In　order　to　accurately　estimate　the　effects　of　tidal　scenarios　on　the　CH4　emission　from　tidal　wetlands,　we　examined　the　CH4　effluxes,　dissolved　CH4　concentrations,　and　environmental　factors　(including　in　situ　pH,　Eh　and　electrical　conductivity,　porewater　SO4　2−,　NO3　−,　and　NH4　+)　during　inundation　and　air-exposure　periods　in　high-and　low-tide　seasons　in　the　Min　River　Estuary　in　southeast　China.　By　applying　static　and　floating　chambers,　our　results　showed　that　the　CH4　effluxes　during　the　inundation　periods　were　relatively　constant　and　generally　lower　than　those　during　the　air-exposed　periods　in　both　seasons.　When　compared,　the　CH4　effluxes　during　the　air-exposed　periods　were　significantly　higher　in　the　high-tide　season　than　those　in　the　low-tide　season.　In　contrast,　CH4　effluxes　during　the　inundation　periods　were　significantly　lower　in　the　high-tide　season　than　those　in　the　low-tide　season.　During　the　inundation　periods,　dissolved　CH4　concentrations　were　inversely　proportional　to　in　situ　Eh.　Under　air-exposed　conditions,　CH4　effluxes　were　proportional　to　in　situ　pH　in　both　seasons,　while　the　dissolved　CH4　concentrations　were　negatively　correlated　with　the　porewater　SO4　2−　concentrations　in　both　seasons.　Our　results　highlighted　that　CH4　effluxes　were　more　dynamic　between　inundation　and　air-exposure　periods　compared　to　low-and　high-tide　seasons.　©　2019　by　the　authors.　Licensee　MDPI,　Basel,　Switzerland.