United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S-92/065
October 1992
EPA Project Summary
Chemical Oil Spill Dispersants:
Update State-of-the-Art on
Mechanism of Action and
Laboratory Testing for
Performance
John R. Clayton, Jr., James R. Payne, Siu-Fai Tsang, Victoria Frank, Paul
Marsden, and John Harrington
Chemical dispersants are formula-
tions designed to facilitate dispersion
of an oil slick into small droplets that
disperse to non-problematic concen-
trations in an underlying water column.
This project had two primary objectives:
(1) update information on mechanisms
of action of dispersants and factors
affecting their performance and (2)
evaluate selected testing procedures in
the laboratory for estimating perfor-
mance of different dispersant agents.
The first objective resulted in a report
updating information on chemical dis-
persants, their mode of action, variables
affecting dispersant performance in the
field as well as the laboratory, and a
discussion of a number of laboratory
and rapid-screen field tests for esti-
mating performance, information de-
rived in the course of preparing this
report was used to select three labora-
tory testing procedures for evaluation
of performance characteristics: the
Revised Standard EPA test, the Swirling
Flask test, and the IFP-Dilution test, in
the laboratory, these three procedures
were evaluated for their precision of
results in estimating dispersant perfor-
mance, costs associated with conduct-
ing a given procedure, and the ease of
conducting that procedure (e.g., num-
ber of tests performed in 8 hr, skill
level required of an operator, and
overall complexity of the procedure).
The precision of results for dispersion
performance for all procedures was
approximately the same (standard de-
viation of 7% to 9% in dispersion per-
formance values). Costs to perform a
procedure and ease of conducting that
procedure favored the Swirling Flask
test.
This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project
that is fully documented in the two re-
ports listed at the end of this summary
(see Project Report ordering informa-
tion at back).
Introduction
All tasks performed for this work assign-
ment were elements of the Oil Spills Re-
search Program that was initiated in re-
sponse to the Oil Pollution Act (OPA) of
1990. The work supports the EPA workgroup
concerned with revision of sub-part J (dis-
persant effectiveness and toxicity) of the
National Contingency Plan (NCP) as re-
quired by the OPA. Primary deliverables
from SAIC to EPA's Releases Control
Branch/Risk Reduction Engineering Labo-
ratory (RCB/RREL) include (1) a State-of-
the-Art (SOTA) report on mechanisms of
action and factors influencing dispersant
performance and (2) a laboratory evalua-
tion of candidate National Contingency Plan
protocols for testing dispersant perfor-
mance of candidate agents. The RGB may
use information derived from the SOTA
report as well as the laboratory studies as
part of the work assignment to assist in
evaluation of candidate tests for estimat-
ing performance of dispersant agents as
Printed on Recycled Paper
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well as planning follow-on studies with
chemical dispersants.
State-of-the-Art Report on
Chemical Dispersants
The SOTA report for chemical disper-
sants includes discussions of the follow-
ing topics: (1) the mechanism of action of
chemical dispersants for oil spills, (2) fac-
tors affecting the performance of disper-
sants, (3) some common laboratory
methods used to measure dispersant per-
formance, (4) aspects of the analytical
measurement of dispersant performance
in the laboratory, (5) a brief summary of
dispersant applications and their perfor-
mance in field trials and spills-of-opportu-
nity, and (6) recommendations for future
laboratory studies. The discussion of the
laboratory methods includes detailed in-
formation for a number of the more com-
monly used tests, as well as similarities
and differences among testing procedures.
Differences among tests are particularly
important because they may be respon-
sible for not only significant differences in
results between laboratory testing methods
but also poor correlations between labo-
ratory results and data from field tests.
Four general types of laboratory testing
methods are considered: (a) tank tests,
(b) shake/flask tests, (c) interfacial surface
tension tests, and (d) flume tests. Infor-
mation is presented for general ap-
proaches used in laboratory studies, limi-
tations inherent to the laboratory mea-
surements, and the relevance of laboratory
results to field studies or situations. Brief
descriptions also are presented for a
number of rapid field tests for estimating
dispersant performance. Limitations in-
herent to measurements obtained with the
latter tests are discussed.
General Mechanism of Action
of Chemical Dispersants
Chemical dispersants are designed to
promote the break-up or dispersion of an
oil slick into small droplets that distribute
into a water column. The small oil droplets
should not recombine or coalesce to reform
surface slicks. Ideally, dispersed oil drop-
lets will be subject to not only dilution to
non-problematic concentrations in the
water column but also enhanced microbial
degradation as the oil-water interface in-
creases.
