黄河口滨岸潮滩湿地CO2、CH4和N2O 通量特征初步研究

摘要

2009年8月,运用静态暗箱-气相色谱法对夏季黄河口滨岸潮滩湿地CO2、CH4和N2O通量的日变化特征进行了原位观测.结果表明,夏季低潮滩沉积物-大气界面的CO2、CH4和N2O通量均具有明显日变化特征,日通量范围分别为-18.755～43.731,-0.070～0.224和-0.002～0.008 mg/(m2·h),均值为11.630,0.079和0.005 mg/(m2·h),全天表现为三者的排放"源";中潮滩沉积物-大气界面CO2、CH4和N2O通量的日变化范围分别为-30.780～25.734,-0.111～0.100和-0.004～0.006 mg/(m2·h),均值为4.570,0.011和0.002mg/(m2·h),全天亦表现为三者的排放"源";中潮滩-大气界面CO2、CH4和N2O通量的日变化范围分别为46.253～102.637,-0.211～0.048和-0.008～0.008 mg/(m2·h),均值为76.656,-0.038和-0.002 mg/(m2·h),全天表现为CO2的"源"、CH4和N2O的"汇".本研究还发现,中潮滩的CO2通量与气温呈显著正相关(P＜0.05)关系,低潮滩沉积物的CH4通量与气温、地表温度和5 cm地温呈极显著正相关(P＜0.01)关系,而中潮滩的N2O通量与气温、地表温度和不同深度地温(5,10,20 cm)呈显著(P＜0.05)或极显著(P＜0.01)负相关关系;沉积物基质和翅碱蓬群落是影响CO2、CH4和N2O通量特征的重要因素,而水分、盐分对于三者通量特征的影响也不容忽视.%The diurnal variation characteristics of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes from intertidal flat wetland of the Yellow River estuary were observed in situ with a static-chamber and GC in August 2009. CO2, CH4 and N2O fluxes from the low tidal flat sediment showed an obvious diurnal variation. The flux ranges were from -18. 754 6 to 43. 730 8, -0.0(69 8 to 0. 224 2 and -0. 001 6 to 0. 008 3 mg/(m2·h), and the daily average fluxes were 11. 629 7, 0.078 7 and 0. 004 6 mg/(m2·h), respectively, which showed that the low tidal flat sediment was the source of atmospheric COz, CH4 and N2O. The flux ranges of CO2, CH4 and N2O in the middle tidal flat sediment were from -30. 779 9 to 25. 734 2,-0. 111 3 to 0. 1001 and -0. 004 4 to 0. 006 3 mg/(m2·h), and the daily average fluxes were 4. 569 9,0. 011 3 and 0. 002 3 mg/(m2 · h), respectively, which showed that the middle tidal flat sediment was also the source of atmospheric CO2, CH4 and N2O. The flux ranges of CO2, CH4 and N2O in the high tidal flat were from 46. 253 3 to 102.637 4, -0. 210 9 to 0.047 5 and -0. 008 3 to 0. 007 8 mg/(m2·h), and the daily average fluxes were 76. 656 1, -0. 037 9 and -0. 002 0 mg/(m2·h), respectively, which showed that the high tidal flat was not only the source of atmospheric CO2 but also a sink for atmospheric CH4 and N2O. Further analysis showed that CO2 flux from the middle tidal flat sediment was significantly positively correlated with atmospheric temperatures (P＜0.05), as was the CH4 flux from the low tidal flat sediment (0 and 5cm ground temperatures (P＜0. 01)), but the N2O flux from the middle tidal flat sediment was significantly negatively correlated with atmospheric temperatures and different depths of ground temperatures (5, 10 and 20 cm) (P＜0.05 or 0.01). In addition, sediment solvent and the Suaeda salsa community were the main factors affecting the flux characteristics of CO2, CH4 and N2O, while soil water content and salinity also affected them.