Modelling nitrogen and oxygen isotope fractionation during denitrification in a lacustrine redox-transition zone

Lehmann, Moritz F.; Reichert, Peter; Bernasconi, Stefano M.; Barbieri, Alberto; McKenzie, Judith A.

doi:10.1016/s0016-7037(03)00085-1

Cited by 208 publications

(172 citation statements)

References 65 publications

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“…However, the NO 3 − -N concentration did not increase significantly with the increasing percentages of urban areas, corresponding to the downstream (no increased type; Figure 3b,c). Ohte et al [13] showed that dual NO 3 − isotope data are a powerful tool for tracing anthropogenic sources in most agricultural River (εN = −5.8 , Figure 4a) was approximately double the εO values (εO = −2.2 , Figure 4b), which was consistent with many studies [37,38]. The values of δ 15 N and δ 18 O suggest the effects of denitrification [14,39].…”

Section: Changes In the No3supporting

confidence: 78%

Differences in Stream Water Nitrate Concentrations between a Nitrogen-Saturated Upland Forest and a Downstream Mixed Land Use River Basin

et al. 2017

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Nitrogen (N) saturation of upland forests has been assumed to be a substantial N source downstream. However, removal processes of N, including assimilation and denitrification in the downstream area, have not been clarified. To evaluate the N removal processes, nitrate and organic N concentrations, as well as nitrogen isotope ratio (δ 15 N) and oxygen isotope ratio (δ 18 O) of NO 3 − were measured along three rivers of Tatara River Basin, Japan where upland forests have already been N-saturated. Geographic information system (GIS) based topographical analysis was also conducted to evaluate the land use as urban area in relation to topography. In two of the three rivers, NO 3 − concentrations did not increase from upstream to downstream, despite the potential non-point N sources of urban areas. In another river, NO 3 − concentrations rather decreased.The values of δ 15 N and δ 18 O of NO 3 − and organic N concentrations suggested the presence of denitrification and assimilation over N pollutants in the river whose watersheds have a lower percentage of urban area. The lower percentage of urban area could be explained by the lower topographic index. This study concluded that the NO 3 − leaching from upland N-saturated forests was substantially assimilated or denitrified in the downstream area.

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Section: Changes In the No3supporting

confidence: 78%

Differences in Stream Water Nitrate Concentrations between a Nitrogen-Saturated Upland Forest and a Downstream Mixed Land Use River Basin

et al. 2017

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“…However, the apparent difference in 18 e : 15 e documented in marine vs. freshwater systems, with ,1 in the former and ,0.6 in the latter (Lehmann et al 2003, and references therein), remains a puzzle. In our culture experiments, differences in medium salinity did not seem to change the observed coupling between N and O isotopes of the denitrifiers and thus do not serve as an explanation.…”

Section: Discussionmentioning

confidence: 99%

“…Subsequent lab studies demonstrated that phytoplankton cultures indeed fractionate the N and O isotopes of nitrate with equivalent isotope effects during nitrate assimilation (Granger et al 2004). Measurements of the isotopic composition of nitrate in freshwater and in marine systems suggest that denitrification also imparts proportional heavy atom enrichment on the N and O atoms of nitrate (Lehmann et al 2003;Sigman et al 2005). Nitrate isotope data from suboxic oxygen minimum zones in the ocean show increases in nitrate d 18 O and d 15 N associated with denitrification that follow a trajectory of 1 : 1 or greater, with deviations above unity attributed to additional Ntransforming processes (Sigman et al 2005).…”

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confidence: 99%

Nitrogen and oxygen isotope fractionation during dissimilatory nitrate reduction by denitrifying bacteria

Granger

Sigman

Lehmann

et al. 2008

Limnology & Oceanography

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We report the first measurements of coupled nitrogen (N) and oxygen (O) isotope fractionation of nitrate by laboratory cultures of denitrifying bacteria. Two seawater strains (Pseudomonas stutzeri, Ochrobactrum sp.) and three freshwater strains (Paracoccus denitrificans, Pseudomonas chlororaphis, Rhodobacter sphaeroides) were examined. Among four strains of facultative anaerobic denitrifiers, N and O isotope effects were variable, ranging from 5% to 25%, with evidence for a drop in the isotope effects as nitrate concentrations approached the halfsaturation constant for nitrate transport. O isotope effects were similar to their corresponding N isotope effect, such that the progressive increase in 1] 3 1000), yielded slopes of 0.86 to 1.02, with a mean value of 0.96. R. sphaeroides, a photo-heterotroph that possesses only a periplasmic (nonrespiring) dissimilatory nitrate reductase, showed less variability in nitrate N isotope effects, between 13% and 20%, with a modal value of ,15%. In contrast to the respiratory denitrifiers, R. sphaeroides consistently showed a distinct ratio of d 18 O to d 15 N change of ,0.62. We hypothesize that heavy N and O isotope discrimination during respiratory denitrification occurs during the intracellular reduction of nitrate by the respiratory nitrate reductase, and the observed magnitude of fractionation is likely regulated by the ratio of cellular nitrate efflux relative to uptake. The data for R. sphaeroides are consistent with isotope discrimination directly reflecting the N and O isotope effects of the periplasmic nitrate reductase NAP, without modification by nitrate uptake and efflux.

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“…It has been suggested that ␦ 15 N alteration occurs mainly at the seafloor, and that there may be various changes in the ␦ 15 N of bulk sediments such as increases or decreases during early burial in low-productivity regions, depending on oxic or anoxic conditions, respectively (Lehmann et al, 2003;Robinson et al, 2012). Diagenetic alteration under oxic conditions usually increases the ␦ 15 N composition of organic matter (Gaye et al, 2009;Lehmann et al, 2002;Möbius et al, 2011;Nakanishi and Minagawa, 2003).…”

Section: The Marine Nitrogen Cyclementioning

confidence: 99%

Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: Evidence from nitrogen and organic carbon isotopes

Wang

Struck

Guo

et al. 2015

Precambrian Research

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Modelling nitrogen and oxygen isotope fractionation during denitrification in a lacustrine redox-transition zone

Cited by 208 publications

References 65 publications

Differences in Stream Water Nitrate Concentrations between a Nitrogen-Saturated Upland Forest and a Downstream Mixed Land Use River Basin

Differences in Stream Water Nitrate Concentrations between a Nitrogen-Saturated Upland Forest and a Downstream Mixed Land Use River Basin

Nitrogen and oxygen isotope fractionation during dissimilatory nitrate reduction by denitrifying bacteria

Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: Evidence from nitrogen and organic carbon isotopes

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