Dispersant Effectiveness and Toxicity—An Integrated Approach

2003 ◽  
Vol 2003 (1) ◽  
pp. 335-339
Author(s):  
M.C. Sterling ◽  
R.L. Autenrieth ◽  
J.S. Bonner ◽  
C.B. Fuller ◽  
C.A. Page ◽  
...  
Keyword(s):  
Water Column ◽  
Toxicity Testing ◽  
Integrated Approach ◽  
Droplet Coalescence ◽  
Oil Droplets ◽  
Oil Droplet ◽  
Shear Rates ◽  
Dispersed Oil ◽  
Dispersant Effectiveness ◽  
Experimental Dispersion

ABSTRACT An integrated approach to study chemical dispersant effectiveness and dispersed oil toxicity is presented. Conventional lab scale effectiveness tests generally provide a measure of overall dispersant effectiveness. However, chemical dispersion can be viewed as two processes: (1) dispersant-oil slick mixing and (2) oil droplet transport into the water column. Inefficiencies in either process limit the overall dispersant effectiveness. This laboratory study centered on the latter process and was conducted to focus on the impacts of water column hydrodynamics on the resurfacing of dispersed oil droplets. Using a droplet coalescence model (Sterling et al., 2002), the droplet coalescence rates of dispersed crude oil was determined within a range of shear rates. A controlled shear batch reactor was created in which coalescence of dispersed oil droplets were monitored in-situ. Experimental dispersion efficiencies (C/C0) and droplet size distributions were compared to those predicted by Stokes resurfacing. Experimental C/C0 values were lower than that predicted from Stokes resurfacing. Experimental dispersion efficiency values (C/C0) decreased linearly with increasing mean shear rates due to increased coalescence rates. These results suggested that dispersed oil droplet coalescence in the water column can adversely impact overall dispersant efficiency. To avoid high control mortality in toxicity testing, the toxicity exposure chamber was designed with separate compartments for scaled mixing and organism exposure, respectively. Chamber design includes continuous re-circulation between mixing and exposure chamber. A 1-minute exposure compartment residence time was determined from tracer studies indicating virtually identical oil concentrations in the mixing and exposure compartments. In addition, the 96-hour mortality of 14-day oil Menidia beryllina varied from 2% in the no-oil control tests to 87% in the dispersed oil (200 mg/L) tests. These results show the effectiveness of the integrated vessel for the characterization and toxicity testing of oil dispersions.

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.

scholarly journals WHERE HAS ALL THE OIL GONE? DISPERSED OIL DETECTION IN A WAVE BASIN AND AT SEA

1987 ◽  
Vol 1987 (1) ◽  
pp. 307-312 ◽  
Author(s):  
H. M. Brown ◽  
R. H. Goodman ◽  
Gerard P. Canevari
Keyword(s):  
Water Column ◽  
Large Scale ◽  
The Past ◽  
Controlled Conditions ◽  
Dispersed Oil ◽  
Wave Basin ◽  
Effective Wave ◽  
Dispersant Effectiveness ◽  
Canada Limited

ABSTRACT During the past 10 years, there have been many sea trials of dispersant chemicals for the purpose of demonstrating the effectiveness of specific products or elucidating the processes of oil dispersion into the water column. Unfortunately, most of these tests have proved inconclusive, leading many to believe that dispersant chemicals are only marginally effective. Wave basin tests have been carried out at the Esso Resources Canada Limited laboratory in Calgary, Canada, to measure dispersant effectiveness under closely controlled conditions. These tests show that dispersed oil plumes may be irregular and concentrated over small volumes, so that extensive plume sampling was required to obtain accurate dispersant effectiveness measurements. In large-scale sea trials, dispersants have been shown effective, but only where sufficient sampling of the water column was done to detect small concentrated dispersed oil plumes and where it was known that the dispersant was applied primarily to the thick floating oil.

Subsea Dispersant Injection (SSDI) - Summary Findings from a Multi-Year Research and Development Industry Initiative

2017 ◽  
Vol 2017 (1) ◽  
pp. 2762-2790 ◽  
Author(s):  
P.J. Brandvik ◽  
Ø. Johansen ◽  
E.J. Davies ◽  
F. Leirvik ◽  
D.F. Krause ◽  
...  
Keyword(s):  
Water Column ◽  
Droplet Size ◽  
Oil And Gas ◽  
Two Dimensions ◽  
Worker Safety ◽  
Three Dimensions ◽  
Oil Droplets ◽  
Oil Droplet ◽  
Elevated Exposure ◽  
Oil Droplet Size

