CAJ | 학술논문

甲烷（CH4）和氧化亚氮（N2O）是导致全球气候变暖的2种重要温室气体，探索其源汇及地域排放特征一直是全球变化研究领域的核心内容。CH4和N2O通量的日变化研究是正确估算大时间尺度下CH4和N2O排放量的基础。利用静态箱法原位观测了江苏沿海芦苇（Phragmites australis）、盐蒿（Suada salsa）、光滩、水面以及互花米草（Spartina alterniflora）入侵湿地CH4和N2O排放的日变化特征。结果表明，1）互花米草湿地地上部生物量为1.70 kg·m-2，土壤有机碳质量分数为13.55 g·kg-1；分别是芦苇和盐蒿湿地的2.50~3.43和2.15~4.15倍。2）互花米草和芦苇湿地土壤10 cm处氧化还原电位（Eh）有明显日变化，最低值出现在3：00，最高值出现在12：00；光滩和盐蒿湿地没有明显的日变化。3）互花米草湿地 CH4日平均排放通量为0.52 mg·m-2·h-1，是其他湿地的2.12~6.40倍；N2O日平均通量为-3.24μg·m-2·h-1，显著低于盐蒿湿地、光滩和水面（P<0.05）。互花米草和芦苇湿地CH4排放通量最高值（0.73 mg·m-2·h-1和0.30 mg·m-2·h-1）出现在15：00，最低值（0.37 mg·m-2·h-1和0.17 mg·m-2·h-1）出现在3：00，均与土壤孔隙水中CH4浓度呈显著负相关（P<0.05）。互花米草湿地CH4排放通量与10 cm土温、Eh和生态系统CO2净交换量（NEE）显著正相关（P<0.05）。互花米草和芦苇湿地N2O通量9：00-18：00为负值，21：00—6：00为正值，均与NEE呈显著负相关（P<0.05）。盐蒿湿地、光滩和水面CH4和N2O排放通量没有明显日变化特征。互花米草入侵提高了沿海湿地CH4排放，但降低了N2O排放，植物对CH4传输作用以及向根际传输O2和易分解有机物是导致互花米草和芦苇湿地CH4和N2O排放表现出日变化特征的原因。
갑완（CH4）화양화아담（N2O）시도치전구기후변난적2충중요온실기체，탐색기원회급지역배방특정일직시전구변화연구영역적핵심내용。CH4화N2O통량적일변화연구시정학고산대시간척도하CH4화N2O배방량적기출。이용정태상법원위관측료강소연해호위（Phragmites australis）、염호（Suada salsa）、광탄、수면이급호화미초（Spartina alterniflora）입침습지CH4화N2O배방적일변화특정。결과표명，1）호화미초습지지상부생물량위1.70 kg·m-2，토양유궤탄질량분수위13.55 g·kg-1；분별시호위화염호습지적2.50~3.43화2.15~4.15배。2）호화미초화호위습지토양10 cm처양화환원전위（Eh）유명현일변화，최저치출현재3：00，최고치출현재12：00；광탄화염호습지몰유명현적일변화。3）호화미초습지 CH4일평균배방통량위0.52 mg·m-2·h-1，시기타습지적2.12~6.40배；N2O일평균통량위-3.24μg·m-2·h-1，현저저우염호습지、광탄화수면（P<0.05）。호화미초화호위습지CH4배방통량최고치（0.73 mg·m-2·h-1화0.30 mg·m-2·h-1）출현재15：00，최저치（0.37 mg·m-2·h-1화0.17 mg·m-2·h-1）출현재3：00，균여토양공극수중CH4농도정현저부상관（P<0.05）。호화미초습지CH4배방통량여10 cm토온、Eh화생태계통CO2정교환량（NEE）현저정상관（P<0.05）。호화미초화호위습지N2O통량9：00-18：00위부치，21：00—6：00위정치，균여NEE정현저부상관（P<0.05）。염호습지、광탄화수면CH4화N2O배방통량몰유명현일변화특정。호화미초입침제고료연해습지CH4배방，단강저료N2O배방，식물대CH4전수작용이급향근제전수O2화역분해유궤물시도치호화미초화호위습지CH4화N2O배방표현출일변화특정적원인。
Atmospheric CH4 and N2O are two most potent long-lived greenhouse gases that contribution to global warming. Sources and sinks of CH4 and N2O and the processes driving their spatio-temporal heterogeneity are critically important to global change. Understanding the diel variation in CH4 and N2O emissions is of importance to estimating CH4 and N2O budgets in large spatial and time scales. In this study, diel variations of CH4 and N2O fluxes in coastal salt marsh that invaded by Spartina alterniflora and vegetated with or without native Phragmites australis and Suaeda salsa were measured in site by using static chamber technique. Our results showed that aboveground biomass in S. alterniflora marsh was 1.70 kg·m-2 and SOC concentration was 13.55 g·kg-1, which were 2.50~3.43 and 2.15~4.15 times, respectively, those of P. australis and S. salsa marshes. Soil radox potential at 10-cm depth showed apparent diel variations in S. alterniflora and P. australis marshes, which were both highest at 12:00 am and lowest at 3:00 am. However, no significant diel variations of radox potential were found in S. salsa marsh, bare tidal flat and open water. Mean CH4 flux was 0.52 mg·m-2·h-1 in S. alterniflora marsh, which was 2.14~6.40 times those in other sites. Mean N2O flux was-3.24 μg·m-2·h-1 in S. alterniflora marsh and was significantly lower than those in S. salsa marsh, tidal flat and open water. CH4 fluxes peaked at 0.73 and 0.30 mg·m-2·h-1 at 15:00 and showed the lowest of 0.37 and 0.17 mg·m-2·h-1 at 3:00 in S. alterniflora and P. australis marshes, respectively. CH4 fluxes were negatively (P<0.05) correlated with porewater CH4 concentrations in S. alterniflora and P. australis marshes and it was positively (P<0.05) correlated with soil temperature and redox potential at 10 cm and net ecosystem CO2 exchange (NEE) in S. alterniflora marsh. N2O fluxes were negative at 9:00-18:00 and positive at 21:00~6:00 and were negatively correlated with NEE in S. alterniflora and P. australis marshes. No discernible diel variations were observed in the CH4 and N2O fluxes in S. salsa marsh, tidal flat and open water. Our results suggest that S. alternniflora invasion stimulates CH4 emissions but decreases N2O emissions from Chinese coastal salt marsh, and the extent of diel variations in CH4 flux depend on the gas transport capacity of plants, and capacity of transport O2 and organic substrate supply down to the rhizosphere by plants may drive the diel variations in N2O exchanges.