A typical commercial chemical disper-
sant is a mixture of three types of chemi-
cals: surface active agents (i.e., surfac-
tants), solvents, and additives. Solvents
are primarily present to promote the dis-
solution of surfactants and additives into a
homogeneous dispersant mixture. Addi-
tives may be present for a number of
purposes such as increasing the biode-
gradability of dispersed oil mixtures, im-
proving the dissolution of the dispersant
into an oil slick, and increasing the long-
term stability of the dispersion. For the
actual dispersion process, however, the
most important components in the disper-
sant mixture are the surfactant molecules.
These are compounds containing Irath oil-
compatible (i.e., lippphilic or hydrophobic)
and water-compatible (i.e., hydrophilic)
groups. Because of this amphiphatic nature
(i.e., opposing solubility tendencies), a
surfactant molecule will reside at oil-water
interfaces with the hydrophobic and hy-
drophilic groups positioned toward the oil
and water phases, respectively. As such,
the surfactant will reduce the oil-water in-
terfacial surface tension. The lowering of
oil-water interfacial surface tension will
promote dispersion of oil droplets into the
underlying water with minimal mixing en-
ergy. The oil droplets will remain dispersed
in a water column if they are small enough
to allow for natural water currents or
Brownian motion to prevent rising to reform
surface slicks.
Factors Affecting Chemical
Dispersion of Oil and Its
Measurement
A variety of factors have major influ-
ences on the ability of chemical agents to
disperse oil into water in both laboratory
tests as well as actual field situations.
These factors can include physical and
chemical properties of an oil, the compo-
sition of a dispersant formulation, the
method of applying the dispersant to an
oil slick, the mixing energy available for
dispersing treated oil into a water column,
the dispersant-to-oil ratio, the oil-to-water
ratio, temperature, and salinity. Trie sam-
pling and analysis methods for evaluating
dispersion performance also can influence
measurement results.
Crude and refined petroleum products
are complex mixtures of hydrocarbon
compounds that can contain compounds
in five broad categories: lower molecular
weight (1) aliphatics and (2) arcimatics,
and higher molecular weight (3)
asphaltenes, (4) resins, and (5) waxes.
Interactions between the aliphatics, aro-
matics, asphaltenes, resins, and waxes
allow for all of the compounds to be
maintained in a liquid-oil state. That is,
the lower molecular weight components
(i.e., the aliphatics and aromatics) act as
solvents for the less soluble, higher mo-
lecular weight components (i.e., the
asphaltenes, resins, and waxes). In addi-
tion to inherent differences in chemical
compositions among different parent oils,
oil that is released onto a water surface
will undergo a variety of rapid, dynamic
changes in both chemical composition and
physical properties. Such changes are
known as weathering and result from se-
lective dissolution and evaporation losses
of lower molecular weight components as
well as photooxidation and microbial deg-
radation of selective compounds. Com-
plex crude oil mixtures remain as relatively
stable liquid phases as long as the sol-
vency interactions occurring in the bulk oil
are maintained and thermodynamic con-
ditions remain constant. If this equilibrium
state is changed (e.g., due to weathering
processes), the solvency strength of the
oil may become insufficient to keep higher
molecular weight components in solution
and lead to their precipitation as solid
particles. Accompanying changes in the
physical state and chemical properties of
the oil can affect the way chemical dis-
persants interact with the oil that has un-
dergone such changes. Despite the pre-
ceding complexities associated with dif-
ferent oils, dispersant formulations are
frequently designed with the intent to deal
with a relatively broad range of oil types
and properties.
The dispersant application method can
be one of the most critical elements de-
termining whether a particular dispersant
will produce dispersion of oil or not. In
field situations, dispersant is normally ap-
plied from aircraft (airplanes or helicopters)
or surface vessels (boats). The dispersant
is applied as relatively small droplets that
descend onto a slick in a manner providing
broad spatial coverage. The size of the
applied dispersant droplets is important to
successful application. Droplets that are
too large may penetrate through an oil
slick without interaction. Droplets that are
too small may not reach the slick because
of air or wind transport between the appli-
cation source and the slick.
