Characteristics of Seafloor Morphology and Ferromanganese Nodule Occurrence in the Korea Deep-sea Environmental Study (KODES) Area, NE Equatorial Pacific     

Hoi-Soo Jung  Young-Tak Ko  Sang-Bum Chi  Jai-Woon Moon 《Marine Georesources & Geotechnology》2001,19(3):167-180

Seafloor morphology and ferromanganese nodule occurrence were studied using a multibeam side scan sonar (SeaBeam, 2000) and a deep-sea camera system in the Korea Deep-sea Environmental Study (KODES) area, northeast equatorial Pacific. Seafloor morphology and nodule abundance are highly variable even in this small study area. The NNE-SSW oriented hills are parallel and about 100-200 m high. Valleys are very flat-floored, while hilltops are rugged with depressions of tens of meters. Cliffs to about 100 m bound the valleys and the hills. The study area can be classified into three types based both on nodule occurrence and seafloor morphology, mostly G- and B-types and some M-type. G-type is characterized by high nodule abundance, ubiquitous bioturbation, and flat seafloor morphology, while B-type is characterized by irregular-shaped nodules, variable nodule abundance, occurrence of giant nodules and sediment lumps, rugged bottom morphology with depressions, and white calcareous surface sediments. Medium nodule abundance and a generally flat seafloor characterize M-type. G-type occurs mostly in the valley regions, while B-type is on the hilltop areas. M-type is located between the hilltop and the valley. Tectonic movement of the Pacific plate resulted in the elongated abyssal hills and cliffs. The rugged morphology on hilltops resulted from erosion and redistribution of surface siliceous sediments on hilltops by bottom currents, outcropping of underlying calcareous sediments, and dissolution of the carbonate sediments by corrosive bottom water undersaturated with CaCO 3 . Sediment eroded from the hills, which is relatively young and organic-rich, is deposited in the valleys, and diagenetic metal supply to manganese nodules in the valley area is more active than on the hills. We suggest that tectonic movement ultimately constrains morphology, surface sediment facies, bottom currents and sediment redistribution, bioturbation, thickness of the sedimentary layer, and other conditions, which are all interrelated and control nodule occurrence. The best potential area for mining in the study area is the G-type valley zones with about 3-4 km width and NNW-SSE orientation.  相似文献   

Bathymetry of the Reykjanes Ridge     

Keeton  J. A.  Searle  R. C.  Peirce  C.  Parsons  B.  White  R. S.  Sinha  M. C.  Murton  B. J.  Parson  L. M. 《Marine Geophysical Researches》1997,19(1):55-64

We present a series of 1:200,000 scale maps of the bathymetry of the Reykjanes Ridge. The data are divided into four maps, extending 630 km along the ridge axis and between 30 and 100 km off-axis. This compilation of bathymetry data is extremely detailed, gridded at approximately 100 m resolution, and with almost no gaps. The Reykjanes Ridge is one of the best examples of a hotspot-dominated ridge, whose characteristics are influenced by its proximity to the Iceland plume. Many fundamental questions may be addressed at the Reykjanes Ridge, which is why the BRIDGE programme identified it as one of its four regional projects. These maps represent a BRIDGE contribution to the general scientific community.  相似文献   

Wind effects on sub-tidal currents in Puget Sound     

Hiroshi Matsuura  Glenn A. Cannon 《Journal of Oceanography》1997,53(1):53-66

Wind effects on sub-tidal currents are studied using current meter records obtained at six moorings across the main basin of Puget Sound. High correlations between wind speeds and currents are found near the surface and at mid-depths of about 100 m. Empirical Orthogonal Function analysis applied to the axial currents in 1984 and 1985 shows that mode 1, containing over 60% of the variance, is highly correlated with wind speed even without any near surface current records. When near surface stratification is strong, direct wind effects are limited to the upper 30 m with counter currents in the lower layer indicating a baroclinic response. The transport in the lower layer almost balances the transport in the upper layer. When near surface stratification is weak, direct wind effects on currents can be detected to about 100 m. In this case, there is no clear and consistent depth at which one can separate the upper from the lower layer. Time series show that the acceleration in the surface layer initially increases in the same direction as the wind when the wind starts blowing, but it reaches a maximum, starts decreasing, and eventually changes to the opposite direction (decelerates) while the wind continues to blow in one direction. Results of a continuously stratified normal mode model and estimations from the observations suggest that friction at solid boundaries is a major cause of these phenomena. The model shows that modal currents of normal modes 2 and 3 are as important as mode 1, although the resultant vertical structure of total current shows a two-layer type pattern with only one zero crossing. The effect of the baroclinic pressure gradient is only apparent at low frequencies and among lower modes.  相似文献   

分析海浪方向谱的EEV方法的一种迭代形式     

管长龙 《中国海洋大学学报(自然科学版)》1996,(1)

