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(16-27) Bioavailability of polycyclic aromatic hydrocarbons in clay-rich, creosote polluted soils subjected to bioremediation. Ortega-Calvo, José Julio*,1, Niqui - Arroyo, José Luis1, Bueno - Montes, Marisa1, 1 Instituto de Recursos Naturales y Agrobiología, CSIC, Sevilla, Spain ABSTRACT- The present study is focused on the difficulties caused to bioremediation by soils rich in clay fractions. The bioavailability of PAH in creosote-polluted soils from a wood-treating facility in Southern Spain was studied. Mineralization by indigenous populations and added inocula of 14C-labelled, target PAH (phenanthrene, pyrene, fluoranthene and anthracene) freshly added to the soils was measured under laboratory conditions. Measurements of the indigenous PAH by vigorous solvent extraction and HPLC was also performed to determine residual fractions. In spite of using optimal conditions for microbial activity (shaking slurries, inoculation, nutrients, etc.), biodegradation often stopped or occurred at very slow rates after the decontamination of a significant fraction of the initially present PAH. The resulting levels were still above legal standards. Tenax extraction of sterilized soil suspensions revealed the presence of a desorption-resistant PAH fraction of the same order of magnitude as the residual PAH after bioremediation. The implications for bioremediation of the site will be discussed. Key words: bioremediation, creosote |
