Dissolved organic carbon in a tropical wetland dominated by Cyperus papyrus

To improve understanding of carbon budgets in tropical wetlands, there is need to include estimates of fluxes of dissolved organic carbon (DOC) which are usually influenced by hydrological conditions. In this study, an assessment was made to test the hypotheses that tropical wetlands show significant fluvial losses of organic carbon and that these fluvial losses vary seasonally depending on the rate of water movement through the wetland. Measurements were made on a wetland dominated by Cyperus papyrus near Kampala, Uganda. DOC loads were computed from inflows and outflows discharge during wet and dry season. The inflow and outflow DOC concentrations ranged between 5.99 and 7.48 mg l⁻¹ and 5.88–10.6 mg l⁻¹ during dry season, and 6.24–8.48 mg l⁻¹ and 6.20–23.65 mg l⁻¹ during wet season respectively. There was little difference (12.5 %) in the load coming in and going out in the wet season, so DOC loss was not detected at this time. In the dry season, the loads were much smaller but there was more going out than coming in (32.6 %), but nevertheless there was a detectable loss of carbon from the wetland at this time.