Biodegradation of MC252 polycyclic aromatic hydrocarbons and alkanes in two coastal wetlands.

Complementary microbial and geochemical assessment techniques investigated the biodegradation of PAHs and alkanes in salt marshes impacted by crude oil following the Macondo spill. Contamination was observed in the top 10 cm of the marsh profile based on PAH analysis and measurement of the δC signature of impacted marsh soils. Measurement of evolution of C depleted CO indicated mineralization of crude oil ranging from 2.

Biogeochemical controls on biodegradation of buried oil along a coastal headland beach.

Laboratory experiments investigated oxygen dynamics in buried oiled sands sampled from areas impacted by the Macondo spill. Measured oxygen fluxes in oil deposits that were permeable to tidal water ranged from 10 to 10 μmol/cm-sec, orders of magnitude higher than fluxes in non-permeable deposits (10 to 10 μmol/cm-sec). Oxygen dynamics were well described by 1-d models that represent increased oxygen consumption in oiled sands.

Transport of crude oil and associated microbial populations by washover events on coastal headland beaches.

Storm-driven transport of MC252 oil, sand and shell aggregates was studied on a low-relief coastal headland beach in Louisiana, USA including measurement of alkylated PAHs and Illumina sequencing of intra-aggregate microbial populations. Weathering ratios, constructed from alkylated PAH data, were used to assess loss of 3-ring phenanthrenes and dibenzothiophenes relative to 4-ring chrysenes. Specific aggregate types showed relatively little weathering of 3-ring PAHs referenced to oil sampled near the Macondo wellhead with the exception of certain SRBs sampled from the supratidal environment and samples from deposition areas north of beach.