Selenium cycle

[2] There are three fates of dissolved selenium in an aquatic ecosystem: 1. it can be absorbed or ingested by organisms; 2. it can bind with suspended solids or sediments; or 3. it can remain in free solution.

Due to the dynamic flow in an aquatic ecosystem, selenium is usually only in the sediments temporarily before being cycled back into the system.

Immobilization processes effectively remove selenium from the ecosystem, especially in slow-moving or still-water areas.

[3] The second process is biological mixing and associated oxidation of sediments from the burrowing of benthic invertebrates and feeding of fish and wildlife.

The third process is represented by physical movement and chemical oxidation from water circulation and mixing, such as current, wind, precipitation, and upwelling.

Selenium pathways and transformations [ 1 ]
Overview of selenium species, pathways and transformations in soil, water, atmosphere and their interfaces. Abiotic and biotic fluxes and transformations are indicated in italics at the corresponding arrows. Potential immobilization processes in soils are listed in the frame-inset.