Potassium incorporation and isotope fractionation in cultured scleractinian corals
Potassium incorporation and isotope fractionation in cultured scleractinian corals
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DOI：
10.1016/j.epsl.2022.117393
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发表时间：
2022-03
影响因子：
5.3
通讯作者：
Wenshuai Li;Xiao-ming Liu;Kun Wang;Yongfeng Hu;A. Suzuki;T. Yoshimura
中科院分区：
文献类型：
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作者：
Wenshuai Li;Xiao-ming Liu;Kun Wang;Yongfeng Hu;A. Suzuki;T. Yoshimura
钾 (K) 参与珊瑚生物活动并在珊瑚骨骼中积累，驱动稳定钾同位素 (41 K/39 K) 的分馏。限制生物和非生物控制对钾同位素分馏的影响对于解释珊瑚记录很重要。然而，调节钾融入珊瑚骨骼以及海水和珊瑚骨骼之间钾同位素分馏的过程和机制仍然未知。在这里，我们结合同位素和基于同步加速器的光谱分析，在水族箱培养实验中评估了 20 至 29°C 海水温度范围内石珊瑚 (Porites australiensis) 珊瑚骨骼中 K 的相位分布和相应的同位素变化。珊瑚骨骼中的钾主要以各种比例的有机-K（K 存在于可溶性和不溶性有机基质中）和碳酸盐-K（K 结合到K 2 CO 3 和霰石中）相形式存在。珊瑚 δ 41 K 值在方向和幅度上与现代海水 δ 41 K 成分 (∼ 0.12‰) 变化很大，显示出从− 2.00 到 0.67‰ 的显着偏差 (Δ 41 K 珊瑚海)。随着海水温度升高，有机钾含量增加，而 δ 41 K 珊瑚减少。 δ 41 K 珊瑚的变化反映了有机结合 K 与碳酸盐相关 K 的相对比例。在大多数情况下，珊瑚晶内有机基质优先螯合同位素较轻的 K，而碳酸盐相更喜欢较重的 K。在相同培养条件下生长的珊瑚骨骼 δ 41 K 的群体间可区分的差异揭示了生理控制对 K 的影响。 分配和同位素分馏。尽管在所研究的珊瑚中，钙化率与温度存在不同程度的相关性，这可能反映了对虫黄藻密度差异的控制，但我们推断钙化率并不是骨骼δ 41 K的主要控制因素。相反，骨骼δ 41 K与K相分配密切相关，这归因于温度敏感的生理调节。
Potassium (K) participates in coral biological activities and accumulates in their skeletons, driving the fractionation of stable K isotopes (41 K/39 K). Constraining the influences of biotic and abiotic controls on K isotope fractionation is important for interpreting coral records. However, the processes and mechanisms regulating K incorporation into coral skeletons and K isotope fractionation between seawater and coral skeletons remain unknown. Here, we combined isotopic and synchrotron-based spectroscopic analyses to evaluate the phase distribution and corresponding isotope variation of K in the skeleton of scleractinian (Porites australiensis) corals at a seawater temperature range from 20 to 29° C in aquaria culture experiments. Potassium in coral skeletons exists mainly as organic-K (K hosted in soluble and insoluble organic matrices) and carbonate-K (K incorporated into K 2 CO 3 and aragonite) phases of various proportions. Coral δ 41 K values vary substantially in both direction and magnitude from the modern seawater δ 41 K composition (∼ 0.12‰), showing marked deviations (Δ 41 K Coral-Sea) from− 2.00 to 0.67‰. As seawater temperature increases, the organic-K fraction increases, whereas δ 41 K Coral decreases. The variation in δ 41 K Coral reflects the relative proportions of organic-bound K to carbonate-associated K. In most cases, coral intracrystalline organic matrices preferentially sequester isotopically lighter K whereas carbonate phases prefer heavier K. Distinguishable inter-colony difference in skeletal δ 41 K of corals growing under the same culturing conditions reveals the influence of physiological controls on K partitioning and isotope fractionation. Although calcification rate correlates with temperature to different degrees in the studied corals, likely reflecting control of the difference in zooxanthellae density, we infer that calcification rate is not a major controlling factor on skeletal δ 41 K. Rather, skeletal δ 41 K correlates closely with K phase partitioning, which is ascribed to temperature-sensitive physiological modulation.