N2O Flux From South Andaman Mangroves And Surrounding Creek Waters

Nitrous oxide (N 2 O) flux from mangroves and their surrounding creek waters were estimated in the south Andaman mangroves of Wright Myo (Andaman Sea) and Red Skin Island (Bay of Bengal). These regions may play an important role in greenhouse gas cycling and so water (dissolved N 2 O) and air samples were analyzed. Importantly, previous studies excluded emissions estimates for creek waters surrounding mangroves. This study includes direct emission estimates for both mangrove forest sediment and surrounding mangrove creek waters made using static and free-floating chambers respectively. Additionally, indirect estimates for creek waters based on dissolved gas concentrations and a relationship between gas transfer velocity and wind speed were made. In the present study, the N 2 O emission rates from Andaman mangroves varied between 0.161 and 3.02 μmol N 2 O m-2 h-1. The average direct emission rate from the mangrove sediments were 0.416 μmol N 2 O m-2 h-1 and 0.873 μmol N 2 O m-2 h-1 from the mangrove creek waters. This was extrapolated for the entire mangrove cover of Andaman to give 230.96 g yr-1 of N 2 O. High N 2 O emissions from mangrove creek waters than from the mangrove forest sediments may be attributed to nitrification in the water column but it is unclear what relative proportions of the creek fluxes derive from terrestrial and marine carbon and nitrogen sources.