模拟盐度脉冲耦合潮汐过程对闽江河口湿地土壤含碳温室气体排放的影响

Modelling the effects of salinity pulses coupled with tidal processes on carbonaceous greenhouse gas fluxes in wetlands of the Min River estuary

为了探究台风风暴潮导致的盐度脉冲、潮汐涨落以及两者的耦合作用对河口湿地土壤二氧化碳(CO_(2))与甲烷(CH_(4))排放产生的影响,选取闽江河口道庆洲短叶茳芏湿地土壤为研究对象,通过室内模拟实验,研究不同潮汐过程情景下由于盐度和潮水涨落变化,河口湿地CO_(2)与CH_(4)排放特征并分析其主要影响因子。研究结果表明:(1)潮汐淹水显著抑制CO_(2)排放,但促进CH4排放(P<0.05)。盐度增加(0—8‰)促进了土壤CO_(2)排放(P>0.05);0—2‰盐度促进土壤CH_(4)排放(P>0.05),2‰—8‰盐度抑制土壤CH_(4)排放(P<0.05)。(2)盐度脉冲耦合潮汐过程显著抑制了CH_(4)排放(P<0.05),且一定程度上抑制了CO_(2)排放(P>0.05)。(3)CO_(2)排放与孔隙水中的氨态氮(NH_(4)^(+)-N)呈极显著正相关(P<0.01),与硝态氮(NO_(3)^(-)-N)、可溶性有机碳(DOC)和土壤pH呈显著负相关(P<0.05)。盐度脉冲耦合潮汐过程对CO_(2)与CH_(4)排放的影响是一个正负消长的博弈过程,在0—8‰的盐度内,潮汐淹水对CO_(2)排放的影响更大,而盐度在CH_(4)排放中起主导作用。相较于盐度,潮汐淹水是影响闽江河口湿地含碳温室气体全球增温潜势的主导因素。

In order to explore the effects of salinity pulses,tidal fluctuations and their coupling effects on estuarine wetland soil carbon dioxide(CO_(2))and methane(CH_(4))emissions caused by typhoon storm surge,the soils of the Cyperus malaccensis wetland at Daoqingzhou in the estuary of the Min River were selected as the research object,and an indoor tidal simulation device was used to study the characteristics of CO_(2) and CH_(4) emissions from estuarine wetlands due to changes in salinity and different tidal processes,as well as the main influencing factors.The results showed that:(1)tidal flooding significantly inhibited CO_(2) emissions but promoted CH_(4) emissions(P<0.05);the increased salinity(0—8‰)promoted CO_(2) emissions(P>0.05);0—2‰ salinity promoted soil CH_(4) emissions(P>0.05),while 2‰—8‰ salinity inhibited soil CH_(4) emissions(P<0.05).(2)Salinity pulses coupled with tidal processes significantly suppressed the emissions of CH_(4)(P<0.05),and suppressed the emissions of CO_(2) to some extent(P>0.05).(3)CO_(2) emissions were highly significantly positively correlated with ammoniacal nitrogen(NH_(4)^(+)-N)in pore water(P<0.01),significantly negatively correlated with nitrate nitrogen(NO_(3)^(-)-N),dissolved organic carbon(DOC)and soil pH(P<0.05).The effect of salinity pulses coupled tidal processes on CO_(2) and CH_(4) emissions was a positive and negative game process.Under the salinity range of 0 to 8‰,tidal flooding had a greater effect on CO_(2) emissions,while salinity played a dominant role in CH_(4) emissions.Compared to salinity,tidal flooding was the dominant factor affecting the integrated warming potential of carbon-based greenhouse gases in Min River estuarine wetlands.