title: Methane and nitrous oxide emissions from a subtropical coastal embayment (Moreton Bay, Australia).
abstract: Surface water methane (CH4) and nitrous oxide (N2O) concentrations and fluxes were investigated in two subtropical coastal embayments (Bramble Bay and Deception Bay, which are part of the greater Moreton Bay, Australia). Measurements were done at 23 stations in seven campaigns covering different seasons during 2010-2012. Water-air fluxes were estimated using the Thin Boundary Layer approach with a combination of wind and currents-based models for the estimation of the gas transfer velocities. The two bays were strong sources of both CH4 and N2O with no significant differences in the degree of saturation of both gases between them during all measurement campaigns. Both CH4 and N2O concentrations had strong temporal but minimal spatial variability in both bays. During the seven seasons, CH4 varied between 500% and 4000% saturation while N2O varied between 128 and 255% in the two bays. Average seasonal CH4 fluxes for the two bays varied between 0.5±0.2 and 6.0±1.5 mg CH4/(m2·day) while N2O varied between 0.4±0.1 and 1.6±0.6 mg N2O/(m2·day). Weighted emissions (t CO2-e) were 63%-90% N2O dominated implying that a reduction in N2O inputs and/or nitrogen availability in the bays may significantly reduce the bays' greenhouse gas (GHG) budget. Emissions data for tropical and subtropical systems is still scarce. This work found subtropical bays to be significant aquatic sources of both CH4 and N2O and puts the estimated fluxes into the global context with measurements done from other climatic regions.
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, Brisbane, Qld 4072, Australia. Electronic address: musenzers@yahoo.com.
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Musenze
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, Brisbane, Qld 4072, Australia.
authors.forename: Ursula
authors.initials: U
authors.lastname: Werner
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, Brisbane, Qld 4072, Australia; School of Civil Engineering, The University of Queensland, Brisbane, Qld 4072, Australia.
authors.forename: Alistair
authors.initials: A
authors.lastname: Grinham
authors.affiliation: Healthy Waterways Ltd., Brisbane, Qld 4003, Australia.
authors.forename: James
authors.initials: J
authors.lastname: Udy
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, Brisbane, Qld 4072, Australia. Electronic address: z.yuan@awmc.uq.edu.au.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D001315:Australia; D061006:Bays / Q000737:chemistry*; D008697:Methane / Q000737:chemistry*; D009609:Nitrous Oxide / Q000737:chemistry*; D045483:Rivers; D012621:Seasons; D012623:Seawater / Q000737:chemistry; D013997:Time Factors; D014919:Wind
chemical_list: D000393:Air Pollutants; D009609:Nitrous Oxide; D008697:Methane
keywords: Bay; Greenhouse gas emissions; Methane; Nitrous oxide; Subtropical aquatic systems; Uncertainty