Emerson, Steven R. Department of Oceanography, University of Washington, Seattle, Washington.
Thomas, Helmuth Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada.
Last reviewed:October 2019
- Reduction-oxidation (redox) reactions
- Reaction kinetics
- Related Primary Literature
- Additional Reading
Oxygen-depleted regions in marine environments. The dynamic steady state between oxygen supply and consumption determines the oxygen concentration. In regions where the rate of consumption equals or exceeds the rate of supply, seawater becomes devoid of oxygen and thus anoxic. In the open ocean, the only large regions that approach anoxic conditions are in the equatorial Pacific between 50 and 1000 m (165 and 3300 ft) depth and in the northern Arabian Sea and the Bay of Bengal in the Indian Ocean between 100 and 1000 m (330 and 3300 ft) depth. The Pacific oxygen-depleted region consists of vast tongues extending from Central America and Peru nearly to the middle of the ocean in some places. In parts of this zone, oxygen concentrations become very low, 15 micromoles per liter (atmospheric saturation is 200–300 μmol/L). Pore waters of marine sediments are sometimes anoxic a short distance below the sediment–water interface. The degree of oxygen consumption in sediment pore waters depends upon the amount of organic matter reaching the sediments and the rate of bioturbation (mixing of the surface sediment by benthic animals). In shallow regions (continental shelf and slope), pore waters are anoxic immediately below the sediment-water interface; in relatively rapid sedimentation-rate areas of the deep sea, the pore waters are usually anoxic within a few centimeters of the interface; and in pore waters of slowly accumulating deep-sea sediments, oxygen may never become totally depleted. See also: Marine sediments
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 45 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information