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The balance between biogenic silica production and its dissolution in the surface ocean

生物二氧化硅的产生与其在表层海洋中的溶解之间的平衡

基本信息

批准号：
17310005
负责人：
TAKEDA Shigenobu
金额：
$ 10.46万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17310005/
关键词：
Earth science Marine ecosystem Silicon Diatoms Stable isotope Mass spectrometry Biogenic silica Phytoplankton ケイ藻地球化学ケイ酸

项目摘要

Production and dissolution rates of biogenic silica (diatom frustules) in the surface waters were determined simultaneously using silicon stable isotope tracer to investigate balance between biogenic silica production and its dissolution in the surface waters of the western subarctic North Pacific Ocean. New analytical method for the determination of silicon isotope ratios was developed using a high-resolution Inductively Coupled Plasma-Mass Spectrometry. By correcting background Si peaks, analytical precision and sensitivity similar to those of the thermal ionization mass spectrometry were obtained. This method was used for the determination of the rates of biogenic silica production and dissolution in the Oyashio surface water of the western subarctic North Pacific. Column integrated dissolution rate of biogenic silica exceeded production rate by diatoms within the euphotic layer, suggesting active silicic acid dissolved from particulate biogenic silica and its utilization by diatoms in the surface mixed layer. Batch dissolution experiments of diatom frustules obtained from the western subarctic North Pacific were also conducted in the laboratory to investigate differences in dissolution kinetics between the dominant diatom groups. Observed dissolution rates indicated that degree of solubility of diatom frustules is different between the diatom species as well as the site of the frustules. Morphological changes of diatom frustules during the dissolution process seem to be an important factor affecting surface/volume ratio of the frustules and consequently its dissolution rate. From these results, most of the biogenic silica produced by diatoms was estimated to be recycling in the surface ocean. However, existence of diatom frustules in the deep layers implies that rapid sinking of diatom containing feral pellets should be considered as another important process in the marine silicon cycles.

使用硅稳定同位素示踪剂同时测定地表水中生物硅（硅藻壳）的产量和溶解速率，以研究亚北极西部北太平洋表层水中生物硅产量与其溶解之间的平衡。使用高分辨率电感耦合等离子体质谱法开发了测定硅同位素比率的新分析方法。通过校正背景Si峰，获得了与热电离质谱相似的分析精度和灵敏度。该方法用于测定北太平洋亚北极西部亲潮地表水中生物二氧化硅的产生和溶解速率。生物硅的柱综合溶解速率超过了透光层内硅藻的生产速率，表明活性硅酸从颗粒状生物硅中溶解出来并被表面混合层中的硅藻利用。实验室还对从西亚北极北太平洋获得的硅藻壳进行了批量溶解实验，以研究主要硅藻类群之间溶解动力学的差异。观察到的溶解速率表明，硅藻壳的溶解程度在硅藻种类以及硅藻壳的位置之间是不同的。硅藻壳在溶解过程中的形态变化似乎是影响硅藻壳表面积/体积比及其溶解速率的重要因素。根据这些结果，硅藻产生的大部分生物二氧化硅估计会在表层海洋中循环利用。然而，深层硅藻壳的存在意味着含有硅藻的野生颗粒的快速下沉应被视为海洋硅循环中的另一个重要过程。