Evaluating the utility of 15N and 18O isotope abundance analyses to identify nitrate sources: A soil zone study

Minet, Eddy; Coxon, Catherine; Goodhue, Robbie; Richards, Karl G.; Kalin, Robert M.; Meier‐Augenstein, Wolfram

doi:10.1016/j.watres.2012.03.004

Cited by 39 publications

(29 citation statements)

References 20 publications

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“…Nevertheless, soil water below the root zone (-13.5 to -7.1‰) and precipitation (-27 to -5.2‰) ( Our findings were in agreement with other studies, highlighting that a major part of nitrate input (mineral and organic fertilizers, atmospheric deposition) to soil was first incorporated into soil organic matter, subsequently mineralized and nitrified before it was released to the hydrosphere (Sebilo et al, 2013;Somers and Savard, 2011). Therefore, potential contamination with mineral fertilizers and atmospheric deposition was masked since their distinctive δ 18 O (NO3) signature was altered due to biological processes which was also found in other soil water studies (Granger et al, 2008;Mengis et al, 2001;Minet et al, 2012) and studies conducted in contaminated groundwater (Aravena et al 1993, Hosono et al 2011, Diédhiou et al 2011). However, the analysis of δ 18 O (NO3) still needs to be part of any isotopic nitrate -source investigation, since it provides clear hints if fractionation processes like denitrification and nitrification took place (Koh et al, 2010;Pastén-Zapata et al, 2014).…”

Section: In Groundwatersupporting

confidence: 91%

“…Similar differences in isotope composition between applied fertilizer and collected soil water was reported in Minet et al (2012). δ 15 N (NO3) values from local soil water samples ( Figure 8) and from soil zone studies (Granger et al, 2008;Minet et al, 2012) at grassland sites result from mineralisationimmobilisation turnover processes, demonstrating that microbial activity in soil below permanent grassland blur the distinct isotope composition of nitrate sources. Other studies investigating nitrate source identification in contaminated groundwater had ambiguous δ 15 N (NO3) values too;…”

Section: In Groundwatersupporting

confidence: 69%

“…Considering that nitrate leaching is lower under permanent grassland compared to other land use (Di and Cameron, 2002), δ 15 N (NO3) /δ 18 O (NO3) -studies on groundwater catchments covered with permanent grassland are rare. Soil zone studies were conducted to distinguish between different sources of nitrate under legume monocultures (Oelmann et al, 2007) and permanent grassland (Granger et al, 2008;Minet et al, 2012). Stable isotopes of nitrate in analyzed soil water made it possible to distinguish between atmospheric deposition and mineralization of leguminous and non-leguminous soil organic matter as sources of nitrate (Oelmann et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Stable isotopes of nitrate in analyzed soil water made it possible to distinguish between atmospheric deposition and mineralization of leguminous and non-leguminous soil organic matter as sources of nitrate (Oelmann et al, 2007). In contrast, the isotopic composition of nitrate in soil water under grassland barely mirrored the isotope composition of corresponding N applications (cattle slurry, atmospheric deposition, mineral fertilizer, dairy wastewater), but matched with nitrified soil organic nitrogen (Granger et al, 2008;Minet et al, 2012). Since the mentioned studies investigated soil water, the question arises whether nitrate sources can be identified at catchment scale covered with permanent grassland, which is presumed to be the most appropriate land use for water protection areas besides forest.…”

Section: Introductionmentioning

confidence: 99%

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Tracing freshwater nitrate sources in pre-alpine groundwater catchments using environmental tracers

Stoewer

Knöller

Stumpp

2015

Journal of Hydrology

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Section: In Groundwatersupporting

confidence: 91%

Section: In Groundwatersupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tracing freshwater nitrate sources in pre-alpine groundwater catchments using environmental tracers

Stoewer

Knöller

Stumpp

2015

Journal of Hydrology

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“…Denitrification causes both δ 15 N and δ 18 O values of the residual NO 3 − to increase. Sigman et al (2005) and Granger et al (2008)) found that δ 15 N and δ 18 O values of residual NO 3 − increased at a ratio of 2 during denitrification.However, some other surface and groundwater studies found that denitrification caused δ 18 O and δ 15 N to increase at a ratio of more than 1:1(Minet et al 2012; Dale et al 2014a, b) and some closed to 2(Burns et al 2009;Baily et al 2011;Critchley et al 2014;Wexler et al 2014) in agricultural watersheds. However, these lower ratios were not found in urban watersheds(Kaushal et al 2011), presumable because denitrification was limited by less organic carbon(Barnes and Raymond 2010;Wong et al 2015).…”

mentioning

confidence: 96%

A stable isotope approach and its application for identifying nitrate source and transformation process in water

Kang

Sun

2015

Environ Sci Pollut Res

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Nitrate contamination of water is a worldwide environmental problem. Recent studies have demonstrated that the nitrogen (N) and oxygen (O) isotopes of nitrate (NO3(-)) can be used to trace nitrogen dynamics including identifying nitrate sources and nitrogen transformation processes. This paper analyzes the current state of identifying nitrate sources and nitrogen transformation processes using N and O isotopes of nitrate. With regard to nitrate sources, δ(15)N-NO3(-) and δ(18)O-NO3(-) values typically vary between sources, allowing the sources to be isotopically fingerprinted. δ(15)N-NO3(-) is often effective at tracing NO(-)3 sources from areas with different land use. δ(18)O-NO3(-) is more useful to identify NO3(-) from atmospheric sources. Isotopic data can be combined with statistical mixing models to quantify the relative contributions of NO3(-) from multiple delineated sources. With regard to N transformation processes, N and O isotopes of nitrate can be used to decipher the degree of nitrogen transformation by such processes as nitrification, assimilation, and denitrification. In some cases, however, isotopic fractionation may alter the isotopic fingerprint associated with the delineated NO3(-) source(s). This problem may be addressed by combining the N and O isotopic data with other types of, including the concentration of selected conservative elements, e.g., chloride (Cl(-)), boron isotope (δ(11)B), and sulfur isotope (δ(35)S) data. Future studies should focus on improving stable isotope mixing models and furthering our understanding of isotopic fractionation by conducting laboratory and field experiments in different environments.

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Quantifying uncertainty in stable isotope mixing models

Davis

Syme

Heikoop

et al. 2015

J. Geophys. Res. Biogeosci.

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Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, Stable Isotope Analysis in R (SIAR), a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ 15 N and δ 18 O) but all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated mixing fractions.

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Evaluating the utility of 15N and 18O isotope abundance analyses to identify nitrate sources: A soil zone study

Cited by 39 publications

References 20 publications

Tracing freshwater nitrate sources in pre-alpine groundwater catchments using environmental tracers

Tracing freshwater nitrate sources in pre-alpine groundwater catchments using environmental tracers

A stable isotope approach and its application for identifying nitrate source and transformation process in water

Quantifying uncertainty in stable isotope mixing models

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