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| 细纹灰尖巴蜗牛壳体氧同位素组成的季节性变化 | |
| 引用本文： | 孙小虹,顾兆炎,王旭.细纹灰尖巴蜗牛壳体氧同位素组成的季节性变化[J].第四纪研究,2009,29(5):976-980. |
| 作者姓名： | 孙小虹 顾兆炎 王旭 |
| 作者单位： | 中国科学院地质与地球物理研究所新生代地质与环境重点实验室,北京,100029 |
| 基金项目： | 国家自然科学基金项目 |
| 摘 要： | 陆生蜗牛壳体碳酸盐氧同位素组成，理论上取决于壳体生长季节的降水 18O丰度、温度和湿度，对揭示古气候和古环境变化具有巨大的潜力。然而，同一地区不同属种的蜗牛生长季节存在一定的差异，因此，了解不同季节生长的蜗牛壳体氧同位素特征，是其成为重建古气候、古环境变化的工具的关键。为了进一步阐明降水氧同位素组成和气候月际变化对蜗牛壳体 18O的影响，分别对从江苏镇江逐月采集的现生细纹灰尖巴蜗牛(Bradybaena ravida redfieldi)进行了整体壳体及壳口文石氧同位素组成的分析，结果表明： 1)不同月份采集的样品壳口的 δ18O 值变化较大，从－1.92‰至－6.79‰，幅度达4.87‰，其中，4～6月采集的样品 δ18O 值较正，平均 －2.40±0.42‰，7～9月采集的样品明显偏负，平均 －6.41±0.34‰； 2)整个壳体的 δ18O 值差别不大，平均 －2.61±0.47‰，与 4～6月壳口 δ18O 平均值相近； 3)不同月份蜗牛壳口 δ18O 值呈现出与当地的降水氧同位素组成、温度和大气相对湿度等相似的季节性变化模式，其中降水氧同位素组成对壳口 δ18O 变化的影响是主要的。这些特征说明，蜗牛壳体碳酸盐氧同位素组成受其生长时的环境因素(降水 18O丰度，温度和相对湿度)控制，对于中国夏季风影响地区来说，春季生长的蜗牛壳体相对富集 18O，而夏季生长的壳体 18O相对贫化。换句话说，根据蜗牛壳体碳酸盐氧同位素组成能够推测壳体主要生长季节，或降水 18O丰度及气候温湿程度的特征。对于B.ravida redfieldi来说，氧同位素组成显示了壳体主要生长时期为春季的特征。 |
| 关 键 词： | 巴蜗牛 氧同位素 季节性变化 |
OXYGEN ISOTOPIC VARIATIONS IN THE SHELLS COLLECTED MONTHLY FROM A LIVE SPECIES OF LAND SNAILS AT A LOCALE IN ZHENJIANG, JIANGSU PROVINCE|CHINA |
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| Sun Xiaohong,Gu Zhaoyan,Wang Xu.OXYGEN ISOTOPIC VARIATIONS IN THE SHELLS COLLECTED MONTHLY FROM A LIVE SPECIES OF LAND SNAILS AT A LOCALE IN ZHENJIANG, JIANGSU PROVINCE|CHINA[J].Quaternary Sciences,2009,29(5):976-980. | |
| Authors: | Sun Xiaohong Gu Zhaoyan Wang Xu |
| Institution: | Key Laboratory of Cenozoic Geology and Environment|Institute of Geology and Geophysics|Chinese Academy of Sciences|Beijing 100029 |
| Abstract: | Oxygen isotope compositions of the land snail shell aragonite have a potential to indicate changes in climate and ecology. However，previous studies have shown that the shell aragonite isotope compositions would be affected by multifactors including abundances of 18O in local rainwater and atmospheric vapor，temperature，and humidity. So，the land snail shell isotopic environmental implication is still vague. To constrain the dominant factors influencing on their shell aragonite oxygen isotope composition，isotopic measurements have been carried out on the shells of the live Bradybaena ravida redfieldi land snails collected monthly from April to September,2005，at a locale in Zhenjiang，Jiangsu Province，China. The result gives us following features and clear implications. First,δ18O values for the shell lip samples of the land snail are in a range of －1.92‰～－6.79‰，and vary with the sampling dates，decreasing from spring to summer，which parallels to the monthly changes of local rain water δ18O ，temperature，and humidity. Combined monthly modeled land snail shell 18O data，we can conclude that the shell lip δ18O changes are mainly resulted from the 18O variations of rainwater. In other words，the shells for a species of land snails grown during spring could be rich in 18O，and those for another grown during summer depleted in 18O. Second, δ18O values for the whole shell samples of the land snail vary a little with an average of －2.61±0.47‰ which does not differ from the value of －2.40±0.42‰ for the shell lip samples collected in April，May，and June. So，we can deduce that the shells of B．ravida redfieldi were mostly grown during spring when the rainwater δ18O is the highest in a year. The seasonal rainwaters in the most of China are characterized by oxygen isotope composition，having more 18O for spring and less 18Ofor summer. So，the result from the oxygen isotopic measurements on the shells of B．ravida redfieldi also gives us an implication that a shell δ18O would be as a signal for the land snail active season. |
| Keywords: | land snail(Bradybaena) oxygen isotope seasonal change |
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