United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/070 Jan. 1988
v>EPA Project Summary
Evaluation of Oil Spill Dispersant
Testing Requirements
This research program was initiated
to evaluate the cost and effectiveness
of the procedures for testing oil spill
dispersants as specified in the National
Oil and Hazardous Substances Pollution
Contingency Plan, Annex X. The testing
procedure is described in detail in the
Standard EPA Dispersant Effectiveness
and Toxicity Tests (EPA-R2-73-201) and
in Annex X. These procedures were
examined using No. 2 and No. 6 fuel
oils and six commercial oil spill dis-
persants. The methods were evaluated
in terms of reliability, precision, cost-
effectiveness, and applicability.
Seven laboratory methods for testing
dispersant effectiveness using com-
mercial oil spill products and No. 2 and
No. 6 fuel oils were evaluated. The
tests included the EPA, Mackay,
Russian, French, Warren Spring, and
two interfacial tension test methods
(one based on the du Nouy ring principle
and the other on drop-weight). These
tests were reviewed in terms of type,
scale, method of applying mixing en-
ergy, and the time required to conduct
a product evaluation. The experimental
results, compared in terms of the preci-
sion of the test data and how effective
the six nonionic dispersants were,
demonstrate that the relative effective-
ness found for the dispersants varies
appreciably as a function of the testing
method. Reasons for the variation are
discussed, and recommendations are
presented on how to achieve dispersant
testing data that are more representative
of open-sea conditions.
On the basis of these findings, recom-
mendations for revision to the Standard
Dispersant Effectiveness Test from
Annex X and the Standard Dispersant
Toxicity Test were made and have been
included as part of the full report.
This Project Summary was developed
by EPA's Hazardous Watte Engineering
Research Laboratory, Cincinnati, OH, to
announce key findings of the research
report that Is fully documented In a
separate report of the same title (see
Project Report ordering Information at
back).
Introduction
In 1975 the National Oil and Hazardous
Substances Pollution Contingency Plan
(NCP) was developed in compliance with
the Federal Water Pollution Control Act.
This plan as currently amended (40 CFR
Part 300) provides for a coordinated and
integrated response by the Federal
Government to protect the environment
from the damaging effects of pollution.
One means of minimizing damage from
oil discharges is to emulsify, disperse, or
solubilize the material into the water
column, thereby minimizing surface ef-
fects. Use of chemical treating agents
was specifically covered by Annex X of
the NCP and is controlled under its re-
placement, Subpart H.
Many chemicals have been developed
commercially to combat floating oil. When
applied to oil spills, these chemicals (dis-
persants) accelerate the dispersal of the
oil into small globules and emulsions by
reducing the mixing energy required for
dispersal. When the oil is dispersed as
fine droplets, it will not cling to solid
surfaces and the rate of biodegradation
and chemical transformation will be in-
creased because of the resulting greater
surface area. The effectiveness (in terms
of ability to move floating oil into the
water column) and toxicity of these
chemicals and resulting oil:water:dis-
persant mixtures varies from oil to oil and
product to product.
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Most chemical oil dispersants are pro-
duced and marketed with little information
concerning their relative effectiveness and
toxicity. This makes it difficult to (1) select
products based on their effectiveness for
a particular oil spill, (2) estimate the
effect of the dispersant on the environ-
ment, and (3) determine the costs of
treatment.
A reliable laboratory test procedure for
estimating dispersant effectiveness is
desirable for the selection of the most
economically and environmentally ac-
ceptable formulation. However, it is dif-
ficult to take into account all the test
parameters that adequately represent
real-world conditions on a laboratory
scale. In evaluating laboratory tests, it is
necessary to identify parameters that are
important and those that may be disre-
garded without affecting the precision of
the test results.
The objectives of this study were to
evaluate the Standard EPA Dispersant
Effectiveness and Toxicity Tests (EPA-R2-
73-201, May 1973) when applied to six
commercial oil dispersant chemicals (A,
B, C, D, E, and F) in light of other existing
test protocols and to recommend modifi-
cations to the procedures that will en-
hance the sensitivity and reliability of the
method.
Other methods examined (by literature
review) included the Mackay* test, the
Russian test, the Wareen Spring test
(Warren Spring Laboratory), and the
French test (French Ministry). Two addi-
tional tests based on interfacial tension
were also investigated.
