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

18 Citations (Scopus)
3 Downloads (Pure)

Abstract

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
Volume438
Early online date4 Jul 2022
DOIs
Publication statusPublished - 15 Sept 2022

Bibliographical note

Funding Information:
This research was funded by the Australian Government’s Industry Growth Centre National Energy Resources Australia (NERA) through a National Decommissioning Research Initiative (NDRI) grant to Curtin University (grant number 13266). The NDRI project was funded by eight industry partners including Shell Australia, Esso Australia, Chevron Australia, BHP Petroleum, Woodside Energy, Santos Limited, ConocoPhillips Pipeline Australia, and Vermilion Oil and Gas Australia. Astley Hastings is funded by the National Decommissioning Centre, Scotland, and the University of Aberdeen.

The authors thank Professor Claus Otto (Curtin University) and Professor Richard Neilson (National Decommissioning Centre, Aberdeen, UK.) for comments and support to the project team; and Samantha Jarvis (National Environment Resources Australia), Professor Peter Macreadie, Dr Rick Tinker, and the industry partners of the National Decommissioning Research Initiative for helpful comments to this project. This research was funded by the Australian Government's Industry Growth Centre National Energy Resources Australia (NERA) through a National Decommissioning Research Initiative (NDRI) grant to Curtin University (grant number 13266). The NDRI project was funded by eight industry partners including Shell Australia, Esso Australia, Chevron Australia, BHP Petroleum, Woodside Energy, Santos Limited, ConocoPhillips Pipeline Australia, and Vermilion Oil and Gas Australia. Astley Hastings is funded by the National Decommissioning Centre, Scotland, and the University of Aberdeen. Past research has shown that mercury associates with offshore oil and gas pipelines as well as other products associated with the infrastructure, deeming such materials “hazardous”. However, the current environmental risk assessments for decommissioning activities of such contaminated materials does not take into account the complexity of the compound's nature and the potential harmful effects on e.g. marine food webs. This review paper has outlined these gaps in our current understanding, as well as providing advice on addressing these gaps to ensure that the marine environmental risk assessments reflect the hazardous nature of mercury-contaminated offshore infrastructure.

Publisher Copyright:
© 2022 The Authors

Keywords

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

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