Hydrocarbons and chemicals: Potential effects and monitoring in the deep-sea

For hydrocarbon exploration and production, the inaccessibility of the deep-sea, the low temperature, the high pressure, and the poorly described, but highly diverse biological communities constitute special environmental challenges. For most marine organisms, there is little or no information available on the toxicity of hydrocarbons or any chemical in the deep-sea. Although technical developments have reduced or removed discharges with hydrocarbons and other potentially damaging chemicals by transport to land or re-injection, accidental leaks and spills may occur. Moreover, we may benefit from knowledge-based options for assessing mitigation alternatives and for considering how much an effluent must be cleaned before it possibly can be discharged. Preliminary studies have indicated that high pressure may alter the partitioning of some hydrocarbons between oil, organisms, and water and hence influence effects in biota. Special adaptations in organisms to deep-sea life may possibly also make them vulnerable to industrial activities. It is thus uncertain to what extent knowledge gained in shallow water can be directly transferred to deep-sea environment for risk assessment and environmental monitoring. Recent environmental law regulations emphasize the importance of biological effects. To meet the management needs of the oil and gas industry for deep-sea exploration and production, we are developing an environmental effect and risk estimation methodology for decision-making, impact assessment, and monitoring organised within the Norwegian Deepwater Programme (NDP).