In situ denitrification and DNRA rates in groundwater beneath an integrated constructed wetland

Jahangir, M. M. R.; Fenton, Owen; Müller, Christoph; Harrington, Rory; Johnston, Paul; Richards, Karl G.

doi:10.1016/j.watres.2017.01.015

Cited by 79 publications

(36 citation statements)

References 62 publications

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“…Nonetheless, our results underline substantial differences in the extent of denitrification between near and intermediate groundwater, and suggest that additional processes other than denitrification govern NO 3 − removal at our field site. This is in line with previous studies such as McPhillips et al (), who calculated a contribution of 29%–69% to overall NO 3 − removal by plant uptake, abiotic immobilization, and microbial assimilation, and Jahangir et al (), who assessed a relative contribution of 40%–63% by DNRA. Note that while R den in the near groundwater is generally larger than R den in the intermediate groundwater, this does not necessarily apply to absolute values of NO 3 − removal via denitrification, as these depend on the NO 3 − fluxes through the respective groundwater zones.…”

Section: Discussionsupporting

confidence: 92%

“…Water Resources Research denitrification when C:N ratios are large (Dhondt et al, 2003;Jahangir et al, 2017;Matheson et al, 2002). However, in our study, the mean C:N ratio using the molar concentrations of DOC and N-NO 3 − of the six wells with the largest R add (i.e., above the 75th percentile) was smaller than that of the six wells with the largest R den (i.e., 1.0 vs. 1.5 using the δ 15 N model).…”

Section: 1029/2019wr025528mentioning

confidence: 99%

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How Important is Denitrification in Riparian Zones? Combining End‐Member Mixing and Isotope Modeling to Quantify Nitrate Removal from Riparian Groundwater

Lutz

Trauth

Musolff

et al. 2020

Water Resources Research

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Riparian zones are important buffer zones for streams as they are hotspots of nitrate transformation and removal in agricultural catchments. However, mixing of water from different sources and various transformation processes can complicate the quantification of nitrate turnover in riparian zones. In this study, we analyzed nitrate concentration and isotope data in riparian groundwater along a 2-km stream section in central Germany. We developed a mathematical model combining end-member mixing and isotope modeling to account for mixing of river water and groundwater and quantify nitrate transformation in riparian groundwater. This enabled us to explicitly determine the extent of denitrification (as process leading to permanent nitrate removal from riparian groundwater) and transient nitrate removal by additional processes associated with negligible isotope fractionation (e.g., plant uptake and microbial assimilation) and to perform an extensive uncertainty analysis. Based on the nitrogen isotope data of nitrate, the simulations suggest a mean removal of up to 27% by additional processes and only about 12% by denitrification. Nitrate removal from riparian groundwater by additional processes exceeded denitrification particularly in winter and at larger distance from the river, underlining the role of the river as organic carbon source. This highlights that nitrate consumption by additional processes predominates at the field site, implying that a substantial fraction of agricultural nitrogen input is not permanently removed but rather retained in the riparian zone. Overall, our model represents a useful tool to better compare nitrogen retention to permanent nitrogen removal in riparian zones at various temporal and spatial scales. Plain Language SummaryNitrogen is an important nutrient for agricultural crops. However, excessive nitrogen input into surface water in the form of nitrate can lead to algae blooms and lack of oxygen. The riparian zones of rivers are important buffer zones where groundwater is connected to soils, which are rich in soil organisms and organic matter pools fueling reaction processes. Hence, plants and bacteria can remove nitrate from riparian groundwater before it reaches the river. Bacterial consumption of nitrate (denitrification) leads to complete removal of nitrogen via release of nitrogen gas into the atmosphere. In contrast, other biogeochemical processes such as nitrate uptake by plants merely result in nitrogen retention within riparian zones. To quantify the role of denitrification relative to other processes, we developed a novel model combining concentration and isotope data of nitrate and applied it to a groundwater study site in Central Germany. We found that nitrate removal from riparian groundwater by additional processes largely exceeded denitrification. Hence, a major fraction of nitrogen inputs was retained in the riparian zone and may eventually end up in the river. Such information is highly relevant for many river ecosystems at risk of eutrophication because of high nitr...

