Anoxic waters are areas of sea water or fresh water that does not contain the sufficient amount of oxygen, dissolved in it to sustain aquatic life. In most of the cases, oxygen is prevented from reaching the deeper levels by a physical barrier and also by a pronounced density stratification. Anoxic conditions will occur if the rate of oxidation of organic matter by bacteria is greater than the supply of dissolved oxygen.

Anoxic waters are a natural phenomenon and have occurred during the geological history of the Baltic Sea. Recently, there have been some indications that eutrophication has raised the extent of the anoxic areas in areas including the Gulf of Mexico and the Baltic Sea.

Anoxic conditions result from various factors; for example, density stratification, stagnation conditions, inputs of organic material and strong thermoclines. The bacterial production of sulfide starts in the sediments, where the bacteria find suitable substrates and then expands into the water column.


Anoxic water can occur in many places, including swamps, Peat Bogs, fresh water lakes and even some ocean basins.

Cause of anoxic water

It is caused by Eutrophication which is the process in which phosphates and nitrates from farms, run- off into near by water sources. These chemicals cause algae to grow and when the algal blooms die, bacteria helps decompose them. The bacteria uses huge amounts of oxygen to decompose, which sucks the oxygen from the water source, which creates an Anoxic Environment.

You can help in that by contacting your local farms near water sources and tell them about the risk. Take charge if you need.