Deoxygen

Deoxygen, also known as deoxygenation, is the process by which dissolved oxygen in water decreases to low levels. This condition is often referred to as hypoxia. While oxygen is naturally present in water bodies and essential for aquatic life, various factors can lead to its depletion.

Natural causes of deoxygenation include the decomposition of organic matter, such as dead plants and animals. When these materials break down, microorganisms consume oxygen in the process. Seasonal variations, such as increased water temperatures which hold less dissolved oxygen, can also contribute. Stratification of water bodies, where layers of water with different temperatures and densities form, can prevent oxygen-rich surface water from mixing with deeper, oxygen-poor water.

Human activities are significant contributors to deoxygenation. The primary driver is eutrophication, which is the excessive input of nutrients, particularly nitrogen and phosphorus, into water bodies. These nutrients often come from agricultural runoff, sewage discharge, and industrial wastewater. The increased nutrients stimulate the growth of algae and other aquatic plants. When these organisms die, their decomposition by bacteria leads to a rapid depletion of dissolved oxygen. Thermal pollution, from the discharge of heated water by power plants and industries, also reduces the water's capacity to hold oxygen.

The consequences of deoxygenation are severe for aquatic ecosystems. Fish and other aquatic organisms require dissolved oxygen to survive. Low oxygen levels can cause stress, reduced growth, reproductive problems, and ultimately, mass die-offs. Organisms that cannot escape the hypoxic zones may perish. Deoxygenation can fundamentally alter the structure and function of aquatic communities.