Oil in the Sea IV: Quick Guide for Practitioners and Researchers (2023)
Chapter: Additional Research Recommendations
Additional Research Recommendations
The report includes detailed lists of specific research needed to advance understanding of oil in the sea. The key recommendations to fill these research gaps are summarized here.
Research Recommended to Advance Oil Spill Response and Minimize Effects
4.1 New Fuel Types and Oilfield Production Products: The effectiveness of various response techniques and their windows of opportunity in responding to hybrid fuel oil, particularly low sulfur fuel oils, and to diluted bitumen (“dilbit”) oilfield products, must be carefully evaluated.
4.2 Life-Cycle Analysis of Oil Spill Based on Response Scenarios: A continuous collaboration among academic, government, and industry scientists and response practitioners is needed to develop a comprehensive, multifaceted, and realistic analysis of “cradle to grave” oil slick fate and effects for various response scenarios,
including monitored natural attenuation. This analysis should include all possible variations of response scenarios of a single event so as to give decision makers a complete and comprehensive picture of the decision outcomes in each of the scenarios. At present, it is challenging to create a complete and comprehensive picture from the results of multiple uncoordinated studies with a narrow focus, as these studies are conducted with different goals and conditions in mind and do not lend themselves to a seamless integration.
4.3 Health and Safety Risks to Response Professionals: Research into health risks to and psychological impacts on response personnel involved in various types of response operations should be conducted. This information should be integrated into response decision making.
4.4 Response Tools—Mechanical Recovery: Mechanical recovery technologies would benefit from the research efforts aimed at improving encounter rates, specifically the volume of oil entering the containment devices and available for recovery as well as optimization of a particular technology’s efficiency under various environmental conditions and spill scenarios (e.g., recovery of submerged oil). Mechanical recovery should also be viewed as a multicomponent system involving equipment mobilization and oil collection, recovery, storage, transfer, and disposal. Analysis of potential bottlenecks in this system under different response scenarios will help to identify potential areas for improvements.
4.5 Response Tools—In Situ Burning: Research focused on improving efficiency of and expanding a window of opportunity for in situ burning should continue and include various scenarios. Such scenarios could include burning in conventional booms, use of herders, inland burning, and burning under Arctic conditions.
4.6 Response Tools—Chemical Dispersants: Continuous research efforts focused on increasing natural dispersion processes through use of chemical dispersants (including new formulations and natural materials), and on mechanical dispersion techniques for selected offshore blowout scenarios are recommended.
4.7 Response Tools—Arctic Conditions: Although significant progress has been made in our understanding of the applicability and efficiency of various response techniques under Arctic conditions, these efforts should continue, given the great diversity of potential response scenarios as well as new formulations of fuels that may be encountered in that region.
4.8 Oiled Wildlife Management: Additional research into long-term impacts, survival rates, and return to normal function of treated and released animals would be beneficial to refine oiled wildlife management methods.
Research Needs to Better Understand Fates of Oil in the Marine Environment
5.1 Physical Mechanisms Affecting the Fate of Oil: With new laboratory facilities and methods, significant progress has been made in measuring droplet size distributions for oil jet breakup and for dispersion of floating oil. These data can be used to develop and test models for oil droplet size distribution; however, because the reduced-scale laboratory experiments do not match the field-scale parameter space, field-scale data for oil and gas breakup and dispersion remain an important need. Experiments utilizing SSDI are particularly important to test dispersant mixing at field scale and because treated oil at the field scale falls further outside the parameter space of existing measurements than do untreated releases.
5.2 Chemical Reactions Affecting the Fates of Oil: With the renewed appreciation of photo-oxidation as a significant process
affecting oil chemistry, more research is needed to focus on interactions of photo-chemical products with the physical and chemical properties of oil, its behavior in the water column and on shorelines (e.g., emulsification and adherence to mineral surfaces), and its effect on biodegradation. The fate and effects of oxygenated hydrocarbons, especially in coastal regions, should be examined, as well as the effect of surface or subsurface dispersant addition on photo-oxidation and subsequent processes such as marine oil snow formation.