ABSTRACT New and novel results regarding effectiveness and use of subsea dispersant injection (SSDI) are presented in this paper. These findings are relevant for operational guidance, decision making and improvement of models of subsea releases of oil and gas. More specifically, the paper presents data from a comprehensive set of laboratory experiments to measure the initial formation of oil droplets and gas bubbles from a subsea blowout with and without SSDI. Many subsea blowout scenarios for oil and gas will form relatively large oil droplets (multiple millimeters) which rise rapidly through the water column to possibly form thick slicks on the ocean surface, potentially very near the source. On the other hand, smaller oil droplets (< 500 microns) rise more slowly and can stay suspended in the water column for days to weeks. Our laboratory studies examined the influence of different variables on the initial oil droplet size including oil release velocity, dispersant dosage, dispersant injection method, oil temperature, pressure, gas-to-oil ratio, oil type, and dispersant type. Results revealed that dispersant injection is highly effective at reducing droplet size. SSDI has, for this reason, a potential to reduce floating oil and associated volatile hydrocarbons that may threaten worker health and safety. Reduced surfacing may also reduce the amount of oil that reaches ecologically sensitive shoreline environments. Oil that disperses into the water column, as small droplets, may cause temporarily elevated exposure to marine organisms, but these droplets rapidly dilute and later naturally degrade. Dispersed oil dilutes in three dimensions rather than only the two dimensions available for surface oil, and mostly one dimension available to shoreline oil. Our data fit a modified Weber scaling algorithm that predicts initial oil droplet size for both laboratory and field scales. Predictions indicate that SSDI can reduce oil droplet sizes by an order of magnitude for field scales like those experienced in the Deep Water Horizon. In summary, this paper shows that SSDI applied to a subsea blowout is a highly efficient oil spill response tool that, under the appropriate conditions, can substantially delay oil surfacing, reduce the amount of surfacing and reduce the persistence of surface slicks by reducing oil droplet size. The net result is enhanced worker safety and health as well as reduced oil impacts on the surface and shoreline.

THE SIGNIFICANCE OF DISPERSED OIL DROPLET SIZE IN DETERMINING DISPERSANT EFFECTIVENESS UNDER VARIOUS CONDITIONS

1985 ◽  
Vol 1985 (1) ◽  
pp. 433-440 ◽  
Author(s):  
A. Lewis ◽  
D. C. Byford ◽  
P. R. Laskey
Keyword(s):  
Droplet Size ◽  
Relative Magnitude ◽  
Test Methods ◽  
Oil Droplet ◽  
Dispersed Oil ◽  
Speed Up ◽  
Oil Density ◽  
Dispersant Effectiveness ◽  
Droplet Size Distributions ◽  
Oil Droplet Size

ABSTRACT Oil spill dispersants speed up the rate of natural dispersion by enabling the prevailing energy of the wind and waves to convert an oil slick into droplets. The droplets are then dispersed horizontally and vertically by the mixing action of the sea. Vertical dispersion is countered by the buoyancy of the droplets, which depends on oil density and droplet size. The magnitude of the forces available in the sea to create and disperse droplets varies with sea state. A variety of test methods are used to assess the effectiveness of dispersants. Many of these methods attempt to simulate the shearing and mixing action of the sea. The validity of these simulations is difficult to quantify. The oil droplet size distributions of dispersions produced in the Labofina (inverting flask), MNS (Mackay-Nadeau-Steelman), and Oscillating Hoop tests have been determined. An estimate of the relative magnitude of the forces generated in each method has been deduced from data on oil droplet size. The effects of varying dispersant composition, energy input, dispersant to oil ratio and temperature, are discussed. The lack of correlation between results obtained from the different tests is explained by identifying the predominant processes occurring in each method.

The Fate of Dispersed Oil Under Ice: Results of JIP Phase 1 Program

2014 ◽  
Vol 2014 (1) ◽  
pp. 949-959
Author(s):  
CJ Beegle-Krause ◽  
Miles McPhee ◽  
Harper Simmons ◽  
Ragnhild Lundmark Daae ◽  
Mark Reed
Keyword(s):  
Literature Review ◽  
Water Column ◽  
Droplet Size ◽  
Fluorescent Dyes ◽  
Autonomous Underwater Vehicles ◽  
The Arctic ◽  
Formation Mechanisms ◽  
Oil Droplets ◽  
Mixing Energy ◽  
Dispersed Oil