Following application of a chemical dis-
persant to an oil slick on water, dispersion
of the oil requires input of mixing energy
that results in injection of the oil as droplets
into the underlying water column. The
mixing energy is generally supplied by
ambient wave action in field situations or
mechanical agitation of test solutions in
laboratory systems. Dispersion of the
droplets into the water column is countered
by the buoyancy of the oil droplets, which
depends on the density and size of the
droplets, their rise velocities as described
by Stokes' Law, and natural advective
processes that result in horizontal and
vertical transport and dilution of the oil. In
addition to mixing energy, other factors
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that can affect dispersion performance of
an oil include the ratios of dispersant-to-
oil and oil-to-water as well as ambient
temperature and salinity in the water.
Evaluation of dispersant performance in
the laboratory (as well as the field) must
incorporate appropriate sampling and
analysis methods into a testing procedure.
In the numerous studies that compare dis-
persion-performance values among test-
ing procedures, agreement for results is
generally poor. At least a portion of this
variability is attributable to variations in
the sampling approaches. For example,
different laboratory testing procedures will
collect test samples from reaction vessels
at various times after agitation in the re-
action vessel ends. A settling time (i.e.,
collection of samples only after agitation
has stopped for some predefined period
of time) may be incorporated into a testing
procedure to allow larger, less stable dis-
persed oil droplets to return to a surface
slick before smaller, more stable dispersed
oil droplets are recovered in a subsurface
water sample.
In addition to the preceding issues re-
lated to sampling methodology, the ana-
lytical methods chosen to quantify amounts
of dispersed oil in samples also are im-
portant for dispersion measurements. The
most widely used methods for quantifying
amounts of dispersed oil in laboratory test
samples involve extraction of a water
sample with a suitable solvent and quan-
titation by UV-visible spectrophotometric
or (less frequently) gas chromatographic
methods. However, selection of the ana-
lytical wavelength(s) for spectrophotomet-
ric measurements can be important. Mea-
surements in different laboratory testing
procedures have been made at wave-
lengths from 340 to 620 nmeters, with
wavelengths selected in part on the optical
(or color) characteristics of particular oils
and dispersants being tested as well as
the optical characteristics of the available
spectrophotometric system.
Laboratory Tests for Dispersant
Performance
A variety of laboratory testing methods
have been used to evaluate dispersant
performance. In general, laboratory tests
can be placed into four categories: (1)
tank tests with water volumes ranging from
1 to 150 L, (2) shake/flask tests that are
conducted on a relatively smaller scale
and require less sophisticated laboratory
equipment, (3) interfacial surface tension
tests that measure properties of the treated
oil instead of djspersant performance di-
rectly, and (4) flume tests using flowing
water systems with the capacity for break-
ing/nonbreaking waves to generate en-
ergy regimes that can more closely simu-
late real-world conditions in large water
bodies (e.g., oceans and coastal bays).
Each type of test uses a general approach
of (1) establishing an oil slick on water, (2)
applying dispersant to the slick, (3) apply-
ing energy to the oil-dispersant-water sys-
tem, and (4) measuring the amount of oil
dispersed into the water.
Significant differences are inherent to
the various methods. For example, differ-
ent methods for adding the dispersant to
oil include premixing of dispersant with oil,
slowly pouring dispersant onto the oil,
spraying the oil surface with a fine mist of
either neat dispersant or dispersant
premixed with seawater, or pouring the
dispersant into the water before adding
the oil. Test-specific variations in the ratio
of the oil-to-water volumes can affect not
only the relative performance of dispersant
surfactants (e.g., hydrophilic versus li-
pophilic) but also the magnitude of wall-
effects in test containers. A variety of ap-
proaches have been used to provide mix-
ing energy to test systems, such as circu-
lating pumps and spray hose systems,
high velocity air streams that produce small
waves on the water's surface, raising and
lowering of a metal hoop in the water,
rotating or shaking separatory funnels,
shaking flasks on a shaker table, and
vertically flowing water in a test cylinder.
Another variation concerns the time after
mixing ends that water samples are with-
drawn from the test solutions in the differ-
ent procedures. In summary, the wide va-
riety of test conditions can make compari-
son of results among different methods
quite problematic.
Detailed descriptions of the following
procedures for evaluating performance of
chemical dispersants are presented in the
SOTA report.
1) Tank tests: Mackay/Nadeau/Steelman
(MNS) test, Revised Standard EPA
test, oscillating hoop test, IFP-Dilu-
tion test, and flowing cylinder test.
2) Shake/Flask tests: rotating flask test
(Labofina/Warren Spring Laboratory),
swirling flask test, and Exxon disper-
sant effectiveness test (EXDET).