Previous investigators have tried to
compare the EPA standard test with other
reported methods. The comparison is dif-
ficult because most laboratory methods
differ widely in design and procedure and
test criteria are often unavailable. For
example, mixing energy is supplied by a
spray hose and circulation pump in the
EPA test, by a high-speed propeller in the
Russian test, by rotating separatory
funnels in the Warren Spring and French
tests, and by a high-velocity airstream in
the Mackay test. In the EPA and Russian
tests, dispersant is poured on the test oil
in a containment ring; in the Warren
Spring and MacKay tests, the dispersant
is syringed on top of the test oil. In the
Russian, Warren Spring, and French tests,
samples are withdrawn for analysis after
mixing is stopped; in the EPA and Mackay
Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use.
procedures sampling is conducted under
dynamic conditions.
The present investigation focused on
(1) comparison of test data in terms of
dispersant ranking order, precision of test
results, and time required to complete
the evaluation, (2) identification of key
experimental parameters that contribute
to poor test results, (3) recommendations
for improving current testing methods to
simulate the real world environment more
closely, and (4) development of an im-
proved effectiveness test that is subject
to fewer interferences.
Specifically, the work consisted of the
following tasks:
• Examine the physical and chemical
parameters and test prescribed by
Annex X and evaluate their applic-
ability.
• Conduct laboratory effectiveness and
toxicity tests of the six dispersants
using the Annex X procedures.
• Determine the cost and time required
to establish a facility with the equip-
ment necessary to perform the EPA
tests routinely.
• Evaluate other dispersant effective-
ness test protocols (by literature
review) and compare the results with
the EPA test.
• Modify the EPA test and address its
major deficiencies.
• Suggest alternative testing proce-
dures, such as the drop-weight inter-
facial tension test.
As a result of this work, a revised
standard dispersant effectiveness test, a
revised standard toxicity test, a modified
EPA dispersant effectiveness test proce-
dure, and a drop-weight dispersant effec-
tiveness test procedure have been
prepared, and are presented in the project
report.
Conclusions
Overall test characteristics, advantages
and disadvantages are summarized in
Table 1. Also provided in this section are
conclusions regarding the dispersant ef-
fectiveness tests and the toxicity tests, as
well as the material and equipment
requirements.
Dispersant Effectiveness Tests
The Standard EPA Test
• Test results varied with the type of
oil and the dispersant/oil ratio.
• Data variance for the initial three
products tested (C, E, and F) was
greater than the value suggested in
EPA-R2-73-201.
• Data variance after modifications foi
tank cleaning and oil/ dispersant
addition (products A, B, and D) was
less than the value suggested in
EPA-R2-73-201.
• Considerable amounts of oil adhere
to the walls of the tank and the
plastic pumping system.
• Excessive time is required to conduct
a dispersant evaluation.
• The test can be revised to improve
its performance (see Recommenda-
tions).
The Modified Test
• Test addresses major deficiencies of
standard EPA test: application of
constant mixing energy and elimina-
tion of circulation pumps and plastic
sampling system.
• Test results improve with increasing
spray pressure.
• Optimized sampling position is 5.08
cm (2 inches) below the water sur-
face and 7.62 cm (3 inches) from the
tank wall.
• Effectiveness test results for dis-
persants B, D, and E are considerably
lower than standard EPA test results.
For dispersants A and C, approxi-
mately the same results were ob-
tained for both tests.
• Dispersant effectiveness test results
of dispersants A and B increase (by
different factors) with increasing
paddle speed.
• Oxygen mass transfer coefficient
measurements for the modified test
suggest that the mixing energy is a
factor of about 3.5 less than that for
the standard test.
Du Nouy Ring Interfacial
Tension Test
• The test is unsuited for heavy oils
such as No. 6 fuel oil because of
cleanliness problems and the curved
meniscus of the oil.
The Drop-Weight Interfacial
Tension Test
• The test is superior to other methods
in terms of simplicity, required work-
ing space, and time.
• The test measures the fundamental
physical property that applies to all
surfactant/oil systems: the lowering
of the interfacial tension between
oil and water.
• Test results are difficult to compare
with other methods because no
mixing energy is required, wall ef-
fects are minimized, sampling prob-
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able 1. Review of Dispersant Effectiveness Tests
Test
EPA ISTD)
EPA (REV)
Mackay
Russian
French
Warren
Spring
Drop-
weight
Du Nouy
Ring
Type
Tank
Tank
Tank
Tank
Separatory
funnel
Separatory
funnel
Interfacial
tension
Interfacial
tension
Scale
(liter)
130
130
6
1
0.25
0.25
0.02
0.07
Mixing
Energy
Source
Spra y/ circulation
pump
Spray/circulation
pump
Air turbulence
Propeller
Rotating sep. funnel
Rotating sep. funnel
—
—
Time per
Test
(hr)
96
96
21
20
17
10
4
<4
Precision of
Test Results
(% S.D.)
