Carbon Dioxide and Methane Emissions from a Wet-Dry Tropical Floodplain in Northern Australia

In order to better understand how global climate change will affect greenhouse gas dynamics in wetland systems, an accurate quantification of global greenhouse gas emissions from these areas is essential. Despite a large proportion of wetlands occurring in tropical areas, data on greenhouse gas fluxes from these areas is limited. This study aimed to quantify carbon dioxide (CO2) and methane (CH4) fluxes from an undisturbed tropical wetland environment in northern Australia, and to evaluate the influence of different habitat types on net emission rates. Fluxes were measured at seven sites, representing different habitat types during the inundation season of 2012. Highest CO2 fluxes, with a maximum at 199.4 mg CO2-C m(-2) h(-1), were measured in open water areas. This likely corresponded to increased mobilisation of sediment organic matter and high water turbulence, as inferred from turbidity measurement. CH4 fluxes, however, were greatest in densely vegetated areas and peaked at 153.2 mg CH4-C m(-2) h(-1), a possible result of increased transport through plant stems. Carbon dioxide and methane fluxes over the whole wetland averaged 86.0 mg CO2-C m(-2) h(-1) and 25.3 mg CH4-C m(-2) h(-1), respectively.