High Nitrite Levels off Northern Peru: A Signal of Instability in the Marine Denitrification Rate

Codispoti, Louis A; Friederich, Gernot; Packard, Theodore T.; Glover, Hilary E.; Kelly, P. J.; Spinrad, Richard W.; Barber, Richard T.; Elkins, James W.; Ward, Bettie; Lipschultz, Fredric; Lostaunau, Nelson

doi:10.1126/science.233.4769.1200

Cited by 163 publications

(67 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Denitrification exactly matches total nitrogen fixation and is equally divided into water-column and benthic denitrification. The benthic denitrification was set to be proportional to the POC flux to the sea floor, and the water-column denitrification was evenly spread over all volumes where dissolved oxygen is below 20 mmol kg À1 : This places most of the denitrification in the Pacific and Indian Ocean between 100 and 800 m depth, in agreement with observational evidence (Codispoti and Christensen, 1985;Codispoti et al, 1986;Howell et al, 1997).…”

Section: Biogeochemical Parametersmentioning

confidence: 68%

Carbon export fluxes in the Southern Ocean: results from inverse modeling and comparison with satellite-based estimates

Schlitzer

2002

Deep Sea Research Part II: Topical Studies in Oceanography

305

266

View full text Add to dashboard Cite

The use of dissolved nutrients and carbon for photosynthesis in the euphotic zone and the subsequent downward transport of particulate and dissolved organic material strongly affect carbon concentrations in surface water and thus the air-sea exchange of CO 2 : Efforts to quantify the downward carbon flux for the whole ocean or on basin-scales are hampered by the sparseness of direct productivity or flux measurements. Here, a global ocean circulation, biogeochemical model is used to determine rates of export production and vertical carbon fluxes in the Southern Ocean. The model exploits the existing large sets of hydrographic, oxygen, nutrient and carbon data that contain information on the underlying biogeochemical processes. The model is fitted to the data by systematically varying circulation, air-sea fluxes, production, and remineralization rates simultaneously. Use of the adjoint method yields model property simulations that are in very good agreement with measurements.In the model, the total integrated export flux of particulate organic matter necessary for the realistic reproduction of nutrient data is significantly larger than export estimates derived from primary productivity maps. Of the 10; 000 TgC yr À1 ð10 GtC yr À1 Þ required globally, the Southern Ocean south of 301S contributes about 3000 TgC yr À1 (33%), most of it occurring in a zonal belt along the Antarctic Circumpolar Current and in the Peru, Chile and Namibia coastal upwelling regions. The export flux of POC for the area south of 501S amounts to 10007210 TgC yr À1 ; and the particle flux in 1000 m for the same area is 115720 TgC yr À1 : Unlike for the global ocean, the contribution of the downward flux of dissolved organic carbon is significant in the Southern Ocean in the top 500 m of the water column. Comparison with satellite-based productivity estimates (CZCS and SeaWiFS) shows a relatively good agreement over most of the ocean except for the Southern Ocean south of 501S; where the model fluxes are systematically higher than the satellite-based values by factors between 2 and 5. This discrepancy is significant, and an attempt to reconcile the low satellite-derived productivity values with ocean-interior nutrient budgets failed. Too low productivity estimates from satellite chlorophyll observations in the polar and sub-polar Southern Ocean could arise because of the inability of the satellite sensors to detect frequently occurring sub-surface chlorophyll patches, and to a poor calibration of the conversion algorithms in the Southern Ocean because of the very limited amount of direct measurements. r

show abstract

Section: Biogeochemical Parametersmentioning

confidence: 68%

Carbon export fluxes in the Southern Ocean: results from inverse modeling and comparison with satellite-based estimates

Schlitzer

2002

Deep Sea Research Part II: Topical Studies in Oceanography

305

266

View full text Add to dashboard Cite

show abstract

“…In the ETSP and AS, except for AS Station 17, nitrate reduction rates were roughly correlated with growth rate of cells in the incubation. The observed rates are rapid enough to deplete the ambient nitrate in a few days and clearly are not representative of rates that occur in the ocean ( orders of magnitude (e.g., Devol et al 2006;Naqvi & Shailaja 1993;Cline & Richards 1972;Codispoti et al 1986). In the OMZs, nitrate is never totally depleted and a seasonally and spatially variable secondary nitrite maximum persists.…”