32.3
6.4
10.1
8.8
13.3
14.5
6.0
N.C.
Major
Advantages
Large Scale
Large Scale
Simulates wave
action
Simple, bench scale
Simple, bench scale
Simple, bench scale
Very simple, rapid
Very simple, rapid
Major
Disadvantages
Time and cost; pump shear
effect; mixing energy
Time and cost; pump shear
effect; mixing energy
Expensive apparatus; wave
damping; high mixing energy
Propeller shear effect; bottom
sampling
Bottom sampling; wall effects
Bottom sampling; wall effects;
dispersant and oil premixed
Does not give value for amount
of oil dispersed
Does not give value for amount
of oil dispersed
lems do not apply, and the results
are not interpretable in terms of the
amount of oil dispersed.
• Three interfacial phenomena can be
derived from a single drop-weight
measurement. The critical micelle
concentration (cmc) can be used to
predict the dispersant concentration
at which monolayer coverage is
achieved at the oil water interface;
the initial slope of the cmc curve can
be used to predict the packing ef-
ficiency of surfactant molecules at
the oil water interface; and the drop-
weight reduction is proportional to
the interfacial tension lowering
between oil and water.
The Mackey Test
• Data variance is higher than in the
EPA test.
• The product ranking order is different
than that based on the EPA results.
• Apparatus is not readily portable,
space efficient, or time- and cost-
effective.
• Magnitude of applied mixing energy
appears to be too high.
• Problem of wave damping could
generate an unrealistic ranking trend
in data for a series of dispersants.
The French, Russian, and
Warren Spring Tests
• The amounts of oil dispersed in the
French, Russian, and Warren Spring
tests were generally lower than those
in the EPA and Mackay tests.
• Bottom sampling discriminates
against observation of larger particle
size oil droplets and may skew test
results.
• Wall effects may contribute to the
higher data variance than that ob-
served for the EPA and Mackay test
results.
Dispersant Toxlclty Testa
• Post-test mortality and sublethal
effects in fish exposed to some dis-
persant products indicate that an
LC60 estimate based on the test may
not be adequate for predicting the
environmental impact of a dispersant.
• Because of differences in test
methodologies, comparisons of toxi-
city rankings obtained from bioassays
performed on brine shrimp and
mummichogs are meaningless.
• The higher LC50 values reported for
the toxicity of dodecyl sodium sulfate
to brine shrimp were approximately
five times greater than the lower
LC50 values. A portion of this variation
is probably due to differences in the
age of the dodecyl sodium sulfate
stock solution.
• The standard seawater formulations
given in EPA-R2-73-201 are not
stable at pH 8. For example, pH
levels were as low a 6.9 in control
jars immediately after shaking, even
though the pH of the seawater stock
had been 8.0 ± 0.1 only 30-60
minutes earlier. It appears that
several salts were not included in
the formulations.
• Grass shrimp (Crongon franciscorum)
appear satisfactory as a test organism
using the same experimental proce-
dures and diluent water specified
for the mummichogs.
Time, Material, and Equipment
Requirements
Equipment setup time, performance
time, and cost can have a significant
effect on the general acceptance of a
testing program. As a part of our effort,
we maintained an inventory of the equip-
ment and materials used and a record of
the time required to perform each phase
of the work. The objective of this task
was to identify the cost and time required
to establish a facility with the equipment
necessary to perform the Annex X tests
routinely.
Table 2 summarizes the major equip-
ment required to conduct the Annex X
testing procedures. The estimated costs
do not reflect the purchase of major
equipment (Table 2), which may be sub-
ject to wide price variations.
Recommendations
Dispersant Effectiveness Tests
General
Nome of the laboratory test procedures
adequately tests the effectiveness of
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Table 2. Major Equipment Required to Conduct Annex X Tests
Test Equipment
Dispersant effectiveness
Dispersant toxicity
Standard EPA test tank and spraying apparatus
Beckman Model Zeromatic II pH meter
Turner Model 350 Spectrometer
Constant temperature bath (SRI manufactured}
Shaker table
Assorted gas-tight syringes (Hamilton)
Light box (SRI manufactured)
Blender
Miscellaneous organism maintenance equipment and glassware
Physical properties
Viscosity
Specific gravity
Miscibility
Flash point
pH
Pour point
Ionic activity
Metal content
Chlorinated hydrocarbons
Brook field Model LVF Viscometer
Master line Model 2095 constant temperature bath
Miscellaneous hydrometer tubes. VWR Scientific Co.
