History of carbonate ion concentration over the last 100 million years II: Revised calculations and new data
History of carbonate ion concentration over the last 100 million years II: Revised calculations and new data
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DOI：
10.1016/j.gca.2019.02.041
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发表时间：
2019-07
影响因子：
5
通讯作者：
R. Zeebe;T. Tyrrell
中科院分区：
文献类型：
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作者：
R. Zeebe;T. Tyrrell
在本期刊的早期贡献中，我们提供了过去1亿年海水碳酸盐离子浓度的重建（Tyrrell和Zeebe, 2004；以下为TZ04）。从那时起，关于过去海洋碳酸盐化学、大气CO2和主要离子海水成分的多个新的、更可靠的数据集出现了，这促使了新的CO2系统重建。此外，我们对过去主要离子海水成分对影响co2系统计算的平衡常数的影响有了新的认识，其中最明显的是硫酸盐。在此，我们提出了基于新数据和修正计算的过去海洋碳酸盐化学和大气二氧化碳的新重建，包括误差分析。我们还提供了对过去平衡常数的简单修正，这些修正得到了实验数据的支持，非常适合于数百万年时间尺度上的数值模型和观测研究。我们仅对海水碳酸盐离子浓度（100 Myr前低约2.3至4倍）的更新结果与TZ04相似，表明我们的核心方法是稳健的。然而，所有使用新的烯酮和硼数据的修正重建现在表明，海洋总溶解无机碳（DIC）和总碱度（TA）的长期库存与现代的新生代相似。这一结果与TZ04的一种情景形成强烈对比，后者具有高的古新世-始新世DIC/TA清单，并基于最近修订的硼衍生ph值。由于碳酸盐体系有两个自由度，当确定三个或更多参数时，可以进行一致性检查。总的来说，我们估计的二氧化碳系统参数在整个新生代的长期趋势似乎是一致的，无论我们将碳酸盐离子浓度与烯酮衍生的二氧化碳或硼衍生的ph值结合起来。我们的研究结果表明，新生代大气co2和海水化学的图像趋于一致。最后，我们将过去海水硫酸盐的变化确定为海水ph重建的概念和实际问题。
In an earlier contribution to this journal, we provided a reconstruction of seawater carbonate ion concentration over the last 100 million years (Tyrrell and Zeebe, 2004; TZ04 hereafter). Since then, multiple new and more robust data sets on past ocean carbonate chemistry, atmospheric CO2, and major ion seawater composition have emerged, which prompt new CO2system reconstructions. In addition, we have gained new insight into the effects of past major ion seawater composition on equilibrium constants affecting CO2system calculations — most notably due to sulfate. Here we present new reconstructions of past ocean carbonate chemistry and atmospheric CO2based on new data and revised calculations, including error analysis. We also provide simple corrections for past equilibrium constants, supported by experimental data and well-suited for numerical models and observational studies on multi-million year time scales. Our updated result for just the seawater carbonate ion concentration (∼2.3 to 4-fold lower 100 Myr ago) is similar to TZ04, indicating that our core approach is robust. However, all revised reconstructions using new alkenone and boron data now suggest that long-term ocean inventories of total dissolved inorganic carbon (DIC) and total alkalinity (TA) were similar to modern over the Cenozoic. This result contrasts strongly with one of TZ04’s scenarios, which featured high Paleocene-Eocene DIC/TA inventories and was based on boron-derivedpH values that have recently been revised. Because the carbonate system has two degrees of freedom, consistency checks can be made when three or more parameters are determined. Overall, our estimated long-term trends in CO2system parameters across the Cenozoic appear consistent, regardless of whether we combine our carbonate ion concentration with alkenone-derivedpCO2or boron-derivedpH. Our results suggest convergence towards a consistent picture of Cenozoic atmospheric CO2and seawater chemistry. Finally, we identify changes in past seawater sulfate as a conceptual and practical problem for seawaterpH reconstructions.