罗马湖旁路/离线人工湿地系统CO_2、CH_4和N_2O排放通量动态研究

Dynamic on Emission Fluxes of Carbon Dioxide, Methane and Nitrous Oxide in the Bypass/Offline Constructed Wetlands in Luoma Lake

为了研究旁路／离线人工湿地系统在净化水体时的温室气体排放状况及其与环境因子的关系，于2010年7～11月，采用静态箱～气相色谱法，对罗马湖旁路／离线人工湿地系统的3个不同景观结构单元f温榆河龙道河交叉处河岸带S1采样点、龙道河河道s2采样点和罗马东湖湖岸带s3采样点）的CO2、CH,和N2O排放通量进行了同步采样和对比研究，探讨了影响温室气体排放的主要环境因子。研究结果表明，该湿地系统CO2、CH。和N：O的排放通量都有明显的时空变化特征。从空间上看，S1采样点和s2采样点的CO：月平均排放通量较高，分别为73．5mg／（m2．h）和75．1mg／（m2．h），与其表层（0--5cm）沉积物中较高的有机质含量（7．04±29．4g／kg）有关。S2采样点的CH4月平均排放通量[4．78mg／（m2·h）]高于s1采样点[1．59mg／（m2·h）]和s3采样点[1．70mg／（m2·h）]，其与该采样点水体中的氧化还原电位显著负相关（r=-0．779，p〈0．01）。3个不同景观结构单元的N2O排放通量差异不大[0．022~0．025mg／（m2．h）】；相关性分析结果表明，N2O排放通量与表层沉积物的N02-—N含量显著正相关fr=0．689，p〈0．05）。从时间上看，水温是影响旁路／离线人工湿地系统运行时CH4和N2O排放通量的重要环境因子。

From July to November of 2010, the emission of carbon dioxide （CO2）, methane （CH,） and nitrous oxide （N20） from the three different landscape zones of the bypass/offline constructed wetlands in Luoma Lake （the riverine area at the intersection of Wenyu River and Longdao River, sampling site S 1; the channel of Longdao River, sampling site S2; the littoral area of East Luomahu Lake, sampling site S3） were determined using the static opaque chamber-GC techniques. The environmental factors influencing the greenhouse gas emission were also explored. The study indicated that the emission fluxes of CO2, CH4 and N20 from the con- structed wetlands showed great spatio-temporal variations. The average monthly CO2 emission fluxes in sites S1 and $2 were 73.5 mg/（m2 h） and 75.1 mg/（m： h）, respectively, which were much higher than that in site S3 （17.0 mg/（m2· h））. The phenomenon might be related to the relatively high organic matter contents （7.04-29.4 g/kg） in the surface sediments （0-5 cm） in sites S1 and S2. The average monthly CH, emission flux in site $2 was 4.78 mg/（m2.h） that was the highest among all the three sites, which showed significantly nega- tive correlation with the oxidation-reduction potential of the in-situ water （r = -0.779, p〈0.01）. N20 emission flux showed no significant difference among all the three sites, ranging from 0.022-0.025 mg/（m2- h）. More- over, the correlation analysis indicated that there existed a positive correlation relationship between the N20 emission flux and the NO2---N content in surface sediment （r = 0.689, p〈0.05）. Temporally, the temperature was the main environmental factor influencing the emission fluxes of CH4 and N20 in the constructed wet- lands.