PROCEEPINGS OF THE WORKSHOP ON
THE SEA-SURFACE MICROLASER IN
RELATION TO OCEAN DISPOSAL
December 18-19, 1985
Airlie, Virginia
October 1986
Work Assignment Manager! Pavid Redford
Office of Marine and Estuarine Protection
WH-556F
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
Coordinated by
John T. Hardy
Battelle, Marine Research Laboratory
Sequim, Washington 98382
Jim B. States
Battelle, Pacific Northwest Laboratories
Richland, Washington 99352
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EXECUTIVE SUMMARY
A workshop was convened to Identify information needs concerning the sea-
surface raicrolayer (SSM) that would assist the U.S. Environmental Protection
Agency in the ocean disposal regulatory process. Twenty-two participants from
a, wide diversity of disciplines, including technical experts on the sea-surface
microlayer9 identified and ranked over 30 relevant information needs. Top pri-
ority was given to determining: 1) residence times for components in the SSM
and their alteration by inputs from disposal, 2) the importance of the SSM as a
biological habitat, and 3) the toxicity of disposal wastes applied in a realis-
tic way to the SSM. A research and monitoring plan based on a decision-tree
and containing short- and long-term tasks was outlined. The first step
involves sampling and analysis of the SSM during research ocean disposal activ-
ities. Measured SSM contaminant concentrations would then be compared with
data on toxicity to surface organisms such as neustonic (floating) fish eggs.
111
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CONTENTS .
••••«*••••••••••*••••
iii
1
3
5
EXECUTIVE SUMMARY 0
INTRODUCTION .
OBJECTIVES
SYNOPSIS OF TECHNICAL PRESENTATIONS AND DISCUSSIONS
FORMAT AND PROCEDURES , 9
RESULTS OF WEIGHTING THE RANKING CRITERIA 11
RESULTS OF RANKING THE INFORMATION NEEDS 13
DISCUSSION AND RECOMMENDATIONS FOR RESEARCH AND MONITORING ;...,,.. 19
REFERENCES ,.... 25
APPENDIX A - WORKSHOP PARTICIPANTS A.I
APPENDIX B - THE COMPUTER-ASSISTED DECISION PROCESS B.I
APPENDIX C - TECHNICAL PRESENTATIONS ON THE SEA-SURFACE
MICROLAYER
The Origin and Enrichment of Participate Material Ejected from
the Surface of the Sea
Duncan C. Blanchard, Atmospheric Sciences Research Center
State University of New York at Albany
C.I
Organic Chemistry of the Sea Surface Microlayer C.9
David J. Carlson, Oregon State University
Mixing Down from the Microlayer: The Role of Three-Dimensional
Flows c.15
Robert A. Weller, Woods Hole Oceanographic Institution
Microbial Activity in Marine Surface Microlayers C.33
A. F. Carlucci and 0. B. Craven, University of California,
San Diego
Phytoneuston: Plants of the Sea-Surface Microlayer C.37
John T. Hardy, Battelle, Marine Research Laboratory
Zooneuston: Animals of the Sea Surface C.45
George C. Grant, Virginia Institute of Marine Science
The College of William and Mary
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Processes Contributing to the Concentration of Polychlorina1;ed
Biphenyls at the Sea-Surface Microlayer ...... ............... «
Philip A. Meyers, The University of Michigan
Sea-Surface Contaminant Toxicity •
John. T. Hardy, Battelle, Marine Research Laboratory
APPENDIX D - CRITERIA, RESEARCH ALTERNATIVES, AND SAMPLE
QUESTIONNAIRES
C.63
0.1
vi
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FIGURES
1 Decision-Tree for Microlayer Impact Assessment ...................... 22
TABLES:
1 Concensus From 15 Experts In the Ranking of 30 Research
Alternatives Using 5 Judgment Criteria. .14
2 Top Information/Research Needs Identified by the Workshop
"art1 el pants ............................................<
16
vn
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I INTRODUCTION
The sea-surface microlayer (SSM) (upper millimeter or less of the water
surface) is a vital biological habitat. Neuston form an important element of
the ecosystem in subtropical and boreal offshore waters (Hempel and Weikert
1972). Many fish and shellfish, including cod, sole, flounder, hake, anchovy,
crab, and lobster, have egg or larval stages that develop in this layer. More
information is available from nearshore studies; however, available data sug-
gest that, even far off the east and west coasts of North America, ichthyoneus-
ton concentrate at the surface at certain times (Ahlstrom and Stevens 1975;
Grant et al. 1979). For example, neuston net tows found densities of larvae of
Pacific saury over 250 miles offshore that were equal to or greater than densi-
ties nearshore.(Kendall and Clark 1982). Contaminants from atmospheric deposi-
tion, urban runoff, wastewater outfalls, industrial point sources * and ocean
dumping enter coastal waters and partition. A large portion of these contami-
nants associate with suspended particles and deposit in the bottom sediments.
However, contaminants that have low water solubility or that associate with
floatable particles concentrate at the air-water interface. Consequently, high
concentrations of toxic PAHs, PCBs, and metals have been found in the surface
microlayer at some coastal sites (Hardy et al. 1985, 1986). At present, the
spatial distribution of this SSM contamination remains unknown. Alsoi, the
relative contribution that incineration or disposal of wastes at sea may make
to SSM contamination remains to be assessed.
An initial assessment of the potential impacts of ocean disposal suggested
a need for further information on the fate and effects of wastes vis-a-vis the
SSM (Hardy 1985). In order to meet this need, the U.S. Environmental
Protection Agency (EPA) convened a workshop of technical experts, science
advisors and agency representatives (see Appendix A). This report contains the
technical papers presented at the workshop and summarizes the proceedings,
results, and recommendations of this workshop.
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OBJECTIVES
The objectives of the workshop were to 1) educate the participants and
provide new perspectives that will increase our basic understanding of
processes occurring at the air-sea interface, 2) relate our basic conceptual
models to the fate and potential effects of residuals from ocean disposal
(incineration at sea, dumping of sludge, etc.), 3) identify research needs and
approaches, and 4) describe a scientifically defensible monitoring program for
the sea-surface microlayer.
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SYNOPSIS OF TECHNICAL PRESENTATIONS AND DISCUSSIONS
Darrell Brown (EPA) provided a brief summary of the background and ration-
ale that led to the convening of the workshop. The need for the workshop
became apparent following comments from both the public and the EPA Science
Advisory Board concerning the sea-surface microlayer as an interface that could
play a significant role in the transport and concentration of materials from
waste disposal at sea.
Frank Herr, Office of Naval Research (ONR), then provided a description of
a new research initiative on the SSM at the ONR. The ONR plans to sponsor a
number of research projects to examine the biological, chemical, and physical
processes that influence the optical properties of the SSM. Particular
emphasis will be on how processes such as the production of biogenic organic
films modify infrared and microwave remote sensing signals. He encouraged a
coordination and sharing of information between different SSM research programs
to provide a better understanding of the basic processes involved at the air-
sea interface.
Physical processes of the SSM were described by Duncan Blanchard (SUNY-
Albany). Breaking waves, which on average cover about 1% of the world ocean,
inject bubbles into the water column. As they rise to the surface, the bubbles
scavenge surface-active material from the water column. When they reach the
surface and burst, this material becomes concentrated on the seawater aerosol
that is ejected into the atmosphere.
Dave Carlson (Oregon State University) emphasized that basic research on
the natural organic chemistry of the SSM is a prerequisite to understanding how
contaminants from ocean disposal will behave. Observed chemical enrichments of
the SSM reflect a balance between diffusive and advective input processes and
removals by mixing, chemical alteration, or evaporation. Materials added to
the SSM from ocean disposal will likely partition in ways similar to naturally
occurring compounds. Enrichments are often still observed at sea states of
Beaufort 4 or even 5, but above this, there are no reliable measurements.
Recent studies on physic.al mixing processes in the upper water column were
described by Robert Weller (Woods Hole Oceanographic Institution). A number of
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innovative approaches and instrumentation were used to quantify the current
velocities in the region of LangmUir cells. Weather conditions: frequently lead
to the formation of circulation patterns (Langmuir cells) with strong '•
horizontal surface convergences and vertical downwelling. The depth of these
cells may vary between a few centimeters to the base of the mixed layer.
Bubbles and surface particles (and possibly associated contaminants) may follow
these current patterns. However, sufficient information is not yet available
to provide accurate predictions of the formation and strength of these cells.
Research conducted by Angelo Carlucci (University of California, San
Diego), suggests that, contrary to earlier concepts of the SSM as a photo-
inhibited and biologically inactive region, microbes occur in high densities in
the SSM and are generally quite metabolically active. In oligotrophic waters,
amino acid utilization rates by surface-film microheterotrophs were greater
than that of subsurface (10 cm) populations, whereas in eutrophic waters there
was little difference in these rates. Although there were generally fewer
metabolizing cells in surface microlayers, populations had a greater activity
per eel1.
Results of a number of studies by John Hardy (Battelle) conducted over the
past 15 years indicate that the SSM frequently contains dense populations of
microalgae (phytoneuston). The species populations of these communities are
distinct from the phytoplankton below the microlayer. Photosynthetic carbon
reduction per unit volume is often 20 to 50 times greater in the SSM than in
the bulk water. Greatest densities and activities are found in visible surface
slicks.
George Grant, Virginia Institute of Marine Science (VIMS), provided a
synopsis of studies conducted by VIMS on the distribution of zooneuston off the
raid-Atlantic coast of the United States. Fish eggs and larvae and decapod
larvae, including those of commercially important species, comprise a signifi-
cant portion of the neuston community of the mid-Atlantic shelf area. Neuston
communities in offshore waters also warrant consideration. Contamination of
the sea surface could impact certain unique species as well as organisms that
migrate to the surface at certain times of day to feed.
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^Concentration of organic contaminants such as PCBs in the SSM was dis-
cussed by Philip Meyers (University of Michigan). Hydrophpbic organic contami-
nants fractionate between the SSM and the subsurface water. Atmospheric inputs
tq the water surface can be important in leading to enrichments* A large
portion of PCBs in the microlayer reside in the particulate phase.
Recent studies on the toxicity of SSM contaminants were presented by
John Hardy (BatteTle). Sea-surface microlayer samples were collected from
stations in Puget Sound and returned to the laboratory. Fertilized sole eggs
were exposed to these SSM samples during embryonic development and larval
hatching. Approximately half of the sawptes tested showed high concentrations
of metal and/or PAH contamination. .These same Samples caused reductions in the
hatching succes;$ of the eggs* Current work examined the spatial distribution -
of surface contamination in Puget Sound.
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FORMAT AND PROCEDURES
The workshop used a computer-assisted decision-making process developed by
Battelle that encourages individual input regarding the important technical or
regulatory questions and research needs. The purpose of the decision-making
process applied to the workshop was to make better use of expert opinion in
making recommendations for action on topics that are complex and controversial
(for more detail on the computer-assisted process, see Appendix B).
The process began with a series of eight presentations and technical dis-
cussions intended to develop a common base, of information among participants.
(These technical reports are presented in full in Appendix C). Following the
presentations and discussions, participants were presented with an example of a
list of decision alternatives and a list of criteria by which those alterna-
tives might be rated as to their order of importance.
A basic assumption was that resources are limited; we cannot do all that
we might like to do, and we cannot effectively proceed without some sort of
consensus on priorities. In the workshop, participants first reworked the
straw-man list of ranking criteria. Then they separated into four discussion
groups, loosely organized as to technical discipline, to identify the infor-
mation needs on the SSM, which would be ranked using those criteria. Final
lists of criteria and identified research needs are presented in Appendix D.
To minimize unproductive debate and to maximize the input from each par-
ticipant, questionnaires (Appendix D) were generated using the criteria and
research needs previously identified. Each participant received an equal
opportunity for input by filling out questionaires using his best subjective
and objective judgment. In this way, individual participants were able to pro-
vide their most reasoned advice toward a group consensus.
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RESULTS OF WEIGHTING THE RANKING CRITERIA
The first questionnaire was used to "weight" the judgment criteria (see
Sample Criteria Questionnaire, Appendix 0). The questionnaire provided each
scorer with random pairings of the judgment criteria. Each scorer was asked to
rate the importance of the first member relative to the second member of the
pair along a five-point scale. The computer used the resulting scores to
calculate the importance of each criterion on a percentage basis.
These results may be read as the order of priority given each criterion as
determined from that criterion's weight (percentage out of a possible 100).
One of the advantages of the computer-assisted decision process is that judg-
ments can be retrieved for the entire group or for any subgroup (chemists,
biologists, physical scientists, and agency representatives). Thus, the
priorities assigned reflect, to a considerable degree, the technical background
of the participants at this specific workshop.
In a decision analysis having five criteria, it would be possible to
assign all the importance to one criterion (100%) at one extreme or equal
importance to all criteria (20% apiece) at the other. In this workshop, all
Criteria were considered important, with differences ranging only from 15% for
the criterion ranked the lowest, "Obtainable within technology, time, and money
constraints," to 25% for the criterion ranked the highest. This distribution
means that criteria weights did not drastically alter judgments made in the
following exercise, the ranking of information/research needs.
11
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RESULTS OF RANKING THE INFORMATION NEEDS
In ranking the decision alternatives (in this case, information/research
needs), there are two options available. One is to evaluate each alternative
on its own merits, accepting the possibility that all alternatives might be
attributed approximately equal importance (ranking each alternative over all
ranking criteria). The other is to force a decision in selecting the few best
options (ranking all alternatives under each criterion), even at the risk of
making arbitrary distinctions among them. Because we assumed there would be
inadequate resources to pursue all information needs, at least in the near
future, we chose this second option (see cover sheet and sample questionaire
#2, Appendix D, for a more complete explanation).
The orders of priority given the list of information/research needs by a
group of 15 experts, as a "committee of the whole" and in technical subgroups,
are shown in Table 1. The average weighted scores for the overall group show
two natural breaks dividing the 30 alternatives into 3 groups of 10 information
needs apiece; these are listed in order of priority in Table 2.
Not surprisingly, for a technical field very much in the early stages of
development, items in the. top ten appear to be among the very basic questions
which must be answered before the field can proceed. Those items in the second
group tend to be the more generic, but important questions which might be
answerable once the first ten have been addressed. The bottom group appears to
be an amalgamation of topics, some of which are 1) smaller questions, perhaps
more properly addressed within one of the broader topics, 2) questions
generally seen as unimportant or the importance of which remains controversial,
or 3) topics which were ambiguous or not as clearly defined as the others and
so were rated variously or low. It is interesting to note that questions
relating to modeling of microlayer processes tended to be rated low. The low
rating given to modeling may have resulted from the impression that the state
of the knowledge of microlayer dynamics has not progressed sufficiently to
adequately model the microlayer.
In the application of this computer-assisted decision process, the evi-
dence for "consensus" must be treated very carefully. Where the variable
13
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TABLE 1. Consensus From 15 Experts in the Ranking of 30 Research Alternatives Using 5 Judgment Criteria
Results*are Given for the Entire Group and Various Subgrouplngs as Defined Below.
Rank Order According to Expertise
Original
Number
*
*
*
*
*
•1
2
3
4
5
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Ranking Criteria or Research Alternatives
Usefulness 1n defining Importance of Sea Surface Microlayer
Contribution to ability to collect adequate information
Usefulness in defining impacts of ocean disposal
Contribution to credible basis for regulatory decision
Obtainable within technology, time, money constraints
Net adsorptive fluxes to SSM, natural and contaminant
Net removal fluxes from SSM, natural and contaminant
Residence times 1n microlayers and alteration by disposal
Magnitude of horizontal movements & potential for
concentration
Mesoscale internal & Atmos. features which may impose
on SSM
Deposition area for wet and dry input
Efficiency of input anthropogenic mater, to SSM from
contaminant plume
Dynamic and process models for microlayer
More knowledge on SSM in general, esp. open ocean
Define SSM Markers for Quantifying enrichment factors
Define anthropogenic input markers
ID biological comp. of SSM to detect changes (nat./anthro)
Identify variability (space/time) 1n natural SSM's
Determine varability due to sampling/analy. procedures
Learn to distinguish between point source & long dist.
transport
Measure uptake of SSM components in euneuston
Importance of sites to surface organisms
Importance of SSM as habitat-resource species
Stability of SSM under different wind speeds
Seasonal and diel changes 1n neuston
Seasonal occurrences of fish eggs
Toxicity incinerated residue applied surface microlayer
5
i
3
4
2
5
7
10
1
26
25
6
9
23
11
24
19
14
5
15
18
16
20
2
22
17
8
3
VI
Q.
2
3
1
4
5
4
2
22
25
5
12
14
10
19
24
18
3
27
20
30
29
8
9
18
17
7
S
.£=
O
4
2
3
5
14
18
1
26
30
4
5
29
10
23
19
11
12
8
13
16
25
3
24
21
9
15
o
03
2
4
3
5
9
12
4
22
30
14
13
19
18
25
16
15
7
8
20
6
10
1
29
11
3
2
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TABLE 1 (contd)
Rank Order According to Expertise
en
Original
Number Ranking Criteria or Research Alternatives ____
23 Relationship between diel measurement of org. & chem.
fluxes in SSM
24 Are SSM autotrophs food for near-surface organisms
25 Provide oceanographic & met. data to verify ocean
incineration models
26 Residence time of particles resulting from waste disp.
27 Differences (chem & biol.) between SSM & BW affecting
exposure
28 Effects of acidic plumes on SSM chem. & biol.
29 Chemical form of inputs, importance to global flux
30 Comparison, Calibr. standard, of sampling techniques with
reference to contamination
PARTICIPANTS BY CROUP
PHYS 1 f*AL
Duncan Blanchard - Atmospheric Research Center, State U. of New York
Darrell Brown - U.S. Environmental Protection Agency, Washington, D.t.
Jim Droppo - Earth Sciences (Meteorology), Battelle Northwest, Richland
Robert Weller - Woods Hole Oceanographic Institution, Woods Hole, MA
5
29
25
21
12
13
28
27
4
Q.
21
26
13
6
15
23
28
11
5j
28
20
27
7
22
17
2
0
•FT
CQ
26
24
21
/I*-*
23
17
28
27
CHEMICAL
- Department of Oceanography, Oregon State U., Corvallis, OR
- Department of Atmospheric and Ocean Science, U. of Ml
David Carl son
Philip Meyers ~ uepurwitcii*' vi nbiHu«»i'ii«'i •*• •*«••- *«•*»... —— * -- -_
Thomas O'Connor - National Oceanic and Atmospheric Administration, Rockville, MA
Ted Sauer - Battelle New England Research Laboratory, Duxbury, MA
BIOLOGICAL
Suzanne Bolton
Angelo Carluccl
George Grant
Jack Hardy
Rolf Hartung
Ken Jenkins
John Strand
Battelle Washington Environmental Program, Washington, D.C.
Scripps Inst. of Oceanography, U. of California, La Jolla, CA
Virginia Inst. of Marine Sciences, Gloucester Point, VA
Battelle Marine Research Lab, Sequim, WA
Department of Environmental and Industrial Health, U. of Michigan,
Dept. of Biology, California State U., Long Beach, CA
Battelle Marine Research Lab, Sequim, WA
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TABLE 2.
