江苏启东嘴潮滩敏感粒度组分及环境意义

敏感粒度组分是研究沉积环境变化的重要方法之一。江苏启东嘴潮滩位于江苏海岸与长江岸线交汇处，陆海相互作用强烈；随着社会经济的快速发展，受人类活动的影响也越来越大。在对4个岩芯沉积物进行粒度分析的基础上，应用粒级-标准偏差的方法提取环境敏感粒度组分。结果表明:（1）对环境变化敏感的细组分与粗组分具有明显的负相关关系，岩芯QDZ-1、QDZ-2和QDZ-3中<22 μm、<26 μm、<22 μm的细组分的含量由下向上逐渐增加，符合粉砂淤泥质潮滩下粗上细的沉积规律。（2）在流域强降雨引发的洪水和风暴潮等极端环境的影响下，导致粗组分的含量突然增加。岩芯QDZ-1、QDZ-2和QDZ-3中>22 μm、>26 μm、>22 μm的粗组分，在深度172.5 cm、242.5 cm、142.5 cm处分别剧增至84%、85%和80%。（3）在人类活动的影响下，细组分比粗组分更容易淋失，进而导致岩芯出现粗化趋势。QDZ-2在剖面上部A段>26 μm的粗组分呈增加趋势，是因为受到轮作翻种的农业生产活动和雨水淋溶作用的共同影响。岩芯QDZ-3在剖面上部A段22 μm～88 μm、>88 μm的粗组分和岩芯QDZ-4剖面>63 μm的粗组分呈增加趋势，原因是围垦建堤使原有的水动力得以增加，进而在高能环境下粗颗粒物质能够沉积。

The sensitive grain-size components of core sediments and environmental significance at tidal flat around Qidong cape,Jiangsu province

The sensitive grain-size component is one of the important approaches to analyze sedimentary environment change. Tidal flat around Qidong cape is located at the intersection between the coast of Jiangsu and the river line of the Yangtze River, where with intense land-sea interactivities. With economic development, the area is affected by human activities heavily. Four cores are collected during field investigation. After grain size analysis, the sensitive grain-size components are identified based on standard deviation. The results are as follows: (1) there is a distinct negative correlation between fine components and coarse components. The fine components of <22 μm, <26 μm, <22 μm in the core QDZ-1, QDZ-2 and QDZ-3 sediments gradually increases from bottom to top, which could reflect general law of tidal flat sedimentation. (2) The coarse components suddenly increase under the influence of extreme environmental changes such as floods and storm surges. The coarse components of >22 μm, >26 μm and >22 μm in the core QDZ-1, QDZ-2 and QDZ-3 sediments increased sharply to 84%, 85% and 80% at depths of 172.5 cm, 242.5 cm and 142.5 cm respectively. (3) The fine components are more likely to leach than the coarse components under the influence of human activities, and as a result, that sediment tends to coarsen. The coarse components of >26 μm of QDZ-2 showed an increasing trend in the upper part of the section A. The reason is due to the combined effects of agricultural activities and rainwater leaching. The coarse components of 22 μm～88 μm and >88 μm of QDZ-3 show an increasing trend in the upper part of the section A. The coarse components of >63 μm of QDZ-4 showed the same. The reason is that the sedimentary dynamic enhanced by reclamation dikes constructed. As a result, coarse components are easier than fine components to adapt to high-energy environment and to deposit.