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

Jensen, Jannick Kolbjørn; Engesgaard, Peter; Johnsen, Anders R.; Martí, Vicenç; Nilsson, Bertel

doi:10.1002/2016wr019581

Cited by 26 publications

(38 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Stable oxygen and hydrogen isotope composition of precipitation for a 2-year period from a nearby station (Voulund, UTM-E: 510000, UTM-N: 6210000) has previously been reported [28]. The δ 18 O values of rainfall at Voulund had a weighted average of −7.69‰ and ranged from −5.5 to −10.0‰. δ 2 H values had a weighted average of −51.5‰ and ranged from −38 to −73‰.…”

Section: Water-stable Isotopesmentioning

confidence: 93%

“…δ 2 H values had a weighted average of −51.5‰ and ranged from −38 to −73‰. Stable isotope concentrations, from all piezometers and for all samples collected in the monitoring period, yielded an average δ 18 O value of −7.79‰, ranging from −8.27‰ to −7.20‰. δ 2 H had an average of −51.5‰ ranging from −47.3‰ to −54.0‰.…”

Section: Water-stable Isotopesmentioning

confidence: 99%

“…Electrical Resistivity Tomography (ERT) surveys were done on both sides of the stream similar to surveys carried out in comparable settings [17,18]. A SYSCAL PRO resistivity meter with a Wenner configuration was used.…”

Section: Hydrogeological Characterizationmentioning

confidence: 99%

“…δ 2 H had an average of −51.5‰ ranging from −47.3‰ to −54.0‰. Figure 8 shows the δ 18 O value of springs, the stream and the drain (DR) on the crop side of the stream as a function of time. About 15% of the samples had δ 18 O concentrations outside the δ 18 O mean groundwater signal ± 1 standard deviation, indicated in Figure 8 by grey shading.…”

Section: Water-stable Isotopesmentioning

confidence: 99%

See 3 more Smart Citations

The Role of Management of Stream–Riparian Zones on Subsurface–Surface Flow Components

Steiness

Jessen

Spitilli

et al. 2019

Water

View full text Add to dashboard Cite

A managed riparian lowland in a glacial landscape (Holtum catchment, Denmark) was studied to quantify the relative importance of subsurface and surface flow to the recipient stream. The hydrogeological characterization combined geoelectrical methods, lithological logs, and piezometric heads with monthly flow measurements of springs, a ditch, and a drain, to determine seasonality and thereby infer flow paths. In addition, groundwater discharge through the streambed was estimated using temperature and water-stable isotopes as tracers. The lowland received large groundwater inputs with minimal seasonal variations from adjacent upland aquifers. This resulted in significant amounts of groundwater-fed surface flow to the stream, via man-made preferential flow paths comprising ditches, drainage systems, and a pond, and via two natural springs. Roughly, two thirds of the stream gain was due to surface flow to the stream, mainly via anthropogenic alterations. In contrast, direct groundwater discharge through the streambed accounted for only 4% of the stream flow gain, although bank seepage (not measured) to the straightened and deepened stream potentially accounted for an additional 17%. Comparison to analogous natural flow systems in the catchment substantiate the impact of anthropogenic alterations of riparian lowlands for the subsurface and surface flow components to their streams. through drains to the stream, or from groundwater-fed seeps (focused and/or diffusive) leading to overland flow, which is then routed to the stream.Hill [6] proposed different conceptual flow distribution models, where the hydrological controls were mainly determined by the size of the connected regional aquifer system and the thickness of the riparian aquifer. Several studies have since then, qualitatively confirmed these models. For example, studies [7,8] have demonstrated that flow across the lowland occurred as subsurface flow and groundwater-fed surface flow. Furthermore, Shabaga and Hill [8] demonstrated by dye tracer studies that surface flow took place as a combination of water discharging through macro-pores (soil pipes) and diffusively. Preferential flow through soil pipes in peat deposits has been shown to transmit large fluxes of water and with the possibility of causing springs resulting in overland flow [9].Measuring the individual flow paths is not a trivial task and thus not often done. Brüsch and Nilsson [10] attempted to measure total surface runoff (i.e., the sum of all overland flow) from a riparian zone and found an average surface runoff of 0.3 L s −1 , compared with stream flow of 24-38 L s −1 . Furthermore, diffuse discharge to the surface only accounted for 3% of the runoff, so most of this occurred through focused seeps. Shabaga and Hill [8] measured surface flow directly to a river at one site. Johansen et al. [11] measured flow in three springs and a network of ditches. In none of these studies, the direct seepage through the streambed was measured. It was therefore not possible to quantify the relative role of su...

show abstract

Section: Water-stable Isotopesmentioning

confidence: 93%

Section: Water-stable Isotopesmentioning

confidence: 99%

Section: Hydrogeological Characterizationmentioning

confidence: 99%

Section: Water-stable Isotopesmentioning

confidence: 99%

See 2 more Smart Citations

The Role of Management of Stream–Riparian Zones on Subsurface–Surface Flow Components

Steiness

Jessen

Spitilli

et al. 2019

Water

View full text Add to dashboard Cite

show abstract

“…Aerobic respiration, nitrification, denitrification, and ammonium uptake follow Monod kinetics (Tables and ). DOC is supplied from OM in sediments according to fast equilibrium sorption kinetics (e.g., Gu et al, ; Jardine et al, ) given the multiple lines of evidence illustrating sediment sources of DOC within riparian aquifers (Hill et al, ; Kolbjørn Jensen et al, ; Robertson & Cherry, ).…”

