N<sub>2</sub>O Emissions from a Nitrogen-Enriched River

McMahon, Peter B.; Dennehy, Kevin F.

doi:10.1021/es980645n

Cited by 123 publications

(91 citation statements)

References 16 publications

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“…This contrasts with past results from two river systems, where NO 3 − explained 52-68% of variation in N 2 O emissions over time [McMahon and Dennehy, 1999;Stow et al, 2005]. However, the poorer relationships we report are commonly observed, particularly in areas affected by groundwater N 2 O inputs [Clough et al, 2006].…”

Section: Spatial and Temporal Variation In Stream N 2 O Fluxescontrasting

confidence: 99%

Nitrogen enrichment and the emission of nitrous oxide from streams

Baulch¹,

Schiff²,

Maranger³

et al. 2011

Global Biogeochem. Cycles

125

101

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[1] Nitrous oxide (N 2 O) is a potent greenhouse gas produced during nitrogen cycling. Global nitrogen enrichment has resulted in increased atmospheric N 2 O concentrations due in large part to increased soil emissions. There is also a potentially important flux from streams, rivers and estuaries; although measurements of these emissions are sparse, and role of aquatic ecosystems in global N 2 O budgets remains highly uncertain. Using the longest-term measurements of N 2 O fluxes from streams to date, we found annual fluxes from 14 sites in five streams of south-central Ontario, Canada varied widely-from net uptake of 3.2 ± 0.2 (standard deviation) mmol N 2 O m −2 d −1 to net release of 776 ± 61 mmol N 2 O m −2 d −1 . N 2 O consumption was associated with very low nitrate concentrations (<2.7 mM). Mean annual (log-transformed) N 2 O emissions from our study streams (across sites and years) were positively related to nitrate concentrations (r 2 = 0.59).This nitrate-N 2 O relationship can be generalized across all 20 streams (in Canada, Japan, Mexico, and the midwestern United States) for which published data now exist and could provide a new basis for the IPCC to calculate agricultural emissions from streams. In addition to predicting annual emissions, we present the first measurements of N 2 O concentrations under ice in streams. Nitrate was a strong predictor of N 2 O % saturation during periods of ice cover (r 2 = 0.89), when gas exchange is negligible. Given the small surface area of streams within a catchment and the fact our measured areal fluxes are comparable to reported fluxes from agricultural soils, this suggests streams are a small regional N 2 O source.Citation: Baulch, H. M., S. L. Schiff, R. Maranger, and P. J. Dillon (2011), Nitrogen enrichment and the emission of nitrous oxide from streams, Global Biogeochem. Cycles, 25, GB4013,

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Section: Spatial and Temporal Variation In Stream N 2 O Fluxescontrasting

confidence: 99%

Nitrogen enrichment and the emission of nitrous oxide from streams

Baulch¹,

Schiff²,

Maranger³

et al. 2011

Global Biogeochem. Cycles

125

101

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“…On this basis, we recommend the use of more streamlined circular chambers to minimize the error under drifting conditions. Crawford et al (2013) and McMahon and Dennehy (1999) used streamlined (canoe-shaped) instead of cylindrical or rectangular chambers to minimize the generation of chamber-induced turbulence at the upstream chamber edge during anchored chamber deployments. However, they did not provide evidence that this goal was reached.…”

Section: Correction Methods and Chamber Optimizationmentioning

confidence: 99%

Technical note: drifting versus anchored flux chambers for measuring greenhouse gas emissions from running waters

et al. 2015

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Abstract. Stream networks have recently been discovered to be major but poorly constrained natural greenhouse gas (GHG) sources. A fundamental problem is that several measurement approaches have been used without crosscomparisons. Flux chambers represent a potentially powerful methodological approach if robust and reliable ways to use chambers on running water can be defined. Here we compare the use of anchored and freely drifting chambers on various streams with different flow velocities. The study clearly shows that (1) anchored chambers enhance turbulence under the chambers and thus elevate fluxes, (2) drifting chambers have a very small impact on the water turbulence under the chamber and thus generate more reliable fluxes, (3) the bias of the anchored chambers greatly depends on chamber design and sampling conditions, and (4) there is a promising method to reduce the bias from anchored chambers by using a flexible plastic foil collar to seal the chambers to the water surface, rather than having rigid chamber walls penetrating into the water. Altogether, these results provide novel guidance on how to apply flux chambers in running water, which will have important consequences for measurements to constrain the global GHG balances.