5.3 Biological Effects on the Fates of Oil: Aerobic biodegradation of oil components has been well studied for decades, but the range and kinetics of anaerobic hydrocarbon biodegradation, relevant to seafloor and estuarine sediments and fine-grained shoreline sediments, are less well known. Furthermore, it is not known how the phenomenon of the “lag phase” often seen in laboratory studies of anaerobic biodegradation is manifested in situ; this would affect the time scale of natural attenuation in anaerobic sites. Thus, further research is needed to better understand the kinetics and range of anaerobic biodegradation of oil in the sea as a component of natural attenuation assessment.
A physical factor that is not well studied is high hydrostatic pressure, especially when combined with low temperature and limited nutrients such as in deep-sea sediments, where it likely affects persistence of sedimented and buried oil. Because such conditions are difficult to achieve in the laboratory, technological developments are needed to conduct in situ experiments and/or to collect samples from the deep sea and subsequently manipulate them in the laboratory without depressurization.
The effect of chemical dispersant addition on biodegradation of oil has been controversial in the literature, due at least in part to diverse laboratory conditions that do not mimic in situ spill response circumstances. This controversy should be addressed by adopting “best practices” for designing experiments relevant to spill conditions under which dispersant might be used, such
as whether the oil type being evaluated is suitable for dispersion, the weathered state of the oil, oil concentration, dispersant-to-oil ratio, and the mixing energy applied.
MOSSFA was recognized as a significant transport mechanism for oil spilled during the DWH event (and possibly, in hindsight, during the Ixtoc I spill). However, parallel cases of extreme marine snow sedimentation and flocculation outside the Gulf of Mexico have not yet been documented. Possible reasons for the currently novel DWH observation include the following: (1) DWH was a high-volume offshore spill in water having lower concentrations of suspended mineral particles than previous, more common nearshore, smaller-volume spills with more suspended particles; (2) DWH response involved an unprecedented magnitude of SSDI; and (3) in recent decades significant advances in field sampling and monitoring techniques and instruments (e.g., sediment traps/particle interceptor traps, core sampling of undisturbed surface sediments, and underwater imaging) have provided means for observing marine oil snow (MOS) occurrence. It will be important to tap the potential of these techniques and instruments for future oil spills in areas where marine snow is a natural phenomenon that could lead to MOSSFA events. The presence of natural (oil-free) marine snow in marine ecosystems argues that MOS and MOSFFA may be found to be important at other locations, although the combined roles of deep-sea oil release and implementation of SSDI in fostering other MOSSFA events needs to be ascertained. Because MOS formation involves physical, chemical, and biological processes (e.g., evaporation, adsorption, and enzymatic reactions), such study should be interdisciplinary. Observation of “spills of opportunity” should include measurements of MOS abundance and consider the contribution of MOSSFA to oil sedimentation. If globally significant, oil budget models should incorporate MOSSFA terms.
The process of natural attenuation implies that no intervention is required to enable the native microbiota to biodegrade oil in situ. However, continued research is necessary to evaluate the efficiency and extent of natural attenuation of various hydrocarbon mixtures and response products in diverse environments (e.g., in Arctic versus temperate waters, at different water column depths, in various types of shorelines, benthic sediments). Such inquiries will provide better insight into the applicability of natural attenuation in different scenarios and will generate additional data for assessing oil fate and biodegradation potential.
The power of ‘omics techniques has not yet been fully implemented in oil spill research, but could contribute to baseline studies, prediction of natural attenuation potential, and monitoring of bioremediation trajectories. Considerable research is needed to translate ‘omics data into meaningful information as a bioremediation tool for modeling oil fate and monitoring natural attenuation progress.
