BS ISO 16751:2020,Soil quality — Environmental availability of non-polar organic compounds — Determination of the potential bioavailable fraction and the non-bioavailable fraction using a strong adsorbent or complexing agent.BS ISO 16751:2020 pdf free download.
The solubility of most non-polar organic contaminants is limited and they are sorbed to the soil matrix, They may desorb and become available for organisms, which may result in an effect [toxie degradation or bioaccumulation ).Not all sorbed (adsorbed and absorbed ) contaminants will desorb and become available.
Extractions used in chemical analysis to measure the total concentration, release more contaminants from the soil than are available. It is however also possible that contaminants are so strongly bounded by the soil that they will not be released by chemical extraction.
If a degradable substance enters a soil, part of it will degrade over time (curve a).The area between curve a and c is extractable by exhaustive chemical procedures For risk assessments, this part is considered as the”total concentration “for which values are defined in many regulations. However only a part of this amount is bioavailable. The area between curves a and b is the bioavailable fraction and the area between curves b and c is the non-bioavailable fraction. The method described in this document enables the measurement of the potential bioavailable and the non-bioavailable fraction of a contaminant in soil.
ISO/TS 16751:2018 specifies an extraction method to determine the bioavailable (potential and environmental available) fraction and the non-bioavailable fraction of a contaminant in soil using a “receiver phase” for an organic contaminant with strong sorbing or complexing properties, for example, Tenax^®[1] or cyclodextrin, respectively.