Environmental effects of offshore produced water discharges: A review focused on the Norwegian continental shelf. (December 2020)

• Record Type: Journal Article
• Authors: Beyer, Jonny; Goksøyr, Anders; Hjermann, Dag Øystein; Klungsøyr, Jarle
• Is Part Of: Marine environmental research. Volume 162(2020)
• Publication Date: 2020-12
• Subjects: Offshore produced water discharges -- Environmental effects -- North sea -- Barents sea -- Sensitivity -- Vulnerability -- Effect-based monitoring -- Risk assessment -- Regulation; Marine pollution -- Environmental aspects -- Periodicals; Marine ecology -- Periodicals; Mer -- Pollution -- Aspect de l'environnement -- Périodiques; Écologie marine -- Périodiques; Electronic journals; 577.705
• DOI: 10.1016/j.marenvres.2020.105155
• Languages: English
• ISSNs: 0141-1136

Abstract

Abstract: Produced water (PW), a large byproduct of offshore oil and gas extraction, is reinjected to formations or discharged to the sea after treatment. The discharges contain dispersed crude oil, polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), metals, and many other constituents of environmental relevance. Risk-based regulation, greener offshore chemicals and improved cleaning systems have reduced environmental risks of PW discharges, but PW is still the largest operational source of oil pollution to the sea from the offshore petroleum industry. Monitoring surveys find detectable exposures in caged mussel and fish several km downstream from PW outfalls, but biomarkers indicate only mild acute effects in these sentinels. On the other hand, increased concentrations of DNA adducts are found repeatedly in benthic fish populations, especially in haddock. It is uncertain whether increased adducts could be a long-term effect of sediment contamination due to ongoing PW discharges, or earlier discharges of oil-containing drilling waste. Another concern is uncertainty regarding the possible effect of PW discharges in the sub-Arctic Southern Barents Sea. So far, research suggests that sub-arctic species are largely comparable to temperate species in their sensitivity to PW exposure. Larval deformities and cardiac toxicity in fish early life stages are among the biomarkers and adverse outcome pathways that currently receive much attention in PW effect research. Herein, we summarize the accumulated ecotoxicological knowledge of offshore PW discharges and highlight some key remaining knowledge needs. Highlights: Fish and mussels caged close to offshore PW discharges show mild acute effects. Petrogenic bile metabolites in caged fish show exposure 10 km from PW discharges. Haddock in North Sea are regionally affected by PAH, unclear if PW is main source. North Sea and Barents Sea biota seem largely comparable on sensitivity to PW. More research needed on sub-lethal, long-term impacts of realistic PW exposures.