将Pawka为改进最大似然方法（MLM）而提出的迭代方案应用于扩展本征关方法（EEV），作为EEV的一种迭代形式（IEEV）。用模拟数据检验了IEEV的合理性，并与EEV作了比较。计算结果表明，IEEV的估计性状较EEV有改善。最后将IEEV及EEV用于分析仪器阵列的外海观测数据。  相似文献   

数字式水声语音通信发射器系统的研制     

程恩  王清池 《海洋科学》2002,26(7):47-49

利用纵振换能器的纵向振动与换能器前盖板的弯曲振动相耦合原理，采用纵振换能器与声反射器配合，研制出一种适应在复杂海洋声信道进行高速率传输，具有低频，宽带，大功率等优点的水声换能器。  相似文献   

Contractual solution to the tragedy of property right in coastal fisheries     

Arif Satria  Yoshiaki Matsuda  Masaaki Sano 《Marine Policy》2006

This article aims to analyze how private property regimes can co-exist with common property regimes in a coastal area. The case study shows how the dynamics of private property and common property right holders is in creating commitment to make symbiosis in resource use. This is based on a case study in two villages in West Lombok, Indonesia, where pearl-culture as a private property resource exists in a common property regime. This is a successful story in dealing with the tragedy of property rights in the country wherein established institutional arrangement is still absent. Nevertheless, this may be site specific, and fragile if there is no institutional arrangement combining formal and informal rules and involving both formal and informal authorities. To make a robust solution, multilevel solution must be considered: national, local, and community level, with reference to Japan case.  相似文献   

泛黄海海区的物理海洋特征     

袁业立  郭炳火  孙湘平 《海洋科学进展》1993,(3)

本文扼要综述了至今的我国海洋调查的重要事件,它们包括:1)全国性综合性调查,2)特定海洋现象的专项调查,3)各项中外合作海洋调查.在海洋调查基础上,本文还综述了泛黄海区主要海洋环流分量的特征,并尽可能从数学物理角度简要阐明了这些海洋现象的形成和维持机制.  相似文献   

Retrospective analysis: bile hydrocarbons and histopathology of demersal rockfish in Prince William Sound,Alaska, after the Exxon Valdez oil spill     

Marty GD  Hoffmann A  Okihiro MS  Hepler K  Hanes D 《Marine environmental research》2003,56(5):569-584

Demersal rockfish are the only fish species that have been found dead in significant numbers after major oil spills, but the link between oil exposure and effect has not been well established. After the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, several species of rockfish (Sebastes spp.) from oiled and reference sites were analyzed for hydrocarbon metabolites in bile (1989-1991) and for microscopic lesions (1990 and 1991). Biliary hydrocarbons consistent with exposure to Exxon Valdez oil were elevated in 1989, but not in 1990 or 1991. Significant microscopic findings included pigmented macrophage aggregates and hepatic megalocytosis, fibrosis, and lipid accumulation. Site differences in microscopic findings were significant with respect to previous oil exposure in 1991 (P=0.038), but not in 1990. However, differences in microscopic findings were highly significant with respect to age and species in both years (P<0.001). We conclude that demersal rockfish were exposed to Exxon Valdez oil in 1989, but differences in microscopic changes in 1990 and 1991 were related more to age and species differences than to previous oil exposure.  相似文献   

Caisson breakwaters embodying an OWC with a small opening—Part II: A small-scale field experiment     

Paolo Boccotti  Pasquale Filianoti  Vincenzo Fiamma  Felice Arena 《Ocean Engineering》2007,34(5-6):820-841

A common and intuitive idea is that, before an absorbing breakwater, waves are smaller than before a conventional reflecting breakwater. The theory of Part I has shown that, on the contrary, before a breakwater converter, in some cases, the wave height may be greater than before a conventional reflecting breakwater. Now, an experiment off the eastern coast of the Straits of Messina provides a confirmation of the theory: some huge amplifications of swells are common at a breakwater converter, and as a consequence the energy absorption gets very large. Here, we show the results of the experiment, and, basing ourselves on these results and on the theory of Part I, we suggest some practical way of calculation.  相似文献   

Laboratory Studies on Property Changes in Surrounding Clays Due to Installation of Deep Mixing Columns   总被引：6，自引：0，他引：6  

Shui-Long Shen  Xing-Chun Huang  Shou-Ji Du  Jie Han 《Marine Georesources & Geotechnology》2003,21(1):15-35

This paper has identified six major factors causing property changes in surrounding soils during and after installation of deep mixing columns: soil thixotropy, soil fracturing, cement penetration and diffusion, cementation, consolidation, and heating. Laboratory tests were performed to investigate the effects of soil thixotropy, soil fracturing, and cementation in a soft marine clay, Ariake clay. Laboratory tests were conducted to evaluate property changes in surrounding clays due to installation of deep mixing columns. Test results showed that an influential zone of property changes existed in surrounding clay ranging from the edge of the columns to the distance of about twice the radius of the columns. Within this influential zone, water content decreased as samples neared the columns, while pH values and electric conductivity increased. Test results also showed that undrained shear strengths of the surrounding clays decreased during mixing but regained after a 7-day curing period and continued increasing during 28 days in this study.  相似文献