scholarly journals Development of an Algorithm for Chemically Dispersed Oil Spills

2020 ◽  
Vol 7 ◽  
Author(s):  
Merv F. Fingas ◽  
Kaan Yetilmezsoy ◽  
Majid Bahramian
Keyword(s):  
Wind Speed ◽  
Water Column ◽  
Oil Spills ◽  
Regression Equations ◽  
Oil Viscosity ◽  
Mixing Depth ◽  
Chemical Dispersion ◽  
Closed Form Solutions ◽  
Dispersed Oil ◽  
Chemically Dispersed Oil

An algorithm utilizing four basic processes was described for chemical oil spill dispersion. Initial dispersion was calculated using a modified Delvigne equation adjusted to chemical dispersion, then the dispersion was distributed over the mixing depth, as predicted by the wave height. Then the droplets rise to the surface according to Stokes’ law. Oil on the surface, from the rising oil and that undispersed, is re-dispersed. The droplets in the water column are subject to coalescence as governed by the Smoluchowski equation. A loss is invoked to account for the production of small droplets that rise slowly and are not re-integrated with the main surface slick. The droplets become less dispersible as time proceeds because of increased viscosity through weathering, and by increased droplet size by coalescence. These droplets rise faster as time progresses because of the increased size. Closed form solutions were provided to allow practical limits of dispersibility given inputs of oil viscosity and wind speed. Discrete solutions were given to calculate the amount of oil in the water column at specified points of time. Regression equations were provided to estimate oil in the water column at a given time with the wind speed and oil viscosity. The models indicated that the most important factor related to the amount of dispersion, was the mixing depth of the sea as predicted from wind speed. The second most important factor was the viscosity of the starting oil. The algorithm predicted the maximum viscosity that would be dispersed given wind conditions. Simplified prediction equations were created using regression.

scholarly journals Estimating the Usefulness of Chemical Dispersant to Treat Surface Spills of Oil Sands Products

2018 ◽  
Vol 6 (4) ◽  
pp. 128 ◽  
Author(s):  
Thomas King ◽  
Brian Robinson ◽  
Scott Ryan ◽  
Kenneth Lee ◽  
Michel Boufadel ◽  
...  
Keyword(s):  
Oil Sands ◽  
Oil Spills ◽  
Breaking Waves ◽  
Oil Viscosity ◽  
Chemical Dispersant ◽  
Dispersed Oil ◽  
Initial Release ◽  
Order Of Magnitude ◽  
Chemically Dispersed Oil ◽  
The Impact

This study examines the use of chemical dispersant to treat an oil spill after the initial release. The natural and chemically enhanced dispersion of four oil products (dilbit, dilynbit, synbit and conventional crude) were investigated in a wave tank. Experiments were conducted in spring and summer to capture the impact of temperature, and the conditions in the tank were of breaking waves with a wave height of 0.4 m. The results showed that natural dispersion effectiveness (DE) was less than 10%. But the application of dispersant increased the DE by an order of magnitude with a statistically significant level (p < 0.05). Season (spring versus summer) had an effect on chemical DE of all oils, except for the conventional oil. Thus, the DE of dilbit products is highly dependent on the season/temperature. A model was fitted to the DE as a function of oil viscosity for the chemically dispersed oil, and the correlation was found to be very good. The model was then combined with a previous model compiled by the author predicting oil viscosity as a function of time, to produce a model that predicts the DE as function of time. Such a relation could be used for responders tackling oil spills.

EFFECTIVENESS, BEHAVIOR, AND TOXICITY OF DISPERSANTS

1983 ◽  
Vol 1983 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Donald Mackay ◽  
Peter G. Wells
Keyword(s):  
Water Column ◽  
Oil Spills ◽  
Current Status ◽  
Dispersed Oil ◽  
Chemical Studies ◽  
Key Issues ◽  
Oil Emulsions ◽  
Dispersant Effectiveness ◽  
Individual Hydrocarbons ◽  
Physical And Chemical

