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Current chemical dispersant effectiveness tests for product selection are commonly performed with bench-scale testing apparatus. However, for the assessment of oil dispersant effectiveness under real sea state conditions, test protocols are required to have hydrodynamic conditions closer to the natural environment, including transport and dilution effects. To achieve this goal, Fisheries and Oceans Canada and the US Environmental Protection Agency (EPA) designed and constructed a wave tank system to study chemical dispersant effectiveness under controlled mixing energy conditions (regular non-breaking, spilling breaking, and plunging breaking waves). Quantification of oil dispersant effectiveness was based on observed changes in dispersed oil concentrations and oil-droplet size distribution. The study results quantitatively demonstrated that total dispersed oil concentration and breakup kinetics of oil droplets in the water column were strongly dependent on the presence of chemical dispersants and the influence of breaking waves. These data on the effectiveness of dispersants as a function of sea state will have significant implications in the drafting of future operational guidelines for dispersant use at sea. [Copyright &y& Elsevier]

With the increase in transport of oil by rail, the probability of oil spills in rivers has increased. Traditionally, focus has been placed on oil slicks moving on the water surface. However, the density of bitumen oil carried by rail within and from Canada to the United States can exceed that of freshwater, causing this oil to get submerged in the water column. This also has the potential of forming oil particle aggregates (OPAs) upon interaction with suspended sediments. The energy-dissipation rate is a key parameter for predicting the formation of oil droplets, and for this purpose, expressions are developed to estimate the energy-dissipation rate at various depths in the river using easily measured quantities such as water depth, streambed slope, and streambed roughness. The formulation showed that for a stream 30 m wide with a natural slope of 1/1,000 and roughness height of 1.0 cm, the average and maximum energy-dissipation rates are 0.01 and 0.22 W/kg , respectively. The average value is comparable to spilling breakers of height around 0.3 m, and the maximum value is comparable to those obtained from plunging breakers of 0.30-m-high waves. The large average value suggests that breakup of droplets in streams is higher than in the open sea under regular waves. [ABSTRACT FROM AUTHOR]

We present an analysis of 2225 simulations of artificial oil well blowouts in nearshore and offshore waters of Newfoundland, Canada. In the simulations, we coupled the VDROP-J and TAMOC models to simulate the fate and transport of oil and gas from the release to the sea surface. Simulations were conducted with and without subsea dispersant injection. We analyzed the simulation database to quantify the mass fraction of oil and gas that surfaces, the mass fraction of released benzene that surfaces, and the horizontal offset to the surfacing zone. These data are also synthesized to yield empirical correlations to predict these output metrics from key input parameters. These correlations are summarized in an excel spreadsheet that allows rapid evaluation of spill dynamics with minimal initial knowledge of spill details. We call this tool an offshore response guidance table, which allows exploration of spill dynamics under diverse spill and response options., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:, (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)