抚仙湖沉积物有机碳埋藏特征及来源解析

为探讨近百年来抚仙湖不同湖区沉积物中有机碳埋藏及其来源变化特征，以抚仙湖南北部沉积柱为研究对象，分析有机碳埋藏速率时空变化特征，利用正构烷烃及其分布特征对埋藏在沉积物中的有机碳来源进行解析.结果显示，抚仙湖沉积物中有机碳含量为1.79~29.39mg/g，有机碳埋藏速率为3.07~27.71g/（m²·a），两者均随时间的增加呈现整体上升的趋势，1980年以来增长速度明显加快；沉积物中有机碳含量北部（8.70mg/g）小于南部（12.59mg/g），但有机碳埋藏速率北部（13.54g/（m²·a））大于南部（8.29g/（m²·a）），这与抚仙湖南北部有机质来源类型及人类活动的加剧造成的流域环境变化有关；抚仙湖沉积物中正构烷烃碳数范围为C₁₂~C₃₃，整体以高碳数组分为主，奇偶优势明显，表明沉积物中有机质主要来源于高等植物，Paq指示水生植物中以沉水植物占主导优势，2C₃₁/（C₂₇+C₂₉）与ACL_27~33指示陆生高等植物来源中，草本植物与木本植物的贡献相当，水生植物在北部湖区贡献大于南部，陆生高等植物在南部湖区的贡献大于北部.

Characteristics and source analysis of organic carbon buried in sediments of Fuxian Lake

To investigate the burial and source characteristics of organic carbon in the sediments of Fuxian Lake over the past 100years, the sediment cores in the north and south of Fuxian Lake were taken as objects to analyze the temporal and spatial variation characteristics of organic carbon accumulation rates. The sources variation characteristics of organic carbon buried in sediments were analyzed by using n-alkanes and their distribution characteristics. The results showed that, in sediments the TOC contents ranged from 1.79 to 29.39mg/g, and OCAR ranged from 3.07 to 27.71g/(m²·a), both of which showed an overall upward trend since 1880 and the growth rates accelerated significantly since 1980. The organic carbon contents in the north(8.70mg/g) were less than those in the south(12.59mg/g), while the OCAR were higher in northern(13.54g/(m²·a) than southern(8.29g/(m²·a). It was related to source types of organic matter and the environmental changes caused by the increasing of human activities in Fuxian Lake basin. The carbon numbers of n-alkanes in the sediments ranged from C₁₂ to C₃₃, which were dominated by high carbon components with obvious odd and even advantages, and mainly composed of high carbon arrays, indicated that the organic matters in the sediments mainly came from higher plants. The Paq indicated that submerged plants predominated in aquatic plant. 2C₃₁/(C₂₇+C₂₉) and ACL_27~33 indicated that herbaceous plants and woody plants contributed equally to terrestrial higher plant. The contribution of aquatic plants in the northern lake was greater than that in the southern lake while the contribution of terrestrial higher plants in the southern lake was greater than that in the northern lake.