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南海晚第四纪沉积物中的氮同位素在冰期-间冰期气候旋回中只有微弱的变化,与东太平洋的反硝化记录截然不同,可能反应了局地的氮生物地球化学过程。文章对位于南海南部钻取的一根柱状样MD05-2897的海洋氧同位素阶段(MIS)3～5期的有机氮同位素、反映蓝细菌贡献的2-甲基藿烷指数和反映氨氧化古菌Thaumarchaea的泉古菌醇进行了分析。结果显示,有机氮同位素在MIS 5期有明显降低,对应于这一降低,2-甲基藿烷指数和泉古菌醇都显示了升高的特点,暗示蓝细菌固氮作用和古菌氨氧化作用可能是导致OIS 5期的氮同位素降低的重要过程。
The N isotopes in the Late Quaternary sediments of the South China Sea have only slight changes during the glacial-interglacial climatic cycles, which are quite different from the denitrification records in the East Pacific and may reflect the local nitrogen biogeochemical processes. In this paper, the organic nitrogen isotopes of the third to fifth phases of a marine oxygen isotope (MIS) phase of a columnar sample MD05-2897 drilled in the southern part of the South China Sea reflect the contribution of cyanobacteria to 2-methyl- Quercetin from Thaumarchaea was analyzed. The results showed that the organic nitrogen isotopes decreased significantly in MIS 5 stage. Corresponding to this decrease, the 2-methyl-Khanoane index and Quenpyranol showed the characteristic of increasing, which indicated the nitrogen fixation of cyanobacteria and the oxidation of archaea It may be an important process leading to the decrease of nitrogen isotope in stage 5 of OIS.