Rank
Top Information/Research Needs Identified by the Workshop
Participants
Information/Research Need
Top Ten
1
2
3
(approximately
equal)
(approximately
equal)
- Residence times for components in microlayer and alteration by
inputs from disposal events
- Importance of the SSM as a habitat to resource species
- Toxicity of incinerated residue applied as a surface
mi crolayer
Comparison, calibration, and standardization of sampling
techniques with attention to contamination
- Identify variability in space and time in natural SSM's
- Deposition area for wet and dry input
- Net adsorptive fluxes to microlayer from atmosphere and bulk
ocean (diffusive and advective) for natural and contaminant
materials
- Seasonal occurrence of fish eggs
Efficiency of input of anthropogenic material to microlayer
and microlayer processes affecting input from contaminant
plume
Net removal fluxes from microlayer to atmosphere and bulk
ocean (diffusive and advective) for natural and contaminant
materials
Middle Ten
(approximately
equal)
More knowledge on makeup and extent of SSM in general,
especially open ocean
- Residence time of particles resulting from waste disposal
- Differences in chemistry and biology between microlayers and
bulk water which affect exposure to microlayer biota
- Identify biological components of SSM to be able to detect
changes (natural versus anthropogenic)
- Determine variability due to sampling and analysis procedures
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8
(approximately
equal)
10
(approximately
equal)
Bottom Ten
11
(approximately
equal)
TABLE 2. (contd)
Measure uptake of SSM components In euneuston to establish
biological connection between SSM and food web (worst
case example to maximize observation of an impact)
- Seasonal and die! changes in neuston
- Learn to distinguish local point sources from long distance
transport
Define anthropogenic input markers
Importance of sites to surface organisms
12
(approximately
equal)
13
(approximately
equal)
14
- Provide physical oceanographic and meteorological data
needed to verify ocean incineration models
- Stability of SSM under different wind speeds
- Dynamic and process models for microlayer
- Define markers of SSM (chemical" materials to use a basis for
quantifying enrichment factors)
- Are SSM autotrophs food for near-surface organisms?
- Magnitude of microlayer convergences and divergences
(tangential stresses and diffusion currents) and potential for
causing extreme concentrations
- Chemical form of inputs; importance relative to global flux
- Effects of acidic plumes on microlayer chemistry and biology
- Relationship between diel movement of organisms and chemical
fluxes in SSM
- Mesoscale internal and atmospheric features which may impose
themselves on microlayer dynamics
17
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within and among groups is low, a real consensus can be claimed. For example,
"Residence times for components in microlayer and alteration by inputs from
disposal events," (item 3, Table 1) was seen by all subgroups as important and,
therefore, received the highest score of any item, "Relationship between diel
measurement of organisms and chemical fluxes in SSM" (item 23, Table 1) was
generally rated low by every subgroup and was rated next to last in the overall
result.
However, where there is consistency within groups but differences among
groups we have consensus of another sort. Analysis of these results in greater
depth than is possible in conventional workshops may reveal some important
Insights as to the group biases which are folded into the overall "consensus."
For example, "Importance of the SSM as a habitat to resource species," (item
18, Table 1) has both biological and resource management relevance, so it is
not surprising that its high rating by biologists led to a second-place show-
ing, in spite of its being rated third and eighth by the chemical and physical
subgroups, respectively. On the other hand, a couple of alternative items
which have obvious importance from a physical mechanistic point of view (items
2 and 3, Table 1) were rated high by the physical subgroup, but received only
seventh and tenth place overall rankings because of their low ratings from
chemical and biological subgroups. Each such comparison has its own story to
tell, and it is important that all be honored in the final outcome.
In this workshop, the results in Table 1 were used as a point of departure
for developing an initial strategy to obtain the information most critically
needed on the SSM.
18
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DISCUSSION AND RECOMMENDATIONS FOR RESEARCH AND MONITORING
The purpose of the workshop, as agreed upon by the participants, was to
Identify information.needs for the sea-surface microlayer that will assist EPA
in the ocean disposal regulatory process.
Several participants expressed the need to collect information that is
already available concerning the microlayer. John Hardy noted that two recent
reviews will be available in a few months: one prepared for the U.S. Army
Corps of Engineers (Word et al. 1985) and the other for the National Oceanic .
and Atmospheric Administration (Hardy et al. 1986). Both reports review the
biology of the SSM and the implications of sea-surface contamination. An
interactive computer model of the effects of disposal of contaminated dredge
material on the microlayer should also be available by March 1986 (Hardy and
Cowan 1986).
A number of specific suggestions for near- and long-term approaches to
sampling and monitoring the SSM evolved from discussions of the group. During
planned ocean disposal activities, studies should:
• Collect microlayers and measure concentrations of contaminants.
Participants discussed methods for collecting samples from the
SSM. Several types of sampling devices could be used including the
glass plate, screen, or Teflon-coated rotating drum. Discussion
focused on the advantages and disadvantages of each approach.
Published reports comparing these techniques are available (Carlson
1982; Daumas et al. 1976; Hardy 1982; Huhnerfuss 1981).
Basically, the screen sampler collects a relatively thick layer
(200 to 400 urn) and, hence, dilutes any chemical enrichment that is
generally restricted to less than 50 pm. Plate or screen sampling is
slow, tedious, and provides only small volumes of sample. The
Teflon-coated rotating drum sampler offers many advantages including
convenience, speed and the large volume sample needed for adequate
chemical analysis. This technique was criticized as possibly
collecting only non-polar hydrophobic materials, when the SSM
19
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actually contains mostly water. The collection efficiency Of the
drum for polar organics should be evaluated. However, Teflon has,
been, shown to be a good collector of surface-active materials
(Garrett and Barger 1974; Kjelleberg et al. 1979). Furthermore,
Battelle has developed an improved drum sampler and is currently
testing and calibrating this sampler as well as cross-calibrating it
with the glass plate technique. A published description of the drum
will be available soon (Hardy).
Some discussion focused on a plan for sampling the SSM,during
ocean disposal operations. Since SSM drum samples are collected over
a period of 5 to 20 min along transects of 100 to 300 m, they
represent an integrated surface sample. Replicate (side by side)
transects at different distances from the origin of an ocean disposal
activity could provide gradient information necessary to define
chemical concentrations with respect to distance and angle from the
source as well as variance between replicates.
Measure the input rates of contaminants from the atmosphere or bulk
water to the microlayer.
Collect and analyze air, microlayer, and water samples along
with physical measurements (wind speed, air-sea temperature
differential and surface film pressure surface flow and upper ocean
temperature structure) over a pre-designed grid of stations during
ocean disposal. The importance of supporting physical measurements
was stressed (Weller).
It was suggested (Hardy and Redford) that a SSM sampler, such as
the drum, should be protected from collecting contaminants that may
deposit directly from the atmosphere. This need could be filled by a
protective "fender" arranged over the drum.
In terms of ocean incineration, problems in sampling the plume
were discussed. It was suggested (Blanchard and Droppo) that under
some unstable atmospheric conditions, the plume could rise to
20
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considerable height and touch down at great distance- from the source.
Studies under way using tracers (SF-6) may help define plume charac-
teristics (Redford).
• Determine the toxicity to neuston under conditions that simulate the
microlayer.
The discussion focused on the need for both a short-term
approach as well as consideration of a long-term research program.
In the short-term, collect microlayer samples and test their toxicity
on the standard group of test organisms in the same way as water
samples. In the long-term, develop a "realistic" microlayer/neuston
bioassay.
After some discussion, participants envisioned a preliminary outline and
sequence of activities for a workable research and monitoring program for ocean
disposal and the sea-surface microlayer (Figure 1). The plan involves a
decision-tree approach. For example, if SSM samples collected during disposal
activities show contaminant concentrations that are potentially hazardous to
marine organisms (by comparison to water quality criteria and past studies),
then longer term laboratory studies would need to be developed using approaches
that realistically simulate the fate of the disposed material. If measured
concentrations of contaminants in SSM samples are not potentially hazardous to
marine life, then no toxicity studies would be necessary.
Some stress was placed upon the need for bioassay toxicity tests that are
relevant to the unique physical and biological properties of the SSM (Hartung).
For example, present approaches to testing ocean incineration residuals, proba-
bly remove (by bubbling) most of the surface active organic contaminants that
would normally collect and concentrate in the SSM (Carlson). Initial tests
could be performed on standard marine test organisms; i.e., collected SSM
samples could be tested in parallel with the bioassays of bulkwater samples on
the same set of organisms. Two problems with this approach are 1) it uses
organisms not normally present in the microlayer and 2) the organisms are
completely immersed in the SSM sample (Hartung).
Zl
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Near Term
(Field)
Ocean Disposal
Long Term
(Laboratory)
Collect Microlayer
and Supporting
Physical Measurements
Bioassay Toxicity
on Neuston
Dose-Response
Relationship?
No Further Laboratory
Analysis Indicated
at This Time
Yes
Microlayer
Concentrations
of Contaminants
Potentially
Toxic?
Yes
Compare Field
Concentration and
Lab Toxicity Data
Microlayer
Contaminated
Concentrations Within
Toxic Range
Measured
in Lab?
No Further
Evaluation
Necessary
Evaluate Impact Area
Relative to Valued
Resources
FIGURE 1. Decision-Tree for Microlayer Impact Assessment
22
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One test being used in some laboratories is the floating fish egg bioassay
(Hardy). Currently, this test is restricted to sole and can only be performed
during the spawning season. However, other tests are being developed that
should provide the capability to perform neustonic bioassays year round in a
realistic exposure system. Sea-surface microlayer bioassays are currently
being developed at Battelle (Hardy). If contaminant sources are atmospheric,
then bioassay.tests should expose neustonic organisms by direct atmospheric
deposition, perKaps using flow-through aerosol chambers (Carlson and Hartung).
23
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-------
REFERENCES
Ahlstrom, E. H., and E. Stevens. 1975, "Report on Neuston (surface) Collec-
tions Made on an Extended CalCOFI Cruise During May 1972." Calif. Coop.
Fish. Investig. 28, July 1, 1973 to June 30, 1975.
Carlson, D. 1982. "A Field Evaluation of Plate and Screen Microlayer Sampling
Techniques." Limnol. Qceanogr. 11:189-208.
Daumas, R., P. U Laborde, J. C. Marty, A. Saliot. 1976. "Influence of Sam-
pling Method on the Chemical Composition of Water Surface Film." Limnol.
Oceanogr. 21:319^-326.
Garrett, W. D., and W. R. Barger. 1974. "Sampling and Determining the Concen-
tration of Film-Forming Organic Constituents of the Air-Water Interface."
NRL Memorandum Report 2852, Naval Research Laboratory, Washington, D.C.
Grant, G.-C., J. E. Olney, S. P. Berkowitz, J. E. Price, P. 0, Smyth, M.
Vecchione, and C. J. Womack. 1979. "Middle Atlantic Bight Zooplankton:
Second Year Results and a Discussion of the Two-Year BLM-VIMS Survey." Spe-
cial Report in Applied Marine Science and Ocean Engineering No. 192.
Virginia Institute of Marine Science, Gloucester Point, Virginia.
Hardy, J. T. 1982. "The Sea-Surface Microlayer: Biology, Chemistry and
Anthropogenic Enrichment." Prog. Oceanog. 11:307^382.
Hardy, J. T. 1985. "The Sea-Surface Microlayer." Attachment 1, In Technical
Support for the Ocean Incineration Regulatory Development Process. Letter
Report to the U.S. Environmental Protection Agency, Contract 68-01-6986.
BatteHe Washington Environmental Program Office, Washington, D.C.
Hardy, J. T. and C. Cowan. 1986. Model and Assessment of the Contribution of
Dredged Material Disposal to Sea-surface Contamination in Puget Sound. FiinTl
Report.Prepared for U.S. Army Corps of Engineers, Seattle, by Pacific
Northwest Laboratory, Richland, Washington.
Hardy, J. T*, C. W. Apts, E. A. Crecelius and N. S. Bloom. 1985. "Sea-Surface
Microlayer Metals Enrichments in an Urban and Rural Bay." Estuarine Coastal
Shelf Sci. 20:299-312. —'— ~
Hardy, J. T., E. A. Crecelius and R. Kocan. 1986. Concent rat i on and Toxi ci ty
of Sea-Surface Contaminants in Puget Sound. Final Report CY 1985. Prepared
for National Oceanic and Atmospheric Administration, OAD, by Pacific North-
west Laboratory, Richland, Washington.
Hempel, G. and H. Weikert. 1972. "The Neuston of the Subtropical and Boreal
North-eastern Atlantic Ocean. A review." Marine Biology 13:70-88.
25
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Huhnerfuss, H. 1981. "On the Problem of Sea Surface Film Sampling: A Compar-
ison of 21 Microlayer-, 2 Multilayer-, and 4 Selected Subsurface-samplers.
Parts 1 and 2." Sonderdruck aus Meerestechnik. Part 1. 12(5): 137-142, Part
2. 12(6):170-173.
Kendall, A. W., Jr. and J. Clark. 1982. Ichthyoplanktgn off Washington.
Oregon, and Northern California, April-May 1980. NWAFC Processed Report
82-11.Northwest and Alaska Fisheries Center, NMFS, NOAA, Seattle.
Kjelleberg, S., T. A. Strenstrom and G. Odham. 1979. "Comparative Study of
Different Hydrophibic Devices for Sampling Lipid Surface Films and Adherent
Microorganisms." Mar. Biol. 53:21-25.
Word, J. Q., J. N. McElroy, L. Word, R. Thorn. 1985. The Sea-surface Micro-
layer: Review of Literature and Potential Effects of Dredge Activities in
Puget SouncTDraft Report, Evans Hamilton, Inc. to U.S. Army Corps of Engi»
neers, Seattle, Washington.
26
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APPENDIX A
WORKSHOP PARTICIPANTS
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LIST OF WORKSHOP PARTICIPANTS
(* * Technical Speaker)
*Duncan Blanchard
Atmospheric Sciences Research Center
State University of New York
Albany, New York 12222
(518) 442-3803
Suzanne Bolton
Washington Environmental Program Office
Battel1e
2030 M Street Northwest
Washington, O.C. 20036
(202) 463-6224
DarreH Brown
U.S. Environmental Protection Agency
401 M Street Southwest
Washington, O.C. 20460
(202) 382-7173
*Dav1d Carlson
Department of Oceanography
Oregon State University
CorvalUs, Oregon 97330
(503) 754-4172
*Ange1o Carluccl
Institute of Marine Resources
Scripps Institution of Oceanography
University of California, San Diego
La Jolla, California 92093
(619) 452-3195
Tudor Davies
Office of Marine and Estuarlne Programs
U.S. Environmental Protection Agency (WH-556)
401 M Street Southwest
Washington, D.C. 20460
(202) 382-7166
James G. Droppo
Earth Sciences Department
Battelie-Northwest
P.O. Box 999
R1chland, Washington 99352
(509) 376-7915
*George C. Grant
Virginia Institute of Marine Science
Gloucester Point, Virginia 23062
(804) 642-7000
•A.I.
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LIST OF WORKSHOP PARTICIPANTS (Continued)
*John T. Hardy
Battelle Marine Research Laboratory
439 West Sequim Bay Road
Sequim, Washington 98382
(206) 683-4151
Rolf Hartung
Department of Environmental and Industrial Health
University of Michigan
3125 Fernwood Avenue
Ann Arbor, Michigan 41084
(313) 764-5430 or (313) 971-9690
Frank Herr
Office of Naval Research
800 N. Quincy Street
Arlington, Virginia 22217
(202) 696-4590
Kenneth Jenkins
Department of Biology
California State University
Long Beach, California 90840
(213) 498-4627
*Philip Meyers
Department of Atmospheric and Ocean Science
University of Michigan
2455 Hayward Avenue
Ann Arbor, Michigan 48109-2143
(313) 764-0597
Thomas O1Conner
National Oceanic and Atmospheric Administration
Ocean Assessments Division
Rockwall Building
Rockville, Maryland 20852
(202) 443-8698
John Pawlow
U.S. Environmental Protection Agency
401 M Street Southwest
Washington, D.C. 20460
(202) 472-3400
Marjorie Pitts
U.S. Environmental Protection Agency
WH-585
401 M Street, Southwest
Washington, D.C. 20460
(202) 755-0100
A.2
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LIST OF WORKSHOP PARTICIPANTS (Continued)
David Redford
U.S. Environmental Protection Agency .
401 M Street Southwest
Washington, D.C. 20460
(202) 755-9231
Al Rubin
U.S. Environmental Protection Agency
401 M Street Southwest
Washinton, O.C. 20460
(202) 345-3036
Ted Sauer
Battelle New England Marine Research Laboratory
397 Washington Street
P.O. Box AH
Duxbury, Massachusetts 02332
(617) 934-5682
James States
Earth Sciences Department
Battelle-Northwest
P.O. Box 999
Richland, Washington 99352
(509) 375-2534
John Strand
Battelle Marine Research Laboratory
439 West Sequim Bay Road
Sequim, Washington 98382
(206) 683-4151
*Robert Weller
Woods Hole Oceanographic Institution
Woods Hole, Massachusetts 02543
(617) 548-1400
A.3
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APPENDIX &
THE COMPUTER-ASSISTED DECISION PROCESS
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COMPUTER ASSISTED DECISION PROCESS
INTRODUCTION
Battelle has developed a computer-assisted process to aid in making difficult
decisions on controversial subjects where there are several alternatives The
process is particularly helpful in reaching consensus decisions where there is a-
great deal of both subjective and objective knowledge to be brought to bear on
the decision, more alternatives than there are resources to do them, strongly
differing opinions on what should be done, or simply too much information to
process efficiently and accurately in a standard workshop setting. Its purpose
is to reach a collaborative decision representative of an overall group.
A workshop format with selected participants is used. The .,
to use an Apple II micro-computer. A list of decision alternatives and a list of
criteria by which to judge their relative importance are developed and finalized
through group discussion. Using computer-generated score sheets, each partici-
pant scores first the relative importance of each criterion, then each decision
Sption (based on the established criteria) according to his/her opinion. The
computer processes the scores to assign a value or weight to each criterion,
indicating its importance relative to the rest of the criteria. Next, .the
computer applies those criteria weights to the scores given the decision alter-
natives by the participants to assign a comparative value to each alternative.
The decision alternatives are then listed in the resulting order of importance
as indicated by the participants in their scoring. The final decisions can then
be made based on those results.
DESCRIPTION OF THE PROCESS
The following steps describe the process in detail:
Developing Provisional Lists of Decision Options and Judgement Criteria
A comprehensive, provisional list of decision options and a list of criteria by
which the importance of these options should be judged are developed prior to
the workshop as a starting point. These are usually developed by or with the
assistance of individuals knowledgeable about the available decision options.
Presentations and Information Exchange
Information is exchanged about the various aspects of the decision options by
means of presentations by experts on the subjects and/or through questions and
discussions by the participants. This is intended not as a time for debate but
for forming a common information base for the group decision.
Amending and Refining of the Provisional Lists
During this phase, all suggested items are added to the provisional lists
without criticism or debate in order to ensure that all participants have input.
The two lists are discussed and refined by the participants to- their collective
satisfaction.