5.4 Fates of Oil in Remote Sites: Some ecosystems have been understudied due to their inaccessibility, such as the Arctic and deep sea; regarding the technical difficulties of Arctic research. Within the Arctic, there is a critical research need to collect new data to validate oil-in-ice transport algorithms; to correlate predictions of ice evolution models with mechanisms controlling oil fate and transport; to develop new, more process-oriented models of oil interaction with ice; and to propose observing systems that can be used during oil spill response to collect the data needed to make accurate oil fate and trajectory predictions. Interactions of oil with ice are complex, and determining how oil is dispersed under partial or complete ice coverage remains a major challenge for predicting oil trajectories during response. The new Ocean–Sea Ice Mesocosm facility on Hudson Bay will provide opportunities to study these processes. Furthermore, the application of ‘omics techniques to polar marine regions has
lagged behind studies of temperate marine environments, and further research effort is needed to augment understanding of Arctic ecosystem responses to oil. A better appreciation of the relationship between oil biodegradation kinetics and temperature would benefit both Arctic and deep-sea studies.
5.5 Behavior and Fates of New or Unconventional Oils: Two classes of unconventional oils are due to be transported by ship in increasing volumes within the next decade: diluted bitumen products and LSFOs and VLSFOs. Whereas some research has been conducted on the submergence and sinking potential of dilbit in various environments, there has not yet been a major marine spill of this two-component blend, and the fates of the diluent versus the weathered dilbit warrant further large-scale open-air experimentation to provide insight into potential behavior and fates. The newly mandated marine fuel oil classes are known to be highly variable in composition, but very little is currently known about evaporation, gelling, dispersion, shoreline adherence, and so on. Because the fuels will be used globally, it is essential that laboratory and in situ experiments be conducted under different environmental conditions to increase knowledge and awareness of their potential fates.
A third possible class is biofuels, which have not been discussed extensively in this report but could become a significant transportation fuel. Within this broad category of fuels, the fate of individual components could be inferred from other knowledge, but currently little is known about their composite fate in the sea.
5.6 Refining Models of Oil Behavior and Fate: As our understanding of oil fate and transport in the sea improves, the need to convert our new insights into operational algorithms for oil fate and trajectory modeling also emerges. This includes the need to develop new modeling algorithms, add these algorithms to models, and validate their predictions, ideally using in situ observations. Some of the new insights that are currently being
developed or still need to be parameterized for oil spill models include photo-oxidation, MOSSFA, temperature effects on biodegradation kinetics, and anaerobic biodegradation, among others. There is also a present need to integrate oil spill models with the enormous stream of observation data that may be part of a spill response.
Research Recommended to Advance Understanding of the Effects of Oil in the Sea on the Marine Environment
6.1 Natural Seeps: As relatively understudied habitats, research is needed to increase our understanding of unique chemosynthetic communities near natural seeps, especially deeper sea locations, to identify novel species/biochemical pathways and chemosynthesis, and to identify bacteria that may be useful in oil spill response (i.e., oil degraders), and to understand how organisms and communities respond to the presence of oil.
6.2 Marine Oil Snow: Continuing research on the formation of MOS is needed with respect to influences on processes of oil degradation and eventual hydrocarbon fates, such as flux through the water column, interactions with water column organisms, and short- and long-term deep-water biogenic communities.
6.3 Assessment Techniques: Potential research areas would be the development of sensors for petroleum hydrocarbons and image analysis for plankton in situ, and autonomous underwater vehicles for determination of water column effects.
6.4 Marsh Ecosystem Health: The protocols of natural resource damage assessment for marshes following exposure to an oil spill should incorporate additional measures of the health of marshes, including their structural integrity. Research into other measures or development of technological advances (e.g., portable photosynthesis systems for gas exchange and chlorophyll
fluorescence measurements in plants) may also generate more universal representative indicators.
The longer-term study with multiple integrated features of the salt marsh ecosystem points to the need for these types of studies to integrate the multiple aspects of contamination, salt marsh ecology, trophic structure, predator-prey dynamics, understanding of microhabitats within the marsh, and an integrated approach from genetics and enzymatic responses to ecosystem-level effects.
6.5 Marine Vertebrates: Studies focused on better estimation of mortalities of seabirds, marine mammals, and sea turtles during future spills of opportunity are needed. These studies should include sampling methods that permit estimation of statistical confidence intervals in addition to point estimates of, for example, numbers of animals killed.
6.6 Corals: The numerous environmental and coral health co-stressors should be studied together with additional investigations of species and life stage sensitivities to better understand the impact of oil on these important coral reef ecosystems.
