The Use of Dispersants in Marine Oil Spill Response (2020) / Chapter Skim
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7 RESEARCH AND DECISION-MAKING PROTOCOLS
7 RESEARCH AND DECISION-MAKING PROTOCOLS
Pages 199-228
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From page 199... ...
Key to the application of geochemical approaches is knowledge of the chemical composition of the spilled oil, which in the case of the DWH oil spill was not readily available. Thus, for major oil spill events in the future, spill response operations would benefit if all available information regarding the chemical composition of the spilled oil and applied dispersant was made publicly available, and if oil samples were also made available to the response and scientific communities (see Chapter 5)
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From page 200... ...
. • Seventh, geochemical referencing was used to estimate the trapping of liquid oil droplets in the deep intrusion layers (Gros et al., 2017)
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From page 201... ...
. Emerging Issues and Advances Isotope Tracking In addition to the quantification of compound concentrations described above, numerous isotopic methods proved useful in tracking the transport and fate of discharged materials during DWH; these and a number of emerging isotopic methods may prove useful in future spill scenarios.
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From page 202... ...
The application of these approaches has provided critical insight as to transport, fate, and impacts of oil and dispersed oil from this spill; yet, after 9 years, few of these analytical approaches have been formally adopted by the response community. Biodegradation Protocols State of the Art and Potential Pitfalls The past decade has seen an increase in the use of molecular tools as direct (culture-independent)
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From page 203... ...
Numerous studies published since DWH focused on oil biodegradation. Unfortunately many studies were done with samples collected and stored for weeks to years after they were collected (Bælum et al., 2012; Crespo-Medina et al., 2015; Dubinsky et al., 2013; Hu et al., 2017; Liu et al., 2017a)
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From page 204... ...
. In spill responses, scientists have observed the microbial biomass in the water column slowly decline long after the oil has been depleted.
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From page 205... ...
The governing documents for oil spill response include: • National Response Framework1 • National Oil and Hazardous Substances Contingency Plan2 • Title 40 CFR 300.115 -- Regional Response Teams None of these includes a complete systems approach; for instance, oil biodegradation should be part of any such field sampling plan that would also provide for follow-on laboratory studies that will be critical for the analysis and understanding of the fate and effects of the spilled oil. Figure 7.2 provides an overview of key aspects of that plan in a stepwise fashion to ensure the best 1See https://www.fema.gov/media-library/assets/documents/117791.
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From page 206... ...
. A number of microcosm studies have recently been focused on quantifying changes in microbial structure and function and potential oil biodegradation rates in seawater and ice core 3See https://data.gulfresearchinitiative.org.
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From page 207... ...
. Modeling Biodegradation State of the Art and Pitfalls The modeling of the biodegradation of oil droplets in the water column builds on modeling work on the biodegradation of dissolved hydrocarbons in aquifers and liquid oil in sediments.
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From page 208... ...
(2013) modeled the biodegradation of dispersed oil using Monod kinetics and a quasi-steady-state approximation for the dissolution of low solubility hydrocarbons in the water column, where the oil dissolves before being biodegraded.
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From page 209... ...
Furthermore, in terms of oil biodegradation studies, test facilities systems using artificial and recycled seawater do not have the normal microbiome of the ocean environments being simulated. Tower Tanks Data on oil droplet size and plume behavior for the development and validation of models have been collected from experimental studies using tower tanks.
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From page 210... ...
, and interfacial tension analysis. Scaling of oil droplet size data remains a challenge for the potential use of tower tanks due to limitations in the volume of oil that can be released and the diameter of the nozzle in the injection systems.
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From page 211... ...
FIGURE 7.5 Experimental system setup for the towing of the vertical discharge pipe and instrument package as a unit to allow for plume dilution and the proper monitoring of oil droplets. SOURCE: Ohmsett.
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From page 212... ...
this system can be cooled down to 4°C, is fitted with instrumentation for the characterization of oil droplets, and it has a state-of-the-art delivery system for "live oil" injection. Analysis of oil droplet size from comparable experiments (nozzle, oil type, flow rates, injection techniques, and dispersant product)
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From page 213... ...