ABSTRACT Three key issues must be addressed when deciding on the desirability of using chemical dispersants for mitigating the adverse effects of oil spills: (1) how effective a given dosage of dispersant will be on a given oil slick; (2) how the dispersed oil and dispersant diffuse into the water column, dissolve, volatilize, degrade, and interact with suspended and bottom sediments; and (3) what effects the dissolved and particulate oil and dispersant will have on water column and benthic biota. It is essential that the first two areas (physical and chemical studies) relate closely to the third (biological aspects) in order that bioassay exposure (in terms of concentration of dispersant, classes of and individual hydrocarbons, and duration) addressing the toxicity issue be realistic. Here, we review the current status of a research program which addresses these issues. Under the program, attempts are being made to quantify dispersant effectiveness (including consideration of effectiveness testing using the Mackay-Nadeau-Steelman system for oils which have evaporated and/or formed water-in-oil emulsions to various extents), water column diffusion, and partitioning of specific hydrocarbons among water, oil, and suspended sediment as well as into the atmosphere. A procedure is described which has been used to quantify the acute toxicity of dispersants to copepods and which is being extended to apply also to the toxic contributions of dissolved and particulate oil. Hopefully, by assembling quantitative expressions for effectiveness, behavior, and toxicity, those situations in which dispersion is desirable can be better identified.

OIL SPILL CLEANUP WITH DISPERSANTS: A BOOMED OIL SPILL EXPERIMENT

1981 ◽  
Vol 1981 (1) ◽  
pp. 263-268
Author(s):  
Joseph Buckley ◽  
David Green ◽  
Blair Humphrey
Keyword(s):  
Water Column ◽  
Oil Spill ◽  
Oil Spills ◽  
Sea Water ◽  
Visual Observation ◽  
Oil Droplets ◽  
Oil Boom ◽  
Dispersed Oil ◽  
Vertical Density ◽  
Oil Spill Cleanup

ABSTRACT Three experimental oil spills of 200, 400, and 200 litres (l) were conducted in October, 1978, in a semiprotected coastal area on Canada's west coast. The surface slicks were restrained with a Bennett inshore oil boom. The spilled oil was chemically dispersed using Corexit 9527, applied as a 10-percent solution in sea water and sprayed from a boat. The dispersed oil was monitored fluorometrically for some hours. Surface and dispersed oil were sampled for chemical analysis. The highest recorded concentration of dispersed oil was 1 part per million (ppm). After a short time (30 minutes), concentrations around 0.05 ppm were normal, decreasing to background within 5 hours. The concentrations were low compared to those expected for complete dispersion which, as visual observation confirmed, was not achieved. The dispersed oil did not mix deeper into the water column with the passage of time, in contrast to predicted behaviour and in spite of the lack of a significant vertical density gradient in the sea water. This was attributed to the buoyancy of the dispersed oil droplets and the limited vertical turbulence in the coastal locale of the experiment. The integrated quantity of oil in the water column decreased more rapidly than either the mean oil concentration of the cloud or the maximum concentration indicating that some of the dispersed oil was rising back to the surface. The surfacing of dispersed oil was confirmed visually during the experiment. The mixing action of the spray boat and breaker boards apparently created large oil droplets that did not form a stable dispersion. Horizontal diffusion of the dispersed oil was initially more rapid than expected, but the rate of spreading did not increase with time as predicted. The results imply that the scale of diffusion was larger than the scale of turbulence which again can be attributed to the locale of the experiment.

DEVELOPMENT AND APPLICATION OF DTox: A QUANTITATIVE DATABASE OF THE TOXICITY OF DISPERSANTS AND CHEMICALLY DISPERSED OIL

2014 ◽  
Vol 2014 (1) ◽  
pp. 733-746 ◽  
Author(s):  
Adriana C. Bejarano ◽  
Valerie Chu ◽  
Jeff Dahlin ◽  
Jim Farr
Keyword(s):  
Oil Spill ◽  
Oil Spills ◽  
Biological Effects ◽  
Life Stage ◽  
Data Repository ◽  
Toxicity Data ◽  
Dispersed Oil ◽  
Chemically Dispersed Oil ◽  
Data Source ◽  
High Concentrations

