长江口-杭州湾及其邻近海域不同粒级沉积有机碳分布特征

通过对长江口、杭州湾、舟山海域及东海陆架4个海区表层沉积物样品的粒度敏感组分分析,发现东海陆架与长江口具有相似的三级组分物质组成,杭州湾与舟山海域具有相似的两级组分物质组成.综合4个区域粒级组分分布特征,采用湿分法将4个海域表层沉积物样品分成6个粒级:＜0.004 mm,0.004～0.025 mm,0.025～0.063 mm,0.063～0.125 mm,0.125～0.250 mm和＞0.250 mm,分别提取各级组分和全样进行有机碳及同位素测试.定量分析各级组分有机碳含量、来源及物质组分,除杭州湾海域粗粒级外,基本上＜0.004 mm的粘土组分有机碳含量最高;富集在杭州湾海域粗颗粒中的有机质主要来源于陆源植物碎屑.沉积物颗粒大小、物质组成类型是不同粒级有机质富集的主要控制因素.

Organic Carbon Distribution in the Yangtze River Estuary-Hangzhou Bay and Its Adjacent Sea Area

A study of environmentally sensitive grain-size population was used by the grain size class vs standard deviation values of the surface sediment samples in the Yangtze River Estuary, Hangzhou Bay, Zhoushan archipelago sea area and the East China Sea shelf. Results indicated that there were three similar grain size populations between the East China Sea shelf and the Yangtze River estuary and two similar populations between the Hangzhou Bay and the Zhoushan archipelago sea area. According to the environmentally sensitive grain-size population, wet sieving was performed to separate the four area sediments into six size fractions ( > 0. 250 mm, 0. 125 ～0. 250 mm, 0.063～0.125 mm, 0.025～0.063 mm ,0.004～0.025 mm, and <0.004 mm). Each of these size fractions and the bulk samples were analyzed for the total organic carbon ( TOC) and stable organic carbon isotopic rati-os( δ~(13)C_(org) ). The further quantitative analysis of TOC and δ~(13)C_(org) for each fraction indicated that there was the highest TOC content in the <0.004 mm fraction except the coarse size fractions of the Hangzhou bay where they were rich in the organic matter from the terrestrial source plant debris, and the particle size and type of the sediment component played important role in the organic matter distribution.