Chemical methods for prediction of bioavailability of persistent organic pollutants in solid
                                      environmental matrices

                                           Lucie Bielská

Hydrophobic organic contaminants (HOCs) are ubiquitous in the environment but they have a tendency
to accumulate in soil where they can pose serious risks. However, the toxicity of these
contaminants in soils is not directly related to their total concentration and usually decreases
with pollutant-soil contact time (aging). Therefore, the current way of risk assessment based on
the total soil concentration overestimates risks because it assumes that the whole fraction is
biologically available. Instead of the total concentration of a contaminant in soil rather its
bioavailability should be measured. Bioassays can provide direct information on bioavailability,
however, the methods are often laborious, time consuming, and associated with high variability.
Therefore, chemical methods fulfilling the criteria of fastness, simplicity, and low costs (such as
supercritical fluid extraction (SFE) or solid phase microextraction (SPME)) have been suggested to
estimate risks of the polluted sites. However, so far our knowledge of the ability of SFE and SPME
to reliably predict bioavailability is limited due to the low number of pollutants and samples
tested. Our studies were, therefore, designed to include soils with significantly different
properties that were spiked with various compounds and aged. Samples were extracted by means of SFE
and SPME and extractability of the compounds from various soils was compared to the uptake by
earthworms (Eisenia fetida). This design enabled us to reveal which soil properties drive
bioavailability and extractability and if bioavailability can be estimated using the SFE or the
SPME method.