| 再探温跃层有孔虫B/Ca与温度和[CO32-]的依赖性及其在24 ka以来热带西太平洋次表层碳酸盐系统重建中的应用 |
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| 引用本文： | 郭景腾,李铁刚,熊志方,仇晓华,常凤鸣.再探温跃层有孔虫B/Ca与温度和[CO32-]的依赖性及其在24 ka以来热带西太平洋次表层碳酸盐系统重建中的应用[J].海洋学报(英文版),2019,38(9):71-86. |
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| 作者姓名： | 郭景腾 李铁刚 熊志方 仇晓华 常凤鸣 |
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| 作者单位： | 中国科学院海洋研究所 海洋地质与环境重点实验室, 青岛, 266071;中国科学院大学, 北京, 100049,国家海洋局第一海洋研究所, 青岛, 266061;青岛海洋科学与技术国家实验室 海洋地质过程与环境功能实验室, 青岛, 266237,国家海洋局第一海洋研究所, 青岛, 266061;青岛海洋科学与技术国家实验室 海洋地质过程与环境功能实验室, 青岛, 266237,山东省第一地质矿产勘查院, 济南, 250014,中国科学院海洋研究所 海洋地质与环境重点实验室, 青岛, 266071;青岛海洋科学与技术国家实验室 海洋地质过程与环境功能实验室, 青岛, 266237 |
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| 基金项目： | The Open Fund of Qingdao National Laboratory for Marine Science and Technology under contract No. QNLM2016ORP0205; the Basic Scientific Fund for National Public Research Institutes of China under contract Nos 2017Y07 and 2019S04; the National Natural Science Foundation of China under contract Nos 41230959, 41830539, 91858106 and 41576051; the Taishan Scholars Project Funding; the Shandong Provincial Natural Science Foundation under contract No. ZR2016DQ17; the Scientific and Technological Innovation Project of Qingdao National Laboratory for Marine Science and Technology under contract No. 2016ASKJ13. |
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| 摘 要： | The B/Ca ratio of planktonic foraminifer shells has been used as a proxy for reconstructing past ocean carbonate chemistry. However, recent studies have revealed significant uncertainties associated with this proxy, such as whether seawater temperature or CO_3~(2-)] is the dominant control on the partition coefficient(K_D) of planktonic foraminiferal B/Ca. To address these uncertainties and thus improve our understanding of the planktonic foraminiferal B/Ca proxy, we analysed B/Ca ratios in the tests of Neogloboquadrina dutertrei(300–355 μm) and Pulleniatina obliquiloculata(355–400 μm) in surface sediment samples from the tropical western Pacific and South China Sea. The relationship between these B/Ca ratios and bottom water calcite saturation states(Δ CO_3~(2-)]) is weak, thus suggesting only a small dissolution effect on the B/Ca of the two species. The correlation coefficients(R~2) between the B/Ca ratios of N. dutertrei and P. obliquiloculata and environmental parameters(e.g., temperature, salinity, phosphate, DIC and ALK) in the tropical western Pacific and South China Sea are not high enough to justify using B/Ca ratios as a palaeoenvironmental proxy in the study areas. The significant correlation between K_D values of N. dutertrei and P. obliquiloculata and carbonate system parameters(e.g., CO_3~(2-)], DIC, ALK, pH and HCO_3~-]) in the study area reflect chemical links between the K_D denominator and these variables. Based on our surface sediment calibration, an empirical relationship between the K_D of N.dutertrei and temperature is proposed in the tropical western Pacific. We also generated a record of B/Ca ratios in N. dutertrei(300–355 μm) from Core MD06-3052 in the tropical western Pacific over the past 24 ka to evaluate the application of the revised B/Ca proxy method. Based on the reconstructed empirical relationship for B/Ca and subsurface seawater ALK, we estimated subsurface seawater carbonate system parameters in the tropical western Pacific since 24 ka. In general, the estimated subsurface seawater pH and CO_3~(2-)] show an increase with time, and the record of subsurface seawater pCO_2 shows a decrease with time, in the tropical western Pacific over the past 24 ka. The consistent trends in subsurface seawater pCO_2 and opal flux during deglaciation may imply that the reported increase in subsurface water pCO_2 in the study area was promoted by enhanced upwelling in the Southern Ocean.
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| 关 键 词： | 浮游有孔虫 B/Ca 碳酸盐化学 热带西太平洋 中国南海 |
| 收稿时间： | 2018/4/25 0:00:00 |
Revisiting the dependence of thermocline-dwelling foraminiferal B/Ca on temperature and [CO32-], and its application in reconstruction of the subsurface carbonate system in the tropical western Pacific since 24 ka |
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| GUO Jingteng,LI Tiegang,XIONG Zhifang,QIU Xiaohua and CHANG Fengming.Revisiting the dependence of thermocline-dwelling foraminiferal B/Ca on temperature and [CO32-], and its application in reconstruction of the subsurface carbonate system in the tropical western Pacific since 24 ka[J].Acta Oceanologica Sinica,2019,38(9):71-86. |
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| Authors: | GUO Jingteng LI Tiegang XIONG Zhifang QIU Xiaohua and CHANG Fengming |
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| Abstract: | The B/Ca ratio of planktonic foraminifer shells has been used as a proxy for reconstructing past ocean carbonate chemistry. However, recent studies have revealed significant uncertainties associated with this proxy, such as whether seawater temperature orCO32-] is the dominant control on the partition coefficient (KD) of planktonic foraminiferal B/Ca. To address these uncertainties and thus improve our understanding of the planktonic foraminiferal B/Ca proxy, we analysed B/Ca ratios in the tests of Neogloboquadrina dutertrei (300-355 μm) and Pulleniatina obliquiloculata (355-400 μm) in surface sediment samples from the tropical western Pacific and South China Sea. The relationship between these B/Ca ratios and bottom water calcite saturation states (ΔCO32-]) is weak, thus suggesting only a small dissolution effect on the B/Ca of the two species. The correlation coefficients (R2) between the B/Ca ratios of N. dutertrei and P. obliquiloculata and environmental parameters (e.g., temperature, salinity, phosphate, DIC and ALK) in the tropical western Pacific and South China Sea are not high enough to justify using B/Ca ratios as a palaeoenvironmental proxy in the study areas. The significant correlation between KD values of N. dutertrei and P. obliquiloculata and carbonate system parameters (e.g.,CO32-], DIC, ALK, pH and${\rm {HCO}}_3^{-}$]) in the study area reflect chemical links between the KD denominator and these variables. Based on our surface sediment calibration, an empirical relationship between the KD of N. dutertrei and temperature is proposed in the tropical western Pacific. We also generated a record of B/Ca ratios in N. dutertrei (300-355 μm) from Core MD06-3052 in the tropical western Pacific over the past 24 ka to evaluate the application of the revised B/Ca proxy method. Based on the reconstructed empirical relationship for B/Ca and subsurface seawater ALK, we estimated subsurface seawater carbonate system parameters in the tropical western Pacific since 24 ka. In general, the estimated subsurface seawater pH andCO32-] show an increase with time, and the record of subsurface seawater pCO2 shows a decrease with time, in the tropical western Pacific over the past 24 ka. The consistent trends in subsurface seawater pCO2 and opal flux during deglaciation may imply that the reported increase in subsurface water pCO2 in the study area was promoted by enhanced upwelling in the Southern Ocean. |
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| Keywords: | planktonic foraminifera B/Ca carbonate chemistry tropical western Pacific South China Sea |
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