Evaluation of foraminiferal trace element cleaning protocols on the Mg/Ca of marine ostracod genus Krithe
Evaluation of foraminiferal trace element cleaning protocols on the Mg/Ca of marine ostracod genus Krithe
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DOI：
10.1016/j.chemgeo.2014.05.022
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发表时间：
2014-08-29
期刊：
影响因子：
3.9
通讯作者：
Shevenell, Amelia
中科院分区：
文献类型：
--
作者：
Gray, William;Holmes, Jonathan;Shevenell, Amelia
海洋介形虫属Krithe方解石的Mg/Ca值可能是重建过去大洋底水温变化的重要工具。严格的清洁程序，常规用于去除粘土，有机物和铁锰羟基氧化物涂层的有孔虫的微量元素研究，不定期应用于海洋介形类，尽管镁污染的潜力。在这里，我们应用标准的氧化和还原有孔虫清洗程序，核心顶部Krithe pernoides阀从boxcore OCE 205 - 50 BC（26.23度N，77.7度W，817米水深），以评估污染的影响镁/钙比，并评估污染物去除和介形类阀化学清洗技术的影响。研究结果表明，粘土和铁锰羟基氧化物对石英的Mg/Ca有影响。在甲醇/超纯水中超声处理后，Mg/Ca降低1.6 mmol/mol（11%）（相当于重建温度降低1.5 ℃），表明这是制备用于Mg/Ca分析的Krithe阀的关键步骤。用缓冲过氧化氢氧化对我们工厂的瓣膜的Mg/Ca几乎没有影响。还原清洁将阀间变化从12%降低到5%，从而实现+/- 0.6 ℃的等效温度精度。然而，由于阀表面的部分溶解，还原清洁也降低Mg/Ca比。还原性清洗提供了改善Krithe镁/钙古温度重建的潜力，并应在未来的Krithe镁/钙研究中使用。未来的工作还应旨在限制瓣膜表面部分溶解的影响。(C)2014作者由爱思唯尔公司出版
The Mg/Ca of calcite from the marine ostracod genus Krithe may be an important tool for reconstructing past changes in oceanic bottom water temperature (150-4000 m water depth). Rigorous cleaning procedures, routinely used to remove clays, organic matter and Fe-Mn oxyhydroxide coatings in trace element studies of foraminifera, are not regularly applied to marine ostracods despite the potential for Mg contamination. Here we apply standard oxidative and reductive foraminiferal cleaning procedures to core top Krithe pernoides valves from boxcore OCE205-50BC (26.23 degrees N, 77.7 degrees W, 817 m water depth) to evaluate the effects of contamination on Mg/Ca ratios and assess the impact of cleaning techniques on contaminant removal and ostracod valve chemistry. Our results show that clays and Fe-Mn oxyhydroxides influence the Mg/Ca of Krithe. Following sonication in methanol/ultrapure water, there is a 1.6 mmol/mol (11%) decrease in Mg/Ca (equivalent to a reduction in reconstructed temperature of 1.5 degrees C), indicating that this is a critical step in the preparation of Krithe valves for Mg/Ca analyses. Oxidation with buffered hydrogen peroxide has little effect on the Mg/Ca of valves fromour site. Reductive cleaning reduces inter-valve variability from 12% to 5%, resulting in an equivalent temperature precision of +/- 0.6 degrees C. However, reductive cleaning also decreases Mg/Ca ratios due to the partial dissolution of the valve surface. Reductive cleaning offers the potential to improve Krithe Mg/Ca paleotemperature reconstructions and should be utilised in future Krithe Mg/Ca studies. Future work should also aim to constrain the effects of partial dissolution of the valve surface. (C) 2014 The Authors. Published by Elsevier B.V.