Current understanding of the ecological risk of mercury from subsea oil and gas infrastructure to marine ecosystems

Fenny Kho, Darren J. Koppel, Rebecca von Hellfeld*, Astley Hastings, Francesca Gissi, Tom Cresswell, Stuart Higgins

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

6 Citations (Scopus)


Many oil and gas fields are nearing production cessation and will require decommissioning, with the preferred method being complete infrastructure removal in most jurisdictions. However, decommissioning in situ, leaving some disused components in place, is an option that may be agreed to by the regulators and reservoir titleholders in some circumstances. To understand this option's viability, the environmental impacts and risks of any residual contaminants assessed. Mercury, a contaminant of concern, is naturally present in hydrocarbon reservoirs, may contaminate offshore processing and transmission infrastructure, and can biomagnify in marine ecosystems. Mercury's impact is dependent on its speciation, concentration, and the exposure duration. However, research characterising and quantifying the amount of mercury in offshore infrastructure and the efficacy of decontamination is limited. This review describes the formation of mercury-contaminated products within oil and gas infrastructure, expected exposure pathways after environmental release, possible impacts, and key research gaps regarding the ecological risk of in situ decommissioned contaminated infrastructure. Suggestions are made to overcome these gaps, improving the in situ mercury quantification in infrastructure, understanding environmental controls on, and forecasting of, mercury methylation and bioaccumulation, and the cumulative impacts of multiple stressors within decommissioned infrastructures.

Original languageEnglish
Article number129348
Number of pages18
JournalJournal of Hazardous Materials
Early online date4 Jul 2022
Publication statusPublished - 15 Sep 2022


  • Contaminated pipelines
  • Environmental impact assessment
  • Offshore decommissioning
  • Rigs to reefs


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