We present a record on carbon stable isotopic composition (δ 13C), covering 75 through 10 thousands years ago (ka B.P.), from Hulu Cave, Nanjing. The overlapping δ 13C pro-files are very similar in pattern and range...We present a record on carbon stable isotopic composition (δ 13C), covering 75 through 10 thousands years ago (ka B.P.), from Hulu Cave, Nanjing. The overlapping δ 13C pro-files are very similar in pattern and range, indicating that they mainly record climatic signal. Dur-ing the last glacial-interglacial transition, the >6‰ change of δ 13C values implies different con-tributions of C3 vs. C4 type plants in soils. On millennial scale, however, the increased calcite δ 13C during the warm Dansgaard-Oeschger (DO) events suggests a decrease of dissolved bio-genic CO2 when water flux rate through soil is large. This correlation between heavier δ 13C and higher precipitation is consistent with our previous report on the samples’ stable oxygen isotope records (Wang et al., 2001). Comparison of coeval δ 13C and δ 18O of stalagmites indicates that kinetic fractionation of carbon isotope is closely related to growth rate of stalagmites. This study also shows that local vegetation changes may lag behind precipitation changes by ~700 years during the deglaciation.展开更多
文摘We present a record on carbon stable isotopic composition (δ 13C), covering 75 through 10 thousands years ago (ka B.P.), from Hulu Cave, Nanjing. The overlapping δ 13C pro-files are very similar in pattern and range, indicating that they mainly record climatic signal. Dur-ing the last glacial-interglacial transition, the >6‰ change of δ 13C values implies different con-tributions of C3 vs. C4 type plants in soils. On millennial scale, however, the increased calcite δ 13C during the warm Dansgaard-Oeschger (DO) events suggests a decrease of dissolved bio-genic CO2 when water flux rate through soil is large. This correlation between heavier δ 13C and higher precipitation is consistent with our previous report on the samples’ stable oxygen isotope records (Wang et al., 2001). Comparison of coeval δ 13C and δ 18O of stalagmites indicates that kinetic fractionation of carbon isotope is closely related to growth rate of stalagmites. This study also shows that local vegetation changes may lag behind precipitation changes by ~700 years during the deglaciation.
