Oxygen distribution and aerobic respiration in the north and south eastern tropical Pacific oxygen minimum zones

Laura Tiano, Emilio Garcia-Robledo, Tage Dalsgaard, Allan H. Devol, Bess B. Ward, Osvaldo Ulloa, Donald Eugene Canfield, Niels Peter Revsbech

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Abstrakt

Highly sensitive STOX O-2 sensors were used for determination of in situ O-2 distribution in the eastern tropical north and south Pacific oxygen minimum zones (ETN/SP OMZs), as well as for laboratory determination of O-2 uptake rates of water masses at various depths within these OMZs. Oxygen was generally below the detection limit (few nmol L-1) in the core of both OMZs, suggesting the presence of vast volumes of functionally anoxic waters in the eastern Pacific Ocean. Oxygen was often not detectable in the deep secondary chlorophyll maximum found at some locations, but other secondary maxima contained up to similar to 0.4 mu mol L-1. Directly measured respiration rates were high in surface and subsurface oxic layers of the coastal waters, reaching values up to 85 nmol L-1 O-2 h(-1). Substantially lower values were found at the depths of the upper oxycline, where values varied from 2 to 33 nmol L-1 O-2 h(-1). Where secondary chlorophyll maxima were found the rates were higher than in the oxic water just above. Incubation times longer than 20 h, in the all-glass containers, resulted in highly increased respiration rates. Addition of amino adds to the water from the upper oxycline did not lead to a significant initial rise in respiration rate within the first 20 h, indicating that the measurement of respiration rates in oligotrophic Ocean water may not be severely affected by low levels of organic contamination during sampling. Our measurements indicate that aerobic metabolism proceeds efficiently at extremely low oxygen concentrations with apparent half-saturation concentrations (K-m values) ranging from about 10 to about 200 nmol L-1. (C) 2014 The Authors. Published by Elsevier Ltd.
OriginalsprogEngelsk
TidsskriftDeep-Sea Research Part I: Oceanographic Research Papers
Vol/bind94
Sider (fra-til)173-183
ISSN0967-0637
DOI
StatusUdgivet - dec. 2014

Emneord

  • oxygen
  • community respiration
  • oxygen minimum zone
  • Eastern tropical Pacific
  • STOX sensor
  • nitrogen-cycle
  • water-column
  • amino-acids
  • denitrification
  • ammonium
  • carbon
  • remineralization
  • atlantic
  • sensors

Fingeraftryk Dyk ned i forskningsemnerne om 'Oxygen distribution and aerobic respiration in the north and south eastern tropical Pacific oxygen minimum zones'. Sammen danner de et unikt fingeraftryk.

Citationsformater