Dear Ashkan Jahandari,

"Bioaccessibility. This term refers to the fraction of the total amount of a substance that is potentially available for absorption. In this study, laboratory methods were used to extract these bioaccessible portions from the soils. Bioaccessibility is therefore used to help predict bioavailability. "

California Department of Toxic Substances Control:

https://www.dtsc.ca.gov/InformationResources/upload/Bioaccessibility_Def.pdf

" Bioaccessibility or Environmental Availability .The portion of total metal in soil, sediment, water, or air that is available for physical, chemical, and biological modifying influences (e.g., fate, transport, bioaccumulation) is termed the environmentally available fraction. Environmentally available metal is not sequestered in an environmental matrix, and it represents the total pool of metal at a given time in a system that is potentially bioavailable to (able to contact or enter into) an organism. The bioaccessible fraction (BF) of metal is the portion (fraction or percentage) of environmentally available metal (e.g.,

Metals are available in the form of different salts. All salts are not water soluble and are not available to plants. When there is change in pH, temperature or dissolved water contents, that metal (s) become water available. Accessibility depend on root system.

Acessibile metals are not bioavailable as there are chelating factors in the soil

I agree with Tomasz

Dr. Tomasz has provided appropriate details.

Bio-availability of heavy metal in soil is the amount that is available whereas bio-accessibility of heavy metal in soil is the amount that can be taken by the plants.

Article Bioaccessibility of Metals in Soils for Different Liquid to ...

I agree with Dr. Tomasz Grabowski.

I agree with Dr. Tomasz.

Thanks Dr. Tomasz. , T. H. Al-Noor , Sergei A. Ostroumov, Rakesh Prasad Bhagat, and Abhijit Mitra for your cordial response.