ABSTRACT Ice infested waters pose unique challenges to preparedness and response for potential oil spills. An international team of researchers are working together to create a model to aid in evaluating use of dispersants in ice. The model will be designed to evaluate whether or not dispersed oil droplets formed under continuous or concentrated ice could resurface under the ice to form a significant accumulation within two days. The goal is to develop a tool to support contingency planning decisions with respect to dispersant use. Phase I of the project was to perform a literature review to develop recommendations to fill data gaps in the ice, current, and turbulence data needed to run a model. Phase II will include field work to collect data and model development and testing. The model will require information about the oil and dispersed oil droplet size distribution and water column information to predict mixing energy that could keep the oil droplets suspended. Droplet size distributions can be easily measured. The challenge is to provide representative information about the water column. We are evaluating several types of oceanographic observational technologies to collect data on under ice mixing energy such as fluorescent dyes, Turbulent Instrument Clusters (TICs), Autonomous Underwater Vehicles (UAVs), and Acoustic Doppler Current Profilers (ADCPs). From our review, we expect to be able to collect the required environmental parameters within reasonable cost and time. There are a variety of ice formation mechanisms and ice types in the Arctic and Antarctic. Bottom roughness and ice concentration play keys rolls controlling the amount of mixing energy available under the ice. Heavier ice concentrations absorb surface wave energy, which provides the mixing energy for open water dispersant operations. The literature review indicates that good measurements and a good turbulence closure model are key to obtaining good predictions. We are interested in feedback from the IOSC audience regarding our vision of framing the predictive model as an appropriate decision support tool for the Planning and Response Communities.

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.

Fabrication of a Portable Large-Volume Water Sampling System To Support Oil Spill Nrda Efforts

1999 ◽  
Vol 1999 (1) ◽  
pp. 1179-1184 ◽  
Author(s):  
James R. Payne Payne ◽  
Timothy J. Reilly ◽  
Deborah P. French
Keyword(s):  
Water Column ◽  
Oil Spill ◽  
Water Samples ◽  
Detection Limits ◽  
Water Sampling ◽  
Sampling System ◽  
Oil Droplets ◽  
Early Stages ◽  
Dispersed Oil ◽  
Dissolved Components

ABSTRACT A field-portable water-sampling system was designed and fabricated for collecting adequate volumes of seawater to meet the quantitation requirements to support Natural Resource Damage Assessment (NRDA) toxicity determinations and modeling efforts following an oil spill. This system is a significant improvement to conventional water sampling equipment and includes the ability to filter water samples at the time of collection, thereby providing critical differentiation between truly dissolved constituents and dispersed oil droplets. The system can be quickly and easily deployed from shoreline structures (piers and breakwaters) and/or vessels of opportunity to provide essential data during the early stages of a spill. Likewise, data collected with the system can be used to document dispersant effectiveness and provide information relating to seafood exposure, tainting, and toxicity issues. In many oil-spill NRDA efforts, water-column effects from dissolved components and dispersed oil droplets have not been adequately quantified or documented because: (1) samples are not obtained early enough after the spill event; (2) insufficient volumes are collected; and (3) the wrong constituents are analyzed. Generally, EPA hazardous-materials sampling approaches are followed, leading to inadequate sample sizes (e.g., 40 mL for volatile component analyses and 1-L samples for dissolved/dispersed constituents). Analytically, EPA semivolatile gas chromatography/mass spectrometry (GC/MS) SW-846 Method 8270 is often specified for polynuclear aromatic hydrocarbons (PAH). These sample sizes are not large enough to meet the detection limits required for most marine hydrocarbon analyses (de Lappe et al., 1980; Payne, 1997 and references therein), and the EPA PAH target analyte list does not include the majority of alkyl-substituted one-, two-, and three-ring aromatics that are the primary dissolved constituents actually present in the water column following an oil spill (Sauer and Boehm, 1991). As a result, water column effects are often written off as being short-lived or insignificant. Alternatively, impacts are often assessed by computer modeling efforts with limited field validation. In either event, there is inadequate profiling of the extent and duration of petroleum hydrocarbon exposure to marine organisms. Furthermore, when adequate volumes of water have been collected and the proper target analytes have been specified, provisions have not been taken to differentiate between truly dissolved components and dispersed oil droplets. Consequently, later data analyses are unreliable in their ability to reflect conditions as they actually existed during the early stages of the spill. For example, PAH analyses of unfiltered water samples are confounded by the facts that: (1) a significant, but unknown fraction of discrete oil droplets in the water column will rise to the surface with time; (2) high levels of dispersed oil droplets will raise detection limits of dissolved PAH; and (3) it is impossible to determine how much of the PAH is in the truly dissolved state where it will persist as a toxic fraction to exposed organisms and how much is simply associated with slightly less toxic oil droplets that are subject to relatively rapid removal by resurfacing. The equipment and field implementation approach described in this paper can provide samples that are not subject to the aforementioned problems.

Sign in / Sign up

Export Citation Format

Share Document