Constant temperature bath
Miscellaneous glassware and chemicals
Setaflash Model OJSF
Beckman Model Zeromatic II
Pour point jars, VWR Scientific Co.
Miscellaneous glassware and chemicals
Varian Model AA6 Atomic Absorption Spectrometer
Microtek Model 220 gas chromatograph
Coulson Electrolytic Conductivity Detector
two-dimensional dispersants. The surface
and interfacial tension measurements
discussed later are the only evaluation
methods currently available, and these
have not been systematically studied.
A series of standard test oils should be
established. One or two crude oils should
be added to the Annex X testing; No. 2
fuel oil could be eliminated because it is
unlikely that dispersants would be used
on it in the field.
The manufacturers of several products
recommend application rates [that is, ratio
of dispersant to oil
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Table 3. Recommendations for Improving the EPA Dispersant Effectiveness Test"
Problem
Effect on
test numbers Recommendations
Effect of Na2S04 drying ~5% high
material
Effect of dispersant on oil ~5% high
measurement
Dispersant blank correction not Variable
linear with concentration
Water and oil blanks not High
required
Oil hfs on pump and tubing Variable
parts
Oil loss to tank walls and ring Low
during spraying and foaming
Recirculation pumping rate Variable
not constant
Impossible to supply repeated Variable
mixing energy
Eddy currents around water Variable
return tube
Tank and tubing cleaning Variable
Dispersant application may be Variable
different from field condition?
Eliminate step because H2O does not interfere
with method
Make blank correction
Measure dispersant blank correction at
different concentration levels
Measure blanks and make appropriate
correction
Use Teflon or PVC (see compatibility
test results)
Coat tank with lipophobic material such as
Teflon
Use constant voltage power supply or
constant speed pump
Use fine spray over ring or use constant speed
propeller mixer
Extend tube deeper into tank
Coat tank with lipophobic material; use
demountable pump and tubing connections
Follow manufacturer's recommended
application method and fate
6 EPA-R2-73-201.
D/0 ratios is incorrect. Such blanks
should be incorporated in any revised
procedure.
Modified EPA Dispersant
Effectiveness
The modified EPA Dispersant Effective-
ness Test addresses the three major areas
that needed improvement in the Standard
EPA Test: (1) a repeatable way to apply
the mixing energy; (2) a sampling device
to eliminate the circulation pump and
connecting plastic tubing; and (3) an
energy source for simulating wave and
tidal action after the application of mixing
energy. The modified EPA Dispersant Ef-
fectiveness Test apparatus consists es-
sentially of the Standard EPA Test tank
and containment ring with the following
modifications:
• Mixing energy is supplied by a full
cone synthetic seawater spray de-
livered by a standard spray nozzle.
The spray covers the entire tank
surface, including the oil/dispersant
containment ring.
• Spraying is actuated by a solenoid
valve.
• Spray nozzle is adjustable in height
to maintain full surface coverage at
different spraying energies (pres-
sures).
• The energy source for simulating
wave and tidal action is a low-shear
paddle stirrer operated at a calibrated
speed.
Because oxygen mass transfer coefficient
(k K) measurements for the modified test
showed that the applied mixing energy is
about 3.5 times less than that for the
standard test, additional dispersant effec-
tiveness tests using the modified proce-
dure should be conducted at a higher
mixing energy to increase k £ to at least
20 cm h °, which is characteristic of a
medium sea state condition.
The du Nouy Ring Interfacial
Tension Test
This should be dropped from further
consideration because the ring method
gives unreliable results for heavy oils
such as No. 6 fuel oil.
Drop-Weight Interfacial
Tension Test
The Drop-Weight Interfacial Tension
Test measures the fundamental physical
property that applies to all surfactants:
the lowering of the interfacial tension
between oil and water. This test is also
superior to other methods in terms of
simplicity, required working space, and
test time.
Several features of the Drop-Weight
Test that need additional development
include:
• Develop the test so it can be used
with crude oils; this will involve using
a finer bore capillary to increase the
oil-drop detachment time.
• Evaluate a broader range of dis-
persant products to obtain statistics
concerning the precision of test
results.
