Hypersaline Pore Water in Gulf of Mexico Beaches Prevented Efficient Biodegradation of Deepwater Horizon Beached Oil

Xiaolong Geng, Charbel Abou Khalil, Roger C. Prince, Kenneth Lee, Chunjiang An, Michel C. Boufadel

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The 2010 Deepwater Horizon (DWH) blowout released 3.19 million barrels (435 000 tons) of crude oil into the Gulf of Mexico. Driven by currents and wind, an estimated 22 000 tons of spilled oil were deposited onto the northeastern Gulf shorelines, adversely impacting the ecosystems and economies of the Gulf coast regions. In this work we present field work conducted at the Gulf beaches in three U.S. States during 2010-2011: Louisiana, Alabama, and Florida, to explore endogenous mechanisms that control persistence and biodegradation of the MC252-oil deposited within beach sediments as deep as 50 cm. The work involved over 1500 measurements incorporating oil chemistry, hydrocarbon-degrading microbial populations, nutrient and DO concentrations, and intrinsic beach properties. We found that intrinsic beach capillarity along with groundwater depth provides primary controls on aeration and infiltration of near-surface sediments, thereby modulating moisture and redox conditions within the oil-contaminated zone. In addition, atmosphere-ocean-groundwater interactions created hypersaline sediment environments near the beach surface at all the studied sites. The fact that the oil-contaminated sediments retained near or above 20% moisture content and were also eutrophic and aerobic suggests that the limiting factor for oil biodegradation is the hypersaline environment due to evaporation, a fact not reported in prior studies. These results highlight the importance of beach porewater hydrodynamics in generating unique hypersaline sediment environments that inhibited oil decomposition along the Gulf shorelines following DWH.

Original languageEnglish (US)
Pages (from-to)13792-13801
Number of pages10
JournalEnvironmental Science and Technology
Volume55
Issue number20
DOIs
StatePublished - Oct 19 2021

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

Keywords

  • Deepwater Horizon oil spill
  • Gulf beaches
  • beach hydrodynamics
  • capillary potential
  • evaporation
  • hypersaline condition
  • oil biodegradation

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