蚯蚓方解石颗粒——一种新的古气候信息记录载体

Earthworm Calcite Granule——A New Proxy for Paleoenvironmental Reconstruction

近年的研究表明在第四纪土壤和沉积物中广泛存在由蚯蚓特殊腺体产生的方解石颗粒(ECG)。它们一方面可为放射性碳测年提供有效的测年材料,另一方面能够反映其形成时的温度和降水特征。ECG作为潜在的古环境变化信息的新载体,成为古气候研究领域的新方向。在前人研究工作的基础上,分析了ECG的研究现状,介绍了ECG的产生机理及特征,详细阐述了ECG的碳、氧同位素反映古气候、古环境变化的原理与机制,并介绍了其在年代学、古气候环境重建中的应用,探讨了其作为新指标的可靠性及存在的问题,展望了该领域的研究方向和趋势,希望能对未来的黄土古气候研究提供参考。

Earthworm calcite granules（ ECG）,generally produced in Morren＇s glands of the earthworm Lumbricus terrestris and Lumbricus rubellus,are commonly preserved in Quaternary soils and sediments well. These granules can not only provide radio-carbon dating（ Carbon-14） with the efficacious materials,but accurately record a wealth of climatic and environmental information on temperature and precipitation. For instance,researchers from France reconstructed the paleotemperature and paleoprecipitation during the last glacial in west part of Europe by taking advantage of δ^（18）O and δ^（13）C signal contained in ECG. Additionally,scientists from Germany and France carried out radiocarbon dating of ECG from two different loess-paleosol sequences,and the results showed consistency with the dating results of other materials（such as charcoal,bone,plant calcified root cells,etc.）. Therefore,this new bio-indicator has been confirmed as a proxy for paleoenvironmental and paleoclimatic reconstruction,hopefully becoming the golden key to understanding the paleoclimate change. This paper,based on the previous literatures,reviewed the present research status of ECG in paleoclimatology,mainly consisting of five aspects：（i） ECGs＇ production mechanism and their characteristics;（ii） The theoretical foundation of stable carbon and oxygen isotopes in terrestrial fossil earthworm calcite granules for paleoclimatic reconstruction;（iii） The pre-treatment of ECG samples;（iv） Current applications in chronology and paleoclimatology of earthworm calcite granules;（v） Major problems at present regarding paleoclimatic explanation and radiocarbon-14 dating of ECG. Finally,we proposed the future research and development direction in this field,which is expected to make a reference to the future researches.