• Develop the drop-time test to elimi-
nate the need to weigh the oil drop
and simplify the apparatus for field
application.
• Modify the test to obtain information
concerning relative diffusion rates
of dispersant through an oil column.
• Calculate the drop-weight reduction,
which is proportional to the inter-
facial tension lowering, from the test
results, and use this value to predict
dispersant efficiency.
The Mackay Test
The major advantage of the Mackay
Test is that it attempts to simulate the
was/e action of the open-sea environ-
ment. The problem of wave damping, that
is, the reduction or elimination of circu-
lating waves for some oil/dispersant
combination during testing, needs addi-
tional study to relate the magnitude of
the effect to the environment
The French, Russian, and
Warren Spring Tests
Because the French, Russian, and
Warren Spring tests suffer from unrealis-
tic mixing energy applications, large wall
effects, and bottom sampling, which dis-
criminates against larger particle size oil
droplets, these tests should not be con-
sidered as reliable indicators of dispersant
performance.
Alternative Dispersant
Effectiveness Methods
It may be desirable to develop new
testing methods to supplement or replace
procedures that address the question of
mixing energy variations and those
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specific areas not covered by the drop-
weight method.
A simple test based on participate size
counting or light scattering (described in
the project report) could be developed at
reasonable cost to provide information
not derived from other current testing
methods. An effective surfactant will
generate a finer oil droplet distribution
than a less effective product given the
same mixing energy and temperature
conditions. It would appear that a testing
method based on this approach could
provide information that is fundamentally
related to dispersant effectiveness.
Dispersant Toxicity Tests
There are fundamental differences in
the procedures given in Annex X for
shrimp and fish toxicity tests. It is not
meaningful to compare the sensitivities
of these organisms because any observed
differences could be due to differences in
the test procedures and not to physiology.
Implementation of the following recom-
mendations should eliminate the major
differences between the test protocols as
well as reduce variability related to
acclimation stress.
• The same seawater formulation
should be used for brine shrimp and
fish tests, unless tests show that
physiological differences exist that
mandate otherwise.
• The technique used to mix toxicant
solutions should be the same for
both bioassays. The blender used for
the brine shrimp tests provides vio-
lent mixing that is probably less
consistent with the mixing energy
available in natural systems than is
the energy from the shaker method
used for the fish tests.
• Since many manufacturers suggest
application rates that are less than
the 1 part dispersant to 10 parts oil
recommended in the EPA procedures,
the toxicity associated with the re-
commended application rate should
also be evaluated.
Fish and Brine Shrimp Bioassays
The test protocol does not require oil-
only bioassays. Such bioassays should
be incorporated into the protocol.
The response of test organisms to the
reference toxicant, dodecyl sodium sulfate
(DSS), appears to vary with the age of the
toxicant. Another compound should be
used as a reference toxicant. Phenol
appears to have some promise, but tests
with grass shrimp indicate that toxicity
can vary, depending on the manufacturer.
As stated earlier, the standard seawater
formulations do not appear to be stable at
pH 8. The pH of the fish formulation was
adjusted with NaOH, but the brine shrimp
solution could not be adjusted with either
NaOH or NaHC03, because a precipitate
formed almost immediately. The brine
shrimp formulation exhibits a pH of 8 for
a short time after mixing, but becomes
less basic very quickly. If 8 is the desired
pH, a suitable buffer should be incorpo-
rated into the formulation. The seawater
formulation in EPA-R2-73-201 differs
from those given by Tarzwell in that
NaHC03 was omitted from both formula-
tions and Na2S04 was omitted from one.
Addition of NaHC03 would undoubtedly
improve the pH stability.
At least one of the products tested
appeared to leave the dispersed phase
fairly quickly after mixing. To reduce vari-
ability in the response due to exposure to
different degrees of dispersion, all test
organisms should be introduced to the
test containers at the same time relative
to the end of mixing. That is, all con-
centrations in one replicate or all repli-
cates at one concentration should be
mixed simultaneously and the organisms
added at approximately the same time
(within 5 minutes) after mixing.
It is unclear from EPA-R2-73-201 what
constitutes a desirable test program. For
instance, should all tests be performed
simultaneously or can they be performed
at different times? The optimum experi-
mental design would be to initiate all
bioassays (oil, dispersant, dispersant/oil,
reference toxicant) simultaneously for any
given organism and dispersant. This
would ensure a uniform test population
and simplify comparisons of dispersant
and dispersant/oil toxicity.
