摘要:选取鄱阳湖流域内从初级支流到最大干流再到湖区（香溪→架竹河→赣江→鄱阳湖）这一联通水系线路为研究对象，通过对该流域多尺度碳、硅输送进行监测，并对其浮游植物群落分布进行研究，揭示鄱阳湖流域多尺度碳、硅输送对浮游植物分布的影响。结果表明：（1）鄱阳湖通江流域的碳、硅浓度与碳硅比呈明显空间变化。香溪流域和鄱阳湖湖区溶解态硅（DSi）浓度显著低于架竹河流域和赣江流域，而溶解性总碳（DTC）和溶解性有机碳（DOC）浓度变化则与之相反；碳硅比随流域尺度的扩大呈现先下降后上升的趋势，西鄱湖高于东鄱湖，冬季高于其他季节。（2）碳、硅对浮游植物分布特征的影响随着流域尺度的变化而变化。架竹河流域浮游植物主要受碳影响，且硅藻对溶解性无机碳（DIC）浓度变化最敏感，赣江流域，硅成为影响浮游植物分布的主要因子，进入鄱阳湖湖区后，硅对浮游植物分布的影响减弱；DIC虽然不是鄱阳湖流域浮游植物生长的限制性因子，但可通过影响水体pH值间接影响浮游植物群落结构。（3）浮游植物密度随着流域面积的扩大而成倍增加，鄱阳湖湖区浮游植物密度约为架竹河流域的11倍，湖区生态环境及水体污染问题不容忽视。



Abstract:The multiscale waterflow watershed system which were from the primary tributary to the mainstream in the Poyang Lake, and then entering into the lake area (Xiangxi River→Jiazhu River→Gangjiang River→Pangyang Lake), was selected as the study site. By monitoring the carbon and silicon transportation at multiscale in the Poyang Lake watershed, we aim to understand the relationship between the distribution of phytoplankton community and the carbon and silicon transport at multiscale in Poyang Lake. The results showed that C, Si, and C/Si ratio of the Poyang Lake watershed exhibited spatial changes. The concentrations of dissolved silicon (DSi) in the Xiangxi River and Poyang Lake basins were significantly lower than those in the Jiazhu River and the Ganjiang River, while the dissolved total carbon (DTC) and dissolved organic carbon (DOC) concentrations showed opposite results. The trend of C/Si ratio with seasonal change showed the decreasing and then increasing, wherein the west Poyang Lake were higher than the east. The DTC and DOC concentrations in winter were higher than those in other seasons. The effects of C and Si on the distribution characteristics of phytoplankton depended on watershed scale. The phytoplankton in the Jiazhu River was mainly affected by C, and the diatoms were most sensitive to the change of dissolved inorganic carbon (DIC) concentration. While in the Ganjiang River basin, Si was the main factor affecting the distribution of phytoplankton. After flowing into the Poyang Lake, the influence of Si on the distribution of phytoplankton became small. Overall, the DIC was not the limiting factor for phytoplankton growth in Poyang Lake watershed, but it could indirectly affect phytoplankton community structure by influencing the pH of water. The density of phytoplankton increased exponentially with the increase of the watershed scale. The density of phytoplankton in the Poyang Lake was about 11 times than that of the Jiazhu River, so the ecological environment and water pollution problems for the lake cannot be ignored.





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