Increases　in　salinity　and　electron　acceptors　have　a　significant　impact　on　pore　water　and　sediment　geochemistry　and　organic　matter　mineralization　in　tidal　wetlands.　In　this　study,　artificial　saltwater　and　Fe　(III)　were　applied　to　in　situ　mesocosms　of　the　tidal　freshwater　Sagittaria　trifolia　L.　wetland　of　the　Min　River　Estuary.　Pore　water　geochemistry,　including　dissolved　CH4,　dissolved　organic　carbon　(DOC),　the　ratio　of　DOC　to　dissolved　organic　nitrogen　(DON),　pore　water　Fe2+　and　ΔSO42-,　and　various　species　of　solid　Fe　(non-sulfidic　Fe(II),　amorphous　Fe(III),　crystalline　Fe(III),　FeS,　and　FeS2)　were　analyzed　to　compare　treatments　between　spring　and　summer.　The　results　suggest　that　dissolved　CH4　and　DOC　were　suppressed　due　to　seasonal　treatment　using　saltwater　and　Fe(III).　The　addition　of　Fe(III)　increased　non-sulfidic　Fe(II)　and　crystalline　Fe(III),　whereas　the　addition　of　saltwater　decreased　pore　water　ΔSO42-.　The　pore　water　ΔSO42-　values　correlated　with　DOC,　DOC:DON,　Fe2+,　and　dissolved　CH4.　The　addition　of　Fe(III)　and　saltwater　may　enhance　microbial　iron　and　sulfate　respiration,　respectively,　as　both　concurrently　inhibit　methane　production,　thus　shifting　the　pathway　of　organic　mineralization.　©　2018,　Science　Press.　All　right　reserved.