Field investigation and numerical simulation of long-term sedimentary processes in a bay

海湾长期沉积过程现场调查与数值模拟

• 批准号: 15360263
• 负责人: SASAKI Jun
• 金额: $ 8.7万
• 依托单位: Yokohama National University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15360263/
• 关键词: Bay; Sediment environment; Numerical model; Long-term reproduction; Environmental record; Sediment grain size; Water content; Organic analysis; 内湾環境; 長期予測; 底泥堆積; 環境再現計算

We first conducted a field survey to reveal the thickness of polluted mud layer in Tokyo Bay using a method of bottom sounding based on two supersonic waves. There were, however, some problems for this method. We thus tried to reveal spatial variation in mud quality directly on the basis of sediment core sampling. We developed a core sampling method using an Ekman barge sampler altered to take mud core samples efficiently. We collected more than 50 core samples in the inner part of the bay and sliced them every about 1cm from the surface of the sediment to the deep layer. Then we measured water content, sediment grain size distribution, total organic carbon and nitrogen, and carbon and nitrogen stable isotope ratio. We elucidated higher organic content mud is accumulated around the central part of the inner bay while lower organic content sediment is accumulated around it. A three-dimensional and multi-class sediment accumulation model was developed to reproduce and understand the sediment accumulation processes considering the variation in sediment grain size. We reproduced muddy sediment accumulation processes in the bay. On the basis of field investigation and numerical experiments as well as former field data, we analyzed the mechanism of the formation of these sedimentary processes such that finer particles adsorb larger amount of organic matter and settling and resuspension processes are dominant factors. Moreover, observed lower C/N values at the central part are also one of the major causes of the formation of spatial variation in sediment quality because the waters in the central part are exposed to hypoxia for longer time than those of their surrounding waters, which makes the rate of mineralization lower.

首先，我们进行了现场调查，以揭示东京湾的污染泥层的厚度，使用基于两个超声波的海底探测方法。然而，这种方法存在一些问题。因此，我们试图揭示直接的沉积物芯取样的基础上，泥浆质量的空间变化。我们开发了一种岩心取样方法，使用Ekman驳船取样器，该取样器经过改装可有效地采集泥浆岩心样品。我们在海湾内部采集了50多个岩心样品，从沉积物表层到深层每隔约1cm切片一次。在此基础上，对沉积物的含水量、沉积物粒度分布、总有机碳和总有机氮以及碳和氮稳定同位素比值进行了测定。通过对沉积物粒度变化的分析，建立了一个三维多层次的沉积物堆积模型，再现了沉积物的堆积过程，揭示了有机质含量较高的泥质在内湾中部堆积，有机质含量较低的沉积物在内湾中部堆积。我们再现了海湾泥沙淤积过程。在野外调查和数值试验的基础上，结合前人的野外资料，分析了这些沉积过程的形成机制，即细颗粒吸附了大量的有机质，沉降和再悬浮过程是主导因素。此外，中部较低的C/N值也是形成沉积物质量空间变异的主要原因之一，因为中部沃茨较周围沃茨缺氧时间长，矿化速率较低。

项目成果

Numerical Analysis of Wind-Wave Climate Change and Spatial Distribution of Bottom Sediment Properties in Sanbanze Shallows of Tokyo Bay

东京湾三板泽浅滩风浪气候变化及底质空间分布的数值分析

• 发表时间: 2007
• 期刊: J.Coastal Res SI50
• 作者: Achiari;Hendra;Jun Sasaki
• 通讯作者: Jun Sasaki

Simple methodology for environmental evaluation of tidal flats and shallows focusing on oxygen consumption rate

以耗氧率为重点的滩涂浅滩环境评价简易方法

• 发表时间: 2007
• 期刊: Proc. 4the Int. Conf on Asian and Pacific Coasts
• 作者: Sasaki;Jun;Shusaku Maeda.
• 通讯作者: Shusaku Maeda.

Nnumerical analysis of characteristics of annual accumulated sediment in Tokyo Bay

东京湾年积沙量特征的数值分析

• 发表时间: 2006
• 期刊: Proc.Techno-Ocean 2006/19th JASNAOE Ocean Eng.Symp (in CD-ROM)
• 作者: Rasmeemasmuang Thamnoon;Jun Sasaki
• 通讯作者: Jun Sasaki

東京湾流域圏におけるリン循環の推定と社会的変化による応答予測

东京湾流域磷循环估算及社会变化的响应预测

• 发表时间: 2006
• 期刊: 海岸工学論文集 53
• 作者: Rasmeemasmuang Thamnoon;Jun Sasaki;上田 嘉通・佐々木 淳
• 通讯作者: 上田 嘉通・佐々木 淳

Field investigation and numerical modeling of solft mudaccumulation in an estuarine embayment

河口海湾软泥淤积现场调查与数值模拟

• 发表时间: 2007
• 期刊: ndo-Japan Workshop on Coastal Problems and Mitigation Measures-Including the Effects of Tsunami-
• 作者: Sasaki;Jun;Thamnoon Rasmeemasmuang
• 通讯作者: Thamnoon Rasmeemasmuang