Oxygen content in water refers to the total amount of dissolved molecular oxygen (O₂) present per unit volume, typically expressed in milligrams per liter (mg/L) or as percent saturation relative to atmospheric equilibrium. It is governed by gas solubility equilibria (primarily Henry’s law), temperature, salinity, and pressure, as well as biological and chemical processes such as photosynthesis, respiration, and oxidation reactions. Oxygen content is a key parameter in aquatic system characterization, influencing redox conditions, biogeochemical cycling, and habitat suitability, and is routinely measured using electrochemical or optical sensors in limnological, oceanographic, and water-quality research.
A build-up of ultra-fine sediment in riverbeds is creating oxygen-starved conditions that threaten fish spawning grounds and freshwater invertebrates, new research on the River Taw in Devon has revealed. The study is published ...
Plants & Animals
Oct 21, 2025
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The explosion of animal life in Earth's oceans half a billion years ago during and after the Cambrian Period is commonly attributed to a substantial and sustained rise of free oxygen (O2) in seawater. Some researchers even ...
Earth Sciences
Sep 4, 2025
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Some 390 million years ago in the ancient ocean, marine animals began colonizing depths previously uninhabited. New research indicates this underwater migration occurred in response to a permanent increase in deep-ocean oxygen, ...
Earth Sciences
Aug 25, 2025
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NOAA-supported scientists announced today that this year's Gulf of Mexico "dead zone"—an area of low to no oxygen that can kill fish and marine life—is approximately 4,402 square miles, 21% smaller than estimates from early ...
Environment
Aug 1, 2025
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An international study led by the Institute of Environmental Science and Technology at the Universitat Autònoma de Barcelona (ICTA-UAB), Spain, has investigated how marine ecosystems responded to past episodes of ocean deoxygenation. ...
Ecology
Jul 31, 2025
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Marine life may be more resilient to climate stress than previously thought, thanks to shifting oxygen levels in coastal waters.
Ecology
Jul 28, 2025
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New research from the University of California, Davis, the Chinese Academy of Sciences and Texas A&M University reveals that massive emissions, or burps, of carbon dioxide from natural Earth systems led to significant decreases ...
Earth Sciences
Jun 23, 2025
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Methods to enhance the ocean's uptake of carbon dioxide (CO₂) are being explored to help tackle the climate crisis. However, some of these approaches could significantly exacerbate ocean deoxygenation. Their potential impact ...
Earth Sciences
Jun 14, 2025
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NOAA is forecasting this summer's Gulf of America (formerly Gulf of Mexico) "dead zone" to be average-sized, covering approximately 5,574 square miles—an area roughly three times the size of Delaware. The dead zone, or hypoxic ...
Environment
Jun 12, 2025
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Several key moments in Earth's history help us humans answer the question "How did we get here?" These moments also shed light on the question "Where are we going?" and offer scientists deeper insight into how organisms adapt ...
Earth Sciences
May 29, 2025
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