title: Pristine mangrove creek waters are a sink of nitrous oxide.
abstract: Nitrous oxide (N2O) is an important greenhouse gas, but large uncertainties remain in global budgets. Mangroves are thought to be a source of N2O to the atmosphere in spite of the limited available data. Here we report high resolution time series observations in pristine Australian mangroves along a broad latitudinal gradient to assess the potential role of mangroves in global N2O budgets. Surprisingly, five out of six creeks were under-saturated in dissolved N2O, demonstrating mangrove creek waters were a sink for atmospheric N2O. Air-water flux estimates showed an uptake of 1.52 ± 0.17 μmol m(-2) d(-1), while an independent mass balance revealed an average sink of 1.05 ± 0.59 μmol m(-2) d(-1). If these results can be upscaled to the global mangrove area, the N2O sink (~2.0 × 10(8) mol yr(-1)) would offset ~6% of the estimated global riverine N2O source. Our observations contrast previous estimates based on soil fluxes or mangrove waters influenced by upstream freshwater inputs. We suggest that the lack of available nitrogen in pristine mangroves favours N2O consumption. Widespread and growing coastal eutrophication may change mangrove waters from a sink to a source of N2O to the atmosphere, representing a positive feedback to climate change.
authors.affiliation: School of Environment, Science and Engineering, Southern Cross University, Lismore, 2480 Australia.
authors.forename: Damien T
authors.initials: DT
authors.lastname: Maher
authors.affiliation: School of Environment, Science and Engineering, Southern Cross University, Lismore, 2480 Australia.|National Marine Science Centre, Southern Cross University, PO Box 4321, Coffs Harbour, NSW 2450, Australia.
authors.forename: James Z
authors.initials: JZ
authors.lastname: Sippo
authors.affiliation: School of Environment, Science and Engineering, Southern Cross University, Lismore, 2480 Australia.|National Marine Science Centre, Southern Cross University, PO Box 4321, Coffs Harbour, NSW 2450, Australia.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Tait
authors.affiliation: School of Environment, Science and Engineering, Southern Cross University, Lismore, 2480 Australia.|National Marine Science Centre, Southern Cross University, PO Box 4321, Coffs Harbour, NSW 2450, Australia.
authors.forename: Ceylena
authors.initials: C
authors.lastname: Holloway
authors.affiliation: School of Environment, Science and Engineering, Southern Cross University, Lismore, 2480 Australia.|National Marine Science Centre, Southern Cross University, PO Box 4321, Coffs Harbour, NSW 2450, Australia.
authors.forename: Isaac R
authors.initials: IR
authors.lastname: Santos
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D001272:Atmosphere / Q000737:chemistry*; D001315:Australia; D057231:Climate Change; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000737:chemistry*; D005843:Geography; D009584:Nitrogen / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis*; D012987:Soil / Q000737:chemistry; D053833:Wetlands
chemical_list: D000393:Air Pollutants; D012987:Soil; D009609:Nitrous Oxide; D009584:Nitrogen