Isotopic Composition of Paleosol Carbonates and Organic Matter

塞林博士将继续他的NSF资助的研究，并检查土壤碳酸盐含有有用的气候信息的程度。他的初步研究表明，在受控的现代条件下，碳同位素直接反映了上面的植物群落，在此基础上，有可能确定“C3”和“C4”物种的相对数量。C4植物适应水分胁迫的条件，因此提供了一个有用的气候指标。由于雨水中的氧同位素组成受温度影响，变化幅度几乎为每毫升20个，如果保存在古土壤碳酸盐中，也可能产生气候信息。塞林博士分析了与人类学意义重大的材料有关的几系列化石土壤，并提取了有用的气候信号。在他的新研究中，塞林博士将继续他对现代和化石土壤的研究。他将研究一些现代土壤，以进一步了解古土壤碳酸盐中的氧同位素记录，并继续研究石灰岩上形成的土壤，以便它们也可以用于古生态重建。他还将把这些新兴技术应用于旧大陆的古生物和人类学遗址，以阐明中新世、上新世和更新世期间发生的气候变化。这项研究很重要，因为如果成功，它将提供一个重要的人类学工具。要了解人类是如何发展的，就必须了解他们生活的环境，以及这些环境是如何随着时间的推移而变化的。虽然海洋沉积物的技术已经成熟，但陆地物质更难解释，所做的工作也很少。这个项目应该有助于补救这种情况。

Dr. Cerling will continue his NSF supported research and examine the extent to which soil carbonates contain useful climatic information. His preliminary research, under controlled modern conditions, has shown that carbon isotopes directly reflect the overlying plant community, and on this basis it is possible to determine the relative amounts of "C3" and "C4" species. C4 plants are adapted to water stressed conditions and thus provide a useful climatic indicator. Since oxygen isotope composition in rainwater is affected by temperature and may vary by almost 20 per mil, if this is preserved in paleosol carbonate it also may yield climatic information. Dr. Cerling has analyzed several series of fossil soils associated with anthropologically significant materials and has extracted useful climatic signals. In his new research, Dr. Cerling will continue his study of both modern and fossil soils. He will examine some modern soils to further understand the oxygen isotopic record in paleosol carbonates and continue to work on soils formed on limestones so that they may be used in paleoecologic reconstructions as well. He will also apply and evaluate these emerging techniques to paleoontologic and anthropologic sites in the Old World to shed light on climatic changes which occurred during the Miocene, Pliocene, and Pleistocene. This research is important because, if successful, it will provide an important anthropological tool. To understand how humans developed it is essential to understand the environments in which they lived and how these changed over time. While techniques are well established for marine sediments, terrestrial materials are much more difficult to interpret and very little work has been done. This project should help to remedy the situation.