Denitrification in a Grassed and a Wooded, Valley and Ridge, Riparian Ecotone

Schnabel, R. R.; Cornish, L. F.; Stout, W. L.; Shaffer, J. A.

doi:10.2134/jeq1996.00472425002500060009x

Cited by 58 publications

(37 citation statements)

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“…This corresponds with studies concerning N and P output to groundwater under agricultural fields (e.g. Jemison and Fox 1994;Schnabel et al 1996). In addition, we also found high K concentrations (between 50 and 74 mg l À1 ) in groundwater below the cornfields.…”

supporting

confidence: 90%

Is Nutrient Contamination of Groundwater Causing Eutrophication of Groundwater-Fed Meadows?

et al. 2005

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There is an ongoing debate as to whether nutrient contamination of groundwater under agricultural fields may cause nutrient-enrichment and subsequent eutrophication in discharge areas. Often, there is only circumstantial evidence to support this supposition (proximity of agricultural fields, direction of water flow, highly productive vegetation). Research on solute transport along a flow path is necessary to evaluate the risk for eutrophication. In this paper we present results of such a study. Two transects were established in a discharge meadow, a few meters downstream from fertilized cornfields. Highly productive vegetation in parts of the meadow suggested nutrient-enrichment caused by inflow of contaminated groundwater. This supposition was supported by an analysis of groundwater flow paths, residence times and chloride as tracer for pollution. However, the fate of nutrients along the flow path indicated otherwise. While we found high concentrations of DIN (dissolved inorganic nitrogen), P and K under the cornfields, DIN and P concentrations drop below detection limit when groundwater enters the meadow. Only K progressed into the meadow but did not enter the root zone. We conclude that (1) polluted groundwater from the cornfields did not cause the nutrientenrichment, as indicated by the highly productive vegetation. Restoration projects in discharge areas should not focus upon measures in upstream areas if only circumstantial evidence is available. Solute transport should be considered as well. (2) Because K clearly showed to be the most mobile nutrient, its importance for nutrientenrichment in discharge wetlands merits more attention in future research.

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supporting

confidence: 90%

Is Nutrient Contamination of Groundwater Causing Eutrophication of Groundwater-Fed Meadows?

et al. 2005

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“…In this class, nitrate availability limits denitrification activity. The role of organic carbon availability on denitrification was similarly demonstrated either by emphasising a correlation between total organic carbon (Beauchamp et al, 1980;Burford and Bremner, 1975) or by showing the influence of adding carbon on denitrification activity (Ashby et al, 1998;Schnabel et al, 1996). Secondly, on the one hand, a high denitrifying capacity is related to finely textured samples, while, on the other hand, denitrification rates were significantly improved by the creation of an anaerobic atmosphere in all classes.…”

Section: Definition Of Functional Horizonsmentioning

confidence: 92%

The modelling of soil-process functional units based on three-dimensional soil horizon cartography, with an example of denitrification in a riparian zone

et al. 2003

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This article aims to propose an approach for estimating the three-dimensional (3D) variability of denitrification. The concept of functional horizons is applied to the process of biological denitrification and 3D soil horizon cartography is used to estimate its spatial variation. On one hand, detailed fieldwork (186 pedological auger holes) was undertaken to map 3D horizon distribution within a 3-ha riparian area using Geographical Information Systems (GIS). On the other hand, three classes of denitrifying capacities were defined according to the distribution of the denitrifying enzyme activity of 51 samples. The relationship between the process of denitrification and the cartography is assessed through soil characteristics, which both differentiate soil horizons and control the process of denitrification: organic carbon and textural fractions. This allows a class of denitrifying capacity to be attributed to each soil horizon. This information was inserted into the 3D soil horizon cartography and the denitrifying functional horizons could be delimited. With this approach, field criteria are used and variations of the 3D distribution of

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“…Nitrate removal was then estimated from the changes in NO 3 À : Br À ratios and NO 3 À and Br À mass with time, assuming that Br À is not taken up by plants or processed by soil microorganisms (Schnabel et al 1996;Whitmer et al 2000). Addy et al (2002) successfully demonstrated the use of the push-pull method to determine in-situ subsurface water denitrification and NO 3 À removal rates in riparian zones.…”

Section: Introductionmentioning

confidence: 99%

Nitrous oxide generation, denitrification, and nitrate removal in a seepage wetland intercepting surface and subsurface flows from a grazed dairy catchment

Zaman¹,

Nguyen

Gold

et al. 2008

Soil Res.

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Abstract.Little is known about seepage wetlands, located within agricultural landscapes, with respect to removing nitrate (NO 3 À ) from agricultural catchments, mainly through gaseous emissions of nitrous oxide (N 2 O) and dinitrogen (N 2 ) via denitrification. These variables were quantified using a push-pull technique where we introduced a subsurface water plume spiked with 15 N-enriched NO 3 À and 2 conservative tracers [bromide (Br À ) and sulfur hexafluoride (SF 6 )] into each of 4 piezometers and extracted the plume from the same piezometers throughout a 48-h period. To minimise advective and dispersive flux, we placed each of these push-pull piezometers within a confined lysimeter (0.5 m diameter) installed around undisturbed wetland soil and vegetation. Although minimal dilution of the subsurface water plumes occurred, NO 3 À -N concentration dropped sharply in the first 4 h following dosing, such that NO 3 À -limiting conditions (<2 mg/L of NO 3 -N) for denitrification prevailed over the final 44 h of the experiment. Mean subsurface water NO 3 À removal rates during non-limiting conditions were 15.7 mg/L.day. Denitrification (based on the generation of isotopically enriched N 2 O plus N 2 ) accounted for only 7% (1.1 mg/L.day) of the observed groundwater NO 3 À removal, suggesting that other transformation processes, such as plant uptake, were responsible for most of the NO 3 À removal. Although considerable increases in 15 N-enriched N 2 O levels were initially observed following NO 3 À dosing, no net emissions were generated over the 48-h study. Our results suggest that this wetland may be a source of N 2 O emissions when NO 3 À concentrations are elevated (non-limited), but can readily remove N 2 O (function as a N 2 O sink) when NO 3 À levels are low. These results argue for the use of engineered bypass flow designs to regulate NO 3 À loading to wetland denitrification buffers during high flow events and thus enhance retention time and the potential for NO 3 À -limiting conditions and N 2 O removal. Although this type of management may reduce the full potential for wetland NO 3 À removal, it provides a balance between water quality goals and greenhouse gas emissions.

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Denitrification in a Grassed and a Wooded, Valley and Ridge, Riparian Ecotone

Cited by 58 publications

References 0 publications

Is Nutrient Contamination of Groundwater Causing Eutrophication of Groundwater-Fed Meadows?

Is Nutrient Contamination of Groundwater Causing Eutrophication of Groundwater-Fed Meadows?

The modelling of soil-process functional units based on three-dimensional soil horizon cartography, with an example of denitrification in a riparian zone

Nitrous oxide generation, denitrification, and nitrate removal in a seepage wetland intercepting surface and subsurface flows from a grazed dairy catchment

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