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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.

利用硅稳定同位素示踪法同时测定了表层水中生物硅(硅藻)的产生量和溶解速率，以研究西北太平洋次北极表层水中生物源二氧化硅的产生量和溶解速率之间的平衡。建立了高分辨率电感耦合等离子体质谱分析硅同位素比值的新方法。通过对本底硅峰的校正，获得了与热电离质谱仪相近的分析精度和灵敏度。用该方法测定了北太平洋西亚北极表层水中生物二氧化硅的生成速率和溶解速率。生物硅柱的整体溶解速率超过硅藻在真光层的产出率，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。在实验室中还对取自北太平洋西部次北极的硅藻进行了批量溶解实验，以考察主要硅藻类群之间的溶解动力学差异。观察到的溶解速率表明，不同种类的硅藻以及不同位置的硅藻，其溶解程度不同。硅藻球茎在溶解过程中的形态变化似乎是影响球茎表面积/体积比从而影响其溶解速度的一个重要因素。根据这些结果，由硅藻产生的大部分生物二氧化硅被估计在表层海洋中循环使用。然而，深层硅藻的存在意味着含有野生硅藻颗粒的硅藻的快速下沉应该被认为是海洋硅循环的另一个重要过程。