8.1
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Shortening and Finalizing of the Lists
Workshop participants next work to collectively shorten the lists of criteria
and decision options to manageable lengths. In screening the lists for final-
ization, some objectives would be to: 1. eliminate duplicative items, 2.
eliminate mutually exclusive items, 3. eliminate items not directly relevant to
the decision at hand, 4. cover the range of subjects that must be considered in
prioritizing the decision alternatives.
Weighting of the Final List of Judgement Criteria
The selected criteria provide a common basis for judging the importance of the
decision options. A list of random pairs of criteria is computer-generated.
Each participant scores the importance of the first member relative to the
second member of each pair on a five-point scale. The computer will use these
judgements to calculate the importance or weight to be given to each criterion
on a scale of 0 to 100%. These weights are later applied in ranking the list of
decision alternatives.
The paired comparison approach overcomes the inherent difficulties involved in
making simultaneous comparisons among several criteria. Participants are
required to indicate comparative importance between only two alternatives at any
one time. All possible pairings are offered to ensure that each criterion is
evaluated against every other criterion on the list. Randomization minimizes
the possibility that weightings of the criteria would be influenced by the order
of their treatment rather than intrinsic value.
Prioritization of Decision Alternatives
The computer next generates score sheets on which each participant will make his
own ranking judgements, independently of the rest of the group. Each partici-
pant will rank the importance of each decision alternative based on the criteria
previously established. Participants are asked to indicate "no response" for
any item on which they feel unqualified to make a judgement. Resulting scores
from all participants are then entered into the computer which applies the
criteria weights determined earlier and then sums these products to provide a
weighted score for each alternative. The alternatives are then listed in order
by those scores giving a prioritized list of decision alternative. This indi-
vidual ranking process allows each participant to evaluate the decision alterna-
tives based on his/her own evaluation without pressure or interference from
other participants. This also minimizes the opportunity for the session to
degenerate into divisive debate and allows each participant equal input into the
final decision.
Feedback Session
Results of the computer analysis are presented to participants in the final
session of the workshop. Each participant is given an opportunity to comment on
the results. It is in this session that important dissenting views, which might
otherwise be lost in the consensus process, are captured. Frequently, this is
also the time when innovative ideas develop from the new perspective afforded by
an overview of the results.
B.2
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ADVANTAGES OF THE DECISION PROCESS
The advantages offered by this process over standard workshop procedures may be
summarized as follows:
Maximizes Capture of Information
The process allows Incorporation of the best subjective and objective knowledge
and experience of every participant. It offers an opportunity for all partici--
pants to contribute both to the list of options and to the criteria by which
their importance is judged, to clarify the options offered, and to express
opinions both pro and con. Discussions leading up to final lists of weighted
judgement criteria and options prove to be a valuable process of mutual educa-
tion whereby a common information base is developed for sound group judgement.
Minimizes Conflict
By providing each participant with an equal opportunity to express his or her
views and offering individual scoresheets for the final ranking exercise,
nonproductive and divisive debate is minimized and at the same time a sense of
"community" is developed.
Achieves Consensus
The final, computerized result is a clear summary of the group judgement.
Although an individual participant may not agree with that judgement in general,
he recognizes that he has had an equal opportunity to influence the result.
Provides for In-Depth Analysis of Results
Computer tabulation of results provides for a better record and more thorough
analysis of results than is possible under other presently accepted workshop
procedures. In addition to analysis of group consensus, the process offers the
option of analyzing the results by subgroupings such as disciplines, affil-
iations, or even individuals. The final computer printout offers in-depth
information such as standard deviation (which provides a measure of the diver-
sity of opinion on any given issue and allows insight into how agreement or
disagreement is distributed among criteria.)
Provides Good Closure
Feedback and results are available during the process and final results are
available to participants at the close of the workshop, thus enabling them to
leave with a clear understanding of the outcome. The opportunity for each
participant to comment on the result offers a satisfying sense of accomplishment
and closure of the workshop and enables workshop leaders to capture important
dissenting views that might otherwise be lost in a typical consensus report. Par-
ticipants are also more likely to leave with a willingness to cooperate in the
implementation of the group decision than in a standard group-decision process.
B.3
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APPENPIX C
TECHNICAL PRESENTATIONS ON THE SEA*SURFACE MICROIAYER
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The Origin and Enrichment of Particulate. Material Ejected
from the Surface of the Sea
(Paper prepared for the Workshop on the Sea Surface Microlayer in
Washington, D.C., 18-19 December 1985)
Duncan C. Blanchard
Atmospheric Sciences Research Center
State University of New York at Albany
Albany, NY 12222
The surface microlayer
The surface of the sea is a curious place. It is neither sea nor air.
The boundary between sea and air, the microlayer, is a transition zone
with thickness measured in units from angstroms to centimeters, depending
upon the material one is concerned with. Although there can be a
microlayer in the atmospheric side of the sea surface where temperature,
humidity, and aerosol concentration can be vastly different from that just
a meter above, most workers are concerned only with the microlayer
extending downward from the surface.
Numerous studies have shown that a variety of materials can
concentrate and thus be enriched in the surface microlayer. These range
from organic surface-active films (Garrett 1967; Maclntyre 197M; Hunter and
Liss 1981) to various neuston (Cheng 1975, Hardy 1982), bacteria
(Kjelleberg and Hakansson 1977) and heavy metals (Hardy et al. 1985).
The surface microlayer, once formed, will not exist indefinitely.
Upwelling water in Langmuir circulations (Weller et al. 1985) causes
surface divergence that can destroy the microlayer and concentrate the
materials in visible slicks nearly parallel with the wind. Breaking waves
or whitecaps also destroy the surface microlayer. The percentage coverage
of the sea with whitecaps increases with more than the cube of the wind
speed (Monahan and O'Muircheartaigh 1980). On average, about 1$ of the
world ocean is covered with whitecaps. Assuming that the averge life of a
whitecap is 10 sec, it follows that for a \% coverage (produced by 10-m
elevation winds of 10 m sec ) a wave will break to produce a whitecap on
any given spot on "the sea about every 17 minutes. The microlayer is
destroyed by being mixed downward, and a few seconds later a portion of the
microlayer material may be ejected into the atmosphere.
Mechanism of sea-to-air transfer of materials
Breaking waves entrain large amounts of air into the sea in the form
of a spectrum of air bubbles ranging in size from less than 0.1 mm to over
10 mm diameter. The spectrum is heavily weighted toward the small end.
Many of the bubbles rise within seconds to burst at the surface, but some
of those < 0.1 mm are mixed by turbulence throughout the upper few meters
of the sea to produce a low-level background concentration of bubbles
(Johnson and Cooke 1979). These background bubbles, wit,h their small rise
speeds, provide excellent tracers for sonar detection of what appears to be
Langmuir circulations (Thorpe et al. 1982).
C.I
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Since the internal pressure of a bubble is proportional to the surface
tension but inversely proportional to bubble radius, many of the background
bubbles decrease rapidly in size and go into solution long before they can
rise to the surface. Some of these bubbles resist going into solution,
being stabilized by organic surface-active material that is adsorbed onto
the bubble .and compressed (Johnson and 'Cooke 1981). These stable
microbubbles of 1 to 10 urn diameter provide a mechanism for converting
dissolved to particulate organic material in the sea (Blanchard 1975).
Rough estimates suggest that the number of background bubbles that
rise to the surface of the sea are only about 10$ of those that rise within
seconds after a wave breaks (Blanchard 1983)". In spite of many efforts
over the past 30 years, we have yet to obtain adequate data on the bubble
spectrum produced by breaking waves at sea. Because of the many
difficulties, laboratory experiments have been carried out to model wave
breaking and bubble production (Cipriano and Blanchard 1981; Baldy and
Bourguel 1985). The bubble flux to the surface in Cipriano"and Blanchard's
(1981) laboratory "breaking wave" was about 2 x 10° m s . In addition
to breaking waves, rain and snow falling into the sea produces bubbles
(Blanchard and Woodcock 1957). But. precipitation as a bubble producer
appears to be important only on a local and not on a global scale.
Upon bursting, some of the surface free energy of the bubble is
converted into kinetic energy of a jet of water that rises rapidly from the
bottom of the collapsing bubble cavity (Blanchard 1963; Maclntyre 1972).
The jet becomes unstable and breaks up into 1 to 10 drops, the number of
drops decreasing as bubble size increases. The uppermost or top jet drop
is about one-tenth the bubble diameter; the lower drops are somewhat
larger. The maximum drop ejection height increases with bubble size,
reaching nearly 20 cm for 2-mm bubbles. For larger bubbles, the ejection
height decreases and for bubbles > 7 or 8 mm no jet drops are produced
(Hayami and Toba 1958; Blanchard 1963).
Sea-salt particles in the Marine atmosphere
Turbulence and convection carry many of the jet drops throughout the
sub-cloud layer. Although the water in the drops tends to evaporate, the
sea salt does not and thus the salt concentration rises. At relative
humidities below about 75$ the drops are supersaturated with salt and a
phase change may occur to produce a "dry" salt particle one-quarter the
diameter of the parent seawater drop. These salt particles produce the
haze so often seen at higher wind speeds in marine atmospheres. The
salt-particle distribution as a function of wind speed was first documented
by Woodcock (1953).
Of all the particulate material cycled through the earth's atmosphere
each year, the largest component appears to be sea salt. Estimates of the
global sea-salt production (Blanchard 1985) vary between 109 and 1010 t
yr (t - metric ton, or 10^ kg). Agreement on the various estimates will
C.2
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not be obtained until it is clear what altitude one is concerned with in
the cycling process. The amount of salt cycled through the first meter, .of
the atmosphere must be vastly more than that cycled through the first
1,000 m.
Enrichment of the bubble-produced aerosol
Although laboratory experiments show that materials concentrated in
the surface microlayer can be transferred to the aerosol produced by
extensive bubbling through the liquid (Sutcliffe et al. 1963), few studies
have been carried out to understand the mechanics by which a single
bursting bubble produces the enrichment on jet drops, Blanchard (1963)fand
Bezdek and Carlucci (197*0 allowed bubbles to burst individually at a water
surface covered with an organic surface-active film and found the film
enriched on the jet drops. This, however, is no proof that a
surface-active film on the open sea will be effectively removed,by bursting
bubbles from breaking waves. Tens of thousands of bubbles are produced by
a whitecap. Their drag on the water as they rise produces upwelling that
results in divergence or outflow of the water at the surface. This outflow
pulls some of the surface monolayer with it, producing a region momentarily
free of organic films. Some of the bubbles burst in this clean region.
Research, however, is badly needed, since we do not know what fraction of
the total number of bubbles burst before the surface outflow weakens and
the monolayer returns.
Probably a more important source than the sea-surface organic
microlayer for the organic enrichment of the bubble-produced -aerosol is the
organic microlayer at the surface of the bubble. As a bubble rises through
the water, its microlayer will become more and more concentrated by
adsorption of dissolved surface-active material from the bulk seawater.
Accordingly, the bubble's surface free energy decreases with time. Since
the kinetic energy of the jet drops is a function of the bubble's surface
free energy, we would expect to find a decrease of the jet-drop ejection
height with bubble age, being most pronounced in waters with a high organic
concentration. This has been observed (Blanchard and Hoffman 1978).
Laboratory measurements of the enrichment of organic carbon on the
aerosol produced from bubbles of 100 to 300 ym showed enrichment factors of
from 100 to 1,000 (Hoffman and Duce 1976). When the bubble-producing frit
was moved from a depth of 33 to 101 cm beneath the surface, the aerosol
enrichment factors increased by about a factor of 2. Clearly, in these
experiments the enrichment of the bubble microlayer and not the bulk
surface microlayer produced the aerosol enrichment. Although salt
particles may be enriched in this manner, most of the organic carbon on the
marine aerosol appears to be on particles other than sea salt (Hoffman and
Duce 1977).
Other experiments have also shown an aerosol enrichment increasing
with the distance a bubble moves through the water before bursting.
Blanchard et al. (1981) let single bubbles rise known distances through
bulk suspensions of bacteria. They found the bacterial enrichment factors
C.3
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on the jet drops to increase rapidly with bubble rise distance, from a
value of less .than 10 when the bubble was released just beneath the surface
to about 500 when the bubble was allowed to rise and scavenge bacteria from
a depth of only 5 cm. Jet drop bacterial enrichments are complicated,
however, and depend on other factors than just bubble scavenging distance.
A review of this work has been prepared by Blanchard (1983).
Experiments on the North Atlantic with the Bubble Interfacial
Microlayer Sampler (BIMS) revealed that many trace metals were enriched
relative to seawater in the aerosol from bursting bubbles (Weisel et al.
1981). Enrichment factors determined for Al, Co, Cu, Fe, Mn, Pb, V, and
Zn ranged from 10 to 20,000. Perhaps of more interest, the enrichment
factors of Fe, Pb, Sc, and Zn showed a strong positive correlation with
bubble generation depth, indicating that bubble scavenging was responsible
for the aerosol enrichment.
Elements recycled from the sea
Trace elements in the atmosphere that originate from the earth's crust
and human activities can be found over the oceans far removed from the
continents. But these elements may not have traveled directly from their
source to the point where they were measured. Some of the material may
have fallen into the sea only to be recycled back into the atmosphere
aboard bubble-produced aerosol. Thus, if one wishes to determine the net
deposition of a particular element, the amount recycled from the sea must
be subtracted from the measured or gross deposition. How does one
determine, say, the recycled component of Pb in rainwater that falls into
the sea? First, by using the BIMS or other such experimental device,
determine the" Pb/Na ratio on the aerosol rising from bursting bubbles (Na
is not enriched in the aerosol). Then multiply this ratio by the Na
concentration measured in the rain. This will give you the concentration
of Pb in the rainwater that has been recycled from the sea. Subtracting
this from the Pb measured in the rainwater gives the net deposition into
the sea. Arimoto''et al. (1985) found that some 30% of the Pb in marine
rain was recycled from the sea. They also determined the recycled
components of other elements not only for wet but for dry deposition.
Are film drops important in water-to-air transfer processes?
Jet drops are not the only class of drops produced when a bubble
bursts. When the thin film of water that comprises the cap or dome of the
bubble disintegrates to start the bursting process, it produces what are
called film drops. The film-drop spectrum can cover 5 orders of magnitude,
from about 0.01 to 100 pm diameter, but most are < 1 ym. Unlike jet drops,
whose numbers decrease with increasing bubble size, the number of film
drops increases rapidly with bubble size (Blanchard 1963; Day 1964).
Bubbles < 0.3 mm produce no film drops but one of 6 mm can produce a
maximum of about 1000. Thus, the question of whether the film-drop flux
exceeds that of jet drops depends critically upon the bubble-size
distribution in breaking waves.
C.4
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The laboratory experiments of Cipriano and Blanchard (1981) to
simulate breaking waves suggest that the flux of film drops may exceed that
of jet drops by several times. However, since jet drops are on average
larger than film drops, the mass flux of seawater to the'atmosphere may be
carried by jet drops. Cipriano et al. (1983) think it possible that the
sea-salt mass concentrations found in the marine atmosphere (Woodcock 1953)
arise from jet drops but that the salt particles that contribute most to
cloud condensation nuclei originate as film drops. But this conclusion is
based on an assumption concerning the production of film drops as a
function of bubble size. At the moment it is not known within 1 to 2
orders of magnitude the number of film drops that will be produced for a
given bubble burst (Blanchard 1983). Closing this gap in understanding
should be a top research priority.
The difficulties in understanding film drop production are many, among
them the fact that surface-active monolayers on the water where the bubbles
burst will nearly eliminate film-drop production (Blanchard 1963; Paterson
and Spillane 1969). Also, film-drop production tends to 'decrease with
increasing distance a bubble moves through the water before bursting
(Blanchard and Syzdek 1982), presumably because surface-active material is
continuously being adsorbed to a bubble while it rises through the water.
Research needs
To understand more about the role of bubbles in disrupting the
microlayer at the surface of the sea and transporting material into the
atmosphere, we need more research to answer the following questions:
1.
as a
2.
3.
the
What is the bubble-size distribution in breaking waves
function of wind speed and water temperature?
What are the factors that determine the variability in
production of film drops?
How significant is the non-bubble produced aerosol (spray blown
from the tops of breaking waves at high wind speeds) in the
water-to-air transfer of material?
4. What fraction of the bubbles produced by breaking waves burst at a
surface that is momentarily free of an organic microlayer?
5. How does the fractional coverage of the sea with whitecaps vary
with water temperature?
References
ARIMOTO, R., R. A. DUCE, B. J. RAY, and C. K. UNNI. 1985. Atmospheric
trace elements at Enewetak Atoll, 2, Transport to the ocean by wet
and dry deposition, J. Geophys. Res. 90(D1); 2391-2108.
BALDY, S., and M. BOURGUEL. 1985. Measurements of bubbles in a stationary
field of breaking waves by a lasar-based single-particle scattering
technique. J. Geophys. Res. 90(C1): 1037-1047.
BEZDEK, H. F., and A. F. CARLUCCI. 197*». Concentration and removal of
liquid microlayers from a seawater surface by bursting bubbles.
Limn. Oceanog. 19: 126-132.
BLANCHARD, D. C. 1963- The electrification of the atmosphere by particles
from bubbles in the sea. Prog. Oceanog. 1: 71-202.
C.5
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BLANCHARD, D. C. 1975. Bubble scavenging and the water-to-air transfer of
organic material in the sea. Adv. Chem. Ser. 145: 360-387.
BLANCHARD, D. C. 1983- The production, distribution, and bacterial
enrichment of the sea-salt aerosol, in The Air-Sea Exchange of Gases
and Particles (eds. P. S. Liss and W. G. N. Slinn): 407-454.
D. Reidel Pub. Co.
BLANCHARD, D. C. 1985. The oceanic production of atmospheric sea salt.
J. Geophys. Res. 90(C1): 961-963.
BLANCHARD, D. C., and E. J. HOFFMAN. 1978. Control of jet-drop dynamics by
organic material in seawater. J. Geophys. Res. 83: 6187-6191.
BLANCHARD, D. C., and L. D. SYZDEK. 1982. Water-to-air transfer and
enrichment of bacteria in drops from bursting bubbles. Appl. Environ.
Microbiol. 43: 1001-1005.
BLANCHARD, D. C., L. D.' SYZDEK, and M. E. WEBER. 1981. Bubble scavenging
of bacteria in freshwater quickly produces bacterial enrichment in
airborne drops. Limn Oceanogr. 26: 961-964.
BLANCHARD, D. C., and A. H. WOODCOCK. ' '1957. Bubble formation and
modification in the sea and its meteorological significance.
Tellus 9: 145-158.
CHENG, L. 1975. Marine pleuston-animals at the sea-air interface.
Oceanogr. Mar. Biol. Ann. Rev. 13: 181-212.
CIPRIANO, R. J., and D. C. BLANCHARD. 1981. Bubble and aerosol spectra
produced by a laboratory ^breaking wave.1 J. Geophys. Res. 86:
8085-8092.
CIPRIANO, R. J., D. C. BLANCHARD, A. W. HOGAN, and G. G. LALA.
