定年，考察最近2000年来不同泥炭地泥炭纤维素碳同位素序列是否具有共性特征；二是对泥炭地周围的气象站所获得的气象观测数据（1951～2010）中的气温、降雨量和相对湿度序列与气象学家定义的各种东亚季风强度指数序列进行相关分析，并计算这三种气象参数变化空间上的关联性，分析泥炭地分布区对区域性和东亚季风气候变化的敏感性。 结果表明，吉林省双阳鹿乡、辉南金川、柳河哈尼三个泥炭剖面苔草纤维素2000年来的碳同位素序列不呈现有意义的相关关系；不同时段：如过去500年来、1000年来、1500年来和2000年来碳同位素序列的长期趋势也不相关，序列中包含的周期也不同。这说明泥炭纤维素碳同位素组成记录的是当地性的而不是区域性的气候或环境信号。从吉林省5个气象观测点现代气象观测数据和季风指数相关性分析得出，季风强度的变化与吉林省地区温度空间配置关系较为单一，强季风对应较高的气温；弱季风对应较低的气温。但东亚季风与降水量和相对湿度的空间配置关系十分复杂，不能仅用降水量和相对湿度的多少来认定季风的强弱。基于此，仅将单个泥炭地的降水记录来表示整个季风区的降水变化和季风强度变化缺乏逻辑合理性。 综上所述，将泥炭纤维素碳同位素比值作为东亚季风强度变化的代用指标的合理性值得怀疑。 |
| 其他摘要 | The East Asian monsoon is one of the largest and most complex monsoon systems on the earth. It concerns the survival of over more than 2 billion people as well as the global scale water cycles. Understanding its dynamics is highly dependent on paleomonsoon high-resolution reconstructions from various natural archives on annual to centennial time scales. The widely-distributed peat archives in China mainland have a potential to provide monsoon evolution histories on time scales from five years to one hundred years. In terms of peat paleoclimatology, the carbon isotopic composition of peat cellulose has been traditionally regarded as a proxy for East Asian monsoon. The basic logic behind this theory is that in East Asian monsoon areas the precipitation is generally positively correlated with the monsoon intensity while the former is negatively related to the carbon isotopic ratio of peat cellulose. If this was correct, then the carbon isotope time series extracted from closely-distributed peatlands would be of high similarity, due to the universality and regionality of monsoon influence. Based on these considerations, this thesis deals with the reasonability of the above-mentioned logic on both spatial and temporal aspects. Spatially, sedge residue cellulose samples over the past 2000 years were prepared from three peat profiles obtained in three closely-formed peatlands, e.g. Luxiang, Jinchuan and Hani peatlands in Jilin province, NE China. Their carbon isotopic ratios were determined and corresponding ages were arranged according to the AMS-dated 14C data. The so-obtained three time series were checked for the general characteristics, including general trend and cyclicity. Temporally, modern meteorological data (temperature, precipitation and relative humidity) over the period from 1951 to 2010 were obtained for five stations nearest to three peatlands. These meteorological time series were analyzed for the spatial correlationships as well as their relationships with East Asian monsoon indices defined by different meteorologists. The main purpose to do so is to test the sensitivity of three peatlands to regional and monsoonal climate variations. The results indicated that three time series for peat cellulose carbon isotopic composition were insignificantly correlated for different periods, such as for the past 500 years, 1000 years and 2000 years. The general trends included in these time series were quite different. These facts imply that the carbon isotopic composition of peat cellulose is probably a recorder of local climate, not regional or monsoonal climate variations. On the other hand, meteorological data analysis indicates that the temperature generally has a good relationship with the monsoon intensity, e.g. the higher the temperature, the stronger the intensity. However, the precipitation and relative humidity present very complex relationships with the monsoon intensity. It is not recommended that the precipitation and relative humidity could be used as the proxy for East Asian monsoon variations. Thus, the precipitation in a single peatland used as a representative for the whole monsoon region or for the monsoon intensity is not logical. Overall, it is concluded that it is still open to discussion to use the carbon isotopic composition of peat cellulose for the proxy of East Asian monsoon variations. |
| 学科领域 | 环境地球化学
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| 语种 | 中文
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| 文献类型 | 学位论文
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| 条目标识符 | http://ir.gyig.ac.cn/handle/352002/5848
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| 专题 | 研究生_研究生_学位论文
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推荐引用方式
GB/T 7714 |
郭敏. 泥炭纤维素碳同位素组成作为东亚季风代用指标的可行性[D]. 北京. 中国科学院研究生院,2013.
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