Global Warming Potential of Nitrous oxide Fluxes from Sediments of Mangrove Ecosystem in Waiheru Coastal Area, Ambon Bay

Mangrove ecosystems can be a source or a sink of N₂O and other greenhouse gases. The Inner Ambon Bay area, including the Waiheru coast, gets organic matter inputs deposited in sediments, which has the potential to trigger an increase in greenhouse gas flux. This research was conducted to evaluate the flux and global warming potential of N₂O in sediments of the mangrove ecosystem in the area of Waiheru coastal, Ambon Bay. The sediment-trapped gas was collected from the chambers of three different types of sediments viz. sandy, muddy sand, and sandy mud sediments. The gas was extracted from chambers using a syringe and injected into the 10 ml glass bottle. N₂O concentrations in the samples were analyzed using gas chromatography. Average N₂O concentrations were compared between samples from different sediments using one-way ANOVA. The result showed that the mean concentration of N₂O was significantly different between the sediment types (P < 0.05). The highest N₂O flux in mangrove sediments was found in the sandy substrate (0.0278 mg.m^-2.h^-1) and the lowest in the muddy sand substrate (0.0135 mg.m^-2.h^-1). The average Global Warming Potential (GWP) in mangrove sediments of Waiheru coastal area was 6.29 CO₂-eq mg.m^-2.h^-1, which was contributed by sandy substrate (8.30 CO₂-eq mg.^-2.h^-1), sandy mud substrate (6.57 CO₂-eq mg.m^-2.h^-1) and muddy sand substrate (4.01 CO₂-eq mg.m^-2.h^-1). The reported values of GWP were relatively low based on the standard value of IPCC, which is 298 CO₂-eq mg.m^-2.h^-1 indicating that the nitrification and denitrification processes producing N₂O gas flux are still in normal condition, which would not cause air pollution.