On the production of Aitken nuclei from breaking waves and
role in the atmosphere. J. Atraos Sci. 40: 469-479.
DAY, J. A. 1964. Production of droplets and salt nuclei by the bursting of
air bubble films. Quart. J. Roy. Met. Soc. 90: 72-78.
GARRETT, W. D. 1967. The organic-' chemical composition of
surface. Deep-Sea Research 14: 221-227.
HARDY, J. T. 1982. The sea surface" microlayer: biology,
anthropogenic enrichment. Prog. Oceanog. 11: 307-328.
HARDY, J. T., C. W. APTS, E. A. CRECELIUS, and N. S.
Sea-surface microlayer metals enrichments in an urban and rural bay.
Estuarine, Coastal and Shelf Sci. 20: 299-312.
HAYAMI, S., and Y. TOBA. 1958. Drop production by bursting of air bubbles
on the sea surface (1) Experiments at still sea water surface.
J. Ocean. Soc. Japan 14: 145-150.
HOFFMAN, E. J., and R. A. DUCE. 1976. Factors influencing the organic
carbon content of marine aerosols: a laboratory study. J. Geophys.
Res. 81: 3667-3670.
HOFFMAN, E. J., and R. A. DUCE. 1977. Organic carbon in marine atmospheric
'particulate matter: concentration and particle size distribution.
Geophys. Res. Letters 4: 449-452.
HUNTER, K. A., and P.S. LISS. 1981. Organic sea surface films. Chapter 9
of the book Marine Organic Chemistry, edited by E. K. Duursma and
R. Dawson: 259-298. Elsevier Pub. Co.
JOHNSON, B., and R. C. COOKE. 1979. Bubble populations and spectra in
coastal waters; a photographic approach. J. Geophys. Res. 84:
3761-3766.
1983.
their
the ocean
chemistry and
BLOOM. 1985.
C.6
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JOHNSON, B. D., and R. C. COOKE. 1981, Generation of stabilized
microbubbles in seawater. Science 213: 209-211.
KJELLEBERG, S., and N. HAKANSSON. 1977. Distribution of lipolytic,
proteolytic, and amylolytic marine bacteria between the lipid film and
the subsurface water. Marine Biology 39: 103-109.
MacINTYRE, F. 1972. Flow patterns in breaking bubbles. J. Geophys. 'Res.
77: 5211-5228.
MacINTYRE, F. 1974. Chemical fractionation and sea-surface microlayer
processes. The Sea 5 (Marine Chemistry): 245-299. John Wiley and
Sons.
MONAHAN, E. C., and I. O'MUIRCHEARTAIGH. 1980. Optimal power-law
description of oceanic whiteeap coverage dependence on wind speed.
J. Phys. Oceanogr. 10: 2094-2099.
PATERSON, M. P., and K. T. SPILLANE. 1969. Surface films and the
production of sea-salt aerosol. Quart. J. R. Met. Soc. 95: 526-534.
SUTCLIFFE, W. H., JR., E. R. BAYLOR and D. W. MENZEL. 1963. Sea surface
chemistry and Langmuir circulation. Deep-Sea Research 1.0: 233-243.
THORPE, S. A., A. R. STUBBS, and A. J. HALL. 1982. Wave-produced bubbles
observed by side-scan sonar. Nature 296: 636-638.
WEISEL, C. P., R. A. DUCE, J. L. FASCHING, and R. W. HEATON. 1984.
J. Geophys. Res. 89: 11,607-11,618.
WELLER, R. A., J. P. DEAN, J. MARRA, J. F. PRICE, E. A. FRANCIS, and
D. C. BOARDMAN. 1985. Three-dimensional flow in the upper ocean.
Science 227: 1552-1556.
WOODCOCK, A. H. 1953- Salt nuclei in marine air as a function of altitude
and wind force. J. Meteor. 10: 362-371.
C.7
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Organic Chemistry of the Sea Surface Microlayer
David J. Carlson
College of Oceanography
Oregon State University
Corvallis, OR 97331
Microlayers at the ocean surface interupt normal physical-chemical and
geochemical controls on fluxes of energy and material through atmosphere and
ocean. The nature of these raicrolayers and the extent of this interuption is
determined by a combination of physical and organic chemical properties -
surface slicks are familiar visible examples. Understanding organic chemical
influences on microlayer structure and chemistry is therefore prerequisite to
understanding fluxes and alterations of natural or contaminant materials
passing between ocean and atmosphere.
The dissolved organic content of oceanic surface microlayers is low, less
than 4 parts per million (mg liter"1) of organic carbon, an excess of no
more than 2 or 3 ppm over underlying waters (Carlson 1983). This slight
enrichment consists of a mixture of compounds (Williams et al. 1986; Williams
and Carlson in prep.) which are too heterogeneous and in insufficient quantity
to form coherent films or monolayers (Hunter and Liss 1981; Carlson 1983);
those terms are misnomers. Nonetheless, microlayer organics influence surface
physical (e.g., capillary wave spectra) and chemical (e.g., partition coeffi-
cient) properties. Microlayers also contain consistent but highly variable
enrichments of particulate organic materials (Williams 1967; Carlson 1983;
Williams et al. 1986); particulate variability presumably reflects patchy
oceanic particle production, sporadic atmospheric input, or advective particle
accumulation processes.
Microlayer dissolved organic materials appear to be distributed over
relatively thick layers, perhaps the upper 100-200 urn of water (Hunter and
C.9
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Liss 1981; Carlson 1983). Organic enrichment in these layers is a balance
between diffusive or advective input processes and removals by turbulent
mixing, chemical alteration, or evaporation. Input pressures are constant;
cleaned or "new" surfaces are consistently, sometimes rapidly, re-enriched
(Jarvis 1967; Williams et al. 1980; Carlson 1982b; Van Vleet and Williams
1983; Carlson 1983). Because microlayer enrichments are not continually
increasing, removal processes keep enrichments low. Microlayers are often-
times depleted in dissolved organic materials relative to underlying waters
(Dietz et al. 1976; Carlson 1983), evidence that removals can occasionally
overwhelm inputs. Microlayer total organic enrichments do not change with
increasing surface roughness over wave states up to Beaufort 4 (wind speeds of
8 m sec ) but phenolic components show decreased enrichments starting at
Beaufort 3 and apparent thicknesses of organic microlayers change significant-
ly and continuously from calm conditions through Beaufort 4 (Carlson 1982b;
Carlson 1983); these observations suggest reordering or input limitations at
low wind speeds with erosion and removals dominating as waves begin to break.
Comparisons of input or removal rates with observed enrichments allow esti-
mates of microlayer residence times. These estimates range from a few seconds
to many hours for trace metals (Hoffman et al. 1974; Hunter 1980; Eisenreich
" • •
1982; Hardy et al. 1985); the large range reflects differences in chemical
forms and affinities of trace metals, differences in chemical conditions of
raicrolayers, and differences in surface roughness. Tracer organic materials
have several-hour residence times under calm conditions (Carlson in prep.)-
One chemical effect of the organically-enriched microlayers is to accom-
modate or affect the distribution of materials otherwise chemically uncomfort-
able seawater. This accommodation can involve co-solution of hydrophobic
organic solutes (Meyers and Quinn 1973; Platford 1982; Whitehouse et al.
C.10
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1985), an effect especially pertinant to most hydrocarbon waste or waste by-
products. Natural materials apparently undergo analagous co-solution; micro-
layer organic enrichments decrease with increasing bulkwater organic concen-
trations (Carlson 1983). The accommodation may also involve binding of organ-
ic solutes to other microlayer organic materials (Carlson et al. 1985). trace
metals may be leached from source particles (Elzerman 1982), chelated (Piotro-
wicz et al. 1974; Lion and Leckie 1981; Pellenbarg 1981; Armstrong and Elzer-
man 1982), or scavenged onto organic aggregates (Wheeler 1975) as a conse-
quence of residence in microlayers. Eacy of these interactions may extend
trace metal residence times in microlayers or in water columns and enhance
their availability to "biota.
Microlayer organic materials may be subject to photochemical alteration;
irradiation and concentrations of potential reactants are highest at the
surface. Photosensitive tracers such as the simple phenol phloroglucinol are
effectively degraded in microlayers (Williams and Carlson, in prep.). Natural
materials with similar phenolic characteristics, however, appear to be stable
under natural microlayer irradiation conditions.
Determination and quantification of microlayer residence times and organ-
ic interactions or alterations requires tracers; the total organic enrichment
is too complex for reliable description. Natural phenolic materials are
unique in having predictable microlayer enrichments and consistent relation-
ships to visible surface conditions Such as wave state and the presence of
slicks (Carlson 1982a; 1983), making them useful tracers. Many hazardous
organic wastes also have phenolic characteristics or incomplete combustion
products with phenolic characteristics; phenolic tracers can be indicators of
microlayer processes affecting natural as well as contaminant materials.
C.ll
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Armstrong, D.E. and A.W. Elzerman. 1982. Trace metal accumulation in surface
microlayers. J. Great Lakes Res. 8: 282-287.
Carlson, D.J. 1982a. Surface microlayer phenolic enrichments indicate sea
surface slicks. Nature 296: 426-429.
Carlson, D.J. 1982b. A field evaluation of plate and screen microlayer sam-
pling techniques. Mar. Chem. 11: 198-208.
Carlson, D.J. 1983. Dissolved organic materials in surface microlayers:
Temporal and spatial variability and relation to sea state. Limnol.
Oceanogr. 28: 415-431.
Carlson, D.J., L.M. Mayer, M.L. Brann, & T.H. Mague. 1985. Binding of mono-
meric organic compounds to macromolecular dissolved organic matter in
seawater. Mar. Chem. 16: 141-153
Dietz, A.S., L.J. Albright, and T. Tuominen. 1976. Heterotrophic activities
. of bacterioneuston ad bacterioplankton. Can. J. Microbiol. 22: 1699-1709.
Eisenreich, S.J. 1982. Atmospheric role in trace metal exchange at the air-
water interface. J. Great Lakes Res. 8: 243-256.
Elzerman, A.W. 1982. Modeling trace metals in the surface microlayer. J.
Great Lakes Res. 8: 257-264.
Hardy, J.T., et al. 1985. Sea-surface microlayer metals enrichments in an
•urban and rural bay. Est. Coastal Shelf Sci. 20: 299-312.
Hoffm-an, G.L., et al. 1974. Residence time of some particulate trace metals
in the ocean surface microlayer: significance of atmospheric deposition.
J. Rech. Atmos. 8: 745-759.
Hunter, K.A. 1980. Processes affecting particulate trace metals in the sea
surface microlayer. Mar. Chem. 9: 49-70.
Hunter, K.A. & P.S. Liss. 1981. Organic sea surface films, p. 259-298. In:
E.K. Duursma and .R. Dawson (edd.), Marine organic chemistry. Elsevier.
Jarvis, N.L. 1967. Adsorption of surface-active material at the air-sea
interface. Limnol. Oceanogr. 12: 213-221.
Lion, L.W. and J.O. Leckie. 1981. The biogeochemistry of the air-sea inter-
face. Ann. Rev. Earth Planet. Sci. 9: 449-486.
Meyers, P.A. and J.G. Quinn. 1973. Factors affecting the association of fatty
acids with mineral particles in seawater. Geochim. Cosmochim. Acta 37:
1745-1759.
Pellenbarg, R. Trace metal partitioning in the aqueous surface microlayer of
a salt marsh. Est. Coastal Shelf Sci. 13: 113-117.
Piotrowicz, S.R. et al. 1972. Trace metal enrichment in the sea-surface
microlayer. J. Geophys. Res. 27: 5243-5254.
C.12
-------
Platford, R.F. 1982. Pesticide partitioning in artificial surface films. J.
Great Lakes Res. 8: 307-309.
Van Vleet, E.S. & P.M. Williams. 1983. Surface potential and film pressure
measurements in seawater systems. Liranol. Oceanogr. 28: 401-414.
Whitehouse, B. 1985. The effects of dissolved organic matter on the aqueous
partitioning of polynuclear aromatic hydrocarbons. Est. Coastal Shelf
Sci. 20: 393-402.
Williams, P.M. 1967. Sea surface chemistry: Organic carbon and organic and
inorganic nitrogen and phosphorus in surface films and subsurface waters.
Deep-Sea Res. 14: 791-800.
Williams, P.M., E.S. Van Vleet, and C.R. Booth. 1980. In situ measurements
of sea-surface film potentials. J. Mar. Res. 38: 193-204.
Williams, P.M., et al. 1986. Chemical and microbiological studies of sea-
. surface films in the southern Gulf of California and off the west coast
of Baha California. Mar. Chem. in press.
Wheeler, J.H. 1975. Formation and collapse of surface films. Limnol.
Oceanogr. 20: 338-342.
C.13
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Mixing Down from the Microloyer:
The Role of Three-Dimensional Flows
for the Workshop on the Sea-Surface Microloyer
Robert A. Weller
Woods Hole Oceanographic Institution
Woods Hole, MA 02543
(617) 548-1400 ext. 2508
C.15
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Mixing Down from the Microloyer: The Role of Three-Dimensional Flows
Introduction
In lakes* along the coast and in the open ocean narrow, elongated regions of
relatively smooth water that sometimes also contain floating derbris, plants, and
animal life are commonly observed. These regions, which are aligned roughly
parallel to the wind, are covered by a thin layer or slick of organic material
that damps capillary waves. The source and nature of the slick has been
discussed elsewhere (see the associated papers by Blanchard, Carlson, Hardy, and
Myers). This paper discusses the flow within the surface mixed layer (The
surface mixed layer is the nearly isothermal wind-stirred upper layer, ranging
from several meters to hundreds of meters in depth.) that causes surface films
to form into narrow bands and suggests that those flows play a role in carrying
material deposited on the surface down into the interior of the mixed layer.
flverview of the mixed lover
Surface tension forces stabilize the surface microlayer (Hardy, 1982). In
the surface mixed layer (see Figure 1) the input of heat and fresh water
stabilize the fluid near the surface by making it more buoyant. When heating
dominates wind-mixing, the water in the mixed layer is essentially isolated from
the fluid below. When the mixed layer deepens as the wind becomes stronger,
deeper cooler fluid is entrained and mixed into the surface layer. Only in the
winter, when cooling dominates and convective deepening is observed, is the
surface water able to penetrate to great depth.
Mixing at the base of the layer occurs when the vertical shear of the
C.17
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horizontal velocity is large compared to the stabilizing density jump across that
interface. In that case the fluid overturns and mixes. Within the mixed layer
mean horizontal velocities have been considered to be large compared to mean
vertical velocities. As a result, vertical transfer within the mixed layer was
thought to occur primarily through small-scale turbulent or eddy diffusion on a
time scale comparable to the local inertial period (12/sine hours, where
8 is the latitude). One result of such slow vertical diffusion would be the
Ekman spiral, in which the largest wind-driven velocities remain near the
surface* the source region for the horizontal momentum.
If turbulent diffusion was indeed the only means for vertical mixing,
material deposited on the sea surface as well as momentum from the wind and heat
from the solar radiation Cwhich decays exponentially with depth), might enter
only very slowly Into the mixed layer. However, the narrow, elongated slicks
mentioned in the introduction ore very commonly observed; and to understand the
Physics of the mixed layer it is necessary also to consider the source of the
slicks, Langmuir Circulation.
\ angmuir rirculation
After observing long rows of seaweed aligned parallel to the wind during an
Atlantic crossingsi Langmuir C1938) carried out experiments in Lake George that
identified the cause of those rows. Within the mixed layer there were helical
flows that created alternating regions of convergent and divergent flow at the
surface. The seaweed was swept into the convergences. Woodcock C1950) found
that the flow was strong enough to submerge the buoyant Sargassum . Sutcliffe
et al. C1963) observed that organo-phosphate films collected in the convergence
. "' - , t!' ' • •
zones and spectulated that pieces of the surface film mi.ght be carried down and
C.18
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introduced into the Hater column in the regions of downward flow. Owen C1966)
found zooplankton concentrated at the surface within the convergences.
L,eibovich (1983) and Pollard (1977) summarize these and many other
observations. Figure 2> which is taken from Pollard (1977), is a good summary of
the characteristics often attributed to Langmuir Circulation. The vertical
velocities reported by most investigators, typically between 2 and 6 cm s"1,
were relatively small, and three-dimensional flows within the mixed layer were
not considered by most to be a dominant mixing mechanism.
: observaions
However, observations made within the last three years show that three
dimensional flows ore stronger than previously thought and suggest that they play
an important role in mixing down from the surface. Thorpe has made observations
with a thermistor chain (Thorpe and Hall, 1982) and with a side-scan sonar that
visualizes the distribution of air bubbles in the mixed layer (Thorpe and Hall,
1983; Thorpe, 1984). The thermistor chain data clearly showed warm water being
drawn down from the surface in the region of the slicks (Figure 3). Similarly,
the side-scan sonar data showed air bubbles penetrating to depths of up to 10 m
below the wind rows (Figure 4).
In studying the daily cycle of restratification and mixing that accompanies
solar heating during spring and summer days (Figure 5), Price et al (1985) found
that fresh inputs of momentum available at the surface following a shift in wind
speed or direction were rapidly distributed in the vertical, over the entire
depth of the mixed layer, so that the instantaneous vertical profile of
horizontal velocity was not spiral-like, but was uniform, The observation that
the momentum was distributed within minutes prompted a series of experiments to
C,19
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determine if the flow associated with Langmuir Circulation was larger than
previously reported and thus could be responsible for the observed rapid vertical
mixing.
In 1982 and 1983 three cruises were made on the Research Platform FLIP off
the coast of California (Figure 6). In the first cruise vertical velocities of
up to 23 cm s~1 were found beneath in the convergence zone (Weller et al.,
1985). The second and third cruises have added more information about the
characteristics of the Langmuir Circulation. Though the flow varies greatly in
strength? typically it is present near the surface (Figure 8). Stronger winds
generate stronger three dimensional flows that penetrate deeper into the mixed
layer. The vertical structure of the vertical velocity is not unlike that
reported by Pollard (1977) (Figure 2)> though it is more concentarted at
mid-depth of each cell than he reported. The horizontal velocity has a
pronounced downwind maximum below the surface (Figure 9)> near the depth of the
maximum downwelling. The downwind jet was observed to have speeds relative to
the mixed layer of UP to 40 cm s~".
While Langmuir Cells of many different scales appeared to coexist, the
largest cells were the strongest. Downwelling velocities are a maximum at
mid-depth in the mixed layer. Because the downwelling maximum coincides with a
maximum in downwind flow of equal magnitude, the fluid is drawn from the surface
at roughly a 45 degree angle. Coincident Doppler Sonar measurements made by
Pinkel (Scripps Institutuion of Oceanography) during the last cruise confirmed
the existence of a field filled with the large scale, strong cells on November
9-11. The vertical velocity in the convergence zones of these cells was as high
as 25 cm s-1. The downwind horizontal velocity relative to the mixed layer
was as high as 40 cm s"1, but was more typically 20 cm s—'. Thus, at
C.20
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times, the three-dimensional flow of the Langmuir Cells dominated the mixed
layer.
