湖相沉积中的有机质含量随有机质堆积条件变化而发生波动。本文以三水盆地下第三系土布心组二段地层为例 ,对其作高分辨率岩芯取样并结合地球化学方法 ,分析生物学因素对有机碳分布的影响。在较干燥的气候条件下 ,水生浮游生物是有机质的主要来源 ,由于此时湖泊与海洋沟通 ,出现半咸水环境 ,硫酸盐还原作用显著 ,不利于有机质保存。所取岩芯段的中上部即是这种情况 ,以低TOC和高SRI值为特征。而当气候湿润时 ,植物繁荣 ,湖水淡化 ,陆源有机质丰富。缺氧条件下的有机质降解主要是效率极低的发酵作用。有利于有机质保存。这种情形出现于岩芯段的下部 ,以较高TOC和较低SRI值为特征 The organic matter content in lacustrine sediments fluctuates with the accumulation of organic matter. In this paper, taking the second member of the third member of the earth system in the Lower Silt of the Sanshui Basin as an example, this paper analyzes the influence of biological factors on the distribution of organic carbon by high-resolution core sampling combined with geochemical methods. In drier climates, aquatic plankton is the main source of organic matter. As the lakes and oceans communicate at this time, the brackish water environment appears and the sulfate reduction effect is significant, which is not conducive to the preservation of organic matter. This is the case in the upper middle section of the core segment taken, characterized by low TOC and high SRI values. When the climate is humid, the plants are prosperous, the water is desalinated, and the terrestrial organic matter is abundant. The degradation of organic matter under hypoxic conditions is mainly the fermentation with extremely low efficiency. Is conducive to the preservation of organic matter. This condition occurs in the lower part of the core segment, characterized by higher TOC and lower SRI values