title: Biogeochemical characterization of MC252 oil:sand aggregates on a coastal headland beach.
abstract: MC252 oil:sand aggregates, termed surface residue balls (SRBs), were sampled for physical, chemical and microbial characteristics from different tidal zones on a coastal headland beach in Louisiana, USA. Supratidal SRBs were smaller, had low moisture content, and salinities that were <2 ppt. Intertidal SRBs were hypersaline and had higher N and sulfate concentrations, consistent with regular tidal inundation. Crude oil components were highest in the intertidal "oil mat" SRBs with C1- and C2-phenanthrenes, C2- and C3-dibenzothiophenes comprising the majority of the PAH concentrations. In the other SRB categories, PAHs and alkanes were depleted and profiles were skewed toward higher molecular weight compounds. Oxygen microelectrode measurements demonstrated that saturated O2 is present immediately after wetting, but O2 consumption in the interior of the aggregate occurs after a few days. Microbial populations varied with position on the beach but sequences similar to known PAH-degrading taxa (Mycobacterium sp. and Stenotrophomonas sp.) were observed.
authors.affiliation: Department of Civil & Environmental Engineering, Louisiana State University, Baton Rouge, LA 70803, United States.
authors.forename: Marilany
authors.initials: M
authors.lastname: Urbano
authors.forename: Vijaikrishnah
authors.initials: V
authors.lastname: Elango
authors.forename: John H
authors.initials: JH
authors.lastname: Pardue
mesh_terms: D000473:Alkanes / Q000032:analysis; D001673:Biodegradation, Environmental; D004784:Environmental Monitoring / Q000379:methods*; D008145:Louisiana; D010578:Petroleum / Q000032:analysis* / Q000706:statistics & numerical data; D059392:Petroleum Pollution / Q000032:analysis* / Q000706:statistics & numerical data; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis
chemical_list: D000473:Alkanes; D010578:Petroleum; D011084:Polycyclic Aromatic Hydrocarbons
keywords: Biodegradation; Crude oil; Deepwater Horizon; Oil-sand aggregates; PAHs; Weathered oil