Possible role of the three-dimensional flow
During the experiments, the naturally occurring surface slicks were
difficult to see and used computer cards were often scattered on the surface to
provide an indication of the presence and strength of the Langmuir Circulation,
At times of strong dpwnwelling a fraction of the computer cords were observed to
p# carried down below the surface into the downwind, downwelling flow. This
pbservtion is not unlike that made by Woodcock (1950) years earlier. However,
t$p flow beneath the surface is much stronger than previously thought; and there
if evidence that Langmuir Circulation acts to rapidly vertically distribute
momentum and other properties that enter at the sea surface. Temperature
anomalies found in association with the downwelling show that Langmuir
Circulations are actively skimming the surface of the mixed layer from below*
withdrawing surface water that is heated during the day and cooled at night.
Film covered bubbles injected by breaking surface waves or rain into the
mixed layer, aggregates that form in the convergence zone, and matter that can
escape the surface tension in the slicks should thus be quickly drawn below trhe
surface and exported downward and downwind from the site. Once into the mixed
layer, dense matter might sink into the deeper ocean and neutral or positively
buoyant matter might be carried back toward tha surface by the more diffuse
upward flow found in the region between the surface slicks.
C.21
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ferences
Hardy, J. T- 1982- The sea surface microlayer: biology* chemistry and
anthropogenic enrichment. Prog. Oceanog. 11: 307-328.
Langnuir, I. 1938. Surface motion of water induced by wind. Science. 87:
119-123-
Leiboivich, S- 1983- The form and dynamics of Langmuir Circulations. Ann. Rev.
Fluid nech. 158 391-427.
Owen, R. U., Jr., 1966- Small-scale, horizontal vortices in the surface layer of
the sea. Jour. Mar. Res. 24: 56^66. ; ,21.
Pollard, R. T. 1977. Observation and theories of Langmuir Circulations and ^
their role in near surface mixing. In A Voyage of Discovery: George Deacon 70th
Anniversary Volume, ed. M. Angel, PP. 235-251. Oxford: Pergammon. A.J, •
Price, J. F., R» A- Weller, and R. Pinkel. 1985- Diurnal cycling: Observations
and models of the upper ocean response to diurnal heating, cooling, and wind >
mixing. Jour. Geophys. Res. in press. *l;
Sutcliffe, W. H., Jr., E- R. Baylor, and D. W. Menzel. 1963. Deep-Sea Res. =10:
233-243. . , , : ;J;
Thorpe, S- A. and A. J. Hall. 1982. Observations of the thermal structure of;
Langmuir Circulation. Jour. Fluid Mech. 114: 237-250. V4;v
'<'• j> .'••
Thorpe, S. A- and A. J. Hall. 1983- The characteristics of breaking waves,
bubbles clouds, and near-surface currents observed using side-scan sonar.
Continental Shelf Res. 1: 353-384. • -
Thorpe, S. A- 1984. The effect of Langmuir Circulation on the distribution of
submerged bubbles caused by breaking wind waves. Jour. Fluid Mech. 142: ij
151-170.
Weller, R. A-, J. P- Dean, J. Marra, J. F. Price, E. A- Francis, and D. C.
Boardnan. 1985. Three-dimensional flow in the upper ocean. Science. 227:
1552-1556.
Woodcock, A- H. 1950- Subsurface pelagic Sargassum. Jour. Mar. Res. IX:
77-92.
C.22
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Figure raptions
Figure 1. Schematic overview of the physical processes found in the surface
mixed layer. Typical vertical profiles of potential temperature in the marine
atmospheric boundary layer and of the temperature in the mixed layer are shown at
left. Heat, mass* and momentum can be exchanged between the atmosphere and the
ocean. The turbulent vertical exchange of_heat, moisture, and momentum are
symbolized by the indicated averages of (w'T*)» (w7^), and (w7^*), respectively,
where w is the vertical component of velocity, q is a measure of moisture content
in the air, and v is the vector horizontal velocity. The prime denotes the
fluctuating component. Solar heating penetrating the surface and rain would tend
to stabilize the mixed layer by making it buoyant. Longwave radiative loss,
latent heat loss associated with evaporation, and sensible heat loss when the air
was colder than the water would make the surface water denser; the mixed layer
would convectively deepen. The wind (symbolized by *<) is considered to have
a:-i1early logarithmic profile. The wind blowing on the surface accelerates the
fluid in the mixed layer. Strong storms cause significant mixing and deepening
of the mixed layer; hurricanes leave a wake that persists for days. Transient
wind events excite the resonant response of the mixed layer, inertial motion and
have been found to produce q velocity profile, UXz), that is nearly uniform with
depth. Mean winds were at one time thought to produce vertically sheared
velocity structures such as he Ekman spiral as horizontal momentum diffused
downward relatively slowly. Recent measurements show that helical Lqngmuir
Circulations act to quickly transport the heat and momentum available at the
surface into the interior of the mixed layer so that, the mixed layer is most
often well mixed in velocity as well as in temperature. Upwelling, we,
internal wave generation (and the associated downward propagation of energy,
EC», and overturning at low Richardson number (Ri) are processes that occur
at the base of the mixed layer.
Figure 2. Schematic of the flow within Langmuir Circulation based on the
observations made before 1977, drawn by Pollard (1977).
"f • / ' - • -
Figure 3. A drawing of the thermal structure in the mixed layer from Thorpe and
Hall (1982). Beneath the slicks or wind rows, tongues of warm water were
observed.
Figure 4. The maximum depth of bubble clouds observed by side-scan sonar plotted
against wind speed (Thorpe, 1984). The dashed line is the depth predicted based
on an assumed vertical flow beneath the wind rows.
Figure 5. The net heat flux (top) and the temperature structure in the upper 25
m observed during four days (times in local year days) off southern California.
When the wind was light and the sky clear (days 130 and 131) a shallow, warm
mixed layer forms before local noon. As the solar heating decreases in the
afternoon, wind mixing is able to deepen the new mixed layer. From Price et al.,
1985.
Figure 6- Locations of the three cruises on FLIP. During these cruise FLIP was
allowed to drift freely. The dates inicated are the dates of the beginning of
each of the three cruises.
C.23
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Figure 7- Three-dimensional flow observed during the December 1982 cruise. 30
minutes of data ore shown that were collected at a depth of 23 m in a mixed layer
that was 40 to 50 m deep. Computer cards lined up in long rows. Beneath the
computer cards, at 23 m, downward and downwind flow was observed. From Ueller et
al., 1985.
Figure 8. A census of the occurence of Langmuir Circulation made during the
third cruise in late 1983. The net heat flux (top) and wind stress (middle) are
shown. At the bottom the intensity of the observed vertical flow is indicated;
the darker the shading the stronger the flow. Black indicates vertical
velocities of 25 an sn and up. White areas within boxes indicate
measurements were made* but no indication of downwelling was observed. Levels 1
thru 5 correspond to the surface and four progressively deeper depth levels in
the mixed layer at which measurements were made.
Figure 9- Vertical profiles of temperature (background and to the right) and
relative horizontal velocity (foreground and to the left) made in the convergence
zone of a Langmuir Cell. The arrow above the velocity axes' Indicates the
direction of the wind. The downwind velocity Jet had a strength of approximately
40 cm s~'•
C.24
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iimn
C.2S
-------
o -lOcm/sec.
relative to
Figure 2
Figure 3
C.26
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OBSERVED
~ o_
ODEU
AIR/SEA HEAT FLUX'
'i I i—r
-------
FLIP DRIFT TRACKS - DEC 82, MAY 83, OCT 83
0)
T3
2
rvs
vo
30° N
138° W 126° W
W
122° W 120° W 118 W 116 W
Longitude
Figure 6
-------
o
CO
-------
o
•
CJ
700 n
o
-300 J
.3 -
A
^VAAA*AAJ.
Wm
•2
~t r~*-\ 1 1 1
Nm
DiTiiniflnn w\ nr
i LJOi3LJu LJ LJU
B DIDD
D.
II III.I
D
230CT
1983
25 27 29 31 2NOV
~T r
4
"1
6
I - 1 - 1
8 10
12 14
MILDEX
Figure 8
-------
PROFILE 183
DAY 17.28 - 17.30
NOVEMBER 9
Figure 9
C.32
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MICHOBIAL ACTIVITY IN MARINE SURFACE MICROLAYERS
A. F. Carlucci and D. B. Craven
Institute of Marine Resources, A-018
University of California, San Diego
La Jolla, California 92093
Surface microlayers are specialized interface environments subject to
unique physical, chemical and biological perturbations and effects. ^Surface
films concentrate hydrophobia substances, metals, and pollutants (cf . Hardy
£l., 1985), participates (cf. Harvey jjL ai. , 1982) and microorganisms (cf.
Harvey, 1966; Sieburth si Si.- » 1976; Hardy, 1982).
There are relatively few dynamic studies of microbial populations in
marine surface films. Dietz g£. al. (1976), using a glass-plate sampler in
waters off British Columbia, observed greater uptake of 1 ^C-glucose by
subsurface bacteria than by neus tonic populations. However, Passman §£. al«
(1979) found significant amounts of ^H-glutamic acid uptake by screen-collected
surface microheterotrophs in the Atlantic. Kjelleberg ei aL. (1979* 1980)
characterized the majority of surface film bacteria as lipolytic, whereas
Sieburth and associates (Sieburth, 1971; Sieburth e£ al, 1976) found mostly
protolytic bacteria.
The metabolic status of surface microlayers is not well understood.
Surface film microorganisms are repeatedly exposed to ultraviolet irradiation
and some work suggests that they are either inhibited or non- viable (cf.
Albright, 1980). Incident light appears to inhibit certain populations, e.g. 6
C*33
-------
mm depth (Bailey et al. f 1983) but not others (Hermansson and Dahlback, 1983).
We recently evaluated solar radiation effects on surface film
microheterotrophic utilization of ^n-amino acids. Also, we studied ^H-amino
acid metabolism by surface microlayer populations collected in three distinct
oceanic regions: oligotrophic, mesotrophic, and eutrophic. A majority of the
results have been reported (Carlucci jg£. .al., 1985).
Rates of in situ microheterotrophic utilization (incorporation and
respiration) of ^H-leucine and ^H-giutamic acid were measured in surface films w
of waters collected off Baja California and Southern California. Neither
visible nor ultraviolet radiation had a marked detrimental effect on microbial
heterotrophy. At times, ultraviolet radiation appeared to be stimulating.
Surface film microheterotrophs utilized glutamic acid at rates between 0.07 and
0.13 nM h""^ for oligotrophic waters and between 0.43 and 2.1 nM h~1 for
eutrophic waters. Respective turnover times were 101 to 313 h and 8.6 to
21.5 h. Leucine utilization rates in oligotrophic waters were comparable to
glutamic acid but turnover times were shorter. In eutrophic waters utilization
rates of leucine were slower, but turnover times were similar. Utilization
rate values for mesotrophic waters were intermediate between oligotrophic and
eutrophic regimes.
In oligotrophic waters higher amino acid utilization rates were observed
for surface-film raicroheterotrophs than for subsurface (10 cm) populations,
whereas in eutrophic waters utilization rates were similar for surface and
subsurface bacterioplankton. Surface-film microheterotrphs, in most cases, had
an average of 63% amino acid carbon assimilation efficiency. Dissolved free
amino acid utilization was more rapid during the day (0.14-0.38 nM h~1) than at
night (0.04-0.09 nM h"^) in surface films and subsurface waters. However, the
C.34
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percent of utilized amino acid which was respired was always higher during the
ftight (22-57$) compared to the day (14-18$).
We conclude from these studies that surface films contain highly active
populations which are involved in the metabolism and turnover of amino acids.
References
ALBRIGHT, L. J. 1980. Photosynthetic activities of phytoneuston and
phytoplankton. Can. J. Microbiol. 26_: 389-392a
BAILEY, C. A., R. A. NEIHOF, and P. S, TABOR. 1983. Inhibitory effect of
solar radiation on amino acid uptake in Chesapeake Bay bacteria. Appl.
Environ. Microbiol. M: 44-49.
CARLUCCI, A. F., D. B. CRAVEN, and S M. HENRICH. 1985. Surface-film
microheterotrophs: amino acid metabolism and solar radiation effects on
their activities. Mar. Biol. flJSL: 13-22.
DIETZ, A. S., L. J. ALBRIGHT, and T. TUOMINEH. 1976. Heterotrophic activities
of bacterioneuston and bacterioplankton. Can. J. Microbiol. 22.:
1699-1709.
HARDY, J. T. 1982. The sea surface microlayer: biology, chemistry, and
anthropogenic enrichment. Prog. Oceanogr. JJ.: 307-328.
HARDY, J. T., C. W. APTS, E. A. CRECELIUS, and G. W. FELLINGHAM. 1985. The .
sea surface microlayer: fate and residence times of atmospheric metals.
Limnol. Oceanogr. 3Q_: 93-101.
HARVEY, G. W. 1966. Microlayer collection from the sea surface: a new method
and initial results. Limnol. Oceanogr. 11: 608-613*
C.35
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HARVEY, R. W., L. W. LION, L. Y. YOUNG, and J. 0. LECKIE. 1982. Enrichment
and association of lead and bacteria at particulate surfaces in a
salt-marsh surface layer. J. Mar. Res. M: 1201-1211.
HERMANSSON, M., and B. DAHLBACK. 1983. Bacterial activity at the air/water
interface. Microb. Ecol. £: 317-238.
KJELLEBERG, S., and T. A. STENSTROM. 1980. Lipid surface films: interactions
of bacteria with free fatty acids and phospholipids at the air/water
interface. ,J. Gen. Microbiol. 116* 417-423.
KJELLEBERG, S., T. A. STENSTROM, and G. ODHAM. 1979. Comparative study of
different hydrophobia devices for samling lipid surface films and adherent
microorganisms. Mar..Biol. 53.: 21-25.
PASSMAN, F. J., T. J. NOVITSKY, and S. W. WATSON. 1979- Surface microlayers
of the North Atlantic: microbial populations, heterotrophic and
hydrocarbonaclastic activites, p. 214-226. In. A. Bourquin and P. H.
Pritchard (eds.), Microbial degradation of pollutants in marine
environments: workshop proceedings. Pensacola Beach, Florida, U.S.
Environmental Protection Agancy.
SIEBURTH, J. McN. 1971. Distribution and activity of oceanic bacteria.
Deep-Sea Res. 18: 1111-1121.
SIEBURTH, J. McN. P. J. WILLIS, K. M. JOHNSON, C. M. BURNEY, D. M. LAVOIE, K.
R. HINGA, D. A. DARON, F. W. FRENCH III, P. W. JOHNSON, and P. G. DAVIS.
1972. Dissolved organic matter and heterotrophic microneuston in the
surface microlayers of the North Atlantic. Science 1Q4; 1415-1418.
C.36
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BN^-SA-
PHYTONEUSTON: PLANTS OF THE
SEA-SURFACE MICROLAYER
J. T. Hardy
Marine Research Laboratory
Sequim, Washington
December 1985
Presented at the
Sea-Surface Microlayer Workshop
Arlie, Virginia
December 18, 1986
BatteH e
Pacific Northwest Laboratories
Rich!and, Washington 99352
C.37
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WORKSHOP ON THE SEA-SURFACE MICROLAYER IN RELATION TO OCEAN DISPOSAL
PHYTONEUSTON: PLANTS OF THE SEA-SURFACE MICROLAYER
John T. Hardy
December 9, 1985
INTRODUCTION
The sea-surface microlayer (SSM) is an important biological habitat.
Phytoneuston (microalgae inhabiting the SSM) often occur in densities 10 to
10,000 times greater than the phytoplankton living only a few centimeters
below (Hardy 1973; Hardy and Valett 1981; Wandschneider 1979; Manzi et al.
1977; Maynard 1968; Nesterova 1980; Harvey 1966; Bursa 1968). Phytoneuston
provide a food source at the base of a food web linked to plankton in the
underlying water (Zaitsev 1971).
Studies of chlorophyll pigments in the microlayer compared to the bulk
seawater have generally indicated high surface enrichments (Hardy 1973; Hardy
and Apts 1985; Nishizawa 1971; Harvey and Burzell 1972; Gallagher 1975). Like-
wise, studies of photosynthetic productivity showed that ratios of microlayer
to subsurface water are frequently 10 or greater (Hardy 1973; Gallagher
1975). However, several studies suggest that neuston may be stressed in some
way and, therefore, are not as physiologically active as plankton (Marumo et
al. 1971; Dietz et al. 1976). Depletions in microlayer chlorophyll-a (Carlson
1982; Albright 1980) and photosynthetic carbon fixation (Albright 1980) com-
pared to bulk seawater have been attributed to unknown inhibitory factors in
the SSM.
Through production of dissolved organic materials, phytoneuston may
influence surface film formation and alter the exchange rates of gases and
materials between the atmosphere and hydrosphere. Any negative impact on the
health or physiology of neuston, then, could have important implications for
the global cycling of materials. We find it surprising then that few studies
have examined rates of photosynthet.i c carbon reduction in the SSM (Albright
1980). Two of these studies focused on very enclosed lagoon or salt marsh
areas (Hardy 1973; Gallagher 1975).
We conducted microcosm and field studies to test the following hypotheses:
1) the SSM serves as a habitat for an abundant and distinct community of micro-
algae; 2) the SSM is a site of intense productivity (carbon reduction), espe-
cially in visible slicks; and 3) extracellular carbon release is greater in
phytoneuston than in phytoplankton. Studies were conducted primarily in Puget
Sound, but preliminary observations have been made at the proposed ocean incin-
eration site in the Atlantic (Blake Plateau), 150 miles off the east coast of
Florida. This paper presents a brief summary of our results. For the sake of
brevity, we exclude details of the methodology and exceptions to general trends
in the results.
C.39
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METHODS
At the Atlantic site, only microalgal densities were determined; whereas,
the Puget Sound studies also included pigment and photosynthetic measure-
ments. For analysis of species abundance and chlorophyll pigments, samples
were collected in the field, from the microlayer by the glass plate method
(Hardy et al. 1985), and from a 20-cm depth in the bulk seawater by subsurface
opening of bottles. Visible slicks were common and widespread at the Atlantic
site on September 11, 1985, and a micrdlayer sample and subsurface bulk sea-
water sample were collected from such a slick. Microlayer and bulk seawater
samples, collected as described above, were preserved in Lugols' iodine, and
the densities of individual species were enumerated microscopically in
replicate subsamples.
Photosynthetic pigments were extracted in acetone and determined spectro-
photometrically. Photosynthetic experiments were conducted in microcosm tanks.
The tanks were lowered over the bow of a small boat to a depth of about 30 cm
and then brought up slowly to trap the surface microlayer and bulk water. The
hole in the bottom of the tanks was then sealed. Samples were collected from
clean water areas and from adjacent areas with a visible slick. Surface pres-
sure, indicative of the presence of an organic surface film was measured by the
oil-drop-spreading method of Adam (1937).
Photosynthetic tanks were innoculated with sodium bicarbonate carbon-14
and incubated for 4 hours in full summer sunlight in an ambient-temperature
seawater bath. Samples from each tank were collected from the microlayer using
the membrane filter technique and from the bulk seawater by syringe, and pro-
ductivity was determined as described previously (Hardy and Apts 1985). The
quantity of extracellular organic carbon released during photosynthesis was
determined by generally following the techniques described previously (Williams
and Yentsch 1976; Mague et al. 1980).
