【摘要】 潮沟系统是滨海湿地与外界环境之间横向碳交换的重要通道.本研究以长江口滨海湿地典型植物群落(禾本科Poaceae和莎草科Cyperaceae)为研究对象,调查了不同潮汐(小潮期与大潮期)退潮过程中潮沟水体可溶性有机碳(DOC)和颗粒态有机碳(POC)的季节变化.结果表明,潮水向外输出的过程中,DOC和POC从高潮滩到口外浅水光滩均逐渐变化,大潮期时不同生境潮沟的有机碳丰度一般比小潮期高.在具有较高植物生物量和土壤有机碳储量的Poaceae群落中,各季节潮沟水体DOC含量均显著高于Cyperaceae生境潮沟;相反,各季节Cyperaceae群落潮沟POC含量则高于Poaceae群落潮沟.此外,Poaceae群落潮沟在各季节均表现为DOC净输出,而POC为净输入,各季节DOC和POC在Cyperaceae群落潮沟均呈现净输出趋势.更多还原

【Abstract】 Tidal creeks are identified as an important pathway for carbon exchange between coastal wetlands and the adjacent environment. This study investigated the seasonal variations in dissolved organic carbon(DOC) and particulate organic carbon(POC) in tidal creeks within typical vegetation communities(Poaceae and Cyperaceae)in the coastal wetlands of the Yangtze Estuary. The results showed that during ebb the concentrations of organic carbon components changed gradually along the altitude gradient from high marsh to low-lying shallow water areas outside the creeks. Generally, spring tides increased the organic carbon abundance in both creeks, relative to neap tide. In the Poaceae creek, with high plant biomass and soil carbon stocks, the DOC concentrations were significantly higher compared to the Cyperaceae creek during ebb across all seasons.In contrast, the POC contents were lower in the Poaceae creek compared to the Cyperaceae creek. The results of this study indicated that the Poaceae creek functioned as a net export(source) of DOC throughout the year but as a net sink of POC, and the Cyperaceae creek functioned as a net source of organic carbon over all seasons.更多还原