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Diapycnal dissolved organic matter supply into the upper Peruvian oxycline

Abstract.

"The Eastern Tropical South Pacific (ETSP) hosts the Peruvian upwelling system, which represents one of the most productive areas in the world ocean. High primary production followed by rapid heterotrophic utilization of organic matter supports the formation of one of the most intense oxygen minimum zones (OMZ) in the world ocean where dissolved oxygen (O2) concentrations reach well below 1 µmol kg−1. The high productivity leads to an accumulation of dissolved organic matter (DOM) in the surface layers that may serve as a substrate for heterotrophic respiration.  [...]"

Source: Biogeosciences
Authors: lexandra N. Loginova et al.
DOI: 10.5194/bg-2018-284

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Oxygen Pathways and Budget for the Eastern South Pacific Oxygen Minimum Zone

Abstract.

"Ventilation of the eastern South Pacific Oxygen Minimum Zone (ESP‐OMZ) is quantified using climatological Argo and dissolved oxygen data, combined with reanalysis wind stress data. We (1) estimate all oxygen fluxes (advection and turbulent diffusion) ventilating this OMZ, (2) quantify for the first time the oxygen contribution from the subtropical versus the traditionally studied tropical‐equatorial pathway, and (3) derive a refined annual‐mean oxygen budget for the ESP‐OMZ. In the upper OMZ layer, net oxygen supply is dominated by tropical‐equatorial advection, with more than one‐third of this supply upwelling into the Ekman layer through previously unevaluated vertical advection, within the overturning component of the regional Subtropical Cell (STC). [...]"

Source: Oceans
Authors: P. J. Llanillo et al.
DOI: 10.1002/2017JC013509

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Impact of mesoscale eddies on water mass and oxygen distribution in the eastern tropical South Pacific

Abstract.

"The influence of mesoscale eddies on the flow field and the water masses, especially the oxygen distribution of the eastern tropical South Pacific is investigated from a mooring, float and satellite data set. Two anticyclonic (ACE1/2), one mode water (MWE) and one cyclonic eddy (CE) are identified and followed in detail with satellite data on their westward transition with velocities of 3.2 to 6.0 cm/s from their generation region, the shelf of the Peruvian and Chilean upwelling regime, across the Stratus Ocean Reference Station (ORS) (~ 20° S, 85° W) to their decaying region far west in the oligotrophic open ocean. [...]"

Source: Ocean Science (under review)
Authors: Rena Czeschel et al.
DOI: 10.5194/os-2018-5

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Community composition of nitrous oxide consuming bacteria in the oxygen minimum zone of the Eastern Tropical South Pacific

Abstract.

"The ozone-depleting and greenhouse gas, nitrous oxide (N2O), is mainly consumed by the microbially mediated anaerobic process, denitrification. N2O consumption is the last step in canonical denitrification, and is also the least O2 tolerant step. Community composition of total and active N2O consuming bacteria was analyzed based on total (DNA) and transcriptionally active (RNA) nitrous oxide reductase (nosZ) genes using a functional gene microarray. The total and active nosZ communities were dominated by a limited number of nosZ archetypes, affiliated with bacteria from marine, soil and marsh environments. [...]"

Source: Frontiers in Microbiology
Authors: Xin Sun, Amal Jayakumar and Bess B. Ward
DOI: 10.3389/fmicb.2017.01183

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