Some dispersant and/or oil volumes
and viscosities are too great to be handled
conveniently with syringes. The use of
pipettes or graduated cylinders should be
permitted when required for measuring
larger volumes.
The method promulgated in EPA-R2-
73-201 for glassware cleaning appears
to be somewhat more rigorous than is
required, at least with No. 2 oil. Immersion
of the test containers in hexane for 10
minutes requires a considerable amount
of hexane if several containers are done
at once, or a considerable amount of time
if all jars are done separately. As hexane
is quite flammable and expensive, use of
two hexane rinses followed by a hot
water rinse, two detergent scrubbings,
and tap and distilled water rinses would
be safer, more economical, and less time-
consuming. In addition, it is difficult to
see why the results of multiple scrubbings
and rinses cannot be accomplished with
the automatic dishwashing facilities
present in many laboratories.
Fish Bioassay
At present, predominantly wild-caught
mummichogs are used in the dispersant
bioassay. Inherent in the use of such fish
are genetic differences, seasonal varia-
tions, disease, differences in nutritional
state, and variation in availability at dif-
ferent times of the year. The feasibility of
rearing the mummichog in the laboratory
in a manner similar to that now being
used with the fathead minnow should be
investigated. If a successful method was
developed, it would ensure the availability
of healthy fish, in any age class, at all
times of the year. A somewhat different
approach would be to use a different,
easily reared fish species for all ranking
tests. An example of such a species would
be the sheepshead minnow (Cyprinodon
variegatus), which is already quite popular
for use in embryo-eawal and chronic
studies.
Some fish died after being transferred
to clean water following the 96-hour
exposure; these delayed mortalites con-
stitute a loss of information potentially
important to decision-making. A recovery
period of one week in clean seawater
following exposure to the oil/water dis-
persion should be added to the fish
bioassay.
The reference bioassay should be per-
formed in the same manner as the dis-
persant bioassay.
Brine Shrimp Bioassay
In preliminary tests conducted with
brine shrimp, the range of effect for some
toxicants encompassed two orders of
magnitude. No guidance is given in EPA-
R2-73-201 for the concentrations to be
used in definitive tests under such cir-
cumstances. The appropriate concentra-
tion spread to be used for two orders of
magnitude should be determined and
incorporated into the protocol.
Filtering the diluent seawater is not
required for the fish bioassays but is
required for the brine shrimp assay. Why
the seawater must be filtered for the
brine shrimp is uncertain. This step should
be eliminated or a larger pore size filter
(0.7 mm) used when filtering the brine
shrimp water. This will considerably
reduce the time required for filtration
with probably no effect on toxicity.
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Physical Properties
Pass-fail criteria for the physical pro-
perties listed in Annex X should be
developed.
The Weatherburn Ionic Activity test
and the measurement of cyanide should
be eliminated from Annex X. The manu-
facturer should be required to specify
whether the product is cationic, anionic,
or nonionic.
More specific test procedures for heavy
metals and chlorinated hydrocarbons
should be specified in the Annex X
methods. For example, the sensitivity of
the analyses for the heavy metals could
be improved if different techniques were
used. The simplest would be the graphite
furnace method (the estimated sensitivi-
ties are given in Section 4 of the project
report). However, this method requires
specialized equipment that may not be
available in all laboratories. Alternatively,
it should be possible to develop a sample
digestion method to concentrate the
elements for analysis by the aspiration
method. Separate methods would be
required for dispersants based on water
and hydrocarbon solvents and for mercury
and arsenic.
Similarly, it should be possible to
develop a simple procedure for estimating
the concentration of chlorinated hydro-
carbons in the dispersant products. The
dispersant (water- or solvent-based) could
be partitioned between water and hydro-
carbon solvent and the organic layer
analyzed by a gas chromatograph equip-
ped with a halogen-specific detector.
This Project Summary was prepared by staff of Woodward-Clyde Consultants,
Walnut Creek, CA 94596 and SRI International, Menlo Park, CA 94025.
Leo T. McCarthy (deceased) was the EPA Project Officer (see below for present
contact).
The complete report, entitled "Evaluation of Oil Spill Dispersant Testing
Requirements." (Order No. PB 87-232 633/AS; Cost: $18.95. subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
John S. Farlow can be contacted at:
Releases Control Branch
Hazardous Waste Engineering Research Laboratory—Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837
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Environmental Protection
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PERMIT No, G-35
Official Business
Penalty for Private Use $300
EPA/600/S2-87/070
QOQQ329
PS
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