Gas-saturated oil droplets fracture into many smaller droplets when such pressure drops are simulated, consistent with observations of a similar magnitude pressure drop at DWH (Malone et al., 2018)
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From page 214... ...
Monitoring all the potentially important variables with sufficient temporal and spatial resolution is costly at best, and frequently impracticable. For instance, doing a simple mass balance of oil in the water column during a blowout is a significant logistical challenge even in a modestly sized dedicated field experiment.
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From page 215... ...
As discussed in Chapters 2 and 6, oil droplet size is possibly the single-most important factor affecting the fate of oil in a blowout. Much work has been done in improving droplet size models, but the question of how well these models scale up to the field remains largely unanswered.
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From page 216... ...
Validation of Droplet Models State of the Art Since the DWH spill, a great deal of work has been done on developing models of oil droplet sizes emanating from a deepwater blowout. Chapter 2 shows that for DWH-like scales there is a discrepancy of up to four times between the three models examined.
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From page 217... ...
, the authors state that the high-energy WAF (HEWAF) standardized protocol was intended to produce WAFs that more closely emulate the dispersion of oil droplets under high pressure (i.e., the DWH spill)
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From page 218... ...
. Emerging Issues and Advances A large quantity of experimental toxicity data is available that could be analyzed to continue to investigate the question as to whether exposure media containing chemically dispersed oil is more toxic than is media containing physically dispersed oil.
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From page 219... ...
do not consistently include human health. Some have argued that it is unnecessary because human health considerations override all others throughout an oil spill response.
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From page 220... ...
The oil spill response process clearly guides the Response Coordinator to avoid obvious risk of adverse human health consequences, but the trade-off is less clear when it is between ecosystem effects and a lower level of human health risk to workers and to community members, particularly among those who suffer from preexisting conditions that increase their vulnerability. Issues related to the wide variability in human vulnerability also include the difficulty in extrapolation of epidemiological and toxicological findings to those at highest risk.
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From page 221... ...
In situations of uncertainty, people are more likely to respond positively to questions about potential exposure, particularly when the issue has been publicized as one of concern -- such as with dispersants. It is unclear as to whether the possibility of future litigation leading to funding for those exposed may contribute to recall bias in a situation such as the DWH spill response.
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From page 222... ...
While there is some inferential evidence that benzene is more likely to remain in water rather than be volatilized with subsea dispersant application, the committee was unable to find equivalent evidence of a change in PAH levels in seafood as a result of dispersant use. TOOLS FOR OIL SPILL RESPONSE DECISION MAKING Risk Assessment Tools State of the Art The Distinction Between Operational Versus Environmental Monitoring Monitoring during an oil spill response is typically divided into two different categories: • Operational Monitoring (or Type I monitoring)
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From page 223... ...
. Both documents are intended to support development of operational, incident-specific monitoring plans, but they have often been confused with the USCG Special Monitoring of Applied Response Technologies protocols that are aimed at monitoring surface dispersant application at smaller, ephemeral oil spills.
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From page 224... ...
. During the DWH spill response, tens of thousands of water samples were collected and shipped to analytical laboratory laboratories across the United States for later analysis (OSAT, 2010)
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From page 225... ...
, should track emerging technologies and provide support and opportunities for those technologies to be tested for applicability to marine oil spill response. Promising technologies should be supported and brought to a state of application readiness, perhaps with support from industrial partners.
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Recommendation: Analyze the large quantity of available experimental toxicity data to investigate the question whether exposure media containing chemically dispersed oil is more toxic than is exposure media containing physically dispersed oil. The analysis would need to 8As a result of settlements from the DWH spill, $500 million was designated to the development and 30-year endowment of the National Academies Gulf Research Program, whose mission is "catalyzing advances in science, practice, and capacity to generate long-term benefits for the Gulf of Mexico region and the Nation." In furtherance of its mission, the National Academies Gulf Research Program funds grants, fellowships, and activities.
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From page 227... ...
. Finding: There are several limitations to methods used to assess human health effects of previous oil spills, making it difficult to determine causal relationships.
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