ABSTRACT The Deepwater Horizon oil spill revived discussions on the use of dispersants as an oil spill countermeasure. One of the greatest concerns regarding the use of dispersants deals with potential exposure of water column organisms to high concentrations of oil. While toxicity data on dispersants and physically and chemically dispersed oil have been generated for decades under controlled laboratory conditions, the practical use of this information has been limited by the lack of a centralized data repository. As a result, the Dispersant and Chemically Dispersed Oil Toxicity Database (DTox) was created to address that shared need of unrestricted and rapid access to toxicity data. DTox is a quantitative database that gathers existing toxicity data through a careful review and compilation of data extracted from the peer-review and gray literature. Through a rigorously evaluation of the quality of each data source, this database contains pertinent information including species scientific name, life stage tested, dispersant name, exposure type, oil weathering stage, exposure duration, etc. More importantly, this database contains effects concentrations reported on measured or nominal basis. Within the database, each data source is assigned an applicability score based on their relevance to oil spills. Key criteria in the determination of source applicability include exposure type, reported effects concentrations, and reported analytical chemistry. Information in DTox has been further integrated into a user-friendly tool that allows for on-the-fly data searches and data plotting in the form of Species Sensitivity Distributions. To date, +400 papers have been evaluated for potential inclusion into the database, and data extracted from +170 sources. Despite inherent limitations, existing toxicity data are of great value to the oil spill scientific community. Although toxicity data will never be enough to answer all toxicity questions regarding the use of dispersants, this centralized data repository can help inform decisions on dispersant use and can help identify data needs and gaps. The ultimate goal of this tool is its contribution to a better understanding of the biological effects of dispersants and oil in the aquatic environment.

Ocean Experiments And Remotely Sensed Images of Chemically Dispersed Oil Spills

1983 ◽  
Vol GE-21 (1) ◽  
pp. 2-15 ◽  
Author(s):  
William F. Croswell ◽  
John C. Fedors ◽  
Frank E. Hoge ◽  
Robert N. Swift ◽  
Jaret C. Johnson
Keyword(s):  
Oil Spills ◽  
Remotely Sensed ◽  
Dispersed Oil ◽  
Chemically Dispersed Oil ◽  
Remotely Sensed Images

COMPARING CRUDE OIL TOXICITY UNDER STANDARD AND ENVIRONMENTALLY REALISTIC EXPOSURES

1995 ◽  
Vol 1995 (1) ◽  
pp. 1003-1004 ◽  
Author(s):  
Charles B. Pace ◽  
James R. Clark ◽  
Gail E. Bragin
Keyword(s):  
Crude Oil ◽  
Real World ◽  
Petroleum Hydrocarbons ◽  
Oil Spills ◽  
Aquatic Toxicity ◽  
Total Petroleum Hydrocarbons ◽  
Toxicity Tests ◽  
Continuous Exposure ◽  
Dispersed Oil ◽  
Chemically Dispersed Oil

ABSTRACT Standard aquatic toxicity tests do not address real-world, spiked exposure scenarios that occur during oil spills. We evaluated differences in toxicity of physically and chemically dispersed Kuwait crude oil to mysids (Mysidopsis bahia) under continuous and spiked (half-life of 2 hours) exposure conditions. The 96-hr LC50s for physically dispersed oil were 0.78 mg/L (continuous) and &gt;2.9 mg/L (spiked), measured as total petroleum hydrocarbons (TPH). Values for chemically dispersed oil were 0.98 mg/L (continuous) and 17.7 mg/L (spiked) TPH. Continuous-exposure tests may overestimate the potential for toxic effects under real-world conditions by a factor of 18 or more.

Biodegradation of Dispersed Endicott Oil in Controlled Experiments

2014 ◽  
Vol 2014 (1) ◽  
pp. 1126-1140 ◽  
Author(s):  
Yves Robert Personna ◽  
Michel C. Boufadel ◽  
Shuangyi Zhang
Keyword(s):  
Brackish Water ◽  
Oil Spills ◽  
Aerobic Biodegradation ◽  
Initial Concentration ◽  
Dispersed Oil ◽  
Oil Biodegradation ◽  
Simultaneous Operations ◽  
Chemically Dispersed Oil ◽  
Seawater Samples ◽  
Total Oil

