New approach for measuring denitrification in the rhizosphere of vegetated marsh sediments

Koop-Jakobsen, Ketil; Giblin, Anne E.

doi:10.4319/lom.2009.7.626

Cited by 26 publications

(30 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Sediments colonized by vascular plants or other sediments where patchy NO 3 − reduction may occur below the NO 3 − ‐diffusion zone pose another challenge to the whole‐core IPT. A recent adaptation of the IPT is its combination with a push‐pull technique, which was developed for use in vegetated salt marsh (Koop‐Jakobsen and Giblin ) and subtidal seagrass sediments (Aoki and McGlathery ). An additional variation of the push‐pull and IPT method has also been applied to advection‐dominated carbonate sands in combination with flow‐through reactors (Erler et al ).…”

Section: Discussion and Outlookmentioning

confidence: 99%

“…In vegetated sediments, the potential for the combination of IPT with other methods may go some way toward overcoming issues associated with using IPT alone. For example, applying the IPT in push‐pull methods (described further later in this article) may be an additional promising solution to investigate subsurface effects of the rooted plants on sediment N cycling (Koop‐Jakobsen and Giblin ; Aoki and McGlathery ).…”

Section: Environmental Challenges When Applying the Iptmentioning

confidence: 99%

See 1 more Smart Citation

Application of the isotope pairing technique in sediments: Use, challenges, and new directions

Robertson

Bartoli

Brüchert

et al. 2019

Limnology & Ocean Methods

View full text Add to dashboard Cite

Determining accurate rates of benthic nitrogen (N) removal and retention pathways from diverse environments is critical to our understanding of process distribution and constructing reliable N budgets and models. The whole‐core 15N isotope pairing technique (IPT) is one of the most widely used methods to determine rates of benthic nitrate‐reducing processes and has provided valuable information on processes and factors controlling N removal and retention in aquatic systems. While the whole core IPT has been employed in a range of environments, a number of methodological and environmental factors may lead to the generation of inaccurate data and are important to acknowledge for those applying the method. In this review, we summarize the current state of the whole core IPT and highlight some of the important steps and considerations when employing the technique. We discuss environmental parameters which can pose issues to the application of the IPT and may lead to experimental artifacts, several of which are of particular importance in environments heavily impacted by eutrophication. Finally, we highlight the advances in the use of the whole‐core IPT in combination with other methods, discuss new potential areas of consideration and encourage careful and considered use of the whole‐core IPT. With the recognition of potential issues and proper use, the whole‐core IPT will undoubtedly continue to develop, improve our understanding of benthic N cycling and allow more reliable budgets and predictions to be made.

show abstract

Section: Discussion and Outlookmentioning

confidence: 99%

Section: Environmental Challenges When Applying the Iptmentioning

confidence: 99%

Application of the isotope pairing technique in sediments: Use, challenges, and new directions

Robertson

Bartoli

Brüchert

et al. 2019

Limnology & Ocean Methods

View full text Add to dashboard Cite

show abstract

“…Both plant species had roots present to at least 24 cm; as such, every measurement in vegetated sediments was located within the rhizosphere. We chose the depths based on estimated porosity (Koop‐Jakobsen & Giblin, ), which suggested that each denitrification measurement would encompass a diameter of ~6 cm. Post‐sampling calculations with measured porosity revealed that the mean actual diameter was 5.6 cm.…”

Section: Methodsmentioning

confidence: 99%

“…We chose the in situ push–pull isotope pairing technique (Koop‐Jakobsen & Giblin, ) for our denitrification measurements because it was ideal for addressing our hypotheses. There are numerous methods for measuring denitrification, but many are laboratory‐based (e.g.…”

