Groundwater nitrate and chloride trends in an agriculture-intensive area in southern Alberta, Canada

Köhn, Jacqueline; Soto, David X.; Iwanyshyn, Mike; Olson, Barry M.; Kalischuk, Andrea; Lorenz, Kristen; Hendry, M. Jim

doi:10.2166/wqrjc.2015.132

Cited by 34 publications

(15 citation statements)

References 13 publications

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“…Agriculturally derived NO3 -at these two sites with varying lithology is generally restricted to depths < 20 m, consistent with previous studies at CFOs (Robertson et al, 1996;Rodvang and Simpkins, 2001;Rodvang et al, 25 2004;Kohn et al, 2016). Attenuation of agriculturally derived NO3 -in groundwater is a spatially varying combination of mixing and denitrification, with denitrification playing a greater role than mixing at both sites.…”

Section: Discussionsupporting

confidence: 87%

“…earthen manure storage, temporary manure piles, or fertilizer) and the 10 complexity of hydrogeologic systems (Spalding and Exner, 1993;Rodvang et al, 2004;Showers et al, 2008;Kohn et al, 2016). These spatial and temporal variations can result in complex subsurface solute distributions that are difficult to interpret using classical transect studies or numerical groundwater models (Green et al, 2010;Baily et al, 2011).…”

Section: Identification Of the Sources And Fate Of No3mentioning

confidence: 99%

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Sources and fate of nitrate in groundwater at agricultural operations overlying glacial sediments

Bourke¹,

Iwanyshyn²,

Köhn³

et al. 2018

Preprint

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for using a Monte Carlo approach. When denitrification could be quantified, we reconstructed the initial NO3-N concentration and NO3-N/Cl -ratio at the point of entry to the groundwater system. The addition of NO3 -to the local groundwater system from temporary manure piles and pens equalled or exceeded NO3 -additions due to leaching from earthen manure storages at these sites. Nitrate attenuation at both sites is attributed to a spatially 20 variable combination of mixing and denitrification, but is dominated by denitrification. On-site denitrification reduced agriculturally derived NO3 -concentrations by at least half and, in some wells, completely. These results indicate that infiltration to groundwater systems in glacial sediments where NO3 -can be naturally attenuated is likely preferable to off-farm export via runoff or drainage networks. The application of isotopes of nitrate to constrain a mixing model based on concentrations of Cl -and NO3 -, which can be routinely monitored in 25 groundwater, provides a relatively simple method to assess the sources and fate of agriculturally derived NO3 -in these settings.

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Section: Discussionsupporting

confidence: 87%

Section: Identification Of the Sources And Fate Of No3mentioning

confidence: 99%

Sources and fate of nitrate in groundwater at agricultural operations overlying glacial sediments

Bourke¹,

Iwanyshyn²,

Köhn³

et al. 2018

Preprint

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“…The site was located in a region with extensive irrigation and a high density of confined feeding operations, particularly beef feedlots, where a regional groundwater monitoring transect of 115 wells was installed in 1993 and 1994 and sampled from 1994 to 2001 by Rodvang et al (1998Rodvang et al ( , 2002, and partially reactivated from 2009 to 2015 (Kohn et al 2016;Lorentz et al 2014).…”

Section: Site Descriptionmentioning

confidence: 99%

Shallow groundwater quality at a beef feedlot in southern Alberta.

Köhn¹,

Iwanyshyn²,

Miedema³

et al. 2016

Can. Biosyst. Eng.

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Kohn, J., M. Iwanyshyn, L. Miedema, B. Olson and A. Kalischuk. 2016. Shallow groundwater quality at a beef feedlot in southern Alberta. A 6-yr study (2010)(2011)(2012)(2013)(2014)(2015) was carried out in southern Alberta to investigate the effects of a beef feedlot (5000 head) on groundwater quality. Evaluation methods included measuring groundwater levels, groundwater sampling and chemical analysis, modelling of groundwater flow, and nitrate-nitrogen (NO 3 -N) and chloride (Cl) trend analysis. Groundwater samples were collected from 12 monitoring wells, which were distributed outside the feedlot pens but within or adjacent to the feedlot area and ranged in depth from 4.1 to 20 m. Median concentrations of NO 3 -N among the wells ranged from the detection limit (0.05 mg L -1 ) to 115 mg L -1 , with an overall average concentration of 41 mg L -1 . Median concentrations of Cl among the wells ranged from the detection limit (5 mg L -1 ) to 461 mg L -1 , with an overall average concentration of 156 mg L -1 . The deepest piezometer (20 m) showed no evidence of manure contamination, with NO 3 -N less than 3 mg L -1 and Cl less than 20 mg L -1 ; however, high NO 3 -N and Cl concentrations in the shallow water-table wells suggested likely contamination mainly from the feedlot and stockpiled manure. Our results also showed that manure stockpiles might have had a greater effect on groundwater quality than the feedlot itself. Temporal analysis of changes in concentrations showed no significant trends for NO 3 -N and Cl in the majority of the wells (75%), suggesting that concentrations are not expected to change with time under current management practices at this site. Keywords: groundwater quality, feedlot, cattle, manure, nitrate-nitrogen, chloride.Une étude de 6 ans (2010-2015) a été effectuée dans le sud de l'Alberta pour examiner les effets d'un parc d'engraissement des bovins (5000 têtes) sur la qualité des eaux souterraines. Les méthodes d'évaluation utilisées comprenaient la mesure de niveau et l'échantillonnage des eaux souterraines, l'analyse chimique, la modélisation de l'écoulement des eaux souterraines, et l'analyse de tendance des concentrations de nitrate (NO 3 -N) et chlorure (Cl). Des échantillons d'eaux souterraines ont été prélevés dans 12 puits de surveillance, qui ont été distribués en dehors des enclos d'engraissement, mais à l'intérieur ou à côté de la zone de parc d'engraissement et leurs profondeurs étaient comprises de 4,1 à 20 m. Les concentrations médianes de NO 3 -N dans tous les 12 puits variaient du seuil de détection (0.05 mg L -1 ) à 115 mg L -1 , avec une concentration moyenne globale de 41 mg L -1 . Les concentrations médianes de Cl dans tous les puits variaient du seuil de détection (5 mg L -1 ) à 461 mg L -1 , avec une concentration moyenne globale de 156 mg L -1 . Le piézomètre le plus profond (20 mbgs) n'a montré aucun signe de contamination du fumier étant NO 3 -N et Cl inférieur à 3 mg L -1 et 20 mg L -1 respectivement. Les concentrations élevées de NO 3 -N et Cl dans les puits de l...

