Torgeir Bakke

Environmental impacts of produced water and drilling waste discharges from the Norwegian offshore petroleum industry

Operational discharges of produced water and drill cuttings from offshore oil and gas platforms are a continuous source of contaminants to continental shelf ecosystems. This paper reviews recent research on the biological effects of such discharges with focus on the Norwegian Continental Shelf. The greatest concern is linked to effects of produced water. Alkylphenols (AP) and polyaromatic hydrocarbons (PAH) from produced water accumulate in cod and blue mussel caged near outlets, but are rapidly metabolized in cod. APs, naphtenic acids, and PAHs may disturb reproductive functions, and affect several chemical, biochemical and genetic biomarkers. Toxic concentrations seem restricted to <2 km distance. At the peak of discharge of oil-contaminated cuttings fauna disturbance was found at more than 5 km from some platforms, but is now seldom detected beyond 500 m. Water-based cuttings may seriously affect biomarkers in filter feeding bivalves, and cause elevated sediment oxygen consumption and mortality in benthic fauna. Effects levels occur within 0.5-1 km distance. The stress is mainly physical. The risk of widespread, long term impact from the operational discharges on populations and the ecosystem is presently considered low, but this cannot be verified from the published literature.

Environmental effects of the Deepwater Horizon oil spill: A review.

The Deepwater Horizon oil spill constituted an ecosystem-level injury in the northern Gulf of Mexico. Much oil spread at 1100-1300m depth, contaminating and affecting deepwater habitats. Factors such as oil-biodegradation, ocean currents and response measures (dispersants, burning) reduced coastal oiling. Still, >2100km of shoreline and many coastal habitats were affected. Research demonstrates that oiling caused a wide range of biological effects, although worst-case impact scenarios did not materialize. Biomarkers in individual organisms were more informative about oiling stress than population and community indices. Salt marshes and seabird populations were hard hit, but were also quite resilient to oiling effects. Monitoring demonstrated little contamination of seafood. Certain impacts are still understudied, such as effects on seagrass communities. Concerns of long-term impacts remain for large fish species, deep-sea corals, sea turtles and cetaceans. These species and their habitats should continue to receive attention (monitoring and research) for years to come.

Environmental risk assessment of combined effects in aquatic ecotoxicology: a discussion paper.

Environmental regulatory edicts within the EU, such as the regulatory framework for chemicals REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals), the Water Framework Directive (WFD), and the Marine Strategy Framework Directive (MSFD) focus mainly on toxicity assessment of individual chemicals although the effect of contaminant mixtures is a matter of increasing concern. This discussion paper provides an overview of the field of combined effects in aquatic ecotoxicology and addresses some of the major challenges related to assessment of combined effects in connection with environmental risk assessment (ERA) and regulation. Potentials and obstacles related to different experimental, modelling and predictive ERA approaches are described. On-going ERA guideline and manual developments in Europe aiming to incorporate combined effects of contaminants, the use of different experimental approaches for providing combined effect data, the involvement of biomarkers to characterize Mode of Action and toxicity pathways and efforts to identify relevant risk scenarios related to combined effects are discussed.

Managing the environmental effects of the Norwegian oil and gas industry : From conflict to consensus

Abstract In the early days of exploitation of the oil resources on Norway’s continental shelf there was little control over environmental impacts. The oil companies expected effects of their activities to be found to a 1 km radius round platforms. In the late 1980s data started appearing that suggested that effects were over much larger areas. These findings were disputed but subsequent studies showed that a more realistic figure of the area affected was a 3 km radius giving roughly 10 times the area predicted by the companies. The Norwegian authorities reacted by imposing restrictions on discharges of oil-based drilling cuttings and since 1993 oil-based drilling mud or cuttings have not been intentionally discharged to sea on the Norwegian shelf. In 1996 Norway changed its offshore monitoring from field based monitoring of sediments to a regional monitoring of both sediments and the water column. The change makes it possible to obtain a better overview of the environmental conditions, at the same time it also reduces costs for the operators.

A soft-bottom sublittoral mesocosm by the Oslofjord: Description, performance and examples of application

Abstract Controlled experiments and detailed studies of behaviour in the subtidal require diving, submersible vessels or instruments placed in situ. These methods often limit experimental design. Furthermore, experiments with toxic chemicals in the field may not be possible due to lack of dosage control, environmental consequences, and public welfare. Such problems can be overcome by the use of mesocosms. In this paper a soft-bottom mesocosm in the Oslofjord, Norway is described. The mesocosm consists of two indoor basins each with a surface area of 100 m2 and a maximum water depth of 1.7 m. Each basin is divided into three compartments. Soft-bottom sediment sections were collected in the field by a modified USNEL box-corer (0.25 m2). The sediment was transferred to boxes and brought into the mesocosm. The water level in the mesocosm can be lowered so that the sediment surfaces are easily accessible for sampling, manipulation, inspection, or measurements requiring equipment or techniques not compatible wi...

Colonization of amphipods and polychaetes to sediments experimentally exposed to oil hydrocarbons

Field experiments using colonization trays with or without cover, and larger enclosures were used to investigate the effects of the water soluble fractions of oil hydrocarbons (Ekofisk Crude oil) on recruitment of zoobenthos to shallow soft bottoms. The experiments were performed in situ at 8 m depth off Bergen, Norway. The main macrofaunal immigrants (July-December 1980) were amphipods (mainly Corophium bonelli) and polychaetes (mainly capitellids, cirratulids, orbinids, and spionids). Covered trays had lower colonization by polychaetes than open trays, but addition of low levels of oil hydrocarbons did not affect polychaete density. C. bonelli showed similar rates of colonization to open and covered trays, but the latter showed that exposure to oil had a negative effect on population density, especially on juveniles. The reduced density in the oil .exposure treatment may have been due to reduced survival of the marsupial embryos, or increased swifiaming activity (escape reactions to the oil). Natural predation on the amphipods in the uncovered trays was high enough to mask any negative effect of exposure to oil.

