长江口沉积物甲烷产生潜力与产甲烷菌群落特征

采用室内培养与高通量测序技术,研究了长江口沉积物产甲烷潜力及其产甲烷菌群落组成特征.结果表明,研究区沉积物甲烷排放速率为4.15～7.12 nmol·g~(-1)·d~(-1),且表现出厌氧区高、丰氧区低的特点.甲烷产生潜力为丰氧区大于厌氧区,说明甲烷在水体中氧化是减少甲烷排放的重要环境过程.研究区沉积物中产甲烷菌群落组成具有明显的差异.厌氧区沉积物产甲烷菌的优势群落为Methanococcoides(拟甲烷球菌属)、Methanosarcina(甲烷八叠球菌属)和Methanosaeta(甲烷鬃菌属),丰氧区沉积物为Methanosarcina(甲烷八叠球菌属)、Methanosaeta(甲烷鬃菌属)和Methanocella(甲烷胞菌属),因而缺氧过程会对产甲烷菌群落产生重要的影响.通过估算发现,研究区甲烷的排放量为2487～6819 t·a~(-1),表明长江口是甲烷排放的净产生源.因此,由缺氧过程导致的河口环境因子变化会影响甲烷的代谢循环过程及其微生物群落组成,进而对河口生态系统甲烷排放产生重要的影响.

Methane production potential and methanogens community in the sediments of the Yangtze Estuary

In this study, incubation experiments and molecular approaches were used to investigate the methane emission potential and associated methanogens community in the sediments of the Yangtze Estuary. The results indicate that the methane emission rates were in the range of 4.15~7.12 nmol·g^-1·d^-1, which were higher in anaerobic sites than in aerobic sites. However, the methane production potential was higher in aerobic sites than anaerobic sites, which suggested that methane oxidation in water was the important process reducing the methane emission from sediment to atmosphere. The methanogens communities differed across the sampling sites. Methanococcoides, Methanosarcina and Methanosaeta were the dominated communities in the anaerobic sites, and Methanosarcina, Methanosaeta and Methanocella were the important communities in aerobic sites, indicating the importance of oxygen depletion process to alter methanogens community composition. The estimated mean annual amount of methane emission was approximately 2487~6819 t·a^-1, suggesting that Yangtze Estuary is the net source of methane emission. Overall, these results indicate that the variations in environmental factors induced by oxygen depletion process strongly influence the metabolic cycling of methane and associated microbial communities, which further play an important role in regulating the methane emission in estuarine ecosystems.