3) Interfacial Surface Tension tests: drop-
weight test.
4) Flume tests: cascading weir test and
Delft Hydraulics flume test.
Table 1 summarizes features and es-
sential procedural components in these
testing methods. Strengths and limitations
associated with each testing method are
presented in the SOTA report.
In addition to the preceding methods,
descriptions also are presented in the
SOTA report for five rapid-screen field tests
for evaluating dispersant performance (the
EPA field dispersant effectiveness test,
the API field dispersant effectiveness test,
the Mackay simple field test, the Pelletier
screen test, and the Fina spill test kit*).
The detailed laboratory test methods
identified in Table 1 do not readily lend
themselves to onsite applications in the
field. In contrast, the rapid-screen field
tests have been developed to provide fast,
qualitative information regarding an oil's
dispersibility in field situations. These rapid-
screen tests are, however, inherently lim-
ited in the scope of information that they
can provide because of their necessary
simplicity for use in field situations.
Evaluation of Laboratory Test
Procedures to Assess
Dispersant Performance
Primary objectives in evaluations of
laboratory testing procedures were to ob-
tain estimates of the repeatability of mea-
surements for dispersion performance with
different testing procedures, evaluate
comparability of results obtained with the
procedures for selected dispersant agents
and oils, and summarize the qualitative
ease of conducting each testing procedure
(i.e., how many individual test runs can be
performed in a given period of time, the
complexity of a testing procedure in relation
to the required training time and skill level
of an operator, and associated costs for
both equipment and conduct of tests). All
of these objectives have relevance to the
suitability of a testing procedure for use
as a routine laboratory testing method.
Additional advantage could derive from
identifying one or more testing procedures
that could be performed in a more rapid
and efficient manner than the current Re-
vised Standard EPA protocol and that
could provide results giving dispersion-
performance rankings for different disper-
sant agents equivalent to those obtained
with testing procedures used by agencies
in other countries (e.g., Canada and
countries of Western Europe).
Selection and Experimental
Design for Test Procedures
Tests selected for evaluation in the labo-
ratory included the currently accepted Re-
vised Standard EPA test, Environment
Canada's Swirling Flask test (including
three versions: premixed, 1-drop, and 2-
drop dispersant additions), and the IFP-
* Mention of trade names or commercial products does
not constitute endorsement or recommendation for
use.
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Table 1. Summary of Features of Laboratory Methods to Test Dispersant Performance
Water
Energy Energy Volume
Test ID Source Rating1 (mL) OWRt
MNS
Revised Std.
EPA
Oscillating
hoop
IFP-dlliition\
Flowing
cylinder
Labotlna
rotating
flask
Swirling
flask
EXDET
Drop-weight
Cascading
wolf
Delft flume
High velocity 3
air stream
Pump 3
Oscillating 3
hoop
Oscillating 1-2
hoop
Vertical flow 1
ofwator
Rotating 3
vessel
Shaker table 1-2
Wrist-action 1-2
shaker
None 0
Water 2-3
passing over
weirs
Wave paddle 2-4
6000 1:600
130,000 1:1300
35,000 1:175
4000-5000 1:1000, then
decrease
1000 1:1200, than
decrease
250 1:50
120 1:1200
250 Variable
(NA)» (NA)
150,000 Variable
4,500,000 Variable
Dispersant
Application
Method
Dropwise/
premix
Dropwise
Dropwise/
premix
Dropwise
Pramtx
Dropwlso
Premix/
dropwise
Premix/
dropwise
Water-oil
interaction
Spray
Spray
DOR*
Variable
3:100 to
1:4
Variable
Variable
1:25
1:25
1:10 to
1:25
Variable
(NA)
Variable
Variable
Settling
Time
(min)
None
None
None
None
10
1
10
None
(NA)
None
None
Complexity
Rating"*
3
3
3
2
2
1
1
1
2
4
4
'Energy Rating: 0=none; 4=highest.
tOWR* oil-to-water ratio (v:v).
* DOR s dispersant-to-oil ratio (v:v).
"Complexity Rating: 1* lowest; 4 = highest.
H (NA) * not applicable.
Dilution test (Centre de Documentation de
RecherchS et d'Experimentations sur les
Pollutions Accidentelles des Eaux,
Plouzane, France). Test oils used in some
or all portions of the laboratory study in-
cluded Prudhoe Bay crude, South Louisi-
ana crude, Alberta Sweet Mixed Blend
(ASMS), Arabian crude, Bunker C, and
No. 2 fuel oil. Test dispersants used in all
portions of the study included Corexit 9527,
Coraxit CRX-8, and Enersperse 700. Com-
mon elements through tests with all of the
testing procedures included the following.
