PARENT SESSION

PH23 Biorestoration Strategies for Contaminated Sediments
Exhibit Hall
8:00 AM - Thursday

(PH256) Understanding Plant Carbon Inputs on PAH Bioavailability in Sediments.

Gregory, S¹, Dzierzynski, E¹, Ejlali, S¹, Hatcher, P², Guthrie-Nichols, E¹, ¹ NC State University, Raleigh, NC, USA² Ohio State University, Columbus, OH, USA

ABSTRACT- A key component of assessing risk reduction by phytoremediation is a thorough understanding of the impact of plant derived organic matter (PdOM) on contaminant bioavailability in sediment. The purpose of this study is to delineate mechanisms, such as sequestration or degradation, by which PdOM impacts weathered polycyclic aromatic hydrocarbon (PAH) bioavailability. We determined alkylated and non-alkylated PAH concentrations (GC/MS/SIM) and ¹³C (GC/IRMS) signatures for chemical fingerprinting of bulk sediment, humic materials, particle size, and density fractions of PAH contaminated sediments collected along successional, native vegetation gradients in freshwater and estuarine environments. PAH distributions in non-vegetated whole sediments reflect profiles for typical weathered petroleum. Total PAH concentrations decline significantly in vegetated sediments, but PAH distributions reflect non-weathered petroleum profiles. For humin fractions of vegetated and non-vegetated sediments, PAH concentrations were similar, and PAH distribution profiles and ¹³C values for humin indicate non-weathered petroleum. d13C values for bulk humin suggests the presence of PdOM. The mass and total PAH content of light density sediment fractions increased along the vegetation gradient. These results indicate both PAH sequestration and degradation as a result of PdOM. We hypothesize that PdOM may desorb non-weathered PAHs from more recalcitrant sediment fractions. Future work with ¹³C labeled PAHs in vegetated microcosms will elucidate better the role of PdOM in sequestering PAH contamination in new organic matter or enhancing PAH desorption and microbial degradation.

Key words: phytoremediation, pah, bioavailability, sediment