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“…Methane concentrations and emissions are found to be high in estuaries and streams surrounded by forests, agricultural land and peatlands (De Angelis and Lilley 1987;Jones and Mulholland 1998;Hope et al 2001;Dawson et al 2004;Kristensen et al 2008). It is seen that high N 2 O concentrations and emissions occur in systems receiving freshwater from streams or groundwater, this is especially when fertilizer has been applied to the surrounding land producing nutrient rich runoff to the stream (Mosier et al 1998;McMahon and Dennehy 1999;Machefert et al 2004). …”

Section: Introductionmentioning

confidence: 99%

Sources and sinks of methane and nitrous oxide in the subtropical Brisbane River estuary, South East Queensland, Australia

Sturm

Grinham

Ulrich

et al. 2016

Estuarine, Coastal and Shelf Science

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This study investigated sources and sinks of methane (CH 4 ) and nitrous oxide (N 2 O) in the Brisbane River estuary, Australia. Field measurements and laboratory incubation experiments were performed to determine the contribution of the water column, sediments, influent creeks and discharge from a wastewater treatment plant, to greenhouse gas levels occurring in the estuary.Sampling was conducted at 16 sites along the estuary with more detailed studies at three of these sites, located in the lower, middle and upper estuarine reaches, respectively. The estuary is a source of CH 4 and N 2 O with their saturation in the surface water ranging between 2,160 and 26,900% for CH 4 , and between 140 and 230% for N 2 O, relative to their respective atmospheric concentrations. Estuarine sediments were identified as sources for both CH 4 and N 2 O, as concentrations for both dissolved gases were higher in the pore water at the sediment surfaces in comparison to the water column samples at all sites. Methane and N 2 O were produced in silty sediments as shown in sediment-water incubations. Creeks were detected to be a source of CH 4 and N 2 O, as their concentrations were higher in the creek in comparison to those measured at the confluence of the creek and the estuary. The estuarine water column was identified as a CH 4 sink; however, the water column was neither a sink nor a source for N 2 O. A wastewater treatment plant discharging effluent into the tributary did not contribute significantly to the creek CH 4 levels, but may have elevated N 2 O at the direct point of discharge. A budget estimate of the Brisbane River estuary showed that sediments are not the sole source of CH 4 , as the sediment-water fluxes are far less (1%) than what is consumed, emitted or transported to the ocean. An unknown CH 4 source is therefore likely present, which is yet to be revealed. In contrast, most of N 2 O produced in the estuarine sediments was emitted to the atmosphere.

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N₂O Emissions from a Nitrogen-Enriched River

Cited by 123 publications

References 16 publications

Nitrogen enrichment and the emission of nitrous oxide from streams

Nitrogen enrichment and the emission of nitrous oxide from streams

Technical note: drifting versus anchored flux chambers for measuring greenhouse gas emissions from running waters

Sources and sinks of methane and nitrous oxide in the subtropical Brisbane River estuary, South East Queensland, Australia

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N2O Emissions from a Nitrogen-Enriched River

Cited by 123 publications

References 16 publications

Nitrogen enrichment and the emission of nitrous oxide from streams

Nitrogen enrichment and the emission of nitrous oxide from streams

Technical note: drifting versus anchored flux chambers for measuring greenhouse gas emissions from running waters

Sources and sinks of methane and nitrous oxide in the subtropical Brisbane River estuary, South East Queensland, Australia

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N₂O Emissions from a Nitrogen-Enriched River