| DANG Haowen,WANG Tingting,QIAO Peijun,BASSINOT Franck,JIAN Zhimin. 2019. The B/Ca and Cd/Ca of a subsurface-dwelling foraminifera Pulleniatina obliquiloculata in the tropical Indo-Pacific Ocean: implications for the subsurface carbonate chemistry estimation. Acta Oceanologica Sinica, 38(3):138－150 |
| The B/Ca and Cd/Ca of a subsurface-dwelling foraminifera Pulleniatina obliquiloculata in the tropical Indo-Pacific Ocean: implications for the subsurface carbonate chemistry estimation |
| 热带印度-太平洋浮游有孔虫Pulleniatina obliquiloculata的B/Ca和Cd/Ca指标：次表层海水碳化学参数计算的应用 |
| Received:November 03, 2017 |
| DOI：10.1007/s13131-019-1406-6 |
| Key words:Pulleniatina obliquiloculata B/Ca Cd/Ca paleo-pH estimation |
| 中文关键词: P. obliquiloculata B/Ca Cd/Ca 古海水pH值计算 |
| 基金项目:The National Natural Science Foundation of China (NSFC) and NSFC-Shandong Joint Fund for Marine Science Research Centers under contract Nos 41606049, U1606401 and 41376054; the China Postdoctoral Science Foundation under contract No. 2015M581658. |
| Author Name | Affiliation | E-mail | | DANG Haowen | State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China
Laboratoire des Sciences du Climat et de l'Environnement/IPSL, CEA-CNRS-UVSQ, Université
Paris-Saclay, Gif-sur-Yvette 91190, France | hwdang@tongji.edu.cn | | WANG Tingting | State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China | | | QIAO Peijun | State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China | | | BASSINOT Franck | Laboratoire des Sciences du Climat et de l'Environnement/IPSL, CEA-CNRS-UVSQ, Université
Paris-Saclay, Gif-sur-Yvette 91190, France | | | JIAN Zhimin | State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China | |
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| Abstract: |
| Pulleniatina obliquiloculata shells from 16 core-top samples from the tropical Indo-Pacific Oceans are analyzed for the ratios of boron and cadmium to calcium (B/Ca and Cd/Ca). The B/Ca ratios show a very weak positive relationship with[B(OH)4-] and the dissolved carbonate species at the apparent calcification depth of P. obliquiloculata. The boron partition coefficients (KD) between P. obliquiloculata B/Ca and seawater[B(OH)4-]/[HCO3-] distribute around 1.1×10-3-1.3×10-3 with a mean value of (1.19±0.12)×10-3, and are significantly related to the nutrient concentration, especially phosphate. The lack of any clear correlation between the P. obliquiloculata B/Ca and seawater carbonate chemical parameters suggests that the physiochemical controls on boron incorporation are masked by the complexity of natural seawater condition. But the significant dependence of KD on nutrient may likely be explained by a nutrient related growth-rate effect. Cd/Ca of P. obliquiloculata shows significant correlation with seawater phosphate concentration, and its partition coefficients (DCd) are significantly related to temperature. A first-principle methodology of P. obliquiloculata B/Ca is applied, with the aid of Cd/Ca as a phosphate proxy and a constraint on KD, to estimating sea water carbonate chemistry (e.g., pH). The results are fairly promising and allow us to propose the possibility to apply the combination of B/Ca and Cd/Ca proxies (and also Mg/Ca and δ18O for estimating temperature and salinity) for the paleo-reconstruction of seawater carbonate chemistry. |
| 中文摘要: |
| 本研究分析了热带印度-太平洋16个岩芯顶部样品中P. obliquiloculata壳体的B/Ca和Cd/Ca比值。B/Ca比值与该种表观钙化深度的海水[B（OH）4-]和溶解无机碳组分存在很弱的正相关关系，其壳体B/Ca与海水[B（OH）4-]/[HCO3-]的分配系数（KD）集中于1.1–1.3之间、平均1.19±0.12，KD值与海水营养特别是磷酸盐的浓度显著相关。P. obliquiloculata壳体B/Ca与海水碳化学参数之间的相关性并不显著，说明自然海水的复杂状况掩盖了该种吸收硼的生理控制效应。然而，营养与KD值的显著关联很可能反映了由营养调控的生长速率效应。P. obliquiloculata壳体Cd/Ca与海水磷酸盐浓度显著相关，其分配系数（DCd）由温度显著决定。据此我们尝试以Cd/Ca作为磷酸盐指标辅助限定KD值，综合利用B/Ca和Cd/Ca指标进行海水碳化学参数的计算（以pH值为例）。初步结果显示了较好的适用性，从而提示了综合利用P. obliquiloculata壳体B/Ca和Cd/Ca指标方法（以及Mg/Ca和δ18O估算温度和盐度）进行古代海水化学参数记录重建的潜力。 |
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