Bioavailability, in environmental and soil sciences, represents the amount of an element or compound that is accessible to an organism for uptake or adsorption across its cellular membrane.
[1][2][3] In environmental and agricultural applications, bioavailability most often refers to availability of contaminants, such as organic pollutants or heavy metals, in soil systems and is also used frequently in determining potential risk of land application of sewage sludge or other inorganic/organic waste materials.
In these forms, contaminants are relatively inaccessible to microbial or plant uptake and must dissociate and re-dissolve into the soil solution to become biological available.
[7] However, there are a number of chemical and biological tests used to estimate bioavailability including a direct measurement of contaminant bioaccumulation in earthworms (Eisenia fetida).
[7] Fugacity modelling of bioavailability is based on the solubility and partitioning of compounds into aqueous and non-aqueous phases.