Characteristics of Organic Carbon and Nitrogen in Antarctic Marine Sediments and Their Paleoclimatic Significance: A Case Study on the Amundsen Sea
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摘要: 为了更好地理解目前南极冰盖与气候的演化，以及为未来冰盖和气候变化的预测提供依据，通过对A11-02孔沉积物的有机碳、氮含量与稳定同位素值进行分析，结合粒度和地球化学元素等特征，探讨了中全新世以来西南极阿蒙森海沉积物有机质的来源及古气候意义. 沉积物的δ13Corg值指示有机质主要为海源输入，陆源有机质贡献相对较少. 通过分析沉积物总有机碳含量及海源有机质含量变化，结合粒度及元素的变化特征，认为中全新世以来研究区古生产力的变化主要与气候变化有关，进而识别出4 750~4 500 a BP、3 600~3 400 a BP、2 250~2 000 a BP和600~400 a BP 4个寒冷阶段.Abstract: To better understand the current evolution of the Antarctic ice sheet and climate, as well as to provide a basis fo future predictions of ice sheet and climate change, the organic carbon and nitrogen contents and stable isotope values of sediments from Hole A11-02 were analyzed, combined with the characteristics of grain size and geochemical elements, to explore the origin and paleoclimatic significance of organic matter in sediments from the Amundsen Sea, West Antarctic since the mid-Holocene. The δ13Corg value of the sediments indicates that the organic matter is mainly input from marine, and the contribution of terrestrial organic matter is relatively small. By analyzing the changes of sediment total organic carbon content and sea source organic matter content, combined with the variation characteristics of grain size and elements, it is believed that the change of paleoproductivity in the study area since the mid-Holocene is mainly related to climate change, and then it is identified that there are four cold stages at 4 750-4 500 a BP, 3 600-3 400 a BP, 2 250-2 000 a BP and 600-400 a BP.
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图 1 A11-02站位分布、区域洋流及冰芯位置示意图
a. WDC06A-7（Marcott et al., 2014）及EPICA Dome C冰芯（Lüthi et al., 2008）；b. 研究区洋流分布（修改自鞠梦珊，2019）
Fig. 1. A11-02 station location distribution, regional ocean current and ice core location
图 2 A11-02孔沉积物TOC、TN、δ13Corg和δ15N的纵向变化
Fig. 2. Longitudinal changes of TOC, TN, δ13Corg and δ15N of sediments from core A11-02
图 3 A11-02孔沉积物TOC和TN相关性
Fig. 3. Correlation between TOC and TN of sediments from core A11-02
图 4 阿蒙森海A11-02孔沉积物中TOC和海陆源有机碳的变化
Fig. 4. Changes of TOC and marine-terrigenous organic carbon of sediments from core A11-02 in the Amundsen Sea
图 5 阿蒙森海A11-02孔沉积物海源有机碳含量(TOCmar)、 < 22 μm粒级组分的含量（雷子炎等，2022）、Fe/Al、δ15N变化及EPICA DomeC冰芯恢复的大气CO2浓度变化(Lüthi et al., 2008)
Fig. 5. Changes in marine organic carbon content(TOCmar), < 22 μm fraction content(Lei et al., 2022), Fe/Al, δ15N in sediments from core A11-02 in the Amundsen Sea and atmospheric CO2 concentration from EPICA DomeC ice core(Lüthi et al., 2008)
图 6 阿蒙森海A11-02孔沉积物中海源有机碳含量(TOCmar)、 > 63 μm粒级组分的含量（雷子炎等，2022）、生源钡含量变化和WDC06A-7冰芯δ18O记录(Marcott et al., 2014)所重建的中全新世以来古气候演化历史
Fig. 6. The paleoclimate evolution history since the mid-Holocene reconstructed from the δ18O record of WDC06A-7 ice core (Marcott et al., 2014) and the changes of TOCmar, > 63 μm granular component(Lei et al., 2022) and biogenic barium content in sediments from core A11-02 in the Amundsen Sea
表 1 A11-02孔沉积物元素、各粒级组分（雷子炎，2022）及有机碳、氮含量相关性矩阵
Table 1. Correlation matrix of sediment elements, fractions and organic carbon(Lei et al., 2022) and nitrogen contents of sediments from core A11-02
Al2O3 Fe2O3 K2O MgO TiO2 CaO P2O5 MnO Na2O TN TOC 粘土 粉砂 砂 相关性 Al2O3 1.000 Fe2O3 0.434 1.000 K2O 0.884 0.344 1.000 MgO 0.664 0.917 0.497 1.000 TiO2 0.754 0.741 0.511 0.928 1.000 CaO -0.547 -0.874 -0.353 -0.920 -0.861 1.000 P2O5 -0.247 0.251 -0.413 0.233 0.153 -0.068 1.000 MnO -0.124 0.345 -0.334 0.380 0.323 -0.251 0.905 1.000 Na2O 0.460 0.569 0.444 0.651 0.525 -0.427 0.302 0.336 1.000 TN 0.338 0.711 0.044 0.812 0.777 -0.765 0.602 0.731 0.449 1.000 TOC 0.285 0.574 0.060 0.700 0.655 -0.603 0.698 0.849 0.493 0.904 1.000 粘土 0.467 0.822 0.259 0.898 0.846 -0.877 0.341 0.508 0.506 0.853 0.737 1.000 粉砂 0.286 0.591 0.132 0.645 0.617 -0.606 0.294 0.435 0.358 0.626 0.508 0.822 1.000 砂 -0.430 -0.784 -0.230 -0.855 -0.809 0.829 -0.340 -0.506 -0.481 -0.817 -0.696 -0.985 -0.909 1.000 
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表 2 A11-02孔沉积物元素、各粒级组分（雷子炎，2022）及有机碳、氮含量R型因子分析结果
Table 2. R-type factor analysis of sediment elements, fractions(Lei et al., 2022) and organic carbon and nitrogen contents of sediments from core A11-02
F1 F2 F3 因子 方差百分比 累积% Al2O3 0.251 -0.147 0.925 F1 34.091 34.091 Fe2O3 0.855 0.182 0.276 F2 31.883 65.974 K2O 0.096 -0.335 0.875 F3 22.643 88.617 MgO 0.771 0.253 0.558 TiO2 0.656 0.220 0.660 CaO -0.875 -0.087 -0.387 P2O5 0.094 0.932 -0.172 MnO 0.208 0.968 -0.037 Na2O 0.273 0.346 0.536 TN 0.657 0.637 0.270 TOC 0.402 0.804 0.338 粘土 0.828 0.358 0.353 粉砂 0.729 0.281 0.136 砂 -0.830 -0.348 -0.300 Co 0.354 0.921 -0.100 Ni 0.460 0.868 0.133 Mo 0.075 0.978 -0.054 Ba 0.705 0.127 0.634 Th 0.536 0.021 0.790 U -0.686 -0.455 0.373
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