南极罗斯海表层沉积物中生源组分的分布规律及其环境指示意义

Distribution patterns of biogenic components in surface sediments of the Ross Sea and their environmental implications

  • 摘要: 罗斯海陆架是南极边缘海初级生产力最高的区域,是研究冰–海–气相互作用和碳循环的热点区域。 本文分析了中国第31–35次南极科考在罗斯海陆架区域采集的43个表层沉积物中的生源组分生物硅(Opal)、碳酸钙、总有机碳(TOC)、总氮(TN)含量和有机碳δ13C(δ13Corg)等指标,通过对这些指标聚类分析和因子分析,并与环境参数对比,研究了罗斯海生源要素的空间分布规律及其对环境的指示意义。结果显示,在罗斯海陆架区域内,TOC、TN、Opal是因子1的主要变量,代表水体生产力。其含量在西南陆架冰间湖和东南陆架地区显示高值,在阿代尔角外陆架地区显示低值,推测主要受溶解铁浓度的影响。δ13Corg是因子2的主要变量,其含量在特拉诺瓦湾冰间湖以及东北外陆架地区较高,在盆地海槽地区较低。δ13Corg的重值分布与生产力勃发有关,轻值分布与陆源有机碳的输入有关。碳酸钙是因子3的主要变量,含量在阿代尔角以及罗斯海冰间湖较高,在盆地海槽以及东部陆架地区较低,其含量主要受到保存效率的影响。

     

    Abstract: The Ross Sea shelf is characterized by its highest primary productivity among the Antarctic marginal seas, and is a hotspot for studying ice-ocean-atmosphere interactions and carbon cycle. This study analyzed the contents of biogenic components such as biogenic silica (Opal), carbonate, total organic carbon (TOC), total nitrogen (TN), and organic carbon δ13C (δ13Corg) in 43 surface sediments collected during the 31st-35th Chinese Antarctic Research Expeditions on the Ross Sea shelf. Cluster analysis and factor analysis were performed on the resulted data in order to obtain their distribution patterns in relation to the environmental settings. Our results show that TOC, TN and Opal are the main variables for factor 1 representing the productivity of the water column. Their contents show high values in the polynyas on the southwest shelf, and on the southeast inner shelf, in contrast to low values in the Cape Adare and outer shelf, interpreted as related to concentrations of dissolved iron in the water. δ13Corg is the main variable for factor 2, with higher values in the Terra Nova Bay polynyas and the outer northeast shelf, and lower values in the troughs. The heavier δ13Corg is resulted from high primary productivity while the lighter δ13Corg mainly reflects terrestrial carbon accumulation from lateral transport. Carbonate is the main variable for factor 3 showing higher contents at Cape Adare and in the Ross Sea polynyas, and lower contents in the troughs and the south-eastern shelf, primarily related to its preservation.

     

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