• oil types: Prudhoe Bay and South
Louisiana crudes
• dispersant types: Corexit 9527,
Corexit CRX-8, Enersperse 700, and
"no dispersant" controls
• test types: EPA-10 min, EPA-2 hr,
premixed Swirling Flask, and IFP-Di-
lution
• analytical wavelengths: 340, 370, and
400 nmeter absorbance
• duplicate measurements for particu-
lar groups
• water temperature (not a specified
variable of interest for these studies,
but one that did exhibit slight varia-
tions)
Results of Laboratory Tests
Information for the primary objectives of
the laboratory study are summarized in
Table 2. Estimates of precision or repeat-
ability for dispersion-performance values
(i.e., standard deviations about means)
were approximately 7% to 9% for all of
the testing procedures. These values
should be viewed as preliminary estimates,
however, because they are generated with
only a limited number of oils and disper-
sant agents. Furthermore, final estimates
for precision associated with a given test-
ing procedure should incorporate measure-
ments from multiple laboratories. The
nonquantitative criteria in Table 2 (i.e.,
number of tests that can be performed in
8 hrs; costs associated with equipment
acquisition, conduct of tests, and waste
disposal; and qualitative items such as
necessary skill level of an operator and
overall complexity of a testing procedure)
favor the Swirling Flask procedure for
conducting multiple tests in a relatively
short period of time for the least amount
of cost.
General trends for the results of disper-
sion performance in the laboratory tests
are illustrated in Figure 1 for the two com-
mon test oils (Prudhoe Bay and South
Louisiana crudes) with the four primary
testing procedures (Revised Standard
EPA-10 min, Revised Standard EPA-2 hr,
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premixed Swirling Flask, and IFP-Dilution)
and the three dispersants (Corexit 9527,
Corexit CRX-8, and Enersperse 700). Dis-
persion for- all test oils in all procedures
was near zero in the absence of chemical
dispersant agents. With addition of the
dispersants, performance values were con-
sistently highest with the EPA test. Simi-
larities in relative trends for dispersion per-
formance with the different dispersants
were observed in the Revised Standard
EPA and Swirling Flask procedures for
Prudhoe Bay crude. Trends for dispersion
performance with the different dispersants
and South Louisiana crude were less com-
parable In the EPA and Swirling Flask
procedures. Relative performance trends
among dispersants In the IFP-Dllutlon pro-
cedure did not appear to be comparable
to either the EPA or Swirling Flask tests.
Statistical analyses of results showed that
the major portions of differences in disper-
sion-performance values for the three pri-
mary testing procedures (Revised Stan-
dard EPA, premixed Swirling Flask, and
IFP-Dilution) could be accounted for by
-differences in the oils and dispersants used
in tests (i.e., at least 85% of the total
variance for results with each testing pro-
cedure). Dispersion-performance values for
measurements at the three analytical
wavelengths (340, 370, and 400 nmeters)
were negligible (i.e., <0.5% of the total
variance).
Recommendations for
Laboratory Studies
Chemical dispersion of oil into water in
laboratory studies involves complex inter-
actions between many variables including
the chemical and physical properties of
oils and dispersants, the method of appli-
cation (and its effectiveness) and mixing
of a dispersant with an oil, the source and
magnitude of mixing energy available to
the system, the dispersant-to-oil ratio, the
oil-to-water ratio, temperature, and the sa-
linity of the aqueous medium. Extrapola-
tion of results from dispersion performance
studies in a laboratory to field situations
must take into account additional compli-
cating variables including rapid changes
that occur in properties of the oil with time
(i.e., natural weathering), field application
methods and logistics, ambient weather
and meteorological conditions, and local
sea-state or oceanographic conditions
(e.g., wave heights, currents, turbulent mix-
ing regimes, etc.). The breadth of these
variables makes It unlikely that any single
laboratory test will ever be completely suit-
able to quantify performance of chemical
dispersant agents for all possible environ-
mental scenarios. More realistically, many
laboratory test results should be used to
apply relative rankings to performance by
various dispersant agents, including pos-
sible assignment of "pass/fail" status to
individual dispersants. Scientific criteria to
assign "pass/fail" status continue to be
subjects for future discussion and study.
