Development of Safe and Sustainable Systems of Enhanced Bioremediation of PAH Mixtures

Oregon State University, Corvallis OR

Investigators

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Abstract

PROJECT SUMMARY – SEMPRINI PROJECT The goal of this project is to create novel, safe, sustainable systems that treat PAH mixtures while minimizing the formation of hazardous PAH breakdown products. Our approach is to immobilize microbial cultures in hydrogel beads. We will learn to associate primary and secondary PAH transformation products with specific bioremediation technologies, then help stakeholders select the most effective bioremediation technologies for their sites. This project challenges the common assumption that the contamination problem ends when parent PAHs degrade. We will develop novel biological techniques to treat PAH mixtures from contaminated sediments and soils from the Portland Harbor Superfund Site (PHSS). We will reduce toxicity from parent PAHs via microbial processes while monitoring the appearance and the toxicity of degradation products. To identify and measure the products formed during the transformation process, we will rely on advanced targeted and non-targeted high-resolution mass spectrometry methods paired with fractionation and high-throughput effect-directed analysis. We will isolate bacterial cultures from a Superfund site that promote cometabolic or metabolic transformations of PAH mixtures. We will compare the transformation abilities of those cultures with cultures we have studied previously. We will apply our hydrogel technology to create permeable reactive biological barriers (PRBB) that treat PAH mixtures in situ. We also plan to test an ex-situ bench-scale system in which we apply hydrogels to treat soil washing solutions that contain PAH mixtures. Since the biological processes occur within the hydrogel beads, mixtures of beads with different microbes can promote the more complete transformation of PAH mixtures to non-toxic products. We plan to incorporate cultures grown in the presence of PAH mixtures obtained from passive samplers at the PHSS into hydrogel beads for the proposed treatment technologies. We will track the transformation of parent PAHs by GC-MS and UPLC-HRMS methods developed in our past projects. We will evaluate the reduction or increase in toxicity of the transformation products of PAH mixtures in fractionated and non-fractionated samples in collaboration with the Tanguay Project (via the in vivo embryonic zebrafish assay) and the Tilton Project (via the in vitro human lung cell assay). We will correlate bioactivity in sample fractions with accurate masses detected in parallel via UPLC-HRMS. This approach will allow us to identify corresponding structures of masses in active fractions via non-target analysis and suspect screening. We will identify peaks that covary with observed biological effects and attribute these peaks to candidate causative chemicals.