Resolving the dilemma of dispersant use for deep oil spill response

The choice of droplet size probability distribution function for oil spill modeling is not trivial

“…This difference also reflects high surface evaporation rates (de Gouw et al 2011), affecting mostly the largest droplets since they rise faster. Interestingly, the total oil mass from case 2 that sedimented is on the same order of magnitude than the oil that beached in case 1, highlighting that the predictions of oil mass beached versus sedimented is critically important for evaluation response's tradeoff (Murawski et al 2019).…”

“…Faillettaz et al 2021 -Marine Pollution Bulletin -doi : 10.1016/j.marpolbul.2020.111920 This study focuses on the critical choice of the DSD's PDF for modeling the transport and fate of uncontrolled deep-sea oil spills. To determine optimal oil spill responses and access tradeoffs, different scenarios are typically weighted, including considering the application of surface and/or subsea chemical dispersants (Xu et al 2019, Murawski et al 2019. Here, we demonstrate that, even with similar d50, the surfacing time (Figure 1b,d), the distance travelled by droplets, and the patterns of sedimented and beached oil (Figure 2 & 3) will vary based on the two PDFs most frequently used for modeling the DSD during deeps oil spills, lognormal and Rosin-This work is licensed under a CC-BY-NC-ND 4.0 license.…”

“…For the DWH, major differences occur at the edge of the oil distribution, which is of remarkable importance since toxic oil concentrations were present in these regions, yet invisible to satellite imagery (Berenshtein et al 2020). Given the rapid advances in oil spill research following DWH, extending hindcast modeling approaches to consider a range of characteristic DSDs functions (d50 and PDFs) are needed to ultimately help predict the distribution of oil mass and evaluating the response tradeoffs in any future deep-sea spill and response measures (Malone et al 2020, Murawski et al 2019.…”

A Decade of GoMRI Dispersant Science: Lessons Learned and Recommendations for the Future

“…The objectives of using SSDI as a response strategy were to reduce vertical oil transport to the sea surface and subsequent formation of surface slicks, and to reduce the exposure of responders to volatile organic compounds (VOCs) that could be harmful to their health and negatively affect operations (Kujawinski et al, 2011;Gros et al, 2017;Paris et al, 2018;Murawski et al, 2019Murawski et al, , 2020NASEM, 2020). Under SSDI, dispersants reduce the ejection turbulence of oil emanating from the wellhead (Figure 1), allowing the formation of tiny neutrally buoyant oil droplets in the deep sea that can be more readily biodegraded (Hazen et al, 2010;Prince et al, 2013;Prince and Butler, 2014).…”

“…Modeling and experimental work has been undertaken since the spill in an attempt to understand the effects of SSDI on both the quantity of surfacing vs. subsurface oil and whether SSDI reduced the concentration of VOCs around the ship that was drilling a relief well to intercept and kill the blown-out well (e.g., Paris et al, 2012;Gros et al, 2017;French-McCay et al, 2018). At present, there is conflicting evidence as to the efficacy of the use of SSDI (Nedwed et al, 2012;Nedwed, 2017;Gros et al, 2017;Paris et al, 2018;Murawski et al, 2019;Pesch et al, 2018Pesch et al, , 2020.…”