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内源有机碳由地表水体水生光合固定DIC产生,是岩石风化碳汇的重要组成部分。为准确区分河陆地流水体中的内源有机碳及计算其所占比例,本文选取珠江流域作为研究区,通过不同季节的野外采样调查,利用类脂生物标志物法,结合传统水化学特征,揭示河流中有机碳的来源差异;最终根据有机碳的时空分布规律与水-岩-土-气-生相互作用分析,明确流域岩性及气候变化对碳汇的影响。结果表明:(1)珠江流域水体中冬季和夏季内源有机碳占总有机碳比例的平均值分别为65%和54%,表明水生植物光合作用导致的初级生产力的重要性;(2)内源有机碳比例和水生藻类生物量与DIC浓度和呈现出显著的正相关关系,表明DIC对水生植物光合作用具有施肥效应;(3)雨季因降雨稀释DIC浓度和冲刷外源有机质,对水生植物的施肥效应减弱,生成的内源有机质减少,且携带的外源有机质增加,导致内源比例减少;(4)高悬浮质(TSS)可以遮挡水体表层太阳光,减弱水生光合作用强度,降低内源有机碳的形成;但在TSS浓度比较低的情况下,其对水生植物生长繁殖的影响则体现在为其提供空间和营养物,从而增加水生藻类生物量及内源有机碳比例。
Endogenous organic carbon is produced by surface photosynthesis and fixation of DIC by aquatic photosynthesis, and is an important part of rock carbon sequestration. In order to accurately distinguish the endogenous organic carbon in the river-land flow and calculate its proportion, this paper selected the Pearl River Basin as the research area, through the field sampling survey in different seasons, the lipid biomarker method, combined with the traditional hydrochemistry characteristics, Reveal the source of organic carbon in the river; finally, according to the temporal-spatial distribution of organic carbon and the analysis of water-rock-soil-gas-gas interaction, the influence of lithology and climate change on carbon sinks is clarified. The results showed that: (1) The average ratio of total organic carbon to total organic carbon in water bodies in the Pearl River Basin in winter and summer was 65% and 54%, respectively, indicating the importance of primary productivity due to photosynthesis of aquatic plants; (2) The proportion of source organic carbon and the biomass of aquatic algae were positively correlated with the concentration of DIC, indicating that DIC had a fertilization effect on the photosynthesis of aquatic plants. (3) DIC concentrations were diluted by rainfall and the exogenous organic matter was washed away, (4) Suspended aerosols (TSS) can block the surface sunlight of the water, reduce the intensity of aquatic photosynthesis, and reduce the increase of the endogenous organic matter, However, when the concentration of TSS is relatively low, its effect on the growth and reproduction of aquatic plants is reflected in the provision of space and nutrients to increase the biomass of algal biomass and the proportion of endogenous organic carbon.