Section: Methodsmentioning

confidence: 99%

Hydrogeologic Controls of Surface Water‐Groundwater Nitrogen Dynamics Within a Tidal Freshwater Zone

et al. 2019

View full text Add to dashboard Cite

Microbial processing of reactive nitrogen in stream sediments and connected aquifers can remove and transform nitrogen prior to its discharge into coastal waters, decreasing the likelihood of harmful algal blooms and low oxygen levels in estuaries. Canonical wisdom points to the decreased capacity of rivers to retain nitrogen as they flow toward the coast. However, how tidal freshwater zones, which often extend hundreds of kilometers inland, process and remove nitrogen remains unknown. Using geochemical measurements and numerical models, we show that tidal pumping results in the rapid cycling of nitrogen within distinct zones throughout the riparian aquifer. Near the fluctuating water table nitrification dominates, with high nitrate concentrations (>10 mg N/L) and consistent isotopic composition. Beneath this zone, isotopes reveal that nitrate is both denitrified and added over the tidal cycle, maintaining nitrate concentrations >3-4 mg N/L. In most of the riparian aquifer and streambed, nitrate concentrations are <0.5 mg N/L, suggesting denitrification dominates. Model results reveal that oxygen delivery to groundwater from the overlying unsaturated soil fuels mineralization and nitrification, with subsequent denitrification in low-oxygen, high organic matter regions. Depending on flow paths, tidal freshwater zones could be sources of nitrate in regions with permeable sediment and low organic matter content.Plain Language Summary Human activities related to energy and food production add large amounts of reactive nitrogen to the landscape. Rain and snow wash some of that nitrogen into rivers and eventually to the coast. The addition of excess nitrogen to coastal ecosystems can cause excessive algal growth and low-oxygen conditions, which can lead to fish kills. As nitrogen travels to the coast, microbes in the sediment beneath and near the river process and remove large portions of this nitrogen. It is unclear how daily tidal fluctuations within the freshwater tidal zone alter these processes. Geochemical measurements of pore water beneath the stream and within the stream bank reveal that there are different zones of nitrogen processing, where differences in sediment type and water exchange control the supply of reactants. Zones of nitrate production exist within the stream bank aquifer, but conditions favoring nitrate removal dominate the aquifer. Therefore, depending on how water moves through the subsurface, it is possible that tidal fresh water zones could act as a source of nitrate to the stream channel, exacerbating coastal management challenges.

show abstract

Influence of Hydrological Perturbations and Riverbed Sediment Characteristics on Hyporheic Zone Respiration of CO₂ and N₂

et al. 2018

View full text Add to dashboard Cite

Rivers in climatic zones characterized by dry and wet seasons often experience periodic transitions between losing and gaining conditions across the river‐aquifer continuum. Infiltration shifts can stimulate hyporheic microbial biomass growth and cycling of riverine carbon and nitrogen leading to major exports of biogenic CO2 and N2 to rivers. In this study, we develop and test a numerical model that simulates biological‐physical feedback in the hyporheic zone. We used the model to explore different initial conditions in terms of dissolved organic carbon availability, sediment characteristics, and stochastic variability in aerobic and anaerobic conditions from water table fluctuations. Our results show that while highly losing rivers have greater hyporheic CO2 and N2 production, gaining rivers allowed the greatest fraction of CO2 and N2 production to return to the river. Hyporheic aerobic respiration and denitrification contributed 0.1–2 g/m2/d of CO2 and 0.01–0.2 g/m2/d of N2; however, the suite of potential microbial behaviors varied greatly among sediment characteristics. We found that losing rivers that consistently lacked an exit pathway can store up to 100% of the entering C/N as subsurface biomass and dissolved gas. Our results demonstrate the importance of subsurface feedbacks whereby microbes and hydrology jointly control fate of C and N and are strongly linked to wet‐season control of initial sediment conditions and hydrologic control of seepage direction. These results provide a new understanding of hydrobiological and sediment‐based controls on hyporheic zone respiration, including a new explanation for the occurrence of anoxic microzones and large denitrification rates in gravelly riverbeds.

show abstract

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

Cited by 26 publications

References 70 publications

The Role of Management of Stream–Riparian Zones on Subsurface–Surface Flow Components

The Role of Management of Stream–Riparian Zones on Subsurface–Surface Flow Components

Hydrogeologic Controls of Surface Water‐Groundwater Nitrogen Dynamics Within a Tidal Freshwater Zone

Influence of Hydrological Perturbations and Riverbed Sediment Characteristics on Hyporheic Zone Respiration of CO₂ and N₂

Contact Info

Product

Resources

About

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

Cited by 26 publications

References 70 publications

The Role of Management of Stream–Riparian Zones on Subsurface–Surface Flow Components

The Role of Management of Stream–Riparian Zones on Subsurface–Surface Flow Components

Hydrogeologic Controls of Surface Water‐Groundwater Nitrogen Dynamics Within a Tidal Freshwater Zone

Influence of Hydrological Perturbations and Riverbed Sediment Characteristics on Hyporheic Zone Respiration of CO2 and N2

Contact Info

Product

Resources

About

Influence of Hydrological Perturbations and Riverbed Sediment Characteristics on Hyporheic Zone Respiration of CO₂ and N₂