王家凯, 李铁刚, 熊志方, 常凤鸣, 秦秉斌, 王琳淼, 贾奇. 南极罗斯海氧化还原敏感元素沉积地球化学特征及其古海洋意义[J]. 海洋地质与第四纪地质, 2018, 38(5): 112-121. DOI: 10.16562/j.cnki.0256-1492.2018.05.011
引用本文: 王家凯, 李铁刚, 熊志方, 常凤鸣, 秦秉斌, 王琳淼, 贾奇. 南极罗斯海氧化还原敏感元素沉积地球化学特征及其古海洋意义[J]. 海洋地质与第四纪地质, 2018, 38(5): 112-121. DOI: 10.16562/j.cnki.0256-1492.2018.05.011
WANG Jiakai, LI Tiegang, XIONG Zhifang, CHANG Fengming, QIN Bingbin, WANG Linmiao, JIA Qi. Sedimentary gochemical characteristics of the Redox-sensitive elements in Ross Sea, Antarctica: Implications for paleoceanography[J]. Marine Geology & Quaternary Geology, 2018, 38(5): 112-121. DOI: 10.16562/j.cnki.0256-1492.2018.05.011
Citation: WANG Jiakai, LI Tiegang, XIONG Zhifang, CHANG Fengming, QIN Bingbin, WANG Linmiao, JIA Qi. Sedimentary gochemical characteristics of the Redox-sensitive elements in Ross Sea, Antarctica: Implications for paleoceanography[J]. Marine Geology & Quaternary Geology, 2018, 38(5): 112-121. DOI: 10.16562/j.cnki.0256-1492.2018.05.011

南极罗斯海氧化还原敏感元素沉积地球化学特征及其古海洋意义

Sedimentary gochemical characteristics of the Redox-sensitive elements in Ross Sea, Antarctica: Implications for paleoceanography

  • 摘要: 大洋深部氧化还原环境与深部水体流通状况以及表层水体生产力密切相关。表层生产力与深部流通性变化影响着有机碳-呼吸CO2的转化及其在海洋-大气中的转移,最终与大气CO2分压(pCO2)变化密切相关。故探明大洋深部氧化还原环境的变化对于解决大气pCO2冰期旋回机制具有重要意义。本次研究以中国第31和32次南极科考获得的南极罗斯海柱状岩心ANT31-R23及表层样为研究材料。通过元素钙、钛,以及氧化还原敏感元素(RSE)锰、钼、镍、钴、镉的测试分析,以表层样中RSE与Ti的比值作为判断ANT31-R23孔中相应RSE富集程度的背景值。结果显示,Mn在沉积期均表现出富集,表明罗斯海深部在该孔沉积期为氧化环境。根据Mn在不同层位出现的富集峰识别出4次强氧化脉冲事件,可能由南大洋底层水流通性增强和/或生产力降低导致。4次氧化脉冲事件层位中Mo、Ni、Co的明显富集,是由于锰(氢)氧化物对其捕获或吸附所致。此外,推测分析认为罗斯海对冰期大气pCO2降低似乎没有明显贡献,但很可能对冰消期大气pCO2迅速升高起重要作用。然而这些有关南极罗斯海深部氧化还原环境与大气pCO2变化之间关联的推测,有待后续该孔精确年代模式的构建,方可进一步验证。

     

    Abstract: Redox conditions of deep ocean are supposed closely related to deep ocean circulation and surface water production. Facts prove that surface water production and deep water circulation may strongly influence the formation of respiration carbon and its migration from ocean interior to atmosphere, which is closely related to the rise of atmospheric pCO2. Hence, verifying the redox environment evolution of the ocean could help us clarify the mechanism of variation in atmospheric pCO2 in glacial-interglacial cycles. Samples from core ANT31-R23 and the surface sediment of central Ross Sea, which were taken by R/V Xuelong in the 31st and 32th Chinese National Antarctic Research Expedition, are used as research materials in this study. Both the major and minor elements are analyzed, including calcium, titanium and the elements sensitive to paleo-redox environment of deposition, so-called Redox-sensitive elements (RSE), such as manganese, molybdenum, nickel, cobalt and cadmium. RSEs normalized by Ti are adopted as background values to estimate if the RSEs are enriched or depleted. The result shows that enrichment of Mn occurs in the entire core indicating an oxidizing condition. Four strong oxidation pulse events are identified based on Mn peaks in different depths, which may be related to stronger circulation conditions and/or lower surface water production in the Southern Ocean during late Quaternary. The layers enriched by Mo, Co and Ni in addition to Mn, are resulted from absorption, capture or scavenge by Mn-oxyhydroxides. These results suggest that the Ross Sea does not have significant contribution to the reducing of atmospheric pCO2 during glaciation. The strong oxidation pulse events, however, may play an important role in elevating atmospheric pCO2 during deglaciation. Nevertheless, the detailed processes of this mechanism will be effectively revealed by follow-up work after the establishment of accurate chronology framework.

     

/

返回文章
返回