Subsurface nitrate reduction under wetlands takes place in narrow superficial zones

Ribas, David López; Calderer, Montse; Martí, Vicenç; Johnsen, Anders R.; Aamand, Jens; Nilsson, Bertel; Jensen, Jannick Kolbjørn; Engesgaard, Peter; Morici, Claudia

doi:10.1080/09593330.2016.1276220

Cited by 4 publications

(6 citation statements)

References 36 publications

(32 reference statements)

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“…We have no information of local denitrification rates with organic matter. Observations from a similar site just downstream, gave a maximum rate just below the peat layer of 0.25 day –1 (Ribas et al., 2017), that is, very similar to the rate with pyrite denitrification. This rate also compare well with literature‐based estimates (Table 3).…”

Section: Discussionmentioning

confidence: 66%

Nitrogen‐Loads to Streams: Importance of Bypass Flow and Nitrate Removal Processes

et al. 2021

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Section: Discussionmentioning

confidence: 66%

Nitrogen‐Loads to Streams: Importance of Bypass Flow and Nitrate Removal Processes

et al. 2021

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“…High levels of DOC were found only in water sampled close to C2, which contained a thin secondary peat layer at this depth [ Ribas et al . ]. Nitrate, on the other hand, was found up‐stream and below the peat.…”

Section: Field and Laboratory Resultsmentioning

confidence: 99%

“…The constraint within this study, and many others, is the lack of data on nitrate reduction rates in space. The derived nitrate reduction rates used in this study are from single soil cores with a depth of ∼3 m, where nitrate reduction was very low or not detectable for most samples below 2 m [ Ribas et al ., ]. Burt et al .…”

Section: Discussionmentioning

confidence: 99%

“…Determination of nitrate reduction rates . The study is part of a larger investigation of the denitrification capacity of riparian zones and wetlands and the details of the nitrate reduction experiments are reported elsewhere [ Ribas et al ., ]. Here only a brief summary; two intact soil cores (upper 0‐3 m, C1 and C2, Figure ) were collected to determine nitrate reduction potentials and first‐order nitrate reduction rate constants in laboratory experiments.…”

Section: Methodsmentioning

confidence: 99%

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Hydrological mediated denitrification in groundwater below a seasonal flooded restored riparian zone

Jensen

Engesgaard

Johnsen

et al. 2017

Water Resources Research

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A restored riparian zone was characterized to understand the effects of flooding on subsurface hydrological flow paths and nitrate removal in groundwater. Field and laboratory investigations were combined with numerical modeling of dynamic flow and reactive nitrate transport. Flooding enhances nitrate removal in groundwater primarily by two mechanisms. First, by creating a stagnant flow zone beneath the flooded area thereby increasing the residence time and leaving more time for nitrate removal. Secondly, nitrate removal is increased by enhancing upward flow into the highly reactive organic‐rich top layers. Flooding therefore contributes to nitrate removal in “hot spots”, where nitrate is transported to the peat and during “hot moments”, when flow is stagnant. The permeability of the capping peat layer relative to the aquifer is important as it controls both mechanisms. The model shows that the deep‐seated nitrate removal is greater than projected from the laboratory nitrate reduction experiments.

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“…However, this would mean that nitrate removal would be even less. The denitrification rate in the peat layer was assumed high, 0.14 d −1 (half-life of ∼5 days), inspired by the experimental results for Danish riparian zones (Ribas et al 2017). The rate was constant in all scenarios.…”

Section: Research Methods Conceptual Model Of Riparian Zonementioning

confidence: 99%

Numerical Modeling of Nitrate Removal in Anoxic Groundwater during River Flooding of Riparian Zones

Jensen

Nilsson

Engesgaard³

2021

Groundwater

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A numerical study demonstrates the effects of flooding on subsurface hydrological flowpaths and nitrate removal in anoxic groundwater in riparian zones with a top peat layer. A series of two-dimensional numerical simulations with changing conditions for flow (steady state or transient with flooding), hydrogeology, denitrification, and duration of flooding demonstrate how flowpaths, residence times, and nitrate removal are affected. In periods with no flooding groundwater flows horizontally and discharges to the river through the riverbed. During periods with flooding, shallow groundwater is forced upwards as discharge through peat layers that often have more optimal conditions for denitrification caused by the presence of highly reactive organic matter. The contrast in hydraulic conductivity between the sand aquifer and the overlying peat layer, as well as the flooding duration, have a significant role in determining the degree of nitrate removal.

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Subsurface nitrate reduction under wetlands takes place in narrow superficial zones

Abstract: The aim of the present study is to investigate the vertical distribution of the Nitrate Reduction Potential (NRP) at different depths on a natural (Evi

Cited by 4 publications

References 36 publications

Nitrogen‐Loads to Streams: Importance of Bypass Flow and Nitrate Removal Processes

Nitrogen‐Loads to Streams: Importance of Bypass Flow and Nitrate Removal Processes

Hydrological mediated denitrification in groundwater below a seasonal flooded restored riparian zone

Numerical Modeling of Nitrate Removal in Anoxic Groundwater during River Flooding of Riparian Zones

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