摘要
浅海物质循环是国际地圈生物圈计划的研究重点之一。陆架区细颗粒沉积物运动不仅是自然环境变化的重要原因 ,而且也与营养盐物质循环和生态系统密切相关。全球细颗粒物质入海通量每年约有 2 0 0亿吨 ,入海之后一部分在海岸带或陆架水域堆积下来 ,另一部分则离开陆架进入深海。物质循环及其变化的定量预测依赖于数学模型 ,而模型中包含的悬沙的沉降速率、扩散 -混合系数、底部边界层参数、垂向悬浮强度等重要参数 ,则要通过观测数据的分析和物质运动过程的揭示才能获得。细颗粒沉积物向深海的输运受到两种作用的控制 :在狭窄的陆架 ,重力作用形成沿着海底峡谷向深海运动的浊流 ;在宽广的陆架 ,细颗粒沉积物向深海的输运主要是与环流作用和混合扩散作用相联系的。在浅海物质循环研究领域 ,近期的重点包括悬沙通量的变化及其对全球海洋环境和生态系统的影响、海底界面过程、陆架泥质沉积的成因、细颗粒物质沉积层序的模拟等。
Material cycling on continental shelves is one of the critical issues of the International Geo-Biosphere Project. The movement of fine-grained sediment is not only a cause for changes in physical environments, but it is also related closely to nutrient cycling and ecosystems. Globally, the annual flux of fine-grained sediment from land into the sea is around 20 billion tons; a part of the material accumulates in the coastal zone and shelf seas, whilst the remainder is transported towards the deep sea. Quantitative predictions of material cycling and its changes depend upon mathematical modeling, and the parameters required as model input (e. g. settling velocity of particles, bottom boundary layer parameters, diffusion-dispersion coefficients and resuspension flux) can be obtained only by in situ measurements and process studies. The escape of fine-grained material from the shelves is controlled by two mechanisms: on narrow shelves, transport may be due to turbid currents driven by gravity in submarine canyons; on wide shelves, however, the transport is caused by shelf circulation and dispersion. In the research field of shallow marine material cycling, important research topics include variations in suspended sediment fluxes and their influences on the global/regional environments and ecosystems, boundary layer processes, the formation of continental shelf mud deposits, and modeling of the sequence of fine-grained sediment deposition.
出处
《世界科技研究与发展》
CSCD
2000年第5期73-77,共5页
World Sci-Tech R&D
基金
国家杰出青年科学基金项目!(海洋沉积动力学及其在资源环境研究中的应用
编号 4972 5 6 12 )
自然科学基金项目!(北黄海全新世沉积
关键词
浅海物质循环
海洋沉积
入海通量
细颗粒沉积物
suspended sediment transport, shallow sea material cycling, global change, marine sedimentlogy, environment and resource