RESULTS AND DISCUSSION
In Puget Sound, as well as at the Atlantic site, the abundance of micro-
algal taxa was generally much greater in the SSM than in the bulk seawater. At
the Atlantic site, densities of phytoneuston were 400 times greater in the SSM
than in the surface bulk seawater. A high density (bloom) of the blue-green
alga Trichodesmium sp. was present in the microlayer, but completely absent
from the bulk seawater. In Puget Sound, at both slick and nonslick sites,
total densities of phytoneuston were 37 to 154 times greater than phytoplankton
densities. At both sites (Atlantic and Puget Sound), many species that were
present in the microlayer were absent from the bulk seawater and vice versa.
The phytoneuston community was dominated by microflagellates and small pennate
diatoms. High densities of heterotrophic microflagellates, neustonic ciliates*
and tintinnids were frequently present.
In Puget Sound, the total concentration of photosynthetic pigments was
generally greater in the SSM than in the bulk seawater, reflecting the great
densities of organisms in the microlayer. This was especially true in slick
samples where ratios of microlayer to bulk seawater pigments from 10 to 100
C.40
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were common. In the nonslick samples, the concentration of chlorophyll-a in
the microlayer was only about half of that found in the bulk seawater, and the
total pigment concentration was only slightly enriched in the microlayer.
Total pigment concentration in visible slick microlayers was often more than 10
times greater than that in nonslick microlayers, while the bulk seawater showed
no difference in total pigment concentration between slick and nonslick areas.
Reduction of inorganic carbon to particulate organic carbon (microalgal
photosynthesis) per unit volume of surface water was greater in the microlayer
than in bulk seawater. Ratios of photosynthesis in the microlayer to that in
the bulk seawater were generally 10 to 100 in slicks and 1 to 2 in nonslick
areas. Approximately 3 to 8% of the photosynthetically reduced organic carbon
was released in the form of extracellular dissolved organic carbon. In both
neuston and plankton, extracellular carbon release was greater in the dark when
it represented 16 to 65% of the reduced particulate carbon.
We must exercise caution in extrapolating from tank experiments to large-
scale global processes, the importance of phytoneuston on a global scale
remains to be determined; however, studies suggest that, at least at certain
times and locations, dense populations inhabit the microlayer even far off-
shore. Whitecap wave conditions (which would destroy the integrity of the
surface microlayer) represent only 3 to 4% of the total world ocean surface at
any one time (Maclntyre 1974). Dense blooms of the blue-green alga Tricho-
desmium sp. and dinoflagellates similar to what we found at the Atlantic site,
occur in the Black Sea (Nestrova 1980). In the Indian Ocean a similar Tricho-
desmium sp. and dinoflagellate phytoneuston community was stable despite sea
states of Beaufort 3 to 4 (B. Bourgade-Le of the Centre d'OcSanologie de
Marseille, personal communication).
These results suggest that plant communities inhabiting the air-sea
interface may play an important biogeochemical role by providing biologically
mediated high rates of atmospheric carbon dioxide reduction. Phytoneuston
represent a distinct and unique community of organisms that are well adapted to
existence at the air-sea interface.
REFERENCES
ADAM, N. K. 1937. A rapid method for determining the lowering of tension of
exposed water surfaces with, some observations on the surface tension of the sea
and inland waters. Jn_ Proceeding of the Royal Society, Series B 122:134-139.
ALBRIGHT, L. J. 1980. Photosynthetic activities of phytoneuston and phyto-
plankton. Can. J. Microbiol. 26:389-392.
BURSA, A. S. 1968. Epicenoses on Nodularia spumigera in the Baltic Sea. Acta
Hydrobiol. Krakow. 10:267-297.
CARLSON, D. J. 1982. Phytoplankton in marine surface microlayers. Can. J.
Microbiol. 28:1226-1234.
C.41
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DIETZ, A. S., L. J. ALBRIGHT, and T. TUOMINEN.. 1976. Heterotrophic activities
"of bacterioneuston and bacterioplankton. Can. J. Microbiol. 22:1699-1709.
GALLAGHER, J. L. 1975. The significance of the surface film in salt marsh
plankton metabolism. Limnol. Oceanogr. 20:120-123.
HARDY, J. T. 1973. Phytoneuston ecology of a temperate marine lagoon.
Limnol. Oceanogr. 18(4):525-533.
HARDY, J. T., and C. W. ARTS. 1985. The sea surface microlayer: Phytoneuston
productivity and effects of atmospheric particulate matter. Mar. Biol.
82:293-300.
HARDY, J. T., and M. K. VALETT. 1981. Natural and microcosm phytoneuston
communities of Sequim Bay, Washington. Estuar. Coastal Shelf Sci. 12:3-12.
HARDY, J. T., C. W. APTS, E. A. CRECELIUS, and N. S. BLOOM. 1985. Sea-surface
microlayer metals enrichments in an urban and rural bay. Estuar. Coastal Shelf
Sci. 20:299-312.
HARVEY, G. W. 1966. Microlayer collection from the sea surface: A new method
and initial results. Limnol. Oceanogr. 11:608-613.
HARVEY, G. W., and L. A. BURZELL. 1972. A simple microlayer method for small
samples. Limnol. Oceanogr. 17:156-157.
MACINTYRE, F. 1974. The top millimeter of the ocean. Sci. Amer. 230:62-77.
MAGUE, T. H., E. FRIBERG, D. J. HUGHES, and I. MORRIS. 1980. Extracellular
release of carbon by marine phytoplankton: A physiological approach. Limnol.
Oceanogr. 25(2):262-279.
MANZI, J. J., P. E. STOFAN, and J. L. DUPUY. 1977. Spatial heterogeniety of
phytoplankton populations in estuarine surface microlayers. Mar. Biol.
41:29-38.
MARUMO, R., T. NOBUO and T. NAKAI. 1971. Neustonic bacteria and phytoplankton
in surface microlayers of the equatorial waters. Bull. Plankton Soc. Japan.
18:36-41. .
MAYNARD, N. G. 1968. Aquatic foams as an ecological habitat. Z. Allg.
Mikrobiol. 8:119-126.
NESTROVA, D. A. 1980. . Phytoneuston'in the western Black Sea.
Gidrobiologicheskii Zhoraal. 16(5):26-31.
NISHIZAWA, S. 1971. Concentration of organic and inorganic material in the
surface skin at the equator, 155 W. Bull. Plankton Soc. Japan 18:42-44.
C.42
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WANDSCHNEIDER, K. 1979. Vertical distribution of phytoplankton during
investigations of a natural surface film. Mar. Biol. 52:105-111.
WILLIAMS, P. J., and C. S. YENTSCH. 1976. An examination of photosynthetic
production, excretion of photosynthetic products, and heterotrophic utilization
of dissolved organic compounds with reference to results from a coastal
subtropical sea. Mar. Biol. 35:31-40.
ZAITSEV, Y. P. 1971. Marine neustonology. (Trans, from Russian). National
Marine Fisheries Service, NOAA and NSF (NTIS), Washington, D.C., 207 pp.
C.43
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Uorkahon an the Spfl—Surfapp Migralavar
Airlie, Virginia
December 18-19, 1985
Zooneuston: Animals of the Sea Surface1
George C. Grant
Virginia Institute of Marine Science
The College of William and Mary
SUMMAW
Perceptions of the sea surface as an impoverished cone for marine fauna
stea from earlier studies comparing surface and subsurface net collections
taken in the open ocean* In the Gulf of .Mexico (Berkowitz, 1976), total
abundance of animals one meter below the surface exceeded that from the
upper 10-15 cm by a factor of 3.1 during the day and 2.1 at night, and this
difference was attributed to the inability of most organisms to accommodate
to the high intensity of solar radiation absorbed by the sea surface layer*.
In the temperate-boreal waters of the Horth-west Atlantic and in the Gulf
Stream, the surface layer in terms of biomass was also found to be an
impoverished zone (Morris 1975). Absolute surface biomass decreased from
Contribution No. 1319 from the Virginia Institute of Marine Science,
School of Marine Science, the College of William and Mary
C.45
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Seotian shelf waters to the Sargasso Sea, although the ratio of surface
bioaass to subsurface bioaass increased along the same transect. Morris
found no support for the suggestion of greater importance of surface waters
for fish larvae.,
Composition of fauna in surface and subsurface layers is, however*
importantly different. There are elements of the fauna that' are unique to
the surface, many with adaptations to surface life (David, 1965).
Morphological specializations such as floats and bubbles allow well-known
surface-dwellerii, such as the Portuguese Man-0-War, the By-the-Wind Sailor
and Janthina. the purple snail, to reaain at the surface at low energy
expenditure. Also well-documented are the few representative species of
Class Insecta in the marine environment, particularly the water-striders
(genus Halobatea). and the highly-pigmented family of pontellid copepods.
All but the latter are at least partially evident above the surface film.
Typical adaptations to surface life include, in addition to floats and
bubbles, transparency or conversely, intense and varied pigmentation;
flattening of body shape; extension of appendages and inclusion of low-
density fluids.
C.46
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These veil-known surface inhabitants} howevert represent only a small
percentage of the plank tonic community in the top 10-15 cm of the water
column. The most abundant species in that layer* sampled by specially-
designed, surf ace-skimming towed nets, are representative of deeper-living
communities and in some cases, less well-known euneustonts (true surface
layer inhabitants not typically found at greater depths)* Among the latter
in certain regions is the large, heavy-bodied and darkly-pigmented isopod,
Idotea metalliea. and advanced stages of larval lobsters Homarua americanus.
Since the surface layer represents a physical end-point for vertical
migrators, high densities .of strong migrators from deeper levels are
typically evident at night. Thus, the character of surface communities
changes with time of day and from region to region depending upon the nature
of underlying communities and the distance to the bottom.
e
Diel changes in abundance of individual species in the surface layer
may reflect vertical migration habits. Lack of change through a 24-hour
period is typical for truly neustonic species - those restricted to the
surface, while weak migrators are present at all hours, but become more
abundant at night. Strong vertical migrators are absent from the surface in
C.47
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the daytime and reach peak densities, sometimes dominating surface
cooaunities, around midnight. Those open ocean species typically undergoing
extensive vertical migrations (hundreds of meters) disappear from the
neuston as they are excluded from shallower continental shelf regions by the
presence of the bottom. A variation in the above patterns is a feeding
response that results in increased surface density at dusk, a satiated
sinking at midnight, and a secondary rise to the surface at dawn.
While open ocean neuston communities are typically of high diversity
and lowbiomass, this changes as one enters shallower continental shelf
waters. Surface waters closer to the coast tend toward dominance by one or
a few species and toward high biomass. In estuaries, neuston loses its
distinctiveness from underlying communities due to the proximity of the
bottom and general lack of "elbow room" for migratory species. It is over
productive continental shelves that surface layers assume the importance and
character described by Zaitsev (1970) for shallow Russian seas. It is here
that the surface layer serves as the "incubator of the sea".
Fish eggs and larvae and decapod crustacean larvae, including those of
many comtn
ercially important species, have been .found to comprise signficant
C.48
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portions of neuston communities in Che Middle Atlantic Bight (Grant) 1977,
1979). During seasonal peaks of reproduction and developments these young
stages of fishes and decapods frequently dominate neuston collections}
outnumbering at times even the typically dominant copepods. Proportions of
developmental stages in the surface layer are far greater than those seen in
subsurface plankton collections taken from identical sites. The importance
of the surface layer and high local abundance of eggs and larvae cannot be
recognized (and has not been in earlier surveys), using conventional
plankton collecting gear. In the Middle Atlantic Bight, even relatively
large> advanced megalopal stages of rock and jonah crabs (Cancer spp), can
seasonally outnumber smaller, typically numerous, copepods in the surface
layer during the spring and early summer months. Eggs and larvae of hakes,
Urophycis spp., are other important neustonic dominants in warmer months.
These seasonal swarms of developmental stages are subject to any
surface contamination. Ignorance of their presence has led to under-
estimation 'of impacts from oil spills, e.g., often by the same
environmentalists who have strong concerns for beaches and shorebirds.
Movement of spilled oil offshore by favorable winds does not, necessarily,
C.49
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lessen economic
impact to the environment. Extensive surface contamination
with oil or other toxic substances could, during the reproductive season,
decimate entire yearclasses of commercially important,species. Most
vulnerable are those species adapted to development in the surface layer.
While continental shelves are most critical for- these early
developmental stages and. should be,protected from any controlled or directed
dumping or^disposalpf wastes, the neustp* communities itv,;the open ocean
also require some consideration. N.ot only do they contain unique, true
surface species, but also deeper-living migrants to the surface layer that
may
transport contaminants from surface layers to the depths. Holdway and
Haddock (1983a, b) found that migration into the neuston increased mean
faunal density af dusk to 21 times densities at.mid-day. Such vertical
traffic must be fully understood and incorporated into models dealing with
fate and effects of surface contaminants.
REFERENCES
Berkowitz, S.' P. 1976> A comparison of the neuston and near-surface
zooplankton in the northwest Gulf of Mexico. M. S. Thesis, Texas
A&M University, College Park, Texas, 148 pp.
C.50
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David, Pv. M, 1965. The surface fauna of the ocean.
24:95-100
Grant, G. C. 1977. Middle Atlantic Bight zoop lank ton: seasonal bongo
and neuaton collections along a transect pff southern New Jersey.
Virginia Inat. of Marine Sci., Spec. Rep. Appl. Mpar. Sci. ft Ocean
Eng. No. 173, 138 pp.
Grant, G. C. 1979. Middle Atlantic Bight zoop lank ton: second year result.
and a discussion o* the two-year VjMS*BtM survey. Virginia Inat. of
Marine Sci;* Spec. Sep. Appl. Mar. Sci. ft Ocean Eng. Ko. 192, 236 pp.
Holdway, P. and L. Haddock. I983a. A conparative survey of neu« ton:
t ' '
geographical and temporal distribution patterns. M^R. Bi«y^. 76:263-
270.
?. and ^.- Maddock. 1983b. Neustonic diatribwtiona. Mar. Biol«
77:207-214.
Morris, B, F, 1975. The neuaton of the northwest Atlantic. Ph.D.
dissertation, Dalhouaie University, 285 pp.
Zaitsev, X. P. 1970, Marine Neustonology. Nauka Dumk a, Kiev [Trans I. by
Israel Prpgra* for Scientific TrWlatipna, 207 pp., Jeruaalew; Keter
, 1971].
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PROCESSES CONTRIBUTING TO THE
CONCENTRATION OF POLYCHLORINATED BIPHENYLS
AT THE SEA-SURFACE MICROLAYER
Philip A. Meyers
Oceanography Program
Department of Atmospheric and Oceanic Science
The University of Michigan
Ann Arbor, Michigan 48109-2143
prepared for the report of the
Workshop on the Sea-Surface Microlayer
(Arlie House, Virginia, December 18 & 19, 1985)
sponsored by the U.S. Environmental Protection Agency
C.53
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A thin (<1 mm) surface film/ commonly known as the surface microlayer/ is
present on all natural water bodies. Based on its mass and volume/ the
surface microlayer overlying a lake or ocean is miniscule compared to the bulk
water column/ and thus can be ignored in many considerations of aquatic
processes. The chemistry and biology of the surface microlayer are
sufficiently different from the subsurface water/ however/ that this layer
should be regarded as an important and distinct ecological compartment of the
aquatic environment (Rice et al./ 1983). As an example/ Liss (1975) has noted
that enrichments of microorganism populations in the surface microlayer on the
order of 103 are not uncommon. Microorganisms lie at the base of the aquatic
food chain and their ability to incorporate and concentrate significant
quantities of organic and inorganic substances is well documented.
Consequently/ the discovery of enriched concentrations of heavy metals and
chlorinated hydrocarbons in the surface microlayers of both marine (Seba arid
Corcoran/ 1969; Duce et al./ 1972; Bidleman et al./ 1976) and freshwater
environments (Andren et al./ 1976) had led to much concern regarding the
relationship between surface microlayer contaminants/ such as PCBs/ and
ecological cycles.
Constituents of the surface microlayer generally are determined by
laboratory analysis of samples of surface material rather than by in situ
measurements. In this case the thickness is operationally defined by the
sampling method employed (Duce and Hoffman/ 1976). Most studies of this type
have used either the plate-sampler (Harvey and Burzell/ 1972) or the screen-
sampler (Garrett/ 1965), both of which typically recover the upper 1-
2
3 x 10* urn of surface material. Since the true microlayer may extend only to
the depth that surface molecules display preferred orientation, roughly
1CT4 wm to 1CT1 urn, depending on the strength of surface forces (Home, 1969),
the samples collected by these techniques probably are diluted with large but
C.55
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undeterminable amounts of subsurface waters (Piotrowicz et al.* 1972). This
unwanted dilution has not been regarded as a- major analytical problem because
modern analytical techniques are still sensitive enough to detect the various
organic and inorganic pollutants which have been examined thus far., . On :the
other hand/ the uncertainty about the actual concentrations of contaminants in,
the microlayer greatly restricts our ability to evaluate the significance of
the chemical data. For example/ reported enrichments of various pollutants
may/ in fact/ be several orders of magnitude too low. »
Materials in the surface microlayer are generally classified according to
their gross chemistry (organic vs. inorganic) and physical state (dissolved i
vs. particulate). Some investigators have designed analytical schemes that
permit a more detailed classification within these major categories. For
example/ after filtering surface microlayer samples/ Piotrowicz et al. (1972)
have extracted the dissolved phase with chloroform in order to isolate a;'
"chloroform extractable" phase/ presumably containing metal-organic complexes/'^
from the remaining dissolved "inorganic" phase. Similarly/ Meyers and Owen
(1980) and Rice et al. (1985) have measured the organic carbon content of"
surface microlayer samples before and after filtration in order to estimate.
the distribution of organic compounds between particulate and dissolved >
phases. -•• .
The potential significance of surface fi1ms to aquatic ecosystems/"
atonosphere-hydrosphere exchanges/ and geochemical cycles is of wide-spread
interest. It has been observed that the concentration and composition of
microlayers can vary substantially within narrow geographic and time limits/
yet the reasons behind these variations are poorly understood. Furthermore/
relatively little is known about the processes which participate in the
formation/ maintenance/ and dispersion of surface films on natural waters. As
C.56
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a contribution toward better understanding of these phenomena/ we have studied
the distribution of chlorinated hydrocarbons/ natural organic matter
components/ and selected heavy metals in the particulate and dissolved phases
of microlayer and subsurface water samples from Lake Michigan. Our study of
Lake Michigan surface films was begun in 1977 as part of the Michigan Sea
Grant Program. Aspects of earlier phases describing organic-trace metal
compositions of microlayers have been published (Owen et al./ 1979; Mackin
et al./ 1980; Meyers & Owen/ 1980; Meyers et al./ 1981). More recent phases
have concentrated on toxicant fractionation in microlayers (Meyers/ et al./
1983; Rice et al./ 1983, 1985).
