外源氮、硫添加对闽江河口湿地CH4、CO2排放的短期影响

于2015年4月在闽江河口鳝鱼滩湿地原位开展氮、硫添加实验,研究外源氮、硫添加对河口湿地CH_4、CO_2排放通量的短期影响,并同步观测相关环境因子.结果表明,NH_4Cl(NH)和NH_4NO_3+K_2SO_4(NS)添加显著促进了河口湿地CH_4平均排放通量(P0.01),NS耦合添加显著促进了湿地CO_2平均排放通量(P0.05);KNO_3(NO)和K_2SO_4(S)处理在实验期间对CH_4、CO_2排放通量表现为促进与抑制作用的交互影响,并且影响均不显著(P0.05).与对照(CK)相比,NH和NS添加使CH_4平均排放通量分别提高了(286.36%、122.73%),使CO_2平均排放通量分别提高了(39.92%、34.24%).氮、硫添加对河口潮滩湿地CH_4、CO_2排放的影响具有明显的时间变异性,改变了短叶茳芏湿地生长季CH_4排放时间变化规律,但未改变CO_2排放时间规律.相关分析显示,NH和NS添加处理下河口湿地土壤CH_4、CO_2排放通量主要受土温、EC、DOC以及NH+4-N的控制(P0.05或P0.01),NO和S处理主要受土温、EC、pH、DOC、NO_3~--N的控制(P0.05或P0.01),CK处理则主要受土温的影响(P0.01).温度、盐度、氮有效性是影响河口湿地CO_2、CH_4排放的主要因素.

Short-term Effects of Nitrogen and Sulfate Addition on CH4 and CO2 Emissions in the Tidal Marsh of Minjiang River Estuary

In April 2015, using enclosed static opaque chamber-GC techniques, the short-term effects of nitrogen and sulfate addition on the CH₄ and CO₂ emissions were measured in the Cyperus malaccensis marsh in the high tidal flat of the Minjiang River estuary, and the key factors controlling the variation of CH₄ and CO₂ were examined. The influences of nitrogen and sulfate addition on the CH₄ and CO₂ emissions were different in different time scales. CH₄ emission increased significantly under the NH₄Cl (NH) and NH₄NO₃+K₂SO₄ (NS) additions (P<0.01), CO₂emission increased significantly with NS addition (P<0.05), but CH₄ and CO₂ emissions demonstrated an obvious fluctuation pattern with KNO₃ (NO) and K₂SO₄(S) additions. Compared with the control (CK), average CH₄ emissions increased by 286.36% and 122.73%, respectively, in the NH and NS addition treatments, average CO₂ emissions increased by 39.92% and 34.24%, respectively, with the NH and NS additions treatments. The nitrogen and sulfate addition changed the temporal variation of CH₄ and CO₂emissions from the C. malaccensis wetlands in growing season. Significant correlations were found among CO₂, CH₄ emissions, and soil temperature, electrical conductivity (EC), DOC (dissolved organic carbon) and NH₄⁺-N (P<0.05 or P<0.01) in the treatments with NH and NS additions; and soil temperature, EC, DOC and NO₃^--N (P<0.05 or P<0.01) in the treatments with NO and NS additions. Temperature, EC and nitrogen availability were the dominant factors controlling the temporal variations of CH₄ and CO₂emissions in estuarine tidal marsh ecosystem.