Transport and potential attenuation of nitrogen in shallow groundwaters in the lower Rangitikei catchment, New Zealand

Collins, Sarah; Singh, Ranvir; Rivas, Aldrin; Palmer, Alan; Horne, D. J.; Manderson, Andrew; Roygard, J.; Matthews, A. M.

doi:10.1016/j.jconhyd.2017.10.002

Cited by 21 publications

(4 citation statements)

References 33 publications

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“…The use of fertilizers has significantly increased in the United States since the 1940s, particularly in the Midwest U.S. (Cao et al, 2018). Fertilizers, especially nitrogen, have been shown to increase baseflow stream nutrient concentrations, because they are prone to leaching from agricultural soils, into groundwater, and subsequently into streams (e.g., Chand et al, 2011; Collins et al, 2017; Stets et al, 2015). Surprisingly, the percentage of agricultural land cover in a watershed was not significantly related to baseflow TSS concentrations.…”

Section: Discussionmentioning

confidence: 99%

Land cover, stream discharge, and wastewater effluent impacts on baseflow sediment and nutrient concentrations in SW Ohio streams

Spahr,

Lazar,

Grudzinski

et al. 2024

River Research & Apps

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Elevated nutrient and suspended sediment concentrations often result in negative environmental impacts within freshwater environments. Studies that directly compare suspended sediment and bioavailable nutrients between predominantly agricultural and predominantly urban watersheds during baseflow conditions are largely lacking. The purpose of this study was to determine the impacts of land cover, stream discharge, and wastewater treatment plant (WWTP) discharge on nutrient and sediment concentrations, across a large land cover gradient in Southwest Ohio streams. Weekly baseflow samples were collected from eight streams over 1 year from November, 2016 through November, 2017. Total suspended sediment, nitrate, and phosphate concentrations were measured. Results indicate that agricultural land cover and WWTPs increase nitrate and phosphate concentrations in the study area. Total suspended sediment and nitrate concentrations increased with discharge, and discharge was a relatively weak predictor of phosphate concentrations. Seasonal water quality trends varied by parameter and land use also had unique impacts on seasonal water quality trends. Results suggest that to improve water quality in the study area, efforts should focus on improving WWTP effluent treatment and agricultural land management.

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Section: Discussionmentioning

confidence: 99%

Land cover, stream discharge, and wastewater effluent impacts on baseflow sediment and nutrient concentrations in SW Ohio streams

Spahr,

Lazar,

Grudzinski

et al. 2024

River Research & Apps

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“…After equilibration for 16 h, a 30‐ml treatment solution was injected into four cups per depth followed by 5 ml of DI water to flush the tubes. This treatment solution contained 10 mg NO 3 –N L −1 as KNO 3 , 10 mg Br L −1 as KBr, 300 mg glucose C L −1 for an electron acceptor source, a tracer, and an electron donor source for reduction (Collins et al., 2017). Another four cups per depth were injected with 30 ml of DI water to act as a control.…”

Section: Methodsmentioning

confidence: 99%

Reductive dissolution of phosphorus associated with iron‐oxides during saturation in agricultural soil profiles

et al. 2021

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In soils with a fragipan or poor permeability, water may remain in a soil profile long enough to make it anoxic and reductive. The reductive dissolution of iron (Fe)‐ and manganese (Mn)‐oxides can release associated phosphorus (P). Therefore, the dissolved P would be vulnerable to subsurface flow and could contaminate nearby streams. It was hypothesized that single rainfall events could cause subsurface P concentrations to increase via reductive dissolution in wet winter‐spring conditions. Also, dissolution—being microbially mediated—would be buffered by the presence of nitrate (NO3–), which is preferred as an electron acceptor over Fe and Mn in microbial reactions. Unsaturated zone monitoring occurred from May to September in 2017 and 2019, using Teflon suction cups below the surface of a grassland soil in New Zealand. Events in July and August in 2017 and 2019 resulted in reducing conditions [Fe(III)/sulfate‐reducing] and up to 77 and 96% greater P and Fe release, respectively. In an additional experiment in 2019, 100 mm of flood irrigation was applied, and 10 mg NO3––N + carbon was injected into half the cups at the site. The other cups received no N. Cups treated with N yielded up to 45% total dissolved P and 21% less Fe than the no‐N cups. A laboratory incubation of soils from the site confirmed that NO3– inhibited P release. This effect may act to decrease the amount of P lost in subsurface flow in systems regularly fertilized with N but should not be relied on as a method to mitigate P losses.

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“…Leaching and subsurface flow are the major pathways for N losses from agricultural lands to receiving waters. However, a range of landscape features and biogeochemical processes influence N fluxes and its potential attenuation in critical flow pathways (Collins et al, 2017; Elwan et al, 2018; Rivas et al, 2020). Subsurface denitrification (denitrification below the root zone) has been identified as an important nitrate attenuation process that limits N losses in subsurface flow pathways (Rivett et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

The effects of pastoral hill country natural landscape features and land management practices on nitrate losses and its potential attenuation for improved water quality

Chibuike,

Singh,

Burkitt

2024

J of Sust Agri & Env

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Pastoral farming on hill country landscapes influences nitrogen (N) dynamics and its losses to freshwater. This study reviewed the current literature identifying key effects of pastoral hill country landscape features and land management practices on nitrate losses to receiving waters. The review also highlighted the potential effects of inherent landscape features on nitrate attenuation pathways for better water quality outcomes. Intensive land use activities involving high rates of fertiliser application, higher stocking rates and cattle grazing, relative to sheep grazing, are more likely to increase nitrate loss, especially on lower slopes. However, soils with a high carbon (C) storage capacity such as allophanic soils potentially limit nitrate loss via denitrification in subsoil layers. Hill country seepage wetlands also offer an opportunity to attenuate nitrate loss, though their efficacy is largely impacted by hydrological variations in their inflows and outflows. By enhancing the natural nitrate attenuation capacity of seepage wetlands, mapping and strategic use of high subsoil denitrification potential, effective riparian management, efficient fertiliser and grazing practices and the incorporation of these farm management strategies into Freshwater Farm Plans (FWFPs), wider environmental and farm productivity/profitability goals, including improved water quality, would be achieved on pastoral hill country landscapes.

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Transport and potential attenuation of nitrogen in shallow groundwaters in the lower Rangitikei catchment, New Zealand

Cited by 21 publications

References 33 publications

Land cover, stream discharge, and wastewater effluent impacts on baseflow sediment and nutrient concentrations in SW Ohio streams

Land cover, stream discharge, and wastewater effluent impacts on baseflow sediment and nutrient concentrations in SW Ohio streams

Reductive dissolution of phosphorus associated with iron‐oxides during saturation in agricultural soil profiles

The effects of pastoral hill country natural landscape features and land management practices on nitrate losses and its potential attenuation for improved water quality

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