Simulating estuarine nitrous oxide production by means of a dynamic model

Rodrigues, Pedro Paulo Gomes Watts; Barnes, Jonathan; Upstill‐Goddard, Robert C.

doi:10.1016/j.marpolbul.2006.08.039

Cited by 10 publications

(21 citation statements)

References 51 publications

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“…A broad maximum around salinity 20 on 6 September 2000 reflects the nitrification of NH 4 + sourced from the Howdon STW [ Spencer et al , 2007]. In earlier work we applied a dynamic model of N 2 O production in the Tyne based on the equations of momentum, continuity and mass transport [ Rodrigues et al , 2007]. This confirmed that nitrification of Howdon derived NH 4 + dominates the observed N 2 O distribution (Figure 5).…”

Section: Resultssupporting

confidence: 85%

“…Dissolved N 2 O ranged from near atmospheric equilibrium in winter (9 January 2001) to significant supersaturation during summer (17 August 2000), when a low salinity maximum occurred in the vicinity of a weak TMZ [ Rodrigues et al , 2007] (Figure 4), similar to the situation in the Humber and Forth estuaries. A broad maximum around salinity 20 on 6 September 2000 reflects the nitrification of NH 4 + sourced from the Howdon STW [ Spencer et al , 2007].…”

Section: Resultsmentioning

confidence: 99%

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N₂O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N₂O source from European coastal waters

2011

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+ derived from internal resuspension and/or ammonification, or external inputs and were independent of river-borne NO 3 − . We reevaluated total UK and European estuarine N 2 O emissions using these and published data, based on an aerially weighted approach that separately identified inner and outer estuaries, and a downward revision of the total European estuarine area used in a recent synthesis. Our revised estimates, ∼1.9 ± 1.2 × 10 9 g N 2 O yr −1 for the UK and 6.8 ± 13.2 × 10 9 g N 2 O yr −1 for Europe (including UK) are dominated by large (area ∼200-500 km 2 ) anthropogenically impacted macrotidal inner estuaries. By contrast large pristine macrotidal systems, small inner estuaries, and large outer estuaries appear to be comparatively minor N 2 O sources. The UK estuarine N 2 O source is <2% of the UK N 2 O budget. Our revised European estuarine N 2 O emission is around 2 orders of magnitude smaller than a recent previous estimate that set this equivalent to ∼26% of the global estuarine total. We contend that this is an overestimate due to biases in the flux calculations resulting from likely overestimates of the mean N 2 O saturation and mean wind speed for European estuaries, and the European estuarine area. Taking this into account reduces this estimate to be more in line with our revised synthesis.Citation: Barnes, J., and R. C. Upstill-Goddard (2011), N 2 O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N 2 O source from European coastal waters,

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

N₂O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N₂O source from European coastal waters

2011

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“…For our work we chose bathymetric depth (Stubbins et al, 2011) because the water columns in our study area are predominantly well mixed (van Leeuwen et al, 2015). Even so, freshwater induced stratification can lead to upper mixed layer depths of 2e10 m in the lower Tyne estuary and adjacent North Sea (Rodrigues et al, 2007). For illustration, using an upper mixed layer depth of 2e10 m would return k int DMS of 0.03e0.16 d À1 for coastal waters (S > 30), in broad agreement with estimates for the Mackenzie Shelf (0.01e0.11 d À1 ) where mixed layer depths are comparably shallow, at 1e4.5 m (Taalba et al, 2013).…”

Section: Photochemical Dms Turnover and Dmso Productionmentioning

confidence: 99%

Photochemical oxidation of dimethylsulphide to dimethylsulphoxide in estuarine and coastal waters

