人为补水对扎龙芦苇湿地甲烷排放的影响

为研究人为补水对芦苇湿地甲烷排放的影响,分别在补水前5 d、补水后10、20和30 d测定了扎龙芦苇湿地淹水区RH和未淹水区RA的甲烷排放通量。结果表明,补水后30 d RH水深由20 cm上升至120 cm,甲烷排放通量由3.13 mg/(m2·h)增至9.60 mg/(m2·h),是对照组CH的1.62倍;RA在补水后30 d水深达到10 cm,甲烷排放通量由2.80 mg/(m2·h)上升至18.96 mg/(m2·h),为对照组CA的5.31倍。补水期间,RH的水深增加刺激了芦苇生长,从而为甲烷产生提供了更多底物,并增强了厌氧条件,导致甲烷排放增大;RA淹水后,大量有机质分解为甲烷产生提供了碳源以及通气状况的改变是促进其甲烷大量排放的原因。研究表明人为补水过程促进了淹水区和非淹水区的甲烷排放,建议在评估湿地甲烷排放时应考虑人为补水因素。

Effects of Artificial Recharge on Methane Emission from Zhalong Reed Wetland

To study the effects of artificial recharge on methane emission from reed Phragmites australis wetlands,methane flux from Zhalong reed wetland was studied at flooded RH and un-flooded RA sites,at 5 days before recharge and 10 days,20 days,and 30 days after recharge.The results indicated that water depth of RH increased from 20 to 120 cm and methane emission flux increased from 3.13 to 9.60 mg/（m2 · h）,which was 1.62 times what emitted from compared group CH; RA was flooded with the water depth of 10 cm and methane emission flux increased from 2.80 to 18.96 mg/（m2 · h）,which was 5.31 times what emitted from compared group CA on the 30 day after recharge.In the recharge period,water depth increase of RH stimulated reed growth to supply more substrate for methane production and enhance anaerobe condition resulting to methane emission increase; methane emission from RA increased sharply because much decomposed organic matter supplied carbon source for methane production and anaerobe condition enhanced after flooded RA.Artificial recharge increased methane emission from natural reed wetland and should be taken into account when assessing methane emission in reed wetlands.