Forensic Applications of Nitrogen and Oxygen Isotopes in Tracing Nitrate Sources in Urban Environments

Silva, S.R.; Ging, Patricia B.; Lee, R.W.; Ebbert, J.C.; Tesoriero, Anthony J.; Inkpen, E.L.

doi:10.1006/enfo.2002.0086

Cited by 111 publications

(75 citation statements)

References 12 publications

(10 reference statements)

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“…Results from both studies implied that NO 3 in atmospheric deposition could contribute upwards of 50% of the NO 3 in these watersheds. Earlier studies by Ging et al (1996) and Silva et al (2002) using υ 18 O-NO 3 in two urbanized watersheds in Austin, Texas, also pointed to the importance of atmospheric NO 3 in stormflow due to the influence of runoff from impervious surfaces.…”

Section: General Trends In Nomentioning

confidence: 89%

“…For example, studies by Ging et al (1996) and Silva et al (2002) showed 3293 that υ 15 N-NO 3 was a useful tracer of NO 3 from sewage at baseflow, whereas increases in υ 18 O-NO 3 during storms were useful for inferring the importance of atmospheric NO 3 in direct runoff from impervious surfaces during stormflow in two heavily urbanized watersheds in Austin, Texas. More recent studies by Anisfeld et al (2007) and Burns et al (2009) have also suggested that υ 18 O-NO 3 may indicate important shifts to atmospheric NO 3 sources during high flows in urban and suburban watersheds.…”

Section: Introductionmentioning

confidence: 96%

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Dynamics of stream nitrate sources and flow pathways during stormflows on urban, forest and agricultural watersheds in central Pennsylvania, USA

Buda

DeWalle

2009

Hydrological Processes

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Abstract:Understanding the influence of storm events on nitrate (NO 3 ) dynamics is important for efficiently managing NO 3 pollution. In this study, five sites representing a downstream progression of forested uplands underlain by resistant sandstone to karst lowlands with agricultural, urban and mixed land-use were established in Spring Creek, a 201 km 2 mixed land-use watershed in central Pennsylvania, USA. At each site, stream water was monitored during six storm events in 2005 to assess changes in stable isotopes of NO 3 (υ 15 N-NO 3 and υ 18 O-NO 3 ) and water (υ 18 O-H 2 O) from baseflow to peakflow. Peakflow fractions of event NO 3 and event water were then computed using two-component mixing models to elucidate NO 3 flow pathway differences among the five sites. For the forested upland site, storm size appeared to affect NO 3 sources and flow pathways. During small storms (<35 mm rainfall), greater event NO 3 fractions than event water fractions indicated the prevalence of atmospheric NO 3 source contributions at peakflow. During larger storms (>35 mm rainfall), event NO 3 fractions were less than event water fractions at peakflow suggesting that NO 3 was flushed from stored sources via shallow subsurface flow pathways. For the urbanized site, wash-off of atmospheric NO 3 was an important NO 3 source at peakflow, especially during short-duration storms where event water contributions indicated the prevalence of overland flow. In the karst lowlands, very low fractions of event water and even lower fractions of event NO 3 at peakflow suggested the dominance of ground water flow pathways during storms. These ground water flow pathways likely flushed stored NO 3 sources into the stream, while deep soils in the karst lowlands also may have promoted NO 3 assimilation. The results of this study illustrated how NO 3 isotopes and υ 18 O-H 2 O could be combined to show key differences in water and NO 3 delivery between forested uplands, karst valleys and fully urbanized watersheds.

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Section: General Trends In Nomentioning

confidence: 89%

Section: Introductionmentioning

confidence: 96%

Dynamics of stream nitrate sources and flow pathways during stormflows on urban, forest and agricultural watersheds in central Pennsylvania, USA

Buda

DeWalle

2009

Hydrological Processes

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“…Thus, Cl − can be combined with δ 15 N-NO 3 − and δ 18 O-NO 3 − to identify NO − 3 sources and N transformation processes. Silva et al (2002) found that δ 15 N-NO 3 − values were positively related to Cl − concentrations in an urban watershed, indicating that the main NO − 3 source was mixing between baseflow and stormflow. Chen et al (2014) found that mixing processes played an important role in Taihu (Min et al 2002;Shin et al 2013) have found that water chemistry changed from a Ca-HCO 3 -to Na-Cl-NO 3 -dominated system when NO 3 − sources changed from soil organic N to sewage and manure.…”

Section: Combining Nitrogen and Oxygen Isotopes Of Nitrate With Chloridementioning

confidence: 95%

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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“…3 (Kendall 1998;Chang et al 2002;Silva et al 2002). NO 3 -originating from precipitation and synthetic NO 3 -fertilizer has much higher d 18 O values than that from nitrification of reduced N sources, i.e.…”

Section: Seasonal Variations Of Nitrate Sources and Dynamicsmentioning

confidence: 97%

“…This scenario is obviously unrealistic, because precipitation and river water were high in rainy August, which would dilute the contribution of sewage and livestock effluent. In fact, the most contribution of sewage and livestock effluent should be in dry December, Silva et al (2002). The shaded area defines the domain of nitrate from soil organic matter, which partially overlaps that of reduced N fertilizer and manure and sewage with respect to d 15 N. The two horizontal dashed lines delineate the local d 18 O of NO 3 -from these reduced N sources as described in the discussion.…”

Section: Seasonal Variations Of Nitrate Sources and Dynamicsmentioning

confidence: 98%

Nitrate sources and watershed denitrification inferred from nitrate dual isotopes in the Beijiang River, south China

2009

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The great spatial and temporal variability of nitrogen (N) processing introduces large uncertainties for quantifying N cycles in large scales, e.g. a watershed scale, and hence challenges the present techniques in measuring ecosystem N mass balance. The dual isotopes of nitrate (d 18 O and d 15 N) integrate signals for both nitrate sources and N processing, making them promising for studies on large scale N cycling. Here, the dual isotopes, as well as some ion tracers, from a subtropical river in south China were reported to identify the main nitrate sources and to assess the possible occurrence and degree of denitrification in the context of monsoon climate. Our results indicated that nitrification of reduced fertilizer N in soil zones was the main nitrate source, with sewage and manure as another important source in dry winter. Seasonal changes of denitrification was apparent by the *1:2 enrichment of 18 O and 15 N from April to August, and suggested to occur over the watershed rather than in the river. The lowest denitrification (10%) occurred in April, when the fertilizer application was strongest and the monsoon rainfall abruptly increased, causing enhancement of leaching. The highest denitrification (48%) took place in August due to the high soil temperature and moisture. In December, denitrification was significant (26%) perhaps due to the high enough temperature for microbial activities, whereas the low soil moisture appeared to limit the degree of denitrification. This study suggests that the seasonal variations in denitrification should be taken into account when estimating regional N mass balance.

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Forensic Applications of Nitrogen and Oxygen Isotopes in Tracing Nitrate Sources in Urban Environments

Cited by 111 publications

References 12 publications

Dynamics of stream nitrate sources and flow pathways during stormflows on urban, forest and agricultural watersheds in central Pennsylvania, USA

Dynamics of stream nitrate sources and flow pathways during stormflows on urban, forest and agricultural watersheds in central Pennsylvania, USA

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

Nitrate sources and watershed denitrification inferred from nitrate dual isotopes in the Beijiang River, south China

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