| 摘要: |
| 近海悬浮物在海水中的运移受诸多因素影响, 其中由于径流输入导致的水体层化是不可忽视的因素之一, 研究层结水体中沉积物受潮流、波浪影响的再悬浮特征有重要意义。2005 年 5 月 15日在黄河口西侧18海里处的莱州湾口设立了一个周日连续观测站, 试图揭示弱层结水体中悬浮物的再悬浮特征及其水平、沉降通量。利用 ADCP 回声强度反演得到了高分辨率的悬浮物时空分布, 在详细分析潮流、波浪以及密度层结变化的基础上, 指出以上诸因素是影响沉积物再悬浮的主要机制。潮流和波浪联合作用于底床使沉积物起动进入水体, 而层结强度与位置的变化则是起动的沉积物能否有效再悬浮(进入水体中、上层)的调控机制。在波浪和层结的影响下, 涨潮时更多沉积物再悬浮进
入水体, 使得一个半日潮周期内出现指向湾内的悬浮物水平净通量。由于密度层结抑制水体湍流扩散强度, 阻碍层结界面处物质交换, 导致悬浮物浓度垂向梯度增大, 进而增大悬浮物沉降通量。
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| 关键词: 沉积物, 密度层结, 再悬浮, 沉降通量, 莱州湾口 |
| DOI：10.11693/hyhz201101001001 |
| 分类号: |
| 基金项目:国家基础研究规划重点项目, 2005CB422300 号; 国家自然科学基金项目, 40806001 号; 日本综合地球环境学研究所研究项目: 1-2FR“近年黄河急剧水环境变化及其意义”, 2002—2007。 |
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| RESUSPENSION AND ASSOCIATED HORIZONTAL, SETTLING FLUXES OF SEDIMENT IN THE WEAKLY STRATIFIED LAIZHOU BAY MOUTH |
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YUAN Ye1,2, JIANG Wen-Sheng1, GAO Hui-Wang3, GUO Xin-Yu4
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1.Physical Oceanography Institute, Ocean University of China;2.National Marine Environmental Forecasting Center;3.College of Environmental Science and Engineering, Ocean University of China;4.Center for Marine Environmental Studies, Ehime University
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| Abstract: |
| Transportation of suspended particulate matter (SPM) is affected by many factors in coastal seas, among which stratification plays an important part in this matter. Nearly 24-hour continuous data were collected on May 15, 2005 in order to understand the resuspension characteristic, horizontal and settling fluxes of sediment in the weakly stratified Laizhou Bay mouth, which is 18 km west of Yellow River Mouth. This project utilized ADCP instrumentation to estimate the high-resolution of SPM concentration profiles. Combined with the detailed description of tidal current, wave and
stratification status, three significant findings were discovered: (1) both tidal current and wave play the important roles in the incipient motions of sediment, while stratification strength and height determine the turbulence intensities in the water column which influence the diffusion of suspended sediment to higher water levels; (2) because of asymmetry of resuspension arisen by combined wave- and current-induced shear stress, landward tidally-averaged sediment flux was observed; (3) pycnocline is a natural barrier which inhibits the across-interface exchange of suspended sediment, and suppression of sediment resuspension led to increased vertical gradient of concentration, which in turn resulted in an increased settling flux.
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| Key words: , Stratification, Resuspension, Settling flux, Yellow River mouth |