Section: Denitrification Ratesmentioning

confidence: 79%

Organic carbon, and not copper, controls denitrification in oxygen minimum zones of the ocean

Ward

Tuit

Jayakumar

et al. 2008

Deep Sea Research Part I: Oceanographic Research Papers

124

View full text Add to dashboard Cite

“…It is also likely, however, that under denitrifying conditions N 2 O depletion occurs at a faster rate than production, masking the N 2 O production signal. Elevated NO − 2 concentrations (11 µmol L −1 ) along with closeto-detection-limit NO − 3 concentrations in the OMZ further suggest that complete -and more intense -denitrification took place in the OMZ core at the eddy centre (Codispoti and Christensen, 1985;Codispoti et al, 1986). Thus, in general, in the centre of the eddy a higher N 2 O maxima at the upper boundary of the OMZ resulted from enhanced nitrification and partial denitrification, whereas stronger N 2 O depletion at the OMZ's core resulted from enhanced, complete denitrification.…”

Section: )mentioning

confidence: 99%

Influence of mesoscale eddies on the distribution of nitrous oxide in the eastern tropical South Pacific

et al. 2016

View full text Add to dashboard Cite

Abstract. Recent observations in the eastern tropical South Pacific (ETSP) have shown the key role of meso-and submesoscale processes (e.g. eddies) in shaping its hydrographic and biogeochemical properties. Off Peru, elevated primary production from coastal upwelling in combination with sluggish ventilation of subsurface waters fuels a prominent oxygen minimum zone (OMZ). Given that nitrous oxide (N 2 O) production-consumption processes in the water column are sensitive to oxygen (O 2 ) concentrations, the ETSP is a region of particular interest to investigate its source-sink dynamics. To date, no detailed surveys linking mesoscale processes and N 2 O distributions as well as their relevance to nitrogen (N) cycling are available. In this study, we present the first measurements of N 2 O across three mesoscale eddies (two mode water or anticyclonic and one cyclonic) which were identified, tracked, and sampled during two surveys carried out in the ETSP in November-December 2012. A two-peak structure was observed for N 2 O, wherein the two maxima coincide with the upper and lower boundaries of the OMZ, indicating active nitrification and partial denitrification. This was further supported by the abundances of the key gene for nitrification, ammonium monooxygenase (amoA), and the gene marker for N 2 O production during denitrification, nitrite reductase (nirS). Conversely, we found strong N 2 O depletion in the core of the OMZ (O 2 < 5 µmol L −1 ) to be consistent with nitrite (NO − 2 ) accumulation and low levels of nitrate (NO − 3 ), thus suggesting active denitrification. N 2 O depletion within the OMZ's core was substantially higher in the centre of mode water eddies, supporting the view that eddy activity enhances N-loss processes off Peru, in particular near the shelf break where nutrient-rich, productive waters from upwelling are trapped before being transported offshore. Analysis of eddies during their propagation towards the open ocean showed that, in general, "ageing" of mesoscale eddies tends to decrease N 2 O concentrations through the water column in response to the reduced supply of material to fuel N loss, although hydrographic variability might also significantly impact the pace of the production-consumption pathways for N 2 O. Our results evidence the relevance of mode water eddies for N 2 O distribution, thereby improving our understanding of the N-cycling processes, which are of crucial importance in times of climate change and ocean deoxygenation.

show abstract

High Nitrite Levels off Northern Peru: A Signal of Instability in the Marine Denitrification Rate

Cited by 163 publications

References 11 publications

Carbon export fluxes in the Southern Ocean: results from inverse modeling and comparison with satellite-based estimates

Carbon export fluxes in the Southern Ocean: results from inverse modeling and comparison with satellite-based estimates

Organic carbon, and not copper, controls denitrification in oxygen minimum zones of the ocean

Influence of mesoscale eddies on the distribution of nitrous oxide in the eastern tropical South Pacific

Contact Info

Product

Resources

About