Environmental magnetic-study of irrigation ponds sediment

灌溉池塘沉积物的环境磁学研究

• 批准号: 10640424
• 负责人: SATO Takaharu
• 金额: $ 2.05万
• 依托单位: Hiroshima University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640424/
• 关键词: irrigation pond; sediment; Environmental Magnetism; magnetotactic bacteria; core sampler; acguisition mechanism of DRM

1. The method of sampling sediment up to I m in depth from bottom of a lake to about 4 m, without disturbing the surface was established.2. The existence or nonexistence of magneto tactic bacteria has clarified by the pond, and it does not depend on sediment. Moreover, magneto tactic bacteria were distributed in the surface sediment centering on the depth of about I cm, and in many cases, 3 cm, even if they were deep, they were not observed by 5 cm or less.3. The method for separating contribution of the magnetic mineral particle currently not fixed (movable component) and contribution of the magnetic particle already fixed (fixed component) by freezing samples was developed. Although a fixed component may decrease greatly when a fixed component transformed into a movable component in 'the process of defrosting and a freeze, the possible increase in the fixed component deduced by the process is ten or less percent of both sum total in general.4. The movable component was only about 30 - 600/0 even at the surface. In comparatively many cores, the value was seen decrease as it became deep until it became in depth of 10-20 cm.5. There was two cores in which the movable component increases 2000 or more in the depth of 20 cm or deeper. By these cores, the partial inversion phenomenon of the acquisition time of detrital remanent magnetism may arise. A certain amount of correlation between a frequency dependence of initial susceptibility and the movable component was seen in these cores. It is thought that this is because the rate of small magnetite particle of stable single domain is changed and it has contributed to the change of a movable component by change of deposition environment.

1.建立了在不扰动湖面的情况下，从湖底到4 m左右深度1 m的沉积物取样方法.趋磁细菌的有无已由池塘澄清，而不依赖于沉积物。此外，趋磁细菌分布在表层沉积物中，集中在约1厘米的深度，在许多情况下，3厘米，即使他们是深，他们没有观察到5厘米或更少.提出了一种通过冷冻样品分离磁性矿物颗粒中目前未固定的磁性矿物颗粒（可动组分）和已固定的磁性矿物颗粒（固定组分）的方法。虽然在冻结和冻结过程中，固定分量转化为可动分量时，固定分量可能会大大减少，但由该过程推导出的固定分量可能增加的量一般为两者总和的10%或更少。即使在表面上，可移动组件也只有大约30 - 600/0。在相对较多的岩心中，该值随着深度的增加而减小，直到深度达到10-20厘米。有两个核心，其中可移动组件在20厘米或更深的深度增加2000或更多。通过这些岩心，可能会出现碎屑剩磁采集时间的部分反演现象。在这些核心的初始磁化率和可动组件的频率依赖性之间的一定量的相关性。据认为，这是因为稳定的单畴的小磁铁矿粒子的比率发生了变化，并且它有助于通过沉积环境的变化而改变可动组分。