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通过对莱州湾-龙口湾表层沉积物样品中总有机碳(TOC)、总氮(TN)、有机碳与总氮的比值(C/N)、稳定碳氮同位素(δ13C、δ15N)生物地球化学指标的测定,分析了该区域沉积物中有机质的特征和来源.结果显示,莱州湾表层沉积物中TOC含量为0.47％±0.40％,龙口湾TOC含量为0.82％±0.37％,TN含量相差不大,因此龙口湾沉积物有机质相对含量高于莱州湾.港口的建设使龙口湾内水体流速减慢,加上龙口湾入海河流较少,使得龙口湾沉积物平均粒径(19.40 μm)远低于莱州湾(43.89 μm),比较容易吸附有机质.莱州湾沉积物中δ13C值为-24.96％-21.46％,平均值为-23.63％;龙口湾表层沉积物中δ13C值为-23.02％-22.39％,平均值为-22.73％.由此看来,莱州湾沉积物中有机质主要来源于陆生C3植物和藻类,而龙口湾有机质大部分来源于藻类,少数来自陆生C3植物.根据经典的二元模式计算,龙口湾陆源有机质的贡献比例范围为23.15％-33.67％,平均值为28.84％,莱州湾陆源贡献比例范围为7.65％-65.97％,平均值为43.75％.莱州湾沿岸有众多河流入海,尤其是含沙量最多的黄河,给湾内带来大量的陆上有机质,而龙口湾入海河流较少,沉积物中的陆上有机质较少.

Total organic carbon (TOC),total nitrogen (TN),C/N ratios,stable carbon and nitrogen isotope (δ13C,δ15N) in Laizhou Bay and Longkou Bay surface sediments samples were measured to analyze the characteristics and sources of organic matter.The results showed that the content of TOC in surface sediments of Laizhou Bay was 0.47％±0.40％,and that of Longkou Bay was 0.82％ ±0.37％.However,the TN content in the two regions was similar.Because the port construction slowed down the rate of the water flow in Longkou bay,and fewer rivers drained into the bay,the average particle size of sediments in Longkou Bay (19.40 μm) was much smaller than that of Laizhou Bay (43.89 μm).Accordingly,there was more organic matter in Longkou Bay.The δ13C values in sediments of Laizhou Bay ranged from-24.96％ to-21.46％ (The average of them was -23.63％).And that of Longkou Bay were within a range of-23.02％ and-22.39％ (The average of them was-22.73％).Thus,the organic matter in Laizhou Bay surface sediments mainly originated from the terrestrial C3 plants and algae.However,the organic matter in Longkou Bay was mainly from algae and less of it came from the terrestrial C3 plants.Calculated by the classical binary mode,the proportion of terrestrial organic matter ranged from 23.15％ to 33.67％,with an average of 28.84％ for Longkou Bay.It varied from 7.65％ to 65.97％,with an average of 43.75％ for Laizhou Bay.As a result of many rivers along the coast of Laizhou Bay,including Yellow River with the most sandiness,plenty of terrestrial organic matter was brought into Laizhou Bay.Compared with Laizhou Bay,fewer rivers along the coast of Longkou Bay brought less terrestrial organic matter into it.