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“…Identification of the sources and fate of NO − 3 at agricultural operations can be challenging because of spatial and temporal variations in sources (e.g. earthen manure storage, temporary manure piles, or fertiliser) and heterogeneity in hydrogeologic systems (Spalding and Exner, 1993;Rodvang et al, 2004;Showers et al, 2008;Kohn et al, 2016). These spatial and temporal variations can result in complex subsurface solute distributions that are difficult to interpret using classical transect studies or numerical groundwater models (Green et al, 2010;Baily et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…The stable isotopes of NO − 3 (δ 15 N NO 3 and δ 18 O NO 3 ) provide an alternative approach to characterising the source and fate of NO − 3 in groundwater systems. In agricultural areas, multiple sources of NO − 3 are common and could include precipitation, soil NO − 3 , inorganic fertiliser, manure, and septic waste (Komor and Anderson, 1993;Liu et al, 2006;Pastén-Zapata et al, 2014;Clague et al, 2015;Xu et al, 2015). While source identification is theoretically possible using δ 15 N NO 3 and δ 18 O NO 3 (particularly with a dual-isotope approach), in practice this can be difficult due to geologic heterogeneity, overlapping source values, and the complexity of biologically mediated reactions (Aravena et al, 1993;Wassenaar, 1995;Mengis et al, 2001;Choi et al, 2003;Granger et al, 2008;Vavilin and Rytov, 2015;Xu et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Sources and fate of nitrate in groundwater at agricultural operations overlying glacial sediments

Bourke

Iwanyshyn²,

Köhn³

et al. 2019

Hydrol. Earth Syst. Sci.

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Leaching of nitrate (NO − 3 ) from animal waste or fertilisers at agricultural operations can result in NO − 3 contamination of groundwater, lakes, and streams. Understanding the sources and fate of nitrate in groundwater systems in glacial sediments, which underlie many agricultural operations, is critical for managing impacts of human food production on the environment. Elevated NO − 3 concentrations in groundwater can be naturally attenuated through mixing or denitrification. Here we use isotopic enrichment of the stable isotope values of NO − 3 to quantify the amount of denitrification in groundwater at two confined feeding operations overlying glacial sediments in Alberta, Canada. Uncertainty in δ 15 N NO 3 and δ 18 O NO 3 values of the NO − 3 source and denitrification enrichment factors are accounted for using a Monte Carlo approach. When denitrification could be quantified, we used these values to constrain a mixing model based on NO − 3 and Cl − concentrations. Using this novel approach we were able to reconstruct the initial NO 3 −N concentration and NO 3 −N/Cl − ratio at the point of entry to the groundwater system. Manure filtrate had total nitrogen (TN) of up to 1820 mg L −1 , which was predominantly organic N and NH 3 . Groundwater had up to 85 mg L −1 TN, which was predominantly NO − 3 . The addition of NO − 3 to the local groundwater system from temporary manure piles and pens equalled or exceeded NO − 3 additions from earthen manure storages at these sites. On-farm management of manure waste should therefore increasingly focus on limiting manure piles in direct contact with the soil and encourage storage in lined lagoons. Nitrate attenuation at both sites is attributed to a spatially variable combination of mixing and denitrification, but is dominated by denitrification. Where identified, denitrification reduced agriculturally derived NO − 3 concentrations by at least half and, in some wells, completely. Infiltration to groundwater systems in glacial sediments where NO − 3 can be naturally attenuated is likely preferable to off-farm export via runoff or drainage networks, especially if local groundwater is not used for potable water supply.

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Groundwater nitrate and chloride trends in an agriculture-intensive area in southern Alberta, Canada

Cited by 34 publications

References 13 publications

Sources and fate of nitrate in groundwater at agricultural operations overlying glacial sediments

Sources and fate of nitrate in groundwater at agricultural operations overlying glacial sediments

Shallow groundwater quality at a beef feedlot in southern Alberta.

Sources and fate of nitrate in groundwater at agricultural operations overlying glacial sediments

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