南极罗斯海柱样沉积物中有机碳和氮元素地球化学特征及其来源

Geochemical characteristics and source of organic carbon and nitrogen in the column sediments from the Ross Sea,Antarctica

南极周边海域沉积物中的有机碳和氮元素地球化学特征对于深入研究全球碳循环和海洋生态环境演变具有重要意义。本文对取自南极罗斯海的RBA08C柱状样沉积物进行了有机碳和氮元素地球化学特征分析。结果表明:RBA08C柱样中TOC含量在顶部0～12cm呈现随柱深增加而降低的趋势,自12cm以深含量总体相对稳定;TN总体具有与TOC相同的变化趋势,两者含量变化呈现较强正相关性,说明可能具有相同来源;沉积物TOC/TN比值和δ13 C值揭示RBA08C柱样有机质主要为海洋生源沉积,其含量变化应主要受控于上层水体生产力、沉积速率和氧化还原环境等因素的共同作用;RBA08C柱样的TOC埋藏率约为50%,与位于普里兹湾埃默里冰架边缘的IS-4站柱样相同,加之较为相近的TOC和TN含量及变化趋势,表明两者可能具有相近的沉积速率,其所在的海区是南极海域较重要的碳循环和碳储区。

The geochemical characteristics of organic carbon and nitrogen in the Antarctic marine sediments are of great significance to the study of the global carbon cycle and marine ecological environment.In this paper,the geochemical characteristics of organic carbon and nitrogen in sediments of Core RBA08 C collected from the Ross Sea,Antarctica were discussed.TOC content at the top 0~12 cm shows a decreasing trend with depth,and the TOC below the core depth of 12 cm remains relatively stable.The content of TN was totally the same as that of TOC,and the positive correlation between the two probably indicate that they came from same source.The TOC/TN ratio andδ13 C values reveal that the organic matters and its change in content should be collectively controlled by upper water productivity,deposition rate and redox environment and mainly from the marine biogenic deposition.The TOC burial rate of the Core RBA08 C is about 50%,the same as that of the Core IS-4 at the edge of the Emory Ice Shelf,Prydz Bay.Coupled with the similar contents and change trend of TOC and TN,it suggest that their deposition rates are similar.