Modelling and validation of polycyclic aromatic hydrocarbons emissions from offshore oil production facilities.

The development of numerical models for investigating the risks and impact caused by human activities to the marine environment is important. Herein, the recently developed ChemicalDrift Lagrangian dispersion model was coupled to a toxicokinetic model and applied to investigate emissions of polycyclic aromatic hydrocarbons (PAHs) discharged from oil and gas production facilities as produced water. The performance of the model was evaluated with available data from a monitoring survey conducted at two oil fields. The survey provided exposure concentrations by means of passive samplers and bioaccumulation data in caged mussels; multiple depths and locations were assessed. The study included 26 PAHs and alkylated derivatives, showing good agreement between the model and the survey measurements. The compounds dominating the scenario were naphthalenes and phenanthrenes. Model provided contamination gradients were in agreement with the survey results, with levels decreasing with distance away from the main sources and with higher concentrations at 20 m depth. ChemicalDrift and the toxicokinetic model provided detailed time series, showing peaks of C1-naphthalene bioaccumulation significantly higher than values accumulated at the end of the monitored period. The utilised model was able to separate the relative contributions of multiple platforms and to identify the major contamination sources, providing a valuable and versatile tool for assessing the impact of discharges at sea.

Impacts of offshore oil spill accidents on island bird communities: A test run study around Orkney and Svalbard archipelagos.

The sea area around the Orkney archipelago, Scotland is subjected to substantial maritime shipping activities. By contract, the Svalbard archipelago, Norway currently has a rather low marine traffic profile. Future projections, however, indicate that the Trans-Arctic route might change the whole transportation picture and Svalbard may be at the centre of maritime activities. Both archipelagos have sensitive environmental resources at sea and inland, including bird communities. There are, for instance, 13 Red Listed species present in Orkney and 2 in Svalbard. In this regard, it is important to address oil spill risks along existing and projected shipping routes. Hypothetical spills were simulated in twelve scenarios for both the Orkney and Svalbard archipelagos with the OpenDrift open-source software. The results indicate risks to seabird communities. For Orkney, the spills resulted in the most extensive contamination of the sea and land environments in autumn. For Svalbard, autumn spills on the contrary presented the lowest risk to seabirds. Based on the simulations, we recommend increased caution for shipping activities in the problematic seasons, improved local readiness for ship accidents and sufficient pre-incident planning.

A dataset of direct observations of sea ice drift and waves in ice.

Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean, lead to a broad range of complex sea ice dynamics. More in-situ measurements are needed to better identify the phenomena and mechanisms that govern sea ice growth, drift, and breakup. To this end, we have gathered a dataset of in-situ observations of sea ice drift and waves in ice. A total of 15 deployments were performed over a period of 5 years in both the Arctic and Antarctic, involving 72 instruments. These provide both GPS drift tracks, and measurements of waves in ice. The data can, in turn, be used for tuning sea ice drift models, investigating waves damping by sea ice, and helping calibrate other sea ice measurement techniques, such as satellite based observations.

Quantitative assessment of two oil-in-ice surface drift algorithms.

The ongoing reduction in extent and thickness of sea ice in the Arctic might result in an increase of oil spill risk due to the expansion of shipping activity and oil exploration shift towards higher latitudes. This work assessed the response of two oil-in-ice surface drift models implemented in an open-source Lagrangian framework. By considering two numerical modeling experiments, our main finding indicates that the drift models provide fairly similar outputs when forced by the same input. It was also found that using higher resolution ice-ocean model does not imply better results. We highlight the role of sea ice in the spread, direction and distance traveled by the oil. The skill metric seems to be sensitive to the drift location, and drift model re-initialization is required to avoid forecast deterioration and ensure the accurate tracking of oil slicks in real operations.

Long term simulations of potential oil spills around Cuba.

Simulations over eight years of continuous surface oil spills around Cuba are carried out to identify the most likely stranding (beaching) locations. The open source Lagrangian oil drift model OpenOil is applied with high resolution hydrodynamic forcing. The actual fraction of the released oil mass reaching different regions is calculated, revealing small differences between a light and a heavy crude oil type. Similar stranding rates for the two oil types are found. Another important conclusion is that, due to the high temporal variability in stranding rates, short term simulations of a few weeks are not suitable to assess environmental risk. The highest stranding rates are simulated in winter in Northern Cuba. It is also found that oil could reach Northern Cuba, Yucatan or Florida in about 3-5 days after a spill.