Seasonal exports and drivers of dissolved inorganic and organic carbon, carbon dioxide, methane and δ13C signatures in a subtropical river network

•Seasonal measurements of carbon were undertaken in 28 sites in 3 subcatchments.•Seasonal rates of DIC and DOC exports, and CO2 and CH4 evasion were calculated.•Hydrology controlled carbon export and CO2 evasion was the main carbon export pathway.•Riverine carbon dynamics may be influenced by climate change.