Denitrification
Denitrification - Related Videos
07:59
Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors
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Cited by 2 •
2018
This method estimates sediment denitrification rates in sediment cores using the acetylene inhibition technique and microsensor measurements of the accumulated N2O. The protocol describes procedures for collecting the cores, calibrating the sensors, performing the acetylene inhibition, measuring the N2O accumulation, and calculating the denitrification rate.
10:11
The Benthic Exchange of O2, N2 and Dissolved Nutrients Using Small Core Incubations
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Cited by 13 •
2016
Here, we present small core incubations for the measurement of sediment-water gas and solute exchange. These will provide reliable measurements of sediment-water exchange that assess the role of sediment in influencing biological and biogeochemical processes in aquatic ecosystems.
12:48
Blood Collection from the American Horseshoe Crab, Limulus Polyphemus
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Cited by 27 •
2008
The American horseshoe crab, Limulus polyphemus, is arguably the most convenient source for large quantities of blood of any invertebrate. The blood is simple in composition, with only one cell-type in the general circulation, the granular amebocyte, and only three abundant proteins in the plasma, hemocyanin, the C-reactive proteins, and α2-macroglobulin. Blood is collected from the heart and the blood cells and plasma are separated by centrifugation.
09:50
Electrochemically and Bioelectrochemically Induced Ammonium Recovery
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Cited by 31 •
2015
We demonstrate the extraction of ammonium from an ammonium-rich stream using an electrochemical and a bioelectrochemical system. The reactor setup, operation and data analysis are discussed.
FAQs
When oxygen is limited or absent, certain bacteria use nitrate or nitrite as alternative electron acceptors during respiration. This change allows microbial activity to continue while oxidized nitrogen compounds are progressively reduced. Consequently, oxygen availability becomes a major environmental control on where denitrification occurs, including soils, sediments, wetlands, and engineered wastewater systems.
The reduction pathway proceeds through several gaseous and dissolved intermediates rather than converting nitrate directly to atmospheric nitrogen. Nitrate or nitrite is reduced through nitric oxide and nitrous oxide before forming dinitrogen gas. This sequence matters because incomplete progression can leave nitrous oxide as an outcome, linking nitrogen removal to greenhouse-gas emissions.
Both nitrate and nitrite can serve as alternative electron acceptors when oxygen is unavailable, allowing bacteria to maintain respiration under low-oxygen or anoxic conditions. Their participation places denitrification within the broader nitrogen cycle, because oxidized nitrogen is transformed stepwise into gaseous products that can ultimately return nitrogen to the atmosphere.
Denitrification occurs in environments where microbial activity encounters limited oxygen, including soils, sediments, and wetlands. These settings differ physically, but each can support the use of nitrate or nitrite as alternative electron acceptors. Examining them helps biologists understand how local nitrogen transformations influence ecosystem nutrient availability and the movement of nitrogen through the global cycle.
Wastewater treatment systems use denitrification to remove excess nitrogen from water supplies. Under suitable low-oxygen or anoxic conditions, bacteria reduce oxidized nitrogen compounds and convert part of that nitrogen into gaseous forms. This application is important because controlling nitrogen in treated water can help limit nutrient enrichment and improve management of water quality.
Nitrous oxide is an intermediate in the reduction pathway and can also be released as a gaseous product during denitrification. Because it is a greenhouse gas, researchers evaluate nitrogen removal together with its emissions. This perspective helps distinguish effective reduction of excess nitrogen from outcomes that may shift environmental impacts from water pollution toward atmospheric emissions.