Studies of mesophotic and deep-sea corals highlight the need for prior baseline studies of the health of benthic ecosystems, together with long-term follow-up studies on recovery, delayed mortality, and continued declines in health in these species, particularly given their slow growth and lower recruitment compared to other marine species and hence potential for a protracted recovery period.
6.7 Ecosystem-Level Effects: Better understanding of trophic structure in marine systems could be accomplished with experimental design that incorporates populations, the community trophic interactions, multiple stressors, and interrelationships that could anticipate indirect or cascading effects of an oil spill. Field studies that incorporate all these features may not be able to reproduce
the complexity of a marine ecosystem, but models could provide a basis for further exploration.
The addition of longer-term observations and experiments that include higher organization-level components and trophic interactions should be funded by the appropriate agencies and responsible parties. To these ends, appropriate agencies should encourage and support efforts to develop ecological atlases of marine resources that identify especially important ecological areas and habitats of threatened or endangered species, similar to those developed by Audubon, Oceana, and other environmental nongovernmental organizations for the Alaskan Arctic, which may serve to extend to offshore waters the Environmental Sensitivity Index approach currently used for shorelines.
6.8 Shoreline Oiling Characterization: A comparison of Shoreline Cleanup and Assessment Technique (SCAT) oiling categories with chemical characterization of hydrocarbons would benefit subsequent field studies and comparison of effects results based primarily on the four-tier SCAT categories. Also, the use of statistically-based sampling methods to estimate upper and lower bounds of the extent and intensity of shoreline oiling, including estimates of subsurface oil, would permit meaningful comparisons among sampling periods to estimate temporal trends of oil persistence.
6.9 Photo-Oxidation: The toxicity of photo-oxidized products of compounds that dissolve from oil into seawater should be evaluated to determine how much they contribute to acute and chronic toxicity effects on test organisms. Further studies are needed to characterize the array of photo-oxidation products produced from various oils and assess their persistence, bioaccumulation, and toxicity to standard toxicity test organisms. Additional organisms and numerous life stages should be included in these studies.
Further research on ultraviolet (UV) radiation, elevated temperature, and decreased pH is needed to fully assess the effects of these co-factors and changing climate conditions on toxicity and the impact of oil pollution in exposed ecosystems.
6.10 Behavioral Effects of Oil: As a relatively understudied effect, research is needed to more fully evaluate the effects of exposure to oil on organismal behavioral responses.
6.11 Toxicity Studies and Models:
- Redesign the toxicity tests needed to provide data useful for model verification and in the decision-making process (i.e., response trade-offs). Enable further integration among laboratory studies and models useful for oil spill responders. Toxicity studies should focus on chronic, sublethal impacts, particularly of novel mechanisms of action that have health and population-level consequences (e.g., immune responses). The influence of environmental co-variables (e.g., light/photochemical reactions and pressure) should be further evaluated and included in models.
- Revisit and update standard procedures for the preparation and characterization of toxicity test media, and the conduct of toxicity tests, including control of additional covariables and how they are reported (e.g., updating the CROSERF protocols). Descriptions of the types of chemical characterization should be required (e.g., regarding chemical constituent resolution and partitioning [i.e., dissolved and droplet concentrations and droplet size/volume characterization]). The minimum data reporting should be identified and required.
- Study test designs should clearly identify the questions being asked, the ecological relevance, and the species/life stages being used, and employ appropriate chemical analyses (e.g., filtration of exposure media and specific analytes measured)
- in addition to reporting toxicological endpoints appropriate for the study, including the use of toxic units if appropriate.
- Studies should be directed toward investigation of novel exposure pathways (e.g., inhalation in marine mammals, seabirds, and turtles; the influence of maternal transfer pathways) and new focused mechanisms of toxicity (e.g., adrenal function, immune responses, and the influence and importance of the microbiome).
- Studies on the effects of surface oil ingested by fish for cardiotoxic effects of polycyclic aromatic compounds from surface oil and on fish embryos should be supported in laboratory studies and during future spills of opportunity.
