Atmospheric radiocarbon variation during the past 50 ka by the high-resolution analysis of heaven lake sediment

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To investigate the ^<14>C variations in atmospheric CO_2 (^<14>CO_2) during the past 50 ka, we had a high-resolution analyses of the heaven lake sediments from Heilongjiang and Inner Mongolia, northeastern China. We focused on three subjects in this research ; (1) development of analytical methods for reading out climatic signals form the heaven lake sediments with a high-temporal resolution, (2) establishment of high-precision AMS ^<14>C measurements for small-size sample and enhancement of sample preparation throughput and (3) numerical model experiments for reconsidering the atmospheric ^<14>CO_2 changes and marine response on atmospheric changes for ^<14>CO_2.We have developed the system of automatic UV-image analyze and laser-induced breakdown spectroscopy (LIBS) for sediment core analysis. Although we applied newly developed method to the heaven lake sediments, we need more experiments for detecting climatic signals. With a collaboration with UCI-KCCAMS (USA) and KIGAM (Korea), we developed an automatic preparation system for AMS ^<14>C measurement (for >0.3 mg C) and established a technique for extremely small samples (0.07～0.3 mg C). We are planning to apply these techniques developed to the other lake sediments. Finally we modified a global carbon cycle model, and discussed about the ^<14>C response of atmospheric ^<14>CO_2 changes on marine reservoir using the available data set.