Sedimentary gochemical characteristics of the Redox-sensitive elements in Ross Sea,Antarctica:Implications for paleoceanography
WANG Jiakai;LI Tiegang;XIONG Zhifang;CHANG Fengming;QIN Bingbin;WANG Linmiao;JIA Qi;CAS Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences;University of Chinese Academy of Sciences;Key Laboratory of Marine Sedimentology and Environmental Geology,First Institute of Oceanography,SOA;Laboratory for Marine Geology,Qingdao National Laboratory for Marine Science and Technology;
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 pCO_2.Hence,verifying the redox environment evolution of the ocean could help us clarify the mechanism of variation in atmospheric pCO_2in glacial-interglacial cycles.Samples from core ANT31-R23 and the surface sediment of central Ross Sea,which were taken by R/V Xuelongin the 31~(st )and32~(th )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 paleoredox 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 pCO_2during glaciation.The strong oxidation pulse events,however,may play an important role in elevating atmospheric pCO_2during deglaciation.Nevertheless,the detailed processes of this mechanism will be effectively revealed by follow-up work after the establishment of accurate chronology framework.
【Fund】： 国家自然科学基金项目“80万年来热带西太平洋上层水体pH和pCO_2演变及影响机理”(41230959) “MIS 6期以来罗斯海深层水流通性的变化及其对大气CO_2冰期旋回的影响”(41606216);; 青岛海洋科学与技术国家实验室鳌山科技创新计划项目(2016ASKJ13)
【CateGory Index】： P736
【CateGory Index】： P736