Transport and sedimentation of Cu in a microtidal estuary, SE Norway

The transport and sedimentation of copper in the Glomma estuary, SE Norway during a period of 90% reduction in the industrial input of Cu, was studied from sediment trap material and compared to samples of the bottom sediments. Traps were deployed at four stations for several monthly periods during 1990, 1994 and 1995. Trapped material was analysed for suspended particulate matter (SPM), total organic carbon (TOC) and nitrogen (TN), Cu, and Al. Only about 10% of the Cu from the river is trapped in the estuary. Still there was a moderate but significant reduction in Cu concentration in the trap SPM from 1990 to 1994, reflecting the industrial reductions, but only if excluding summer samples apparently influenced by antifouling Cu from boat paint. Settling matter therefore seems appropriate and sensitive for monitoring changes in the Cu load. The results supported the view that TOC is the main carrier of Cu to the sediments.

Polychlorinated Dibenzo-p-Dioxins (PCDDs) and Dibenzofurans (PCDFs) in the Grenland Fjords (Norway)—Disposition, Levels, and Effects

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are regarded as highly toxic. Their lipophilicity and persistence also render them subject to bioaccumulation. The Grenlandfjords (southern Norway) have long been polluted by PCDD/Fs through the magnesium production at Herøya (1951–2002). Therefore, extensive environmental monitoring was performed in the area, and the project “Dioxins in the Grenlandfjords—DIG” was launched to study abiotic mass balances, biotic processes and ecological risk. This article describes some results from DIG on the dispositions of PCDD/Fs in the food web and biological effects. Furthermore, data from the Norwegian monitoring of the Grenlandfjords are described. Differences in cod liver PCDD/F levels were found between stations, with the highest concentrations in the inner fjord (the Frierfjord), closest to the pollution source. Furthermore, considerable decreases in the concentrations followed the large discharge reductions (1975 and 1990). Contrary to earlier food web studies on other organochlorines, it was found that the concentrations of PCDD/Fs decline with higher trophic level. Higher chlorinated congeners also constituted a lower percentage of ∑PCDD/Fs higher in the food chain. The results indicated a limited bioaccumulation of PCDD/Fs, especially of higher chlorinated congeners, likely due to reduced membrane permeability (high molecular size), and possibly slow transport through intestinal aqueous phases. Hepatic cod 7-ethoxyresorufin O-deethylase (EROD) activities differed between the Frierfjord and the Eidangerfjord, showing the different PCDD/F exposure in the two fjords. Furthermore, seasonal variations in cytochrome P-450 (CYP) 1A activity were shown, with different responses between genders. The differences were likely linked to the reproductive cycle of the fish.

In vivo bioaccumulation of contaminants from historically polluted sediments - relation to bioavailability estimates.

Many contaminants are recalcitrant against degradation. Therefore, when primary sources have been discontinued, contaminated sediments often function as important secondary pollution sources. Since the management and potential remediation of contaminated marine sediments may be very costly, it is important that the environmental risks of contaminants present in these sediments and benefits of remediation are evaluated as accurately as possible. The objective of this study was to evaluate the bioavailability of common organochlorine contaminants and polycyclic aromatic hydrocarbons (PAHs) in selected polluted sediments from Norway by simple generic sorption models (free energy relationships), as well as by pore water concentration measurements. Furthermore, the aim was to predict bioaccumulation from these bioavailability estimates for comparison with in vivo bioaccumulation assessments using ragworm (Nereis virens) and netted dogwhelk (Hinia reticulata). Predicted biota-to-sediment accumulation factors (BSAFs) derived from pore water concentration estimates were in better agreement with the bioaccumulation observed in the test organisms, than the generic BSAFs expected based on linear sorption models. The results therefore support that site-specific evaluations of bioaccumulation provide useful information for more accurate risk assessments. A need for increased knowledge of the specific characteristics of benthic organisms, which may influence the exposure, uptake and elimination of contaminants, is however emphasized.

Identification of Fine-Scale Marine Benthic Ecoclines by Multiple Parallel Ordination

The species-environment relationship is a fundamental structural property of natural ecosystems. Marine sedimentary macrofauna is known to be structured by a range of environmental variables; however, the mechanisms by which environmental variables covary to form complex-gradients (i.e., groups of intercorrelated environmental variables), and how these are related to coenoclines (i.e., gradients in species composition), remain poorly understood. We classified our study area into geomorphological features that were used for stratified sampling of macrofaunal polychaetes, molluscs, and echinoderms. The resulting species-by-site matrix was subjected to indirect gradient analysis by a multiple parallel ordination strategy, using detrended correspondence analysis and nonmetric multidimensional scaling. One major and one minor coenocline were identified. Based on the correlation between complex-gradients and the main coenocline we hypothesise the existence of two ecoclines that we have termed Periodic hypoxia and Periodic physical forcing. We conclude that a combination of recurrent (periodical) and extreme events is likely to determine the variation found in the species composition of marine sedimentary ecosystems. Based on the results of our study, we conclude that indirect gradient analysis is a useful tool for enhancement of our basic mechanistic understanding of the processes governing the compositional structure of marine sediment communities.