Partitioning of hydrophobic material between particulate and dissolved
phases appears to reflect primarily biological inputs of organic matter and
not subsequent physical processes. Compositions of hydrophobic materials in
the dissolved and particulate phases have been described in microlayer studies
done by Daumas et al. (1976)/ Marty & Saliot (1976)/ Kattner & Brockman
(1978)/ Marty & Choiniere (1979)/ and Meyers & Owen (1980). In virtually all
cases/ important differences exist in both the types and concentrations of
materials present in the two phases/ and the nature of these differences is
quite variable with time and location. As suggested by Kattner & Brockman
(1978) and Meyers & Owen (1980)/ much of the particulate fatty acid
• .
variability is best explained as being due to patchy distributions of
phytoplankton and neuston. Such uneven biological input would similarly
affect particulate phase hydrocarbon patterns. In addition/ Daumas et al.
(1976) and Meyers et al. (1981) have noted the presence of petroleum-derived
components in particulate hydrocarbons from coastal areas. The input of this
type of hydrophobic organic material can be quite variable.
Fractionation of hydrophobic organic materials between the air-water
surface and subsurface water has many possible causes. In the particulate
C.57
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phase/ hydrophobic matter is preferentially enriched in surface microlayers as
compared to the total particulate organic matter of subsurface waters (Daumas
et al./ 1976; Meyers & Owen/ 1980; Meyers et al./ 1981). Fractionation of
this type can be due to accumulation of bouyant organic debris at the water
surface and to the presence of viable neuston communities. Analyses of fatty
acid conpositions have led Meyers et al. (1981) to suggest that the presence
of neuston/ which differ from subsurface aquatic communities (Hardy/ 1973)/ is
primarily responsible for chemical differences between microlayer and
subsurface particulates and may contribute to the concentration differences.
In addition/ the water surface is the first contact of air-borne material
entering the aquatic system/ and some portion of these particles may
permanently reside there. Simoneit (1977) has shown that land-derived fatty
acids and hydrocarbons can be transported to distant marine locations on
eolian dust particles. The compositions of these lipids will differ
significantly from those of aquatic origin/ and accumulation of such dust
conponents in raicrolayers will contribute to differences in surface/subsurface
organic matter contents. In general/ the compositional differences between
microlayer and subsurface water particulates seem to be largely source-
related/ although such removal processes as particulate sinking also have
their imprint.
For the dissolved phase/ an important factor in fractionation would seem
to be the solubility behavior of individual compounds in water. Hydrophobic
compounds would be expected to accumulate preferentially at the water surface
rather than to be mixed with the bulk water. Surface enrichments of fatty
acids/ hydrocarbons/ and other hydrophobic materials are in fact generally
larger than those reported for dissolved organic carbon (Meyers & Owen/ 1980)/
yet it also seems that fractionation of dissolved organic materials must be
C.58
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much modified by input and removal processes.
The surface microlayer/ with its hydrophobia nature/ provides
opportunities for significant PCB interaction on a world wide basis. It is
generally believed that the major input of PCB to surface microlayers is
through atmospheric transport and deposition. The Great Lakes offer striking
examples of this. For Lake Superior/ Eisenreich et al. (1980) estimated that
85% of the input of PCB to this lake comes from atmospheric deposition. In
Lake Michigan/ where greater industrial activity provides more point-source
discharge/ the estimate for atmospheric input is approximately 60% (Murphy
et al./ 1981). The above estimates for input come mainly from measurements of
rain taken in the various lakes with values exceeding 1150 ng 1~^ (Eisenreich
et al./ 1980).
Another type of PCB input by atmospheric deposition is via dry
deposition. Estimates for the potential significance of this pathway have
been proposed to be as high as 60% of the total of all atmospheric deposition
of PCBs into large bodies of water (Bidleman et al./ 1976). It is in the
realm of dry deposition of PCBs where surface microlayers have a critical
role. Whether wet or dry deposition is the dominant input mechanism will
influence how much of the PCBs in the microlayer are associated with
particulate matter and will control how similar the PCB distribution in air is
to that in the microlayer.
An important factor in investigating processes involved in PCB
distributions in water is their partitioning between particulate and dissolved
phases. In studies of surface microlayers on Lake Michigan/ Rice et al.
(1983) have found that a large fraction of the total PCBs resides in the
particulate phase. This fraction increases in microlayer samples having
higher PCB concentrations. Moreover/ the particulate phases of these enriched
samples contain proportionately more Aroclor 1242 than Aroclor 1254/ contrary
C.59
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to solubility considerations. Both the enhanced particulate loading and the
solubility disequilibrium point towards recent additions of PCBs from
atmospheric dryfall or particle washout. Hence/ study of phase partitioning
indicates the probable importance of atmospheric inputs of contaminants/ such
as PCBs/ to large bodies of water such as the Great lakes.
One of the more striking characteristics of microlayers is their spatial
and temporal variability. This is true for bulk properties as well as for
individual conponents and appears to be a result of uneven distributions of
aquatic sources of film-forming material/ compounded by variations in the
physical environment. Although surface films are present virtually
everywhere/ local inputs and removal processes control their biogeochemical
character/ while physical processes such as turbulence influence their degree
of development.
Removal of microlayer material from the water surface is accomplished
largely through association with sinking particles. Because the suspended
load of water is highest near river mouths and in coastal areas/ surface films
are less developed in these aquatic zones even though potential film-forming
materials are often at their highest concentrations here.
References
Andren/ A.W./ A.W. Blzerman/ and D.E. Armstrong. 1976. Chemical and physical
aspects of surface organic microlayers in freshwater lakes. J. Great
Lakes Res. 2 (Suppl. 1):101-110.
Bidleman/ T.P./ Rice/ C.P./ and Olney/ C.E. 1976. High molecular weight
hydrocarbons in the air and sea: rates and mechanism of air/sea
transfer/ p.323-351. In H.W. Windom and R.A. Duce, (eds) Marine
Pollutant Transfer/ Lexington/ Mass.: D.C. Heath and Company.
Daumas/ R.A./ P.L. Laborde/ J.C. Marty/ and A. Saliot. 1976. Influence of
sampling method on the chemical composition of water surface film.
Limnol. Oceanogr. 21:319-326.
C.60
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Duce/ R.A. and E.J. Hoffman. 1976. Chemical fractionation at the air/sea
interface. Annu. Rev. Earth Planet. Sci. 4:187-228.
Duce/ R.A./ J.G. Quinn/ C.E. Olney/ S.R. Piotrowicz/ B.J. Ray/ and T.L. Wade.
1972* Enrichment of heavy metals and organic compounds in the surface
microlayer of Narragansett Bay/ Rhode Island. Science 176:161-163.
Eisenreich/ S.G./ Looney/ B.B./ and Thornton/ J.D. 1980. Assessment of the
airborne organic contaminants in the Great Lakes. 1980 Annual Report "A
perspective on the problem of hazardous substances in the Great Lakes
Basin Ecosystem. Appendix A/ Background Reports." Toronto:
International Joint Commission. 150 pp.
Garrett/ W.D. 1965. Collection of slick-forming materials from the sea
surface. Limnol. Oceanogr. 10:602-605.
Hardy/ J.T. 1973. Phytoneuston ecology of a temperate marine lagoon. -
Limnol. Oceanogr. 18:525-533.
Harvey/ G.W., and L.A. Burzell. 1972. A simple microlayer method for small
samples. Limnol. Oceanogr. 17:150-157.
Home/ R.A. 1969. Marine chemistry. A.D. Little/ New York/ p.340.
Kattner/ G.G./ and U.H. Brockman. 1978. Fatty-acid composition of dissolved
and particulate matter in surface films. Mar. Chem. 6:233-241.
Liss/ P.S. 1975. Chemistry of the sea surface microlayer/ p. 193-243. In
J.P. Riley and G. Skirrow/ Eds./ Chemical oceanography/ Vol. 2/ 2nd ed.
Academic Press/ New York.
Mackin/ J.E./ R.M. Owen/ and P.A. Meyers. 1980. A factor analysis of
elemental associations in the surface microlayer of Lake Michigan and its
fluvial inputs. J. Geophys. Res. 85:1563-1569.
Marty/ J.C. and A. Choiniere. 1979. Acides gras et hydrocarbures de I'ecume
marine et de la microcouche de surface. Naturaliste Can. 106:141-147.
Marty/ J.C./ and A. Saliot. 1976. Hydrocarbons (normal alkanes) in the
surface microlayer of sea water. Deep-Sea Res. 23:863-873.
Meyers/ P.A./ and R.M. Owen. 1980. Sources of fatty acids in Lake Michigan
surface microlayers and subsurface waters. Geophys. Res. Lett. 7:885-
888.
Meyers/ P.A./ OR.M. wen/ and J.E. Mackin. 1981. Organic Matter and heavy
metal concentrations in the particulate phase of Lake Michigan surface
microlayers/ p.129-141. In S.J. Eisenreich (ed.) Atmospheric Input of
Pollutants to Natural Waters/ Ann Arbor Science Publishers/ Ann Arbor.
Meyers/ P.A./ C.P. Rice/ and R.M. Owen. 1983. Input and removal of natural
and pollutant materials in the surface microlayer on Lake Michigan/
p.519-532. In R.O. Hallberg (ed.)/ Proceedings Fifth international
Symposium on Environmental Biogeochemistry/ Ecological Bulletin
(Stockholm) Volume 35.
C.61
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Murphy/ T.J./ A. Schinsky/ G. Paolucci, and C. Rzeszutko. 1981. Inputs of
PCBs from the atmosphere to Lakes Huron and Michigan/ p.445-458. In
S.J. Eisenreich (ed.)/ Atmospheric Inputs of Pollutants to Natural
Waters/ Ann Arbor Science Publishers/ Ann Arbor.
Owen/ R.M./ P.A. Meyers/ and J.E. Mackin. 1979. Influence of physical
process on the concentration of heavy metals and organic carbon in the
surface microlayer. Geophys. Res. Lett. 6:147-150.
Piotrovd.cz/ S.R./ B.J. Ray/ G.L. Hoffman/ and R.A. Duce. 1972. Trace metal
enrichment in the sea-surface microlayer. J. Geophys. Res. 77:5243-5254.
Rice/ CLP./ P.A. Meyers/ and G.S. Broun. 1983. Role of surface micro layers
in the air-water exchange of PCBs. In D. Mackey (ed.)/ Physical aspects
of PCB cycling in the Great Lakes. Ann Arbor Science Publishers/ Ann
Arbor/ Michigan/ pp.157-179.
Rice/ C.P./ P.A. Meyers/ B.J. Sadie/ and J.A. Robbins. 1985,, Sources/
transport/ and degradation of organic matter components associated with
sedimenting particles in Lake Michigan/ p.123-136. In D.E. Caldwell/
J.A. Brierly/ and C.L. Brierly (eds.)/ Planetary Ecology/ Van Nostrand
Reinhold/ New York.
Seba/ D.B./ and E..F. Corcoran. 1969. Surface slicks as concentrators of
pesticides in the marine environment. Pest. Monitu J. 3:190-193.
Simoneit/ B.R.T. 1977. Organic matter in eolian dusts over the Atlantic
Ocean. Mar. Cheiru 5:443-464.
C.62
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BN-SA-
SEA-SURFACE CONTAMINANT TOXICITY
J. T. Hardy
Marine Research Laboratory
Sequim, Washington
December 1985
Presented at.the
Sea-Surface Microlayer Workshop
Airlie, Virginia
December 18, 1985
Battelle
Pacific Northwest Laboratories
Rich!and, Washington 99352
C.63
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WORKSHOP ON THE SEA-SURFACE MICROLAYER IN RELATION TO OCEAN- DISPOSAL
SEA SURFACE CONTAMINANT TOXICITY
John T. Hardy
December 9, 1985
INTRODUCTION
The sea-surface microlayer (SSM) provides a habitat for abundant popula-
tions of bacteria, microalgae, and small metazoans. But, perhaps the most
significant role of the microlayer, in terms of valued marine resources, is its
importance for pelagic eggs and larvae. Marine fish, including species of
flounder, sole, cod, turbot, anchovy, and many others, have pelagic eggs that
float on the sea surface during embryogenesis. Surface enrichments of eggs
have been found to be stable even at wave forces of 5 to 6 Beaufort (Zaitsev
1971). English sole and sand sole have typical buoyant neustonic eggs. Also,
because of the buoyancy of their large yolk sacks, the newly hatched larvae
often float helplessly upside down at the surface of the water (Budd 1940).
Mixtures of contaminants entering coastal areas generally concentrate at
two interfaces—the water/sediment interface and the air/water interface.
Compared to subsurface bulk seawater only a few centimeters deep, the sea-
surface microlayer (the upper 50 micrometers) often contains high enrichments
(microlayer concentration/bulk seawater concentration) of both natural and
anthropogenic organics and metals. Polycyclic aromatic hydrocarbons are widely
distributed common products of fossil fuel combustion and are present in emis-
sions from gasoline- and diesel-powered vehicles, refuse incineration, coal-
fired power plants, and many other anthropogenic sources. Studies have shown
that aerosol particles are generally coated with organic films that often
contain a large number of different metals and surface active organic contam-
inants (Ketseridis and Eichmann 1978). Results suggest that the microlayer is
a repository for PAHs "...the PAH in aerosols originate from man-made combus-
tion processes... their buildup in the microlayer seems evident, until absorp-
tion and sedimentation...remove them..." (Strand and Andren 1980).
We conducted studies in Puget Sound in order to 1) characterize the types
and concentrations of sea-surface contaminants and 2) evaluate the toxicity of
surface microlayer samples to fish eggs which float on the surface during
embryonic and larval development.
METHODS
Twenty-two microlayer samples were collected from Puget Sound. Stations
included relatively clean uncontaminated rural reference areas far from areas
of contamination, as well as areas of documented water or sediment contamina-
tion. For comparison, subsurface (30 cm depth) bulk seawater samples were
C.65
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collected at some stations. Samples of surface film material were collected
using the glass plate microlayer sampler developed by us and reported previ-
ously (Hardy et al. 1985).
Subsamples were placed on ice and returned to the laboratory within
24 hours to conduct biotoxicity tests using fertilized eggs of sand sole
(Psettichthys melanostictus). At the end of the 6-day bioassay incubation
period, the percent of eggs in each beaker which hatched into live larvae was
recorded. Similar toxicity tests were conducted in situ in polyethylene dishes
held in a styrofoam floatation board. The bottoms of the dishes were open for
water exchange through a 0.5-mm mesh nylon screen. The apparatus was submerged
and slowly brought to the surface to trap the surface film within each dish*
Also, treated and control sole embryos in the blastodisc stage of development
(35 hours post fertilization) were removed from the exposure beakers, fixed in
4% NB formalin and examined for aberrations in anaphase chromosomes (Longwell
and Hughes 1980; Liguori and Landolt 1985).
Samples showing statistically significant, or in some cases even marginal
toxicity, as well as cleaner reference stations were selected for chemical
analysis. Sample extracts were analyzed for organic contaminants by capillary
gas chromatographic techniques described previously (Riley et al. 1981).
Metals (Pb, Zn, Cu, Ag, Hg) were analyzed by atomic absorption spectophotometry
(Hardy et al. 1985).
RESULTS
The results of this study are summarized briefly here and reported in more
detail elsewhere (Hardy 1985). The percentage of embryos hatching to live
larvae at the end of the exposure period ranged from 0 to 96%. Only microlayer
samples from the urban bays showed significant toxicity. No toxicity was found
in bulk seawater samples from either urban or rural bay stations. The greatest
survival, 86 to 96%, occurred in samples from relatively clean reference
sites. When samples were analyzed by ANOVA and ranked by a Newman-Keul's
multiple range test, out of 13 microlayer samples tested from nonreference
ites, 6 showed significant toxicity (i.e., 55% or less live-hatched larvae).
The first in situ bioassay resulted in 90% and 4% live-larval hatch in
rural bay and urban bay, respectively. A second in situ test from an urban bay
had only 38% live larvae--all of which showed morphological abnormalities,
primarily kyphosis (bent spine).
Embryos exposed directly to microlayers collected from urban bays gener-
ally showed significantly greater incidences of chromosomal abnormalities than
those exposed to either microlayer or bulk seawater samples from the reference
stations. Chromosomal anaphase aberrations ranged from 1 to 5% in reference
station seawater to 23% in undiluted urban bay microlayer.
High concentrations of PAHs were found in many of the urban bay samples
with total PAH (naphthalene through benzoperylene) concentrations exceeding
54 micrograms/liter. No detectable PAHs were found in bulk seawater samples
from any sites. Concentrations of pesticides were detected in eight microlayer
C.66
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samples. Highest total pesticides were in urban bay samples, but some pesti-
cides were also detected in reference microlayers. High concentrations of PGBs
measured as Aroclor (1254) were found in four microlayer samples, all from the
urban bay areas. These samples exceeded the U.S. Environmental Protection
Agency !Water Quality Criteria of 0.03 micrograms/liter by approximately one
order of magnitude. Eleven of the samples analyzed from the urban bay micro-
layers had concentrations of several metals which were very high compared to
normal values measured for Puget Sound bulk seawater.
DISCUSSION AND CONCLUSION
Toxicity tests on sea-surface microlayers that contain mixtures of many
contaminants dp not identify the component most responsible for the toxicity.
However, our data strongly suggest that PAHs in the microlayer may be largely
responsible for the reduction in live-larval hatch in most microlayer samples
that showed toxicity. The percent live larvae from the bioassay tests
decreases significantly with increasing total aromatic hydrocarbons in the
field-collected samples. Metals can also be responsible for microlayer toxic-
ity. One sample from inner Elliott Bay had no detectable hydrocarbons but had
no live larvae in the bioassay. The metal analysis demonstrated a high concen-
tration of metals, especially copper and zinc and toxicity in this sample was
undoubtedly due to the high metal content.
The sources of sea-surface contamination in Puget Sound remain to be
identified. Many of the urban bay sites sampled have also been shown to have
highly contaminated sediments (Long 1982; Riley et al. 1981). In Elliott Bay,
a decreasing concentration of total PAH occurred from the inner to the mid to
,the outer bay. This gradient points to a probable source from the Ouwamish
River industrial area. Our previous study (Hardy et al. 1985) suggested that
much of the sea-surface metal enrichment originated either directly or indi-
rectly from atmospheric deposition. This study suggests the predominance of
fossil fuel combustion products as the primary source of sea-surface contamina-
tion. The ratio of methylphenanthrenes to phenanthrene (MP/P) in combustion
mixtures is generally less than 1; whereas, unburned fossil PAH mixtures
typically display a range of values from 2 to 6 (Youngblood and Blumer 1975;
Prahl et al. 1984). Our present data indicate that the toxic samples, with few
exceptions had MP/P ratios of less than 1. Whether these concentrate on the
sea surface from direct atmospheric deposition or secondarily from terrestrial
runoff, remains unclear.
Domestic sewage effluents represent another possible source of sea-surface
contamination in Puget Sound. Mesocosm experiments (Word et al. 1985) indicate!
that about 10% of a typical subsurface sewage release will reach the water
surface. A visible slick containing a high PAH concentration was located above
the West Point Sewage outfall, and its metal content suggested a sewage source.
