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Variation of dust input into the North Pacific Ocean

输入北太平洋沙尘的变化

基本信息

批准号：
14380245
负责人：
FUKUMA Koji
金额：
$ 9.09万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14380245/
关键词：
climate change North Pacific dust environmental magnetism paleomagnetism alkenone magnetostratigraphy

项目摘要

To investigate the impact of dust input on climate and ocean conditions, we studies the relationship between the variation of wind-driven dust input from the Eurasia continent into the North Pacific Ocean and the climate condition in this region. It has been known that many kinds of gases like carbon dioxide are exchanged vigorously between ocean and atmosphere in the North Pacific region, and that the amount of dust input into the ocean affects carbon dioxide content in the atmosphere and would lead to the global climate change. First, we established the age-depth relation for sediment cores collected from the North Pacific Ocean using paleointensity stratigraphy. In the North Pacific high temporal resolution records have been unavailable because existing dating methods such as C14 dating or oxygen isotope stratigraphy are not applicable to siliceous sediments occupying the North Pacific. We used U-channel samplers to cover the whole interval of cored sediments and measured natural re … More manent magnetizations at 2 cm intervals. The stability of natural remanent magnetization was examined using alternating field demagnetization and anhystretic remanent magnetization was used to normalize the intensity of natural remanent magnetization to detemine the paleointensity of geomagnetic field. Comparing the measured paleointesity data with well-dated paleointensity records, we could obtain the high-resolution age models on several sediment cores for the past 800 kyr. Second, dust input was estimated from the content and grain size variations of magnetic minerals. We measured magnetic hysteresis loops, magnetic moments at low temperature and thermomagnetic curves using a newly custom-made Curie balance. Two types of sediments are well distinguished from magnetic hysteresis measurements and they are responsible to variable oxidizing/reducing conditon. Based on the paleointensity stratigraphy we could obtain high-resolution temporal records of many kinds of magnetic properties and found that the variations of dust input and ocean condition in the North Pacific are well correlated to the glacial-interglacial cycle. Less

为了探讨沙尘输入对气候和海洋条件的影响，本文研究了欧亚大陆向北太平洋输入沙尘的变化与该地区气候条件的关系。在北太平洋地区，海洋与大气之间存在着二氧化碳等多种气体的强烈交换，输入海洋的沙尘量影响着大气中二氧化碳的含量，从而导致全球气候的变化。首先，我们使用古强度地层学方法建立了北太平洋沉积岩芯的年龄-深度关系。在北太平洋，由于现有的测年方法如C14测年或氧同位素地层学不适用于北太平洋的硅质沉积物，因此无法获得高时间分辨率的记录。我们用U形通道取样器覆盖整个取心沉积物层段， ...更多信息以2厘米的间隔测量磁化强度。用交变磁场退磁法检验了天然恢复磁化强度的稳定性，用无磁滞恢复磁化强度对天然恢复磁化强度进行归一化，从而确定古地磁场强度。将实测的古强度数据与已有的古强度记录进行对比，可以得到近80万年来几个沉积岩芯的高分辨率年龄模型。其次，根据磁性矿物的含量和粒度变化估算粉尘输入量。我们使用新定制的居里天平测量了磁滞回线、低温磁矩和热磁曲线。两种类型的沉积物很好地区分从磁滞测量，它们是负责可变的氧化/还原conditon。基于古强度地层学，我们可以获得多种磁性的高分辨率时间记录，并发现北太平洋尘埃输入和海洋条件的变化与冰期-间冰期旋回有很好的相关性。少