Desorption kinetics of PAHs from aged industrial soils for availability assessment

- Desorption kinetics of three industrial PAHs contaminated soils are presented.
- Data are correctly fitted using a first-order two-compartment model.
- Old contaminated soils have a very small rapidly-desorbing fraction.
- Tenax® extraction method seems suitable for bioavailability estimate.
- A 30 h extraction period seems adequate for rapidly desorbing fraction estimate.

Persistent organic pollutants (POPs), such as polycyclic aromatic hydrocarbons (PAHs), may be found in high concentrations in soils of former industrial sites including manufactured gas plants or coking plants. Techniques using moderate solvent extraction, biological tests or solid phase extraction have proved useful for pollution availability estimation. However, more accurate and reliable measurement tools specifically adapted to low concentrations are still needed. Based on a solid-liquid extraction using a Tenax® resin, we suggest a protocol to assess the bioavailability of PAHs, dedicated to aged industrial wasteland soils. Desorption kinetics were measured on three representative contaminated industrial soils. Results were modeled using a first order two-compartment model that provided an estimate of the rapidly desorbing fraction, which was considered to be available, over a 30 h extraction period. In conclusion, this method, allowing the measurement of the available fraction, might prove more relevant than the total concentration value when assessing soil contamination related risks. It may also predict achievable bioremediation performances.