气候变化领域集成服务门户(CCPortal): Estuaries as Sources and Sinks of N2O Across a Land Use Gradient in Subtropical Australia

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DOI	10.1029/2017GB005826
	Estuaries as Sources and Sinks of N2O Across a Land Use Gradient in Subtropical Australia
	Wells N.S.; Maher D.T.; Erler D.V.; Hipsey M.; Rosentreter J.A.; Eyre B.D.
发表日期	2018
ISSN	0886-6236
EISSN	1944-9224
起始页码	877
结束页码	894
卷号	32 期号:5
英文摘要	Intensifying agricultural production and coastal urbanization are increasing nitrogen (N) loads to estuaries, potentially increasing emissions of the greenhouse gas nitrous oxide (N2O). Here we present a first assessment of how changes in land use intensity affect estuarine N2O fluxes. We measured N2O concentrations over marine-freshwater transects in the wet and dry seasons in eight subtropical estuaries selected for differences in land use intensity. Daily estuary N loads ranged from 0.5 ± 0.4 kg N km−2 d−1 (minimally impacted) to 51 ± 30 kg N km−2 d−1 (highly impacted), corresponding to higher concentrations of all inorganic N species (nitrate, ammonium, and N2O) in the highly impacted estuaries. Net N2O fluxes from the eight estuaries ranged from −20 μg N2O-N m−2 d−1 (sink) to +300 μg N2O-N m−2 d−1 (source). However, neither N concentrations nor N loads explained the variations in N2O fluxes. Instead, seasonal differences in freshwater flushing times increased either N2O uptake (minimally impacted systems) or N2O efflux (moderately impacted systems) relative to N load. The lack of relationship between freshwater flushing times (kinetics) and N2O fluxes from the highly impacted estuaries, combined with evidence for both low carbon quality and phosphorous limitation in those systems, suggests that N2O emissions from highly impacted estuaries were controlled by stoichiometry rather than kinetics. This study shows that estuaries can shift from net sinks to sources of N2O as land use intensity increases but that the magnitude of this switch cannot be predicted based on N loads alone. (Figure presented.). ©2018. American Geophysical Union. All Rights Reserved.
英文关键词	Greenhouse gasses; land-use; reactive nitrogen; residence time; stoichiometry; sub-tropics
语种	英语
scopus关键词	agricultural production; concentration (composition); estuarine environment; estuarine front; freshwater environment; greenhouse gas; inorganic nitrogen; land use; land use change; nitrous oxide; seasonal variation; stoichiometry; subtropical region; urbanization; Australia
来源期刊	Global Biogeochemical Cycles
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/129824
作者单位	Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, Australia; Southern Cross Geoscience, Southern Cross University, Lismore, NSW, Australia; School of Earth and Environment, University of Western Australia, Crawley, WA, Australia
推荐引用方式 GB/T 7714	Wells N.S.,Maher D.T.,Erler D.V.,et al. Estuaries as Sources and Sinks of N2O Across a Land Use Gradient in Subtropical Australia[J],2018,32(5).
APA	Wells N.S.,Maher D.T.,Erler D.V.,Hipsey M.,Rosentreter J.A.,&Eyre B.D..(2018).Estuaries as Sources and Sinks of N2O Across a Land Use Gradient in Subtropical Australia.Global Biogeochemical Cycles,32(5).
MLA	Wells N.S.,et al."Estuaries as Sources and Sinks of N2O Across a Land Use Gradient in Subtropical Australia".Global Biogeochemical Cycles 32.5(2018).