Artificial Sinks: Opportunities and Challenges for Managing Offsite Nitrogen Losses

Gold, Arthur J.; Addy, Kelly; David, Mark B.; Schipper, Louis A.; Needelman, Brian A.

doi:10.1111/j.1936-704x.2013.03147.x

Cited by 8 publications

(5 citation statements)

References 42 publications

(65 reference statements)

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“…Denitrifying bioreactors are designed to serve as artificial N sinks that can increase the magnitude of denitrification within the landscape and are strategically placed to intercept NO 3 − –enriched groundwater or concentrated flows such as tile drainage (Gold et al, 2013). They function by supporting the activity of denitrifying microorganisms by supplying an organic carbon energy source that, as the system becomes saturated, provides an anaerobic environment favoring the biochemical conversion of NO 3 − –N to N 2 .…”

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confidence: 99%

Effect of Biochar on Nitrate Removal in a Pilot-Scale Denitrifying Bioreactor

2016

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Denitrifying bioreactors (DNBRs) harness the natural capacity of microorganisms to convert bioavailable nitrogen (N) into inert nitrogen gas (N) by providing a suitable anaerobic habitat and an organic carbon energy source. Woodchip systems are reported to remove 2 to 22 g N m d, but the potential to enhance denitrification with alternative substrates holds promise. The objective of this study was to determine the effect of adding biochar, an organic carbon pyrolysis product, to an in-field, pilot-scale woodchip DNBR. Two 25-m DNBRs, one with woodchips and the other with woodchips and a 10% by volume addition of biochar, were installed on the Delmarva Peninsula, Virginia. Performance was assessed using flood-and-drain batch experiments. An initial release of N was observed during the establishment of both DNBRs, reflecting a start-up phenomenon observed in previous studies. Nitrate (NO-N) removal rates observed during nine batch experiments 4 to 22 mo after installation were 0.25 to 6.06 g N m d. The presence of biochar, temperature, and influent NO-N concentration were found to have significant effects on NO-N removal rates using a linear mixed effects model. The model predicts that biochar increases the rate of N removal when influent concentrations are above approximately 5 to 10 mg L NO-N but that woodchip DNBRs outperform biochar-amended DNBRs when influent concentrations are lower, possibly reflecting the release of N temporarily stored in the biochar matrix. These results indicate that in high N-yielding systems the addition of biochar to standard woodchip DNBRs has the potential to significantly increase N removal.

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confidence: 99%

Effect of Biochar on Nitrate Removal in a Pilot-Scale Denitrifying Bioreactor

2016

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“…There is a large body of literature studying the water quality benefits of various types of bioreactors and permeable reactive barriers (Schipper et al, 2010; Addy et al, 2016) and edge‐of‐field wetlands (Kovacic et al, 2000; Díaz et al, 2012). Many of these studies are summarized in Gold et al (2013) and Addy et al (2016) (see http://www.artificialnsinks.org/). For these practices, the water quality benefit is directly tied to the design of the wetland or bioreactor, and the riparian zone is merely a host (Fig.…”

Section: Riparian Zone Management In Multifunctional Landscapesmentioning

confidence: 99%

Twenty Years of Riparian Zone Research (1997–2017): Where to Next?

2019

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Riparian zones have been used for water quality management with respect to NO 3 − in subsurface flow and total P (TP), sediments, and pesticides in overland flow for decades. Only recently has the fate and transport of soluble reactive P (SRP), Hg, emerging contaminants, and greenhouse gas (GHG) fluxes (N 2 O, CO 2 , and CH 4 ) been examined in riparian zones. Overall, riparian zones are efficient at reducing emerging contaminants in subsurface flow and only function as hot spots of methylmercury production in the landscape when dominated by Hg-rich wet organic soils. However, riparian zones do not provide consistent benefits with respect to SRP removal or GHG emissions. Although most existing riparian models almost exclusively focus on NO 3 − removal, recent developments in riparian models demonstrate the potential for using easily accessible digital environmental datasets to simulate and scale up riparian functions beyond NO 3 − removal to include SRP, TP, and GHG dynamics. To further inform integrated watershed management efforts, more research should be conducted on how various practices, including stream restoration, subsurface drainage, two-stage ditches, beaver dam analogues, denitrification bioreactors and permeable reactive barriers, artificial wetlands, and short-rotation forestry crops affect riparian water and air quality functions. Riparian zone benefits should be discussed not only with respect to water and air quality, but also in terms of recreation, habitat for wildlife, and other ecosystem services. More research is needed to fully address potential water quality or air quality tradeoffs associated with riparian zone management in a multicontaminant-multiuse landscape context.

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“…In CWs, microsites with steep gradients of DO can be established, which allow nitrification and denitrification to occur in sequence, in very close proximity to each other (Lee et al, 2009). The denitrification rate is influenced by nitrate concentration, microbial flora, type and quality of organic carbon source, hydroperiods, plant residues, DO, redox potential, soil moisture, temperature, pH, presence of denitrifiers, soil type, water level, and the presence of overlying water (Sirivedhin and Gray, 2006;Golterman, 2004 Denitrification process can be represented as below:…”

Section: Nitrificationmentioning

confidence: 99%

Carbon and nitrogen dynamics and greenhouse gases emissions in constructed wetlands: a review

Jahangir¹,

Fenton²,

Gill³

et al. 2014

Preprint

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Abstract. The nitrogen (N) removal efficiency of constructed wetlands (CWs) is very inconsistent and does not alone explain if the removed species are reduced by physical attenuation or if they are transformed to other reactive forms (pollution swapping). There are many pathways for the removed N to remain in the system: accumulation in the sediments, leaching to groundwater (nitrate-NO3- and ammonium-NH4+), emission to atmosphere via nitrous oxide- N2O and ammonia and/or conversion to N2 gas and adsorption to sediments. The kinetics of these pathways/processes varies with CWs management and therefore needs to be studied quantitatively for the sustainable use of CWs. For example, the quality of groundwater underlying CWs with regards to the reactive N (Nr) species is largely unknown. Equally, there is a dearth of information on the extent of Nr accumulation in soils and discharge to surface waters and air. Moreover, CWs are rich in dissolved organic carbon (DOC) and produce substantial amounts of CO2 and CH4. These dissolved carbon (C) species drain out to ground and surface waters and emit to the atmosphere. The dynamics of dissolved N2O, CO2 and CH4 in CWs is a key "missing piece" in our understanding of global greenhouse gas budgets. In this review we provide an overview of the current knowledge and discussion about the dynamics of C and N in CWs and their likely impacts on aquatic and atmospheric environments. We suggest that the fate of various N species in CWs and their surface emissions and subsurface drainage fluxes need to be evaluated in a holistic way to better understand their potential for pollution swapping. Research on the process based N removal and balancing the end products into reactive and benign forms are critical to assess environmental impacts of CWs. Thus we strongly suggest that in situ N transformation and fate of the transformation products with regards to pollution swapping requires further detailed examination.

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Artificial Sinks: Opportunities and Challenges for Managing Offsite Nitrogen Losses

Cited by 8 publications

References 42 publications

Effect of Biochar on Nitrate Removal in a Pilot-Scale Denitrifying Bioreactor

Effect of Biochar on Nitrate Removal in a Pilot-Scale Denitrifying Bioreactor

Twenty Years of Riparian Zone Research (1997–2017): Where to Next?

Carbon and nitrogen dynamics and greenhouse gases emissions in constructed wetlands: a review

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