添加秸秆碳源对沟渠水体中氮素去除及温室气体排放的影响

Changes of nitrogen removal and greenhouse gas emission in ditch water with straw carbon source

为探究夏季添加纤维素类固体有机碳源(秸秆)对沟渠水体中氮素去除效果及温室气体排放的影响,在试验期内设定密集采样法代替常规采样法探究水体中氮质量浓度的变化,并通过静态箱-气相色谱法测定温室气体排放通量。结果表明,试验期间总氮(TN)质量浓度下降了35.9%,硝态氮(NO_(3)^(-)-N)去除率高达97.6%;温室气体排放较为稳定,氧化亚氮(N_(2)O)排放通量呈现昼高夜低的趋势,甲烷(CH_(4))排放通量出现多个峰值。整体来看,添加秸秆增强了水体中氮素的去除效果,同时矫正系数分析结果表明,试验初期温室气体排放通量变化较大,而在后期较稳定。因此,建议试验前期密集采样,后期可常规采样,后期最佳采样时间为9:00-11:00。

In order to explore the nitrogen removal effect and greenhouse gas emission law in ditch water under the addition of cellulose solid organic carbon source(straw)in summer,dense sampling was set to replace the conventional sampling method to explore the change of nitrogen mass concentration in water during the experimental period,and the greenhouse gas emission flux was measured by static box gas chromatography.The results showed that the mass concentration of total nitrogen(TN)decreased by 35.9%,and the removal rate of nitrate nitrogen(NO_(3)^(-)-N)was as high as 97.6%.Greenhouse gas emissions were relatively stable,nitrous oxide(N_(2)O)emission flux showed a trend of high in the day and low at night,and methane(CH_(4))emission flux showed multiple peaks.In conclusion,the addition of straw enhanced the removal efficiency of nitrogen in water.At the same time,the results of correction coefficient analysis indicated that the greenhouse gas emission flux changed greatly in the early stage of the experiment and was relatively stable in the later stage.Therefore,it is suggested that intensive sampling should be carried out in the early stage,conventional sampling can be carried out in the later stage,and the best sampling time in the later stage is 9:00-11:00.