Models of oxic respiration, denitrification and sulfate reduction in zones of coastal upwelling

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Coastal upwelling zones support some of the highest rates of primary production in the oceans. The settling and subsequent decomposition of this organic matter promotes oxygen depletion. In the Eastern tropical North and South Pacific and the Arabian Sea, large tracts of anoxic water develop, where intensive N2 production through denitrification and anammox accounts for about 1/3 of the total loss of fixed nitrogen in the marine realm. It is curious that despite extensive denitrification in these waters, complete nitrate removal and the onset of sulfate reduction is extremely rare. A simple box model is constructed here to reproduce the dynamics of carbon, oxygen and nutrient cycling in coastal upwelling zones. The model is constructed with five boxes, where water is exchanged between the boxes by vertical and horizontal mixing and advection. These primary physical drivers control the dynamics of the system. The model demonstrates that in the absence of nitrogen fixation, the anoxic waters in a coastal upwelling system will not become nitrate free. This is because nitrate is the limiting nutrient controlling primary production, and if nitrate concentration becomes too low, primary production rate drops and this reduces rates of nitrate removal through N2 production. With nitrogen fixation, however, complete nitrate depletion can occur and sulfate reduction will ensue. This situation is extremely rare in coastal upwelling zones, probably because nitrogen-fixing bacteria do not prosper in the high nutrient, turbid waters as typically in these areas. Finally, it is predicted here that the chemistry of the upwelling system will develop in a similar matter regardless whether N2 production is dominated by anaerobic ammonium oxidation (anammox) or canonical heterotrophic denitrification.
OriginalsprogEngelsk
TidsskriftGeochimica et Cosmochimica Acta
Vol/bind70
Udgave nummer23
Sider (fra-til)5753-5765
ISSN0016-7037
DOI
StatusUdgivet - 2006

Fingeraftryk

denitrification
upwelling
respiration
sulfate
nitrate
primary production
nitrogen fixation
ammonium
water
oxidation
oxygen
nutrient
nitrogen
nutrient cycling
advection
decomposition
organic matter
bacterium
carbon
ocean

Citer dette

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title = "Models of oxic respiration, denitrification and sulfate reduction in zones of coastal upwelling",
abstract = "Coastal upwelling zones support some of the highest rates of primary production in the oceans. The settling and subsequent decomposition of this organic matter promotes oxygen depletion. In the Eastern tropical North and South Pacific and the Arabian Sea, large tracts of anoxic water develop, where intensive N2 production through denitrification and anammox accounts for about 1/3 of the total loss of fixed nitrogen in the marine realm. It is curious that despite extensive denitrification in these waters, complete nitrate removal and the onset of sulfate reduction is extremely rare. A simple box model is constructed here to reproduce the dynamics of carbon, oxygen and nutrient cycling in coastal upwelling zones. The model is constructed with five boxes, where water is exchanged between the boxes by vertical and horizontal mixing and advection. These primary physical drivers control the dynamics of the system. The model demonstrates that in the absence of nitrogen fixation, the anoxic waters in a coastal upwelling system will not become nitrate free. This is because nitrate is the limiting nutrient controlling primary production, and if nitrate concentration becomes too low, primary production rate drops and this reduces rates of nitrate removal through N2 production. With nitrogen fixation, however, complete nitrate depletion can occur and sulfate reduction will ensue. This situation is extremely rare in coastal upwelling zones, probably because nitrogen-fixing bacteria do not prosper in the high nutrient, turbid waters as typically in these areas. Finally, it is predicted here that the chemistry of the upwelling system will develop in a similar matter regardless whether N2 production is dominated by anaerobic ammonium oxidation (anammox) or canonical heterotrophic denitrification.",
author = "Canfield, {Donald Eugene}",
year = "2006",
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Models of oxic respiration, denitrification and sulfate reduction in zones of coastal upwelling. / Canfield, Donald Eugene.

I: Geochimica et Cosmochimica Acta, Bind 70, Nr. 23, 2006, s. 5753-5765.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Models of oxic respiration, denitrification and sulfate reduction in zones of coastal upwelling

AU - Canfield, Donald Eugene

PY - 2006

Y1 - 2006

N2 - Coastal upwelling zones support some of the highest rates of primary production in the oceans. The settling and subsequent decomposition of this organic matter promotes oxygen depletion. In the Eastern tropical North and South Pacific and the Arabian Sea, large tracts of anoxic water develop, where intensive N2 production through denitrification and anammox accounts for about 1/3 of the total loss of fixed nitrogen in the marine realm. It is curious that despite extensive denitrification in these waters, complete nitrate removal and the onset of sulfate reduction is extremely rare. A simple box model is constructed here to reproduce the dynamics of carbon, oxygen and nutrient cycling in coastal upwelling zones. The model is constructed with five boxes, where water is exchanged between the boxes by vertical and horizontal mixing and advection. These primary physical drivers control the dynamics of the system. The model demonstrates that in the absence of nitrogen fixation, the anoxic waters in a coastal upwelling system will not become nitrate free. This is because nitrate is the limiting nutrient controlling primary production, and if nitrate concentration becomes too low, primary production rate drops and this reduces rates of nitrate removal through N2 production. With nitrogen fixation, however, complete nitrate depletion can occur and sulfate reduction will ensue. This situation is extremely rare in coastal upwelling zones, probably because nitrogen-fixing bacteria do not prosper in the high nutrient, turbid waters as typically in these areas. Finally, it is predicted here that the chemistry of the upwelling system will develop in a similar matter regardless whether N2 production is dominated by anaerobic ammonium oxidation (anammox) or canonical heterotrophic denitrification.

AB - Coastal upwelling zones support some of the highest rates of primary production in the oceans. The settling and subsequent decomposition of this organic matter promotes oxygen depletion. In the Eastern tropical North and South Pacific and the Arabian Sea, large tracts of anoxic water develop, where intensive N2 production through denitrification and anammox accounts for about 1/3 of the total loss of fixed nitrogen in the marine realm. It is curious that despite extensive denitrification in these waters, complete nitrate removal and the onset of sulfate reduction is extremely rare. A simple box model is constructed here to reproduce the dynamics of carbon, oxygen and nutrient cycling in coastal upwelling zones. The model is constructed with five boxes, where water is exchanged between the boxes by vertical and horizontal mixing and advection. These primary physical drivers control the dynamics of the system. The model demonstrates that in the absence of nitrogen fixation, the anoxic waters in a coastal upwelling system will not become nitrate free. This is because nitrate is the limiting nutrient controlling primary production, and if nitrate concentration becomes too low, primary production rate drops and this reduces rates of nitrate removal through N2 production. With nitrogen fixation, however, complete nitrate depletion can occur and sulfate reduction will ensue. This situation is extremely rare in coastal upwelling zones, probably because nitrogen-fixing bacteria do not prosper in the high nutrient, turbid waters as typically in these areas. Finally, it is predicted here that the chemistry of the upwelling system will develop in a similar matter regardless whether N2 production is dominated by anaerobic ammonium oxidation (anammox) or canonical heterotrophic denitrification.

U2 - 10.1016/j.gca.2006.07.023

DO - 10.1016/j.gca.2006.07.023

M3 - Journal article

VL - 70

SP - 5753

EP - 5765

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

SN - 0016-7037

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