- Models (e.g., OilTox, Petrotox) should continue to be refined based on inputs (e.g., role of droplets, additional chemical constituents) and influence of environmental variables (e.g., photo-oxidation, UV light, temperature, pressure). Models should also continue to be validated, particularly involving national or global inter-laboratory efforts or in-field trials (if applicable).
6.12 Seafood Safety:
- Update the list of analytes included in risk assessment for seafood safety considerations and refine the current approaches used (e.g., benzo[a]pyrene equivalents).
- The government agencies involved in responding to an oil spill should make a concerted effort to thoroughly reevaluate the health risk basis for the closing and reopening of seafood gathering following an oil spill, including an in-depth analysis of different types of PAHs likely to be present and their relative contribution to health risk. Government agencies should sponsor an ongoing integrated program supporting a broad
- range of risk-related research relevant to decisions about closing and reopening seafood-gathering areas following oil contamination.
- Establish current PAH contaminant concentrations in edible tissues of marine mammals consumed by Indigenous communities in the Arctic.
6.13 Coastal Community Response: Programs to improve community resilience in response to future oil spills must be tailored to the individual communities at risk. Support is needed for social science research initiatives that will incorporate understanding of the broad range of local factors as a basis for preparation for the next oil spill or other disasters. Existing and new findings should be incorporated by EPA and other agencies into disaster planning (e.g., the EPA Handbook on Area Contingency Planning, which at present does not consider community health).
6.14 Follow-Up of Epidemiological Studies: Studies of response workers have noted a longer-term association between cardiovascular and central nervous system effects at levels of petroleum hydrocarbon exposure that are orders of magnitude below currently allowable worker exposures. This association seems unlikely to be causative in the absence of such findings in well-studied workforces exposed to the higher levels for longer periods of time but should not be discounted without further rigorous follow-up.
6.15 Maternal and Child Health: The relative absence of female workers in the petroleum industry in the past has limited the availability of information about potential maternal and child health impacts. Longer-term follow-up of cohorts of women pregnant during the DWH oil spill and of community children should be performed. An increase in the limited amount of toxicological information on the potential reproductive and developmental effects of crude oil derivatives possibly reaching shore communities would also be useful.
COMMITTEE ON OIL IN THE SEA IV: INPUTS, FATES, AND EFFECTS: Kirsi K. Tikka (NAE) (Chair), Maritime Companies, American Bureau of Shipping (retired); Edwin “Ed” Levine (Vice Chair), Scientific Support and Coordination, LLC; Akua Asa-Awuku, University of Maryland; Cynthia Beegle-Krause, SINTEF; Victoria Broje, Shell Projects and Technology; Steven Buschang, Texas General Land Office; Dagmar Schmidt Etkin, Environmental Research Consulting; John Farrington, Woods Hole Oceanographic Institution; Julia Fought, University of Alberta; Bernard Goldstein (NAM), University of Pittsburgh; Carys Mitchelmore, University of Maryland Center for Environmental Science; Nancy Rabalais, Louisiana State University; Scott Socolofsky, Texas A&M University; Berrin Tansel, Florida International University; Helen K. White, Haverford College; and Michael Ziccardi, University of California, Davis.
STUDY STAFF: Kelly Oskvig, Study Director; Megan May, Associate Program Officer; Kenza Sidi-Ali-Cherif, Program Assistant; Grace Callahan, Program Assistant; Nancy Huddleston, Director of Communications and Media; Solmaz Spence, Communications Specialist; Paige Nankey, Communications Associate.
The study was sponsored by the American Petroleum Institute, the Bureau of Ocean Energy Management, the Bureau of Safety and Environmental Enforcement, Fisheries and Oceans Canada, the Gulf of Mexico Research Initiative, and the National Academies of Sciences, Engineering, and Medicine’s Presidents’ Circle Fund. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.
This booklet was prepared by the National Academies based on the committee’s report. For more information or copies, visit the Ocean Studies Board at http://nationalacademies.org/osb.
The booklet and Oil in the Sea IV: Inputs, Fates, and Effects are available from the National Academies Press at http://nap.nationalacademies.org.
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