ABSTRACT We investigate aerobic biodegradation of dispersed Endicott oil in seawater at 15±0.5 °C in laboratory flasks. The objectives of the experiments were to (1) compare the biodegradability of chemically dispersed oil by Corexit 9500 with physically dispersed oil, and (2) determine whether the addition of nutrient affects the biodegradation rates of dispersed oil. The seawater samples (~ 6.5 g/L i.e. brackish water) were collected from Prince William Sound, Alaska. The biodegradation of Endicott oil was investigated for a period of 42 days under high nutrient (HN) (addition of 100 mg NO3-N/L and 10 mg PO4-P/L to background brackish water) and low nutrient (LN) (background brackish water) treatments. In the physically dispersed microcosms, oil biodegradation remained negligible for both HN and LN treatments. However, in the chemically dispersed oil microcosms, 24% and 14% of the total oil biodegraded in the HN (initial concentration= 0.304±0.095 g/L) and LN (initial concentration= 0.298±0.041 g/L) treatments within two weeks, respectively. These results demonstrated that the use of chemical dispersants coupled with nutrient addition can accelerate oil biodegradation. These findings can help develop better bioremediation strategies for addressing oil spills in the sea by focusing on simultaneous operations for rapid oil dispersion and stimulation of microbial growth through the availability of nutrients.

A hazard assessment of chemically dispersed oil spills and seabirds

1987 ◽  
Vol 22 (2) ◽  
pp. 91-106 ◽  
Author(s):  
D.B. Peakall ◽  
P.G. Wells ◽  
D. Mackay
Keyword(s):  
Hazard Assessment ◽  
Oil Spills ◽  
Dispersed Oil ◽  
Chemically Dispersed Oil

COMPARATIVE FATE OF CHEMICALLY DISPERSED AND UNTREATED OIL IN THE ARCTIC: BAFFIN ISLAND OIL SPILL STUDIES 1980–1983

1985 ◽  
Vol 1985 (1) ◽  
pp. 561-569
Author(s):  
Paul D. Boehm ◽  
William Steinhauer ◽  
Adolfo Requejo ◽  
Donald Cobb ◽  
Suzanne Duffy ◽  
...  
Keyword(s):  
Water Column ◽  
Oil Spill ◽  
Large Scale ◽  
The Arctic ◽  
Baffin Island ◽  
Dispersed Oil ◽  
Beach Sediments ◽  
Chemically Dispersed Oil ◽  
Deposit Feeding

ABSTRACT Two experimental oil spill studies designed to assess the comparative short and long term fates and effects of chemically dispersed and untreated nearshore discharges in the Arctic were undertaken as part of the Baffin Island Oil Spill (BIOS) Project. The fates of oil in the water column, in subtidal and beach sediments, and in five species of filter- and deposit-feeding animals were investigated. Analytical results indicate that the discharge of the chemically dispersed oil caused a large but short-lived chemical impact on the water column (up to 50 ppm), a significant initial bio accumulation of oil, and little sediment impact. In contrast, the untreated oil, allowed to beach, did not have a significant water column impact, but did result in a large scale landfall, continual long term erosion of oil off the beach, and increasing oil levels in subtidal sediments and deposit-feeding animals.

DISPERSANT PERFORMANCE: FINDING NEW RESULTS IN EXISTING DATA

2017 ◽  
Vol 2017 (1) ◽  
pp. 704-724
Author(s):  
Kimberly Bittler
Keyword(s):  
Water Column ◽  
Large Scale ◽  
Oil Spills ◽  
Meta Analysis ◽  
Federal Agencies ◽  
Aquatic Environments ◽  
Risks And Benefits ◽  
Dispersed Oil ◽  
History Of ◽  
Dispersant Effectiveness

Abstract No. 092 Abstract: Chemical dispersants are used to mitigate oil spills in aquatic environments. Dispersants promote the breakdown of oil into smaller droplets that more readily diffuse into the water column. Federal agencies, industry, and academia have a long history of investigating dispersant performance at diverse scales and environmental conditions, including several recent publications. Several studies estimate dispersant performance as dispersion effectiveness (DE, measured as the percent of oil retained in the water column for a period of time after treatment), the concentration of oil in the dispersed in the water column, or the size of dispersed oil droplets. While many organizations have drawn qualitative conclusions from this body of work, a quantitative meta-analysis drawing together historic and recent research on the topic of dispersant effectiveness has not been conducted. This paper analyzed controlled studies measuring performance of dispersants across lab, tank, and large-scale studies. Although this paper examined only a subset of commonly tested oils, the findings strongly support that treatment with dispersants is correlated with increased effectiveness across several metrics, studies, and test methodologies. The conclusions provided by this analysis could be a critical tool for weighing the risks and benefits of using dispersants to respond to oil spills in aquatic environments.

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