Radiocarbon Calibration using Speleothems II - Soil carbon-climate interaction

使用 Speleothems II 进行放射性碳校准 - 土壤碳-气候相互作用

• 批准号: 256561558
• 负责人: Professor Dr. Norbert Frank
• 金额: --
• 依托单位: Institut für Umweltphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/256561558?language=en
• 关键词: Radiocarbon; Calibration; using; Speleothems; II

Understanding natural variations of the atmospheric 14C content is an essential prerequisite for radiocarbon dating. The knowledge of past atmospheric radiocarbon variability than allows for improvements in our understanding of the variability of the climate induced global carbon cycle changes, the Earth's magnetic field, the cycling of carbon through the ocean and land biosphere, as well as the precise dating of climatic events. According to recent radiocarbon variations obtained in stalagmites from China, novel opportunities to study global carbon cycle changes and the production of cosmogenic nuclides have come to light. Significant deviations from previous calibration curves (e.g., IntCal13) and large differences in the proportion of dead carbon in various subtropical speleothems raise the issue of reassessment of carbon transport processes in soils and the subsequent transport and storage of radiocarbon in speleothems. In our previous project, we reconstructed the 14C concentration using speleothems from Socotra (Yemen) and Sofular (Turkey) with a time resolution in cases of some hundred years and spanning more than 30,000 years. These records demonstrate dramatic climate-induced changes in the soil carbon cycle. Furthermore, a basic assumption of the previous project to evaluate hydrological influences on the carbon cycle, i.e. covariance of Mg/Ca ratio and radiocarbon in speleothems on time scales of centuries, has been rejected. Although a close association between atmosphere and speleothem 14C was validated in our previous study, the reasons for dramatic centennial climate-induced changes in soil CO2 cycling remain elusive and poorly understood. In this follow-up project, we now aim to profoundly advance our understanding of the mechanisms that lead to variations of 14C in subtropical speleothems driven by climate change, hydrology, and soil CO2 cycling. This will be done through new observations on selected speleothems and modern carbonates and drip water from Larga cave in Puerto Rico, and through the development of a comprehensive numerical model to simulate speleothems 14C under various climate aspects (vegetation, soil carbon cycling, precipitation, isotope fractionation, chemical transient change) to ultimately determine the covering geochemical and climate processes. Armed with a fundamental understanding of the carbon cycle leading to speleothems 14C observations, one can ultimately reevaluate the importance and significance of differences between speleothems and other 14C archives.

了解大气14C含量的自然变化是放射性碳年代的必不可少的先决条件。对过去大气放射性碳变异性的了解要比我们对气候诱发的全球碳循环变化的理解，地球磁场，碳循环通过海洋和土地生物圈的循环以及气候事件的精确约定的了解可以改善我们的理解。根据来自中国的Stalagmites中最近获得的放射性碳变异，研究全球碳循环变化和宇宙核素的产生的新机会已经浮出水面。与先前的校准曲线（例如INTCAL13）的显着偏差和在各种亚热带speleothems中死碳比例的巨大差异增加了土壤中碳转运过程的重新评估以及随后在Speleothems中的扩展和存储的问题。在我们以前的项目中，我们使用来自Socotra（Yemen）和Sofular（Turkey）的Speleothems重建了14C浓度，并在大约一百年内的时间分辨率进行了分辨率，并且跨越了30，000年。这些记录表明，气候引起的土壤碳周期变化急剧。此外，先前项目的基本假设是评估对碳循环的水文影响的基本假设，即在speleothems中以几个世纪的时间尺度在Speleothems中Mg/Ca比和放射性碳的协方差。尽管在我们的先前研究中验证了大气与Speleothem 14c之间的密切关联，但百年纪念气候引起的土壤二氧化碳循环变化的原因仍然难以捉摸且了解不足。在这个后续项目中，我们现在旨在深刻提高我们对由气候变化，水文学和土壤二氧化碳循环驱动的亚热带棘皮动物中14C变化的机制的理解。这将通过对波多黎各的Larga洞穴的选定棘突和现代碳酸盐和滴水进行的新观察，以及开发一个全面的数值模型，以模拟speleothems 14c在各种气候方面（植被，植被，土壤碳循环，沉淀，降水，同位素分数，化学瞬时变化），并确定覆盖范围。凭借对导致Speleothems 14c观察结果的碳周期的基本了解，最终可以重新评估Speleothems和其他14C档案之间差异的重要性和重要性。