Our results also suggest that contaminants are most highly concentrated in
visible natural slicks. In areas remote from contaminant sources, these slicks
may contain little or no contamination. However, in other areas, these natural
films provide a substrate for the concentration of hydrophobic organic
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contaminants. Wind and current patterns collapse the films into thicker
visible slicks. Such slicks are not restricted to urban bays, but appear to
move from place to place. •
Further work should be directed toward characterizing the relative impor-
tance of different sources of sea-surface contamination. Studies are also
needed to determine the temporal and spatial extent of sea-surface contamina-
tion in estuarine, nearshore, and offshore environments.
REFERENCES
BUDD, P. L. 1940. Development of the eggs and early larvae of six California
fishes. State of California, Dept. of Natural Resources, Div. of Fish and
Game, Bureau of Marine Fisheries. Fish Bulletin No. 56., 20 pp.
HARDY, J. T., C. W. APTS, E. A. CRECELIUS, and N. S. BLOOM. 1985. Sea-surface
microlayer metals enrichments in an urban and rural bay. Estuar. Coastal Shelf
Sci. 20: 299-312.
HARDY, J. T. 1985. Contamination and toxicity of the sea-surface microlayer of
Puget Sound'. _In_ Proceedings of the Hanford Life Sciences Symposium, U.S.
Department of Energy, Pacific Northwest Laboratory, Richland, Washington.
KETSERIDIS, G., and R. EICHMANN. 1978. Organic compounds in aerosol samples.
PureAppl. Geophys. 116:274-282.
LIGUORI, V. M., and M. L. LANDOLT. 1985. Anaphase aberrations: An in vivo
measure of genotoxicity. _In_ Short-Term Genetic Bioassays in the Analysis of
Complex Environmental Mixtures IV. M. D. Waters, S. S. Sandhu, J. Lewtas,
L. Claxton, G. Strauss, and S. Nesnow, eds. Plenum Press: New York.
LONG, E. R. 1982. An assessment of marine pollution in Puget Sound. Mar.
Pollut. Bull. 13(11): 380-383.
LONGWELL, A. C., and J. B. HUGHES. 1980. Cytologic, cytogenetic and devel-
opmental state of Atlantic mackeral eggs from sea surface waters of the New
York Bight, and prospects for biological effects monitoring with ichthyo-
placton. Rapp. P-V. ReUn. Cons. Int. Explor. Mer. 179: 275-291.
PRAHL, F. G., E. CRECELIUS, and R. CARPENTER. 1984. Polycyclic aromatic
hydrocarbons in Washington coastal sediments: An evaluation of atmospheric and
riverine routes of introduction. Environ. Sci. Technol. 18:687-693.
RILEY, R. G., E. A. CRECELIUS, M. L. O'MALLEY, K. H. ABEL, and D. C. MANN.
1981. Organic pollutants in waterways adjacent to Commencement Bay (Puget
Sound). NOAA Technical Memorandum OMPA-12, Boulder, Colorado.
STRAND, J. W., and A. W. ANDREN. 1980. Polyaromatic hydrocarbons in aerosols
over Lake Michigan, fluxes to the lake. In Polynuclear Aromatic Hydro-
carbons: Chemistry and Biological Effects. A. Bjorseth and A. J. Dennis,
Symposium. Battelle Press: Columbus, Ohio, pp. 127-137.
C.68
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WORD, J. Q., C. D. BOATMAN, C. C. EBBESMEYER, R. E. FINGER, S. FISCHNALLER, and
Q. J. ST0BER. 1985. -Vertical transport of freon extractable and non-
extractable material and bacteria (feca! coliform and enterococci) to the
surface of marine waters: Some experimental results using secondary sewage
effluent. Report to Metro, Seattle.
YOUNGBLOOD, W. W., and M. BLUMER. 1975. Polycyclic aromatic hydrocarbons in
the environment: Homologous series in soils and recent marine sediment.
Geochim. Cosmochim. Acta. 39:1303-1314.
ZAITSEV, Y. P. 1971. Marine neustonology. (Translated from Russian),
National Marine Fisheries Service, NOAA and NSF, Washington, D.C., 207 pp.
C.69
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APPENDIX D
CRITERIA, RESEARCH ALTERNATIVES, AND SAMPLE QUESTIONNAIRES
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UST OF CRITERIA FOR RANKING RESEARCH ALTERNATIVES
SEA SURFACE
CONTENTS OF FILE - CRITERIA
1. USEFULNESS IN DEFINING THE IMPORTANCE OF THE SEA SURFACE
MICROLASER (SSM)
2. CONTRIBUTION TO THE ABILITY TO COLLECT ADEQUATE INFORMATION
3. USEFULNESS IN DEFINING IMPACTS OF OCEAN DISPOSAL
4. CONTRIBUTION TO CREDIBLE BASIS FOR REGULATORY DECISIONS
5. OBTAINABLE WITHIN TECHNOLOGY, TIME, AND MONEY CONSTRAINTS
0.1
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LIST OF RESEARCH ALTERNATIVES
Page 1 of 2
SEA SURFACE
CONTENTS OF FILE - ISSUES
1. NET ADSORPTIVE FLUXES FROM MICROLAYER TO ATMOSPHERE AND
BULK OCEAN (DIFFUSIVE AND ADVECTIVE) FOR NATURAL AND
CONTAMINANT MATERIALS
2. NET REMOVAL FLUXES FROM MICROLAYER TO ATMOSPHERE AND BULK
OCEAN (DIFFUSIVE AND ADVECTIVE) FOR NATURAL AND
CONTAMINANT MATERIALS
3. RESIDENCE TIMES FOR COMPONENTS IN MICROLAYER AND ALTERATION
BY INPUTS FROM DISPOSAL EVENTS ?
4. MAGNITUDE OF MICROLAYER CONVERGENCES AND DIVERGENCES
(TANGENTIAL STRESSES AND DIFFUSION CURRENTS) AND ;
POTENTIAL FOR CAUSING EXTREME CONCENTRATIONS
5. MESOSCALE INTERNAL AND ATMOSPHERIC FEATURES WHICH MAY
IMPOSE THEMSELVES ON MICROLAYER DYNAMICS
6. DEPOSITION AREA FOR WET AND DRY INPUT
7. EFFICIENCY OF INPUT OF ANTHROPOGENIC MATERIAL TO MICROLASER
AND MICROLAYER PROCESSES AFFECTING INPUT FROM
CONTAMINANT PLUME
8. DYNAMIC AND PROCESS MODELS FOR MICROLAYER
9. MORE KNOWLEDGE ON MAKEUP AND EXTENT OF SSM IN GENERAL,
ESPECIALLY OPEN OCEAN
10. DEFINE MARKERS OF SSM (CHEMICAL MATERIALS TO USE AS A BASIS
FOR QUANTIFYING ENRICHMENT FACTORS)
11. DEFINE ANTHROPOGENIC INPUT MARKERS
12. IDENTIFY BIOLOGICAL COMPONENTS OF SSM TO BE ABLE TO DETECT
CHANGES (NATURAL VERSUS ANTHROPOGENIC)
1-3. IDENTIFY VARIABILITY IN SPACE AND TIME IN NATURAL SSM'S
14. DETERMINE VARIABILITY DUE TO SAMPLING AND ANALYSIS
PROCEDURES
15. LEARN TO DISTINGUISH LOCAL POINT SOURCES FROM LONG-DISTANCE
TRANSPORT
16. MEASURE UPTAKE OF SSM COMPONENTS IN EUNEUSTON TO ESTABLISH
BIOLOGICAL CONNECTION BETWEEN SSM AND FOOD WEB (WORST
CASE EXAMPLE TO MAXIMIZE OBSERVATION OF AN IMPACT)
0.2
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Page 2 of 2
17. IMPORTANCE OF SITES TO SURFACE ORGANISMS
18. IMPORTANCE OF THE SSM AS A HABITAT TO RESOURCE SPECIES
19. STABILITY OF SSM UNDER DIFFERENT WIND SPEEDS
20.' SEASONAL AND DIEL CHANGES IN NEUSTON
21. SEASONAL STAGES OF FISH EGGS
22. TOXICITY OF INCINERATED RESIDUE APPLIED AS A SURFACE
MICROLASER
23. RELATIONSHIP BETWEEN DIEL MOVEMENT OF ORGANISMS AND
CHEMICAL FLUXES IN SSM
24. ARE SSM AUTOTROPHS FOOD FOR NEAR-SURFACE ORGANISMS?
25. PROVIDE PHYSICAL OCEANOGRAPHIC AND METEOROLOGICAL DATA
NEEDED TO VERIFY OCEAN INCINERATION MODELS
26. RESIDENCE TIME OF PARTICLES RESULTING FROM WASTE DISPOSAL
27.
28.
DIFFERENCES IN CHEMISTRY AND BIOLOGY BETWEEN MICROLAYERS
AND BULK WATER WHICH AFFECT EXPOSURE TO MICROLAYER BIOTA
EFFECTS OF ACIDIC PLUMES ON MI'CROLAYER CHEMISTRY AND
BIOLOGY
29. CHEMICAL FORM OF INPUTS, IMPORTANCE RELATIVE TO GLOBAL FLUX
30. COMPARISON, CALIBRATION, AND STANDARDIZATION OF SAMPLING
TECHNIQUES, WITH ATTENTION TO CONTAMINATION
0.3
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COVER SHEET
QUESTIONAIRE # 1 - WEIGHTING THE JUDGMENT CRITERIA
This questionaire allows for the possibility that some of the criteria
participants have chosen for ranking the decision alternatives may be more
important than others. Following is a randomized list of all possible pairings
for the judgment criteria selected by the group:
For each pair, circle the choice representing your best judgment as to the
importance of the first (top)- member of the pair relative to the second (bottom)
•eaber.
The computer will use these Judgments to calculate the importance or "weight to
be given to each criterion relative to all the other criteria on a scale of 0 to
100%. These weights will be applied later when the criteria are used to rank a
list of decision alternatives also chosen by the group.
D.4
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SAMPLE CRITERIA QUESTIONAI RE
SEA SURFACE
Page 1 of 3
NAME:
CIRCLE THE APPROPRIATE DESCRIPTOR.
PAIR 1.
5. OBTAINABLE WITHIN TECHNOLOGY, TIME, AND MONEY CONSTRAINTS
5«3
1.
5<3
2.
5-3
3.
5>3
4.
5»3
5.
3. USEFULNESS IN DEFINING IMPACTS OF OCEAN DISPOSAL
PAIR 2.
2. CONTRIBUTION TO THE ABILITY TO COLLECT ADEQUATE INFORMATION
2«5
1.
2<5
2.
2-5
3.
2>5
4.
2»5
5.
5. OBTAINABLE WITHIN TECHNOLOGY, TIME, AND MONEY CONSTRAINTS
PAIR 3.
3. USEFULNESS IN DEFINING IMPACTS OF OCEAN DISPOSAL
3-1
3.
1.
2.
4.
5.
1. USEFULNESS IN DEFINING THE IMPORTANCE OF THE SEA SURFACE
MICROLASER
PAIR 4.
2. CONTRIBUTION TO THE ABILITY TO COLLECT ADEQUATE INFORMATION
2«3
1.
2<3
2.
2-3
3.
2>3
4.
2»3
5.
3. USEFULNESS IN DEFINING IMPACTS OF OCEAN DISPOSAL
D.5
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SEA SURFACE
NAME:
CIRCLE THE APPROPRIATE DESCRIPTOR.
PAIR 5.
3. USEFULNESS IN DEFINING IMPACTS OF OCEAN DISPOSAL
3«4
1.
3<4
2.
3-4
3.
3>4
4.
3»4
5.
4. CONTRIBUTION TO CREDIBLE BASIS FOR REGULATORY DECISIONS
Page 2 of 3
PAIR 6.
1. USEFULNESS IN DEFINING THE IMPORTANCE OF THE SEA SURFACE
MICROLASER
1«2 1<2 1-2 1>2 1»2
1. 2. 3. 4. 5.
2* CONTRIBUTION TO THE ABILITY TO COLLECT ADEQUATE INFORMATION
PAIR 7.
2. CONTRIBUTION TO THE ABILITY TO COLLECT ADEQUATE INFORMATION
2«4
1.
2<4
'2.
2-4
3.
2>4
4.
2»4
5.
4. CONTRIBUTION TO CREDIBLE BASIS FOR REGULATORY DECISIONS
PAIR 8.
4. CONTRIBUTION TO CREDIBLE BASIS FOR REGULATORY DECISIONS
4«5
1.
4<5
2.
4-5
3.
4>5
4.
4»5
5.
5. OBTAINABLE WITHIN TECHNOLOGY, TIME, AND MONEY CONSTRAINTS
D.6
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Page 3 of 3
SEA. SURFACE
NAME:
CIRCLE THE APPROPRIATE DESCRIPTOR.
PAIR 9.
5. OBTAINABLE WITHIN TECHNOLOGY, TIME, AND MONEY CONSTRAINTS
5-1
3.
1.
2.
4.
5.
1. USEFULNESS IN DEFINING THE IMPORTANCE OF THE SEA SURFACE
MICROLASER
PAIR 10.
4. CONTRIBUTION TO CREDIBLE BASIS FOR REGULATORY DECISIONS
4-1
3.
1.
2.
4.
5.
1. USEFULNESS IN DEFINING THE IMPORTANCE OF THE SEA SURFACE
MICROLASER
D.7
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COVER SHEET
QUESTIONAIRE 12 - RANKING DECISION ALTERNATIVES (Forced Decision Option)
This questionaire gives you an opportunity to estimate the relative importance
of all decision alternatives under a given, judgment criterion. Using the best
subjective and objective knowledge available to you, circle the numbers that
represent where you would place each alternative relative to*all the other
alternatives along a ten-point scale (0-9) under the judgment criterion given
across the top*
Because of United resources, we are trying to force a decision in selecting the
few best options we can affort to implement, even at the risk of making
arbitrary distinctions between them. If you feel unqualified to make a given
Judgment, leave it blank. The computer will multiply the number circled for a
given alternative by the criterion "weight" determined in the first scoring
exercise and then sum these products over all criteria to provide a weighted
score for that alternative.
0.8
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SEA SURFACE
PAGE 1 OF 10
NAME
1. USEFULNESS IN DEFINING THE IMPORTANCE OF THE SEA SURFACE MICROLAYER (SSM)
# SCORE ISSUES
1. 0123456789 NET ABSORPTIVE FLUXES FROM MICROLAYER TO ATMOSPHERE
AND BULK OCEAN (DIFFUSIVE AND ADVECTIVE) FOR NATURAL
AND CONTAMINANT MATERIALS
2. 0123456789 NET REMOVAL FLUXES FROM MICROLAYER TO ATMOSPHERE AND
BULK OCEAN (DIFFUSIVE AND ADVECTIVE) FOR NATURAL AND
CONTAMINANT MATERIALS
3. 0123456789 RESIDENCE TIMES FOR COMPONENTS IN MICROLAYER AND
ALTERATION BY INPUTS FROM DISPOSAL EVENTS
4. 0123456789 MAGNITUDE OF MICROLAYER CONVERGENCES AND DIVERGENCES
(TAGENTIAL STRESSES AND DIFFUSION CURRENTS) AND
POTENTIAL FOR CAUSING EXTREME CONCENTRATIONS
5. 0123456789 MESOSCALE INTERNAL AND ATMOSPHERIC FEATURES WHICH MAY
IMPOSE THEMSELVES ON MICROLAYER DYNAMICS
6. 0123456789 DEPOSITION AREA FOR WET AND DRY INPUT
7. 0123456789 EFFICIENCY OF INPUT OF ANTHROPOGENIC MATERIAL TO
MICROLAYER AND MICROLAYER PROCESSES AFFECTING INPUT
FROM CONTAMINANT PLUME
8. 0123456789 DYNAMIC AND PROCESS MODELS FOR MICROLAYER
9. 0123456789 MORE KNOWLEDGE ON MAKEUP AND EXTENT OF SSM IN GENERAL,
ESPECIALLY OPEN OCEAN
10. 0123456789 DEFINE MARKERS OF SSM (CHEMICAL MATERIALS TO USE AS A
BASIS FOR QUANTIFYING ENRICHMENT FACTORS
11. 0123456789 DEFINE ANTHROPOGENIC INPUT MARKERS
12. 01 2345 6789 IDENTIFY BIOLOGICAL COMPONENTS OF SSM TO BE ABLE TO
DETECT CHANGES (NATURAL VERSUS ANTHROPOGENIC)
13. 0 123456789 IDENTIFY VARIABILITY IN SPACE AND TIME IN NATURAL SSM
14.
15.
0123456789 DETERMINE VARIABILITY DUE TO SAMPLING AND ANALYSIS
PROCEDURES
012 3 456789 LEARN TO DISTINGUISH LOCAL POINT SOURCES FROM LONG
DISTANCE TRANSPORT
D.9
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SEA SURFACE
PAGE 2 OF 10
NAME
1. USEFULNESS IN DEFINING THE IMPORTANCE OF THE SSM (CONTINUED)
16. 0123456789
17. 0123456789
18. 0123456789
19. 0123456789
20. 0123456789
21. 0123456789
22, 0123456789
23. 0123456789
24. 0123456789
25. 0123456789
26. 0123456789
27. 0123456789
28. 0123456789
29. 0123456789
30. 0123456789
MEASURE UPTAKE OF SSM COMPONENTS IN EUNEUSTON TO
TO ESTABLISH BIOLOGICAL CONNECTION BETWEEN SSM AND
FOOD WEB (WORST CASE EXAMPLE TO MAXIMIZE OBSERVATION
OF AN IMPACT)
IMPORTANCE OF SITES TO SURFACE ORGANISMS
IMPORTANCE OF THE SSM AS A HABITAT TO RESOURCE SPECIES
STABILITY OF SSM UNDER DIFFERENT WIND SPEEDS
SEASONAL AND DIEL CHANGES IN NEUSTON
SEASONAL STAGES OF FISH EGGS
TOXICITY OF INCINERATED RESIDUE APPLIED AS A SURFACE
MICROLAYER
RELATIONSHIP BETWEEN DIEL MOVEMENT OF ORGANISMS AND
CHEMICAL FLUXES IN SSM
ARE SSM AUTOTROPHS FOOD FOR NEAR-SURFACE ORGANISMS?
PROVIDE PHYSICAL OCEANOGRAPHIC AND METEOROLOGICAL DATA
NEEDED TO VERIGY OCEAN INCINERATION MODELS
RESIDENCE TIME OF PARTICLES RESULTING FROM WASTE
DISPOSAL
DIFFERENCES IN CHEMISTRY AND BIOLOGY BETWEEN
MICROLAYERS AND BULK WATER WHICH AFFECT EXPOSURE TO
MICROLAYER BIOTA
EFFECTS OF ACIDIC PLUMES ON MICROLAYER CHEMISTRY AND
BIOLOGY
CHEMICAL FORM OF INPUTS, IMPORTANCE RELATIVE TO GLOBAL
FLUX
COMPARISON, CALIBRATION, AND STANDARDIZATION OF
SAMPLING TECHNIQUES, WITH ATTENTION TO CONTAMINATION
0.10
*U.S. GOVERNMENT PRINTING OFFICE: 1987—7 61-002/ 60667
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