Much has been learned about perfor-
mance of dispersants and their mecha-
nisms of action from studies conducted
with the variety of laboratory testing
methods shown in Table 1. Test results
are, however, frequently contradictory for
reasons that are probably related to test-
specific characteristics. Adoption of stan-
dard experimental protocols (e.g., selection
of specific reference oils and dispersants,
consideration of the weathered state of
test oils, use of specific oil-to-water ratios,
selection or not of designated settling-times
to be used in the conduct of experiments,
and consideration of the natural
dispersibilities of oils in a given test) might
lead to closer agreement in performance
results among testing methods. Further
advances in testing methodologies, how-
ever, remain to be developed and refined,
particularly as they relate to the environ-
mental relevance and performance of dis-
persant agents. For example, approaches
used to generate environmentally relevant
mixing energies in laboratory studies could
be improved. Continued investigation and
analysis of dispersed oil droplet sizes might
explain differences in energy levels and
estimates of dispersion performance in dif-
ferent laboratory testing systems, which
could lead to improved, standardized test
designs. In general, laboratory experiments
also have not been designed to evaluate
the effects of herding of oil on dispersion
results. Current testing methodologies are
Inadequate to Investigate dispersion In thin
versus thick slicks, which Is Important for
dispersant applications at sea because
slicks are usually nonuniform In thickness
and distribution on the water's surface. At
the same time, it Is highly desirable that a
laboratory testing method be simple, re-
quire equipment that is relatively easy to
acquire and fabricate, require a minimum
of operator training and sophistication, and
allow for the conduct of a reasonably large
number of tests yielding quantifiable results
in an acceptably short period of time.
From the standpoint of using chemical
dispersants for mitigating effects of oil spills
in real-world situations, development and
refinement of application techniques and
protocols for applying dispersants in the
field remain as critical needs. Successful
application of chemical dispersants in field
situations continues to be extremely prob-
lematic. Further studies in areas of appli-
cation technologies are definitely war-
ranted.
All reports for the work assignment were
submitted in fulfillment of Contract No. 68-
C8-0062 by Science Applications Interna-
tional Corporation under the sponsorship
of the U.S. Environmental Protection
Agency.
Table 2. Results of Test Procedures Used to Evaluate Performance of Chemical Dispersant Agents
Test Procedure
Revised Standard EPA - 10 min
Revised Standard EPA -2hr
Swirling Flask (Premixed) - (2 oils)
Swirling Flask {Premixed) - (4 oils)
IFP-Dilution
-^
Standard
Deviation for
Performance
8.8%*
7.2%
7.8%
8.1%
7.2%
No. Tests/8 hr
2
2
24-36
24-36
4-5
Equip.
Cost
($)
2,280
2,280
1,225
1,225
3,160
Cost
Run
($)
600
600
22
22
202
Complexity of
Procedure
High
High
Low
Low
Moderate
Operator
Skill Level
Moderate
Moderate
Moderate
Moderate
Moderate
* Bold values for standard deviations are estimates because variances among groups are heterogeneous by Bartlett's test for homogeneity.
-------
Prudhoe Bay Crude
Mean DIspersant Performance (%)
EPA - 10 mln EPA - 2 hr Sw. Flask-premix IFP-dilution
Test ID
South Louisiana Crude
Mean DIspersant Performance (%)
C9527
EN700
EPA - 10 mln EPA - 2 hr Sw. Flask-premix IFF'-dilution
Test ID
Figure 1. DIspersant performance for four testing procedures with two oils and three dispersants. Values are means from replicate measurements.
•U.S. Government Printing Office: 1992— 648-080/60139
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John R. Clayton, Jr., Siu-Fai Tsang, Victoria Frank, Paul Marsden, and John Harrington are with
Science Applications International Corporation, San Diego, CA 92121. James R. Payne is
with Sound Environmental Services, Inc., Carlsbad, CA 92008
ChoudhrySarwaris the EPA Project Officer (see below).
Completed reports produced in the project are the following:
(1) "Chemical Oil Spill Dispersants: Update State-of-the-Art on Mechanisms of Action and
Factors Influencing Performance with Emphasis on Laboratory Studies. Final Report,"
(OrderNo. PB92-222 207/AS; Cost: $19.00, subject to change)
(2) " Chemical Oil Spill Dispersants: Evaluation of Three Laboratory Procedures for Estimating
Performance. Final Report," (Order No. PB92-222 041/AS; Cost: $26.00, subject to change)
Both reports will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Edison, NJ 08837-3679
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/S-92/065
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