近百年来长江口启东嘴潮滩沉积物质来源及定量估算

河流入海输沙是海岸稳定的重要物质基础。启东嘴潮滩位于长江北支口门,与江苏海岸线交汇,陆海相互作用强烈。利用电感耦合等离子体质谱仪测定了岩芯沉积物QDZ-1的地球化学元素。根据地球化学元素的分布特征和富集系数,分析了物源指示意义,表明启东嘴潮滩沉积物受到长江物质和南黄海物质的共同影响。基于地球化学元素的沉积物端元定量判识方法,对不同物质来源的贡献率进行了定量估算。在1930年前启东嘴潮滩沉积物主要来自长江的入海输沙,贡献率为68.1%,随着长江北支河槽的衰退,贡献率逐渐减少,在1930-1972年间为38.5%,到1972年后减少到17.5%。苏北沿岸流携带向南输运的南黄海物质,贡献率逐渐增加,在1930年前为27.1%,在1930-1972年间为55.6%,到1972年后增加到75.9%,成为启东嘴潮滩主要物质来源。沉积物来源的阶段性变化,在时间上与北支水动力的阶段性变化基本吻合。

The sediment sources and quantitative evaluation of tidal flat at Qidong foreland,the Yangtze Estuary in recent 100 years

The transport of sediment by rivers to the oceans plays an important role in coastal stabilization. The Qidong foreland is located on the junction between Yangtze Estuary and Jiangsu coast, where strong land-ocean interactions are highly sensitive to environmental changes. In order to examine sediment sources and change, QDZ-1 core sediments were collected at Qidong foreland tidal flat. And the content of micro-elements was analyzed by ICP-MS, further, the source-indicating significance of micro-elements was discussed based on distribution and enrichment coefficient. The result showed that sediment sources derive from the Yangtze River and the south Yellow Sea. In addition, sediment sources were quantitatively evaluated by estimation of sedimentary end-members. The result showed that sediment sources could be divided into three stages. The sediment flew mainly from the sediment transport of the Yangtze River into the sea, with the contribution rate being 68.1%. Then, the contribution rate gradually decreased with the decline of the North Branch, down to 38.5% during the period of 1930-1972, and to 17.5% after 1972. Meanwhile, the suspended sediments from southern Yellow Sea moved mainly to the south by strong tide and Subei coastal current, and the contribution rate was 27.1% before 1930. Subsequently, the contribution rate gradually increased, up to 55.6% during the period of 1930-1972, and to 75.9% after 1972. The sediment sources of Qidong foreland tide flat mainly transformed from the Yangtze sediment to the south Yellow Sea sediment. The changes in stages of sediment source were consistent with the decline of the North Branch.