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1D - Soil and Sediment Contamination (TUP/10) Effects of aging on the bioavailability of PAHs in soil measured via solid phase microextraction. Barendregt, Arjan1, ter Laak, Thomas1, Jensen, John2, Hermens, Joop1, 1 Institute for Risk Assessment Sciences, Utrecht, the Netherlands, the Netherlands2 National Environmental Research Institute, Silkeborg, Denmark, Denmark ABSTRACT- It is well known that aging in soil may reduce bioavailability to biota. The freely dissolved concentration in pore water is an important aspect of bioavailability, but the actual measurement of free concentrations is not simple. Solid phase extraction techniques, under the conditon of negligible depletion, represent useful partition based sampling methods to measure freely dissolved concentrations in complex matrices. This study reports on the effects of aging of PAHs in a lab contaminated soil on the freely dissolved concentration in pore water. Soil was contaminated in the laboratory with three PAHs (phenanthrene, pyrene and benzo(b)fluoranthene) and stored for different periods at 4 degrees C. In samples from each aging time, total concentrations of Phe, Pyr and BF were measued after soxhlet extraction with ethylacetate. Free concentrations were measured in each sample as well using disposable solid phase microextraction (SPME) fibers which were exposed for 48 hours. Initial studies have shown that 48 hours is long enough to reach an equilibrium in the system. The fibers were extracted with acetonitril. The PAHs were analysed on a HPLC with fluorescence detection. Recoveries of the soil and fiber extractions were measured as well. Total concentrations of the three PAHs in the soil are compared to measured free concentrations in the pore water in the samples from each aging period. Research is performed within the EU project Liberation (EVK1-CT-2001-00105). Key words: soil, bioavailability, PAHs, aging |
