规模化人工湿地的温室气体释放通量

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(N₂O、CH₄和CO₂)释放特征与规律. 结果表明,武河湿地工程的N₂O和CH₄平均释放通量分别为14.35和35.54 mg/(m2·d),表现为N₂O、CH₄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CO₂平均释放通量为2 889.4 mg/(m2·d). 人工湿地沿程N₂O、CH₄和CO₂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N₂O释放通量最大,为51.92 mg/(m2·d)；而6#溢流堰处CH₄释放通量最大,为182.03 mg/(m2·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. 

Greenhouse Gas Emissions from Large-Scale Constructed Wetlands

Global warming caused by the emissions of greenhouse gases (N₂O, 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, but 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 (N₂O), methane (CH₄) and carbon dioxide (CO₂) in Wu River CW were determined. The results showed that Wu River CW was a source of atmosphere N₂O and CH₄. The average emission fluxes of N₂O, CH₄ and CO₂ from the CW were 14.35, 35.54 and 2889.4 mg/(m2·d), respectively. However, the emission fluxes of N₂O and CH₄ were lower than the values reported in the literature for sewage treatment plants. The emission fluxes of N₂O, 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 N₂O 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 N₂O, CH₄ and CO₂ from the CW varied seasonally, being higher in spring and summer than in fall and winter.