初级生产力主导了辽河水系颗粒态有机碳的来源

Riverine primary productivity dominated the source of particulate organic carbon in Liaohe River System

作为关键陆源物质,河流颗粒态有机碳(POC)的来源、输运及入海通量是当前关注的热点问题。然而,受水库等人类活动影响,河流颗粒碳的组分正在发生变化,这势必给陆地和海洋间碳的源汇过程和生物地球化学循环机制带来深刻影响。围绕上述问题,以辽河水系为研究区,于2023年7月沿河采集14个样品,将生物地球化学指标分析与最新的基因检测技术相结合,分析了POC含量和来源在流域内的变化规律,探讨了初级生产力主导辽河水系POC来源的可能机制,对比和总结了中国典型河流POC来源改变的共同趋势。研究结果显示,初级生产力是当前辽河水系POC的最主要来源,其中共球藻纲和蓝藻门生物是最主要贡献者;动物可能也是POC的重要来源,未来在分析POC来源时需加以重视;水库拦蓄效应可改变河流浮游生物的组成,进而对河流POC的来源产生重要影响;长江、黄河、珠江以及台湾岛和海南岛的诸多河流POC的浮游生物来源比例也在显著增加。上述趋势性变化,可能导致POC在流域-河口-陆架间的源汇格局发生剧烈变化,需要持续关注。

As a crucial terrestrial source,the source,transport,and flux of riverine particulate organic carbon(POC)to the ocean are currently of significant interest.However,human activities,such as the construction of reservoirs,are changing the composition of river POC,potentially impacting the source-sink processes between land and sea,as well as biogeochemical cycles.To address this issue,the Liaohe River System was selected for this study,in which 14 samples were collected in July 2023,and the trends in POC content and sources within the drainage basin were analyzed using biogeochemical methods and gene detection technology.The potential mechanisms by which riverine primary production(Rpp)has become a dominant POC source in the Liaohe River System was explored and those in other typical Chinese rivers were compared.Results indicate that the Rpp was the predominant source of POC in the Liaohe River System,and Trebouxiophyceae and Cyanobacteria were the primary contributors.Additionally,animals may also play a significant role as POC sources in rivers,warranting further attention in future analyses.The retention effect in reservoirs could alter the composition of river plankton and thus significantly affect the POC sources.Moreover,the proportions of plankton-derived POC in the Changjiang River,Huanghe River,and Zhujiang River in the continent,and rivers in Taiwan and Hainan islands have also seen notable increases.These changing trends could lead to substantial shifts in the patterns of POC sources and sinks across watersheds,estuaries,and continental shelves,meriting considerable attention.