A 35-million-year record of seawater stable Sr isotopes reveals a fluctuating global carbon cycle
A 35-million-year record of seawater stable Sr isotopes reveals a fluctuating global carbon cycle
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DOI：
10.1126/science.aaz9266
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发表时间：
2021-03
期刊：
影响因子：
56.9
通讯作者：
A. Paytan;E. Griffith;A. Eisenhauer;M. Hain;K. Wallmann;A. Ridgwell
中科院分区：
文献类型：
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作者：
A. Paytan;E. Griffith;A. Eisenhauer;M. Hain;K. Wallmann;A. Ridgwell
海洋碳包括有机和无机成分，这两种成分都必须考虑到了解全球碳循环。Paytan等人收集了来自远洋海洋重晶石的稳定锶同位素（88 Sr和86 Sr）的记录，并将其用于重建海洋沉积物中生物碳酸钙沉积和埋藏的变化。这些数据与87 Sr/86 Sr的测量相结合，可以帮助揭示锶源和锶汇的过去变化，以及影响碳循环的碳酸盐沉积变化。《科学》，本期第1346页，海洋重晶石中88 Sr和86 Sr的测量有助于揭示过去碳循环的变化。海水中主要成分的浓度和同位素组成的变化反映了其源和汇的变化。由于控制这些源和汇的许多过程都与碳的循环有关，因此这些记录可以深入了解是什么驱动了大气二氧化碳和气候的过去变化。在这里，我们提出了一个稳定的锶（Sr）同位素记录来自远洋海洋重晶石。我们的δ88/86 Sr记录显示出一种复杂的模式，在3500万年前到1500万年前（Ma）之间首先下降，然后从1500万年到500万年增加，然后从500万年到现在再次下降。数值模拟表明，海水Sr浓度的相关波动相对于现今海水约为±25%。我们解释的δ88/86 Sr数据反映的矿物学和埋藏位置的生物碳酸盐岩的变化。
Carbon cycle history Marine carbon includes organic and inorganic components, both of which must be accounted for to understand the global carbon cycle. Paytan et al. assembled a record of stable strontium isotopes (88Sr and 86Sr) derived from pelagic marine barite and used it to reconstruct changes in the deposition and burial of biogenic calcium carbonate in marine sediments. These data, when combined with measurements of 87Sr/86Sr, can help to reveal past changes in the sources and sinks of strontium, as well as variations in carbonate deposition that affect the carbon cycle. Science, this issue p. 1346 Measurements of 88Sr and 86Sr in marine barite help reveal past carbon cycle variability. Changes in the concentration and isotopic composition of the major constituents in seawater reflect changes in their sources and sinks. Because many of the processes controlling these sources and sinks are tied to the cycling of carbon, such records can provide insights into what drives past changes in atmospheric carbon dioxide and climate. Here, we present a stable strontium (Sr) isotope record derived from pelagic marine barite. Our δ88/86Sr record exhibits a complex pattern, first declining between 35 and 15 million years ago (Ma), then increasing from 15 to 5 Ma, before declining again from ~5 Ma to the present. Numerical modeling reveals that the associated fluctuations in seawater Sr concentrations are about ±25% relative to present-day seawater. We interpret the δ88/86Sr data as reflecting changes in the mineralogy and burial location of biogenic carbonates.