Nitrous oxide in the Schelde estuary: production by nitrification and emission to the atmosphere

Wilde, H.P.J. de; Bie, M.J.M. de

doi:10.1016/s0304-4203(99)00106-1

Cited by 120 publications

(70 citation statements)

References 58 publications

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“…However, previous studies suggest that the highest N 2 O concentrations are usually encountered at low salinities in the vicinity of the turbidity maximum (Robinson et al, 1998;Barnes and Owens, 1998;Zhang et al, 2010). On the other hand, N 2 O maximum concentrations along estuaries may also occur at intermediate salinities (de Wilde and de Bie, 2000). This seems to have been the case during our wet-season campaign, where we observed the highest N 2 O concentrations at salinities between 10 and 20 (Fig.…”

Section: N 2 Osupporting

confidence: 50%

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

et al. 2016

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Abstract. Estuaries are sources of nitrous oxide (N 2 O) and methane (CH 4 ) to the atmosphere. However, our present knowledge of N 2 O and CH 4 emissions from estuaries in the tropics is very limited because data are scarce. In this study, we present first measurements of dissolved N 2 O and CH 4 from two estuaries in a peat-dominated region of northwestern Borneo. Two campaigns (during the dry season in June 2013 and during the wet season in March 2014) were conducted in the estuaries of the Lupar and Saribas rivers. Median N 2 O concentrations ranged between 7.2 and 12.3 nmol L −1 and were higher in the marine end-member (13.0 ± 7.0 nmol L −1 ). CH 4 concentrations were low in the coastal ocean (3.6 ± 0.2 nmol L −1 ) and higher in the estuaries (medians between 10.6 and 64.0 nmol L −1 ). The respiration of abundant organic matter and presumably anthropogenic input caused slight eutrophication, which did not lead to hypoxia or enhanced N 2 O concentrations, however. Generally, N 2 O concentrations were not related to dissolved inorganic nitrogen concentrations. Thus, the use of an emission factor for the calculation of N 2 O emissions from the inorganic nitrogen load leads to an overestimation of the flux from the Lupar and Saribas estuaries. N 2 O was negatively correlated with salinity during the dry season, which suggests a riverine source. In contrast, N 2 O concentrations during the wet season were not correlated with salinity but locally enhanced within the estuaries, implying that there were additional estuarine sources during the wet (i.e., monsoon) season. Estuarine CH 4 distributions were not driven by freshwater input but rather by tidal variations. Both N 2 O and CH 4 concentrations were more variable during the wet season. We infer that the wet season dominates the variability of the N 2 O and CH 4 concentrations and subsequent emissions from tropical estuaries. Thus, we speculate that any changes in the Southeast Asian monsoon system will lead to changes in the N 2 O and CH 4 emissions from these systems. We also suggest that the ongoing cultivation of peat soil in Borneo is likely to increase N 2 O emissions from these estuaries, while the effect on CH 4 remains uncertain.

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Section: N 2 Osupporting

confidence: 50%

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

et al. 2016

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“…4c, d). The O 2 -limited incubations carried out during September, relative to in situ O 2 conditions during the January experiments, could, together with a greater availability of particles occurring at the sampling depth, generate an O 2 -depleted environment, in which the yield of N 2 O formed through nitrifier denitrification Goreau et al, 1980;Lipschultz et al, 1981;de Wilde and de Bie, 2000) or through the "hybrid" pathway (Kozlowski et al, 2016) will increase. There is ample evidence that N 2 O production via nitrification in aquatic systems is increased under conditions of reduced oxygen and abundant ammonium availability McElroy et al, 1978;de Wilde and de Bie, 2000;Löscher et al, 2012).…”

Section: N 2 O Productionmentioning

confidence: 99%

Vertical segregation among pathways mediating nitrogen loss (N<sub>2</sub> and N<sub>2</sub>O production) across the oxygen gradient in a coastal upwelling ecosystem

2017

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Abstract. The upwelling system off central Chile (36.5 • S) is seasonally subjected to oxygen (O 2 )-deficient waters, with a strong vertical gradient in O 2 (from oxic to anoxic conditions) that spans a few metres (30-50 m interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g. anammox, denitrification, and nitrification). During austral spring (September 2013) and summer (January 2014), the main pathways involved in N loss and its speciation, in the form of N 2 and/or N 2 O, were studied using 15 N-tracer incubations, inhibitor assays, and the natural abundance of nitrate isotopes along with hydrographic information. Incubations were developed using water retrieved from the oxycline (25 m depth) and bottom waters (85 m depth) over the continental shelf off Concepción, Chile. Results of 15 N-labelled incubations revealed higher N removal activity during the austral summer, with denitrification as the dominant N 2 -producing pathway, which occurred together with anammox at all times. Interestingly, in both spring and summer maximum potential N removal rates were observed in the oxycline, where a greater availability of oxygen was observed (maximum O 2 fluctuation between 270 and 40 µmol L −1 ) relative to the hypoxic bottom waters (< 20 µmol O 2 L −1 ). Different pathways were responsible for N 2 O produced in the oxycline and bottom waters, with ammonium oxidation and dissimilatory nitrite reduction, respectively, as the main source processes. Ammonium produced by dissimilatory nitrite reduction to ammonium (DNiRA) could sustain both anammox and nitrification rates, including the ammonium utilized for N 2 O production. The temporal and vertical variability of δ 15 N-NO − 3 confirms that multiple N-cycling processes are modulating the isotopic nitrate composition over the shelf off central Chile during spring and summer. N removal processes in this coastal system appear to be related to the availability and distribution of oxygen and particles, which are a source of organic matter and the fuel for the production of other electron donors (i.e. ammonium) and acceptors (i.e. nitrate and nitrite) after its remineralization. These results highlight the links between several pathways involved in N loss. They also establish that different mechanisms supported by alternative N substratesPublished by Copernicus Publications on behalf of the European Geosciences Union. 4796A. Galán et al.: Vertical segregation among pathways mediating nitrogen loss are responsible for substantial accumulation of N 2 O, which are frequently observed as hotspots in the oxycline and bottom waters. Considering the extreme variation in oxygen observed in several coastal upwelling systems, these findings could help to understand the ecological and biogeochemical implications due to global warming where intensification and/or expansion of the oceanic OMZs is projected.