Section: Methodsmentioning

confidence: 99%

The influence of an invasive plant on denitrification in an urban wetland

et al. 2018

View full text Add to dashboard Cite

Wetlands are often biogeochemical hotspots, and they can remove excess N via denitrification and assimilatory uptake. Wetlands are also susceptible to plant invasions, but the effect of invasive plants on denitrification in freshwater wetland sediments is not well‐studied. Two distinct mechanisms suggest the potential for invasive plants to alter denitrification. First, invasive plants often produce more biomass than non‐invasive species, thus potentially providing additional carbon (C) for denitrifiers. Second, some invasive wetland plants funnel more oxygen into the root zone than non‐invasive plants, potentially stimulating coupled nitrification–denitrification. Using the push–pull isotope pairing technique, we measured denitrification and coupled nitrification–denitrification in the sediments beneath monoculture plots of Phragmites australis and Typha domingensis, and beneath unvegetated sediments, in an urban wetland in Melbourne, Australia. We also measured pore water nutrient concentrations and calculated the diffusive flux of nutrients from the sediments into the overlying water column. We hypothesised that plots containing P. australis would have the highest denitrification and coupled nitrification–denitrification rates, followed by plots containing T. domingensis, with the lowest rates in the unvegetated plots, as a result of higher C and oxygen availability. Instead, we found that denitrification and coupled nitrification–denitrification rates were highly variable, with no difference among plot type. However, we did find that diffusive flux of ammonium from the sediments into the water column was lower in the vegetated plots than in the unvegetated plots, suggesting that vegetation enhances wetland N retention via plant assimilatory uptake.

show abstract

“…In addition, the method was adapted for use in the gaseous phase (''gas push-pull test'') to quantify aerobic CH 4 oxidation in the soil vadose zone (e.g., Gomez et al 2009;Urmann et al 2005). While the majority of studies interrogated relatively large subsurface volumes by injecting tens to hundreds of liters of test solution, several recent studies demonstrated the utility of PPTs to quantify microbial processes at smaller scales using injection volumes between 10 and 200 ml (Bassein and Jaffe 2009;Koop-Jakobsen and Giblin 2009;Sanders and Trimmer 2006).…”

Section: Introductionmentioning

confidence: 99%

Circadian methane oxidation in the root zone of rice plants

2011

View full text Add to dashboard Cite

In the root zone of rice plants aerobic methanotrophic bacteria catalyze the oxidation of CH 4 to CO 2 , thereby reducing CH 4 emissions from paddy soils to the atmosphere. However, methods for in situ quantification of microbial processes in paddy soils are scarce. Here we adapted the push-pull tracer-test (PPT) method to quantify CH 4 oxidation in the root zone of potted rice plants. During a PPT, a test solution containing CH 4 ± O 2 as reactant(s), Cl -and Ar as nonreactive tracers, and BES as an inhibitor of CH 4 production was injected into the root zone at different times throughout the circadian cycle (daytime, early nighttime, late nighttime). After a 2-h incubation phase, the test solution/pore-water mixture was extracted from the same location and rates of CH 4 oxidation were calculated from the ratio of measured reactant and nonreactive tracer concentrations. In separate rice pots, O 2 concentrations in the vicinity of rice roots were measured throughout the circadian cycle using a fiberoptic sensor. Results indicated highly variable CH 4 oxidation rates following a circadian pattern. Mean rates at daytime and early nighttime varied from 62 up to 451 lmol l -1 h -1, whereas at late nighttime CH 4 oxidation rates were low, ranging from 13 to 37 lmol l -1 h -1. Similarly, daytime O 2 concentration in the vicinity of rice roots increased to up to 250% air saturation, while nighttime O 2 concentration dropped to below detection (\0.15% air saturation). Our results suggest a functional link between root-zone CH 4 oxidation and photosynthetic O 2 supply.

show abstract

New approach for measuring denitrification in the rhizosphere of vegetated marsh sediments

Abstract: This study presents a new approach for measuring denitrification at depth in the marsh rhizosphere (below 5 cm). The method combines the push-pull technique and the

Cited by 26 publications

References 39 publications

Application of the isotope pairing technique in sediments: Use, challenges, and new directions

Application of the isotope pairing technique in sediments: Use, challenges, and new directions

The influence of an invasive plant on denitrification in an urban wetland

Circadian methane oxidation in the root zone of rice plants

Contact Info

Product

Resources

About