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Section: Discussionsupporting

confidence: 92%

Section: 1029/2019wr025528mentioning

confidence: 99%

How Important is Denitrification in Riparian Zones? Combining End‐Member Mixing and Isotope Modeling to Quantify Nitrate Removal from Riparian Groundwater

Lutz

Trauth

Musolff

et al. 2020

Water Resources Research

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“…Groundwater usually has a reduced environment, with low oxidation‐reduction potential ( E h ) and dissolved oxygen (DO), which is conducive for anaerobic reactions. Therefore, denitrification is recognized as one of the most important processes involved in groundwater N dynamics (Jahangir et al, ; Mander et al, ; Singleton et al, ). In recent years, the anammox process has also been identified in groundwater by many researchers, indicating that it may play an important role in groundwater N transformation (Clark et al, ; Moore et al, ).…”

Section: Introductionmentioning

confidence: 99%

Denitrification in Shallow Groundwater Below Different Arable Land Systems in a High Nitrogen‐Loading Region

Zhou

Well³

et al. 2018

JGR Biogeosciences

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To evaluate the risk of nitrate (NO3−‐N) in groundwater, it is necessary to know the denitrification capacity. In this study, observations were carried out for 2 years to investigate the groundwater denitrification capacity below three arable land systems in eastern China. Denitrification capacity was assessed by measuring the concentration and distribution patterns of nitrous oxide (N2O) and dinitrogen (N2) in groundwater. The results revealed that groundwater denitrification activity was high and consumed 76%, 83%, and 65% of the NO3−‐N in the vineyard (VY), vegetable field (VF), and paddy field (PF), respectively. The high denitrification activity might be attributed to the strong reducing conditions, with high dissolved carbon concentrations in groundwater, which promotes denitrification. During the sampling period, we observed high dinitrogen (excess N2) accumulation in groundwater, which exceeded the total reactive nitrogen (N) in the deep layer. The large amount of excess N2 observed in VY and VF indicated that considerable N was stored as gaseous N2 in groundwater and should not be ignored when balancing N budgets in aquifers where denitrification is high.

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“…As a result, an anoxic or anaerobic environment could be formed within the pores or biofilms of the filter material, and the process of dissimilatory nitrate reduction to ammonium (DNRA) could easily occur, that is, microorganisms used NO 2 --N or NO 3 --N as an electron acceptor to produce NH 4 + -N under the action of nitrite reductase (NiR) or nitrate reductase (NaR) [19]. It has been reported that the DNRA process widely existed in the paddy soil [19], intertidal sediments [20], wetland [21] and other habitats. Schmidt et al [22] found that filling sandy soil was beneficial to the occurrence of DNRA.…”

Section: The Concentration Of Nomentioning

confidence: 99%

Regulation of Partial Nitritation in Constructed Rapid Infiltration System and Analysis of Microbial Community Structure

Chen¹,

Lü²,

Ouyang³

et al. 2019

Pol. J. Environ. Stud.

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Partial nitritation (PN) and the anaerobic ammonium oxidation (ANAMMOX) process provides a novel method to solve the problem of low TN removal efficiency in a constructed rapid infiltration (CRI) system, and PN is the prerequisite to realize the process. In this study, the feasibility of achieving PN in a CRI system by synergistic regulation of free chlorine, filter height and influent pH was investigated. The characteristics of microbial community structure during the stable operation of the PN process were also discussed. The results showed that after adding 3 mg/L of free chlorine continuously for 23 days, adjusting the effluent filter height to 75 cm and the influent pH to 8.2~8.5, the PN process successfully started with the NO 2-N accumulation rate staying stable at about 90% and effluent NO 2-N/NH 4 +-N ratio between 1.23 and 1.35, thus providing suitable influent conditions for the subsequent ANAMMOX. Based on 16S rRNA high-throughput sequencing, a total of 41 phyla, 144 classes and 310 genera were detected from the stable running PN-CRI system. The detected ammonia-oxidizing microorganisms mainly included Nitrosomonas, Nitrosovibrio and Candidatus Nitrososphaera; while only Nitrospira was detected in nitrite-oxidizing bacteria genera with its relative abundance at only 6.7~10.0% of the total abundance of ammonia-oxidizing microorganisms. This indicated that the synergistic regulation strategy could selectively eliminate nitrite-oxidizing bacteria, thus creating favorable conditions for the occurrence of PN. These findings could provide a theoretical basis and scientific reference for efficient and economical nitrogen removal in a CRI system.

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In situ denitrification and DNRA rates in groundwater beneath an integrated constructed wetland

Cited by 79 publications

References 62 publications

How Important is Denitrification in Riparian Zones? Combining End‐Member Mixing and Isotope Modeling to Quantify Nitrate Removal from Riparian Groundwater

How Important is Denitrification in Riparian Zones? Combining End‐Member Mixing and Isotope Modeling to Quantify Nitrate Removal from Riparian Groundwater

Denitrification in Shallow Groundwater Below Different Arable Land Systems in a High Nitrogen‐Loading Region

Regulation of Partial Nitritation in Constructed Rapid Infiltration System and Analysis of Microbial Community Structure

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