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“…Nitrification plays a major role in rivers and estuaries, not only as a key step in the nitrogen cycle, converting ammonium to nitrite and nitrate with N 2 O emissions (Somville et al, 1982;de Wilde and de Bie, 2000;Garnier et al, 2006a), but also in the oxygen balance: in water bodies receiving urban effluents, nitrification can be responsible for a significant and sometimes dominant proportion of their oxygen depletion, as was the case, for example, in the lower Rhine River in the late 1980s (Mu¨ller and Kirchesch, 1985;Admiraal and Botermans, 1989) and in the Pearl River estuary (He et al, 2014). In small, shallow rivers nitrification is mainly a benthic process (Curtis et al, 1975;Cooper, 1984;Pauer and Auer, 2000): very few nitrifying organisms are present in the water column because of their low growth rate and their propensity to attach to particles and to settle with them (Prosser, 1989;.…”

Section: Introductionmentioning

confidence: 99%

“…In turbid estuaries, by contrast, tidal mechanisms concentrate particles in a defined sector of the estuary where suspended solids experience a longer residence time than the water masses themselves, offering the attached nitrifying organisms the opportunity to develop a high biomass (Xia et al, 2004). The maximum turbidity zone of macrotidal estuaries is therefore a spot of high potential nitrification (Billen, 1975;Helder and De Vries, 1983;de Wilde and de Bie, 2000;Garnier et al, 2001;de Bie et al, 2002). Owens (1986) even compared estuarine nitrification to a naturally occurring fluidized bed reaction.…”

Section: Introductionmentioning

confidence: 99%

The response of river nitrification to changes in wastewater treatment (The case of the lower Seine River downstream from Paris)

Aissa-Grouz

Garnier

Billen

et al. 2015

Ann. Limnol. - Int. J. Lim.

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-In the early 2000s, most of the effluents from the Paris agglomeration (12 million inhabitants) were still discharged after only a standard activated sludge treatment of carbon, thus releasing a high ammonium load. This triggered the growth of nitrifying bacteria in the river and caused a deficit of dissolved oxygen concentration 200 km downstream, at the entrance of the estuarine area. From 2007 on, improvements of the wastewater treatment plant (WWTP) helped to nitrify most of the ammonium, and to denitrify 70% of the nitrate produced since 2012. This paper documents the effect of these recent changes in the treatment of Paris effluents, based on measurements of nitrogen species concentrations and nitrifying activities along longitudinal profiles of the lower Seine River. These observations are put into perspective with respect to previous observations, and a modeling approach is developed to evidence the role of ammonium and nitrifying organisms released with the WWTP effluents into the receiving water body. Today, a larger biomass of ammoniumoxidizing microbes is being discharged by the WWTP, but the microorganisms released do not grow, possibly because of the low substrate in the river. The same is true for nitrite-oxidizing microbes, which explains the persistence of nitrite often discharged with the effluents because of incomplete nitrification and/or denitrification in the treatment line. Taking into account the development of microbial populations of nitrifying organisms is essential to explain the observed spatial and temporal pattern of the nitrogen species.

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Nitrous oxide in the Schelde estuary: production by nitrification and emission to the atmosphere

Cited by 120 publications

References 58 publications

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

Vertical segregation among pathways mediating nitrogen loss (N<sub>2</sub> and N<sub>2</sub>O production) across the oxygen gradient in a coastal upwelling ecosystem

The response of river nitrification to changes in wastewater treatment (The case of the lower Seine River downstream from Paris)

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Nitrous oxide in the Schelde estuary: production by nitrification and emission to the atmosphere

Cited by 120 publications

References 58 publications

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of northwestern Borneo

Vertical segregation among pathways mediating nitrogen loss (N&lt;sub&gt;2&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O production) across the oxygen gradient in a coastal upwelling ecosystem

The response of river nitrification to changes in wastewater treatment (The case of the lower Seine River downstream from Paris)

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Product

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Vertical segregation among pathways mediating nitrogen loss (N<sub>2</sub> and N<sub>2</sub>O production) across the oxygen gradient in a coastal upwelling ecosystem