中文摘要：

选择三江平原典型的毛果苔草沼泽湿地为研究对象，测定了沼泽湿地孔隙水中水溶性碳、氮浓度、CH4浓度和CH4排放通量，以及相关环境因子；研究了沼泽水中水溶性有机碳、氮浓度变化特征，探讨了沼泽湿地孔隙水中CH4浓度和排放通量季节性变化及发生原因．结果表明，三江平原沼泽湿地土壤孔隙水中DOC浓度有明显的季节变化（P〈0．01）最高值（剖面平均值为95．1mg·L^-1）出现在6月份，9和10月份出现最低值（剖面平均值均为79．3mg·L^-1），剖面上浓集中心位于15—30cm．孔隙水中NH4^＋-N和NO3^--N浓度也有明显的季节变化，而DON变化不明显．孔隙水中CH4浓度在剖面上的分布特征与DOC一致，高浓度中心位于20～30cm．除6月份外，孔隙水甲烷浓度与土壤温度和DOC浓度有显著的正相关关系，与NH4^＋-N和NO3-N均没有显著相关性．土壤温度和孔隙水中DOC浓度是影响沼泽湿地产CH4能力的重要因素．CH4排放通量与土壤温度和积水深度呈很好的指数关系，与剖面CH4浓度和孔隙水NH4^＋-N浓度有显著的正相关关系．CH4排放通量与孔隙水DOC浓度相关性不显著.

英文摘要：

In this paper, the dissolved organic C （ DOC）, dissolved organic N （ DON）, NH4^＋ -N, NO3^- -N, CH4 concentration in the porewater and CH4 flux in the freshwater marsh were measured, to study seasonal dynamics of DOC, DON, NH4^＋ -N. and NO3^- -N concentrations, and to estimate correlativity between their concentrations and CH4 flux in the freshwater marsh. The results showed that the significant seasonal change of DOC concentrations in the porewater existed in the freshwater marsh of Sanjiang Plain. The highest DOC concentration was found in June with mean value of 95. 1 mg· L ^-1. while the lowest in September and October with mean value of 79.3 mg·L^-1. The higher DOC concentration was observed at top 15 - 30 cm through soil profiles. The seasonal change of NH4^＋ -N and NO3^- -N concentrations in the porewater was also significant, while, the DON concentration did not change obviously. The distribution of CH4 concentration in the porewater was consistent that of DOC concentration, and the higher CH4 concentration was observed at top 20 - 30 cm through soil profiles. CH4 concentration in the porewater was positively correlated to soll temperature and DOC concentration, excepting for June. Therefore, soil temperature and DOC concentration in the porewater were the important factors, affecting CH4 production in the freshwater marsh. There was obvious linear relation between CH4 flux and soil temperature and water depth. In addition, CH4 flux was positively correlated to CH4 concentration and NH4^＋ -N concentration in the porewater. No significant eorrelativity between DOC concentration and CH4 flux was found.