et al. 2017

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h i g h l i g h t sWe observed 1:1 M conversion of DMS to DMSO in estuarine waters. This suggests that DMS photo-oxidation occurred via the CDOM sensitised 1 O 2 pathway. Photochemical rate constants decreased~10-fold from river to seawater. Rate constants were strongly correlated with CDOM absorption coefficients (a 350 ). a 350 -normalised rate constants increased~10-fold from river to seawater. a r t i c l e i n f o a b s t r a c tDimethylsulphide (DMS) photo-oxidation and dimethylsulphoxide (DMSO) photoproduction were estimated in 26 laboratory irradiations of coastal samples from NE England (Tyne estuary) and W Scotland (Loch Linnhe and River Nant at Taynuilt). Pseudo-first order rate constants of DMS photo-oxidation (0.038 h À1 to 0.345 h À1 ) and DMSO photo-production (0.017 h À1 to 0.283 h À1 ) varied by one order of magnitude and were lowest in the coastal North Sea. Estuarine samples (salinity S < 30) had a mean DMSO yield of 96 ± 16% (n ¼ 14), consistent with 1:1 M conversion via photosensitised oxidation by singlet oxygen. Photochemical rate constants were strongly correlated with coloured dissolved organic matter (CDOM) absorption coefficients at 350 nm, a 350 . Variations in a 350 explained 61% (R 2 ¼ 0.61, n ¼ 26) and 73% (R 2 ¼ 0.73, n ¼ 17) of the variability in DMS photo-oxidation and DMSO production, respectively. However, CDOM normalised photochemical rate constants increased strongly towards coastal waters exhibiting lowest CDOM absorbance, indicating water samples of marine character (S > 30) to be most reactive with respect to DMS photo-oxidation. Estimates of water column averaged DMS photo-oxidation rate constants, obtained by scaling to mean daily irradiance (July, NE England) and mid-UV underwater irradiance, were 0.012 d À1 , 0.019 d À1 , and 0.017 d À1 for upper estuary (S < 20), lower estuary (20 < S < 30) and coastal waters (S > 30), at the lower end of previous observations. Comparing our water column averaged DMS photo-oxidation rate constants with estimated DMS losses via air-sea gas exchange and previously reported biological consumption implies that DMS photochemical removal is of only minor importance in our study area.

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“…Regnier et al [25] were probably the first to develop a fully transient one-dimensional reactive transport model, CONTRASTE, which can simulate transport and emission of N 2 O along with DIN (dissolved inorganic nitrogen) components, DO, suspended matter, pH, salinity, dissolved organic matter, CO 2 , etc. Rodrigues et al [26] used a similar one-dimensional hydro-dynamic model for simulating N 2 O emissions from tidal rivers receiving treated wastewater and applied it to the River Tyne, UK. Garnier et al [27] developed a model for nitrogen transformations in the lower Seine river and estuary (France) based on the rain-discharge model, RIVERSTRAHLER and microbial reaction kinetics for nitrification and denitrification.…”

Section: Introductionmentioning

confidence: 99%

“…In both the models, the decision vector comprises of treatment levels at different discharge locations and upstream releases. These waste load allocation models use a water quality simulation model, which numerically solves the complete dynamic equations for water flow, and reactive transport model for N 2 O [26]. The optimisation problem is solved using the well-established simulated annealing technique.…”

Section: Introductionmentioning

confidence: 99%

Managing Municipal Wastewater Treatment to Control Nitrous Oxide Emissions from Tidal Rivers

Akella

Bhallamudi

2019

Water

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Waste load allocation management models were developed for controlling nitrous oxide emissions from a tidal river. The decision variables were treatment levels at wastewater discharging stations and the rate of upstream water release. The simulation model for N2O emissions from the river was embedded in the optimization model and the problem was solved using the simulated annealing technique. In two of the models, the total cost was minimized, while in the third model, emissions from the river were minimized for a specified constraint on the available money. Proof-of-concept studies, with hypothetical scenarios for contaminant loading but realistic flow conditions corresponding to the Tyne River, UK, were carried out. It was found that the treatment cost could be reduced by 36% by treating wastewater discharges in the upper reaches more during the high tide as compared to during low tide. For the same level of N2O emissions, approximately 16.7% lesser costs could be achieved by not only treating the wastewater but also inducing dilution by releasing more water from the upstream side. It was also found that beyond a limit, N2O emissions cannot be reduced significantly by spending more money on treatment and water release.

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Simulating estuarine nitrous oxide production by means of a dynamic model

Cited by 10 publications

References 51 publications

N₂O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N₂O source from European coastal waters

N₂O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N₂O source from European coastal waters

Photochemical oxidation of dimethylsulphide to dimethylsulphoxide in estuarine and coastal waters

Managing Municipal Wastewater Treatment to Control Nitrous Oxide Emissions from Tidal Rivers

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Simulating estuarine nitrous oxide production by means of a dynamic model

Cited by 10 publications

References 51 publications

N2O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N2O source from European coastal waters

N2O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N2O source from European coastal waters

Photochemical oxidation of dimethylsulphide to dimethylsulphoxide in estuarine and coastal waters

Managing Municipal Wastewater Treatment to Control Nitrous Oxide Emissions from Tidal Rivers

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N₂O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N₂O source from European coastal waters

N₂O seasonal distributions and air-sea exchange in UK estuaries: Implications for the tropospheric N₂O source from European coastal waters