规模化人工湿地的温室气体释放通量

Greenhouse Gas Emissions from Large-Scale Constructed Wetlands

基于规模化人工湿地工程——武河湿地的野外原位监测试验,采用静态箱-气相色谱法研究了人工湿地中温室气体(N_2O、CH_4和CO_2)释放特征与规律.结果表明,武河湿地工程的N_2O和CH_4平均释放通量分别为14.35和35.54 mg/(m^2·d),表现为N_2O、CH_4的释放源,但其释放通量低于城市污水处理厂;湿地(主要包括水体和土壤生物呼吸)的CO_2平均释放通量为2 889.4 mg/(m^2·d).人工湿地沿程N_2O、CH_4和CO_2释放特征有所不同,平均释放通量呈先升后降规律,在布水渠处N_2O释放通量最大,为51.92 mg/(m^2·d);而6#溢流堰处CH_4释放通量最大,为182.03 mg/(m^2·d).人工湿地中温室气体释放亦具有明显的季节变化规律,表现为春夏季高于秋冬季.

Global warming caused by the emissions of greenhouse gases （N^O, CH4 and CO2 ） is considered to be the greatest environmental problem in the world. Constructed wetlands （CWs）, as a unique ecological technique, have been widely used in wastewater treatment, hut their potential for greenhouse gas emissions should not be ignored. Based on in-situ monitoring in full-scale CWs, the emission fluxes of greenhouse gas including nitrous oxide （ N2 O）, methane （ CH4 ） and carbon dioxide （ CO2 ） in Wu River CW were determined. The results showed that Wu River CW was a source of atmosphere N20 and CH4. The average emission fluxes of N20, CH4 and COL from the CW were 14.35 , 35.54 and 2889.4 mg/（ m2. d） , respectively. However, the emission fluxes of N20 and CH4 were lower than the values reported in the literature for sewage treatment plants. The emission fluxes of N2 O, CH4 and CO2 from the CW showed significant differences among different sampling units, and the average emission flux increased and then decreased along Wu river CW. The maximum N20 emission flux of 51.92 mg/（m2.d） was observed from the distribution channel, while the emission of CH4 was found to be highest in sixth overflow weir with the flux of 182.03 mg/（ m2·d）. In addition, the emission fluxes of N20, CH4 and CO2 from the CW varied seasonally, being higher in spring and summer than in fall and winter.