anoxic zone

anoxic zone

[a′nak·sik ‚zōn]
(oceanography)
An oxygen-depleted region in a marine environment.
References in periodicals archive ?
Since the air-diffuser position resulted in the formation of aerobic or anoxic zone, the performance of nitrogen removal through SND might be compared to the separated reactions of nitrification and denitrification.
1] (corresponding to R4), difference of NOx-N concentration at aerobic and anoxic zone was around 6.
Scope : Retrofitting two of the existing four primary clarifiers to an anoxic zone and introduction of an internal recirculation pumping system for return of nitrifying bacteria to the anoxic zone and ancillary
They identified big differences between infected tissue and tissue in the preliminary stage of the disease: "In diseased coral tissue two zones develop: A phototrophic zone at the top in which the cyanobacteria produce oxygen and a lower anoxic zone in which the bacteria degrade the necrotic coral tissue.
The oxygen is only found in the top layer, the oxic zone while the hydrogen sulfide is concentrated mostly in the bottom layer, the anoxic zone.
Some are recycled to the anoxic zone to help in the denitrification process.
The microorganisms that live in some sediments off the coast of Louisiana provide a good record of the anoxic zone created by the Mississippi River, says Osterman.
Methanotrophic communities might exhibit similar reactions within spreading oceanic anoxic zones.
The required denitrification will mainly be achieved in the anoxic selector cascade, and by simultaneous denitrification in anoxic zones of the aerated part of tank and within the sludge flocks.
Increasing agricultural efficiency by irrigating and fertilizing the land can add to the strain by boosting erosion and the nutrient run off that creates toxic algal blooms and large anoxic zones in oceans.
In all three basins, sediments accumulate in clearly defined layers within the anoxic zones due to the absence of benthic organisms and the consequent lack of bioturbation.
BNR Process - Each of the four aeration tanks were modified to provide multiple aerobic and anoxic zones and intermediate pumping that are necessary to achieve enhanced biological nitrogen removal (BNR).