中文摘要：

采用野外采样和室内实验的方法,对长江口崇明东滩沉积物胞外酶活性和温室气体排放潜力及其影响因素进行了研究.结果表明,崇明东滩沉积物脲酶活性为0.05～0.35 μmol/g,蔗糖酶活性为0.47～1.34 κmol/g,纤维素酶活性为0.02～0.03μmol/g,过氧化氢酶活性为477.9～659.8 μmol/g,多酚氧化酶活性为86.7～457.8 μmol/g,碱性磷酸酶活性为0.04～0.06 μmol/g.酶活性在空间上存在较大的差异,其中低潮滩沉积物脲酶最高,中潮滩沉积物蔗糖酶、纤维素酶、多酚氧化酶及碱性磷酸酶最高,高潮滩沉积物过氧化氢酶最高.沉积物中脲酶活性与pH、含水量以及NO3-呈极显著正相关,过氧化氢酶活性与盐度和Eh呈显著正相关,蔗糖酶、纤维素酶、多酚氧化酶和碱性磷酸酶活性主要受NO2-、OC、TN和C/N比值的影响.沉积物中CO2排放潜力为（2.69×10-4）～（1.07×10-3） mg/g,CH4和N2O分别为（6.17×10-8）～（5.99×10-6）mg/g和（8.14×10-10）～（2.99×10-7）mg/g.从沉积物中温室气体排放潜力的影响因素来看,CH4排放潜力主要受pH、温度和NO3-的影响,CO2主要受C/N比值和砂粒影响,而NO3-和含水量影响着N2O的排放.CH4和N2O排放潜力与脲酶活性呈显著的正相关关系,而与其他酶活性相关性不显著.河口湿地沉积物温室气体排放主要受到环境因子的影响,而沉积物中胞外酶活性也是一个重要的影响因素.

英文摘要：

The extracellular enzyme activity and greenhouse gases emission potential in the sediments ot Chongming Dongtan wetland in the Yangtze estuary, as well as their relationships with environmental variables, were studied by filed sampling and laboratory experiments. The results showed that the activity of urease, sucrase, cellulose, catalase, polyphenol oxidase and alkaline phosphatase was in the range of 0.05～ 0.35 μmol/g, 0.47～1.34 μmol/g, 0.02～0, 03 μmol/g, 477.9～659.8 μmol/g, 86. 7～457.8 μmol/g and 0.04～ 0. 06 μmol/g, respectively. Significant spatial variations of extracellular enzyme activities in the sediments were observed. The urease activity was the highest in low tidal flat sediment, while sucrase, cellulose, polyphenol oxidase and alkaline phosphatase activities were the highest in middle tidal flat sediment, and catalase activity was the highest in high tidal flat sediment. The urease activity was significantly and positively related with pH, water content and NO3 content of the sediments, while hydrogen peroxide showed significant positive correlation with sediment salinity and Eh. In addition, sucrase, cellulose, polyphenol oxidase and alkaline phosphatase activity were mainly affected by the contents of NO2 , OC and TN and C/N ratio. The potential emission rate of CO2 , CH4 and N2O in the sediments was in the range of （2.69×10-4）～（1.07×10-3） mg/g, （6.17×10 -8）～（5.99×10-6） mg/gand （8.14×10-10） ～（2.99 × 10-7） mg/g, respectively. The potential CH4 emission was mainly affected by pH, temperature and NO3- content and C/N ratio of the sentiments, while CO2 emission was greatly influenced by C/N ratio and sand content, and N2O emission was affected by NOz and water content. The CH4 and N2O emission potential were significantly and positively correlated with urease activity, while did not correlated with other enzyme activities. To conclude, greenhouse gas emission in the sediments of estuarine wetland is mainly affected by environmental factors, and extr