Potential Methane Production Associated with Aquatic Macrophytes Detritus in a Tropical Coastal Lagoon

摘要

Anaerobic decomposition of aquatic macrophytes in the sediment of wetlands is a key source of methane to the atmosphere. An experiment was conducted in order to evaluate the potential methane production (PMP) in the sediment colonized by three species of aquatic macrophytes and in the limnetic region of a tropical coastal lagoon. The incubations were prepared and maintained (70 days) at 25.0 A degrees C, and the PMP was measured by gas chromatography. The initial concentrations of dissolved organic carbon (DOC), carbohydrates and methane in the sediment were also measured. The sediment colonized by emergent aquatic macrophytes showed higher PMP due to the higher amounts of carbohydrates. On the other hand, PMP was lower in the limnetic region, which showed lower amounts of carbohydrates. The carbon found in the limnetic region is mainly originated from the refractory detritus of aquatic macrophytes that reaches the central region of the lagoon, with lower carbohydrate content. These results indicate that detritus quality, which means highest concentration of carbohydrates in the DOC, was the main controlling factor of methanogenesis.