United States Environmental Protection Agency
CBP/TRS 20/88
May 1988
903R88104
5
Review of Technical Literature
and Characterization of
Aquatic Surface
Microlayer Samples
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FINAL REPORT
, • v.i Froteclicn Agency
i...j;.'uutiOn
841 Ches'nutStraet
Pnilaselphia, PA 19107
REVIEW OF TECHNICAL LITERATURE
AND CHARACTERIZATION OF
AQUATIC SURFACE
MICROLAYER SAMPLES
Contract No. 68-03-3319
Work Assignment 1-82
May 10, 1988
to
U.S. ENVIRONMENTAL PROTECTION AGENCY
Chesapeake Bay Program Office
Annapolis, MD
Prepared by
Battelle Marine Reseach Laboratory
Sequim, WA
and
Anne Arundel Community College
Arnold, MD
BATTELLE
Ocean Sciences
397 Washington Street
Duxbury, MA 02332
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ACKNOWLEDGEMENTS
The following persons deserve special thanks for their many
contributions: Kimberly Durrell, team leader, neuston identification;
Robert Allard, Thomas Wilson, team members; Steve Jordan, Maryland
Department of Natural Resources, for making boat time available for the
Choptank neuston collections; Marria O'Malley, U.S. EPA, chief scientist
R/V Anderson, for upper bay neuston collection assistance; Eric Crecelius and
Timothy Fortman for analysis of organotin; William Steinhauer for organic
chemical analysis; Valerie Cullinan for sampling design; and John Strand for
technical and editorial review. Finally, we gratefully acknowledge the
helpful contributions of the many researchers that we contacted during our
study. A list of these persons is provided in Appendix B.
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EXECUTIVE SUMMARY
*
No comprehensive studies of surface-dwelling organisms (neuston)
have been conducted in Chesapeake Bay. However, previous studies of plankton
in the bay (with reference to near-surface collections), studies of neuston
on the Atlantic shelf, and our preliminary sampling at several sites, all
•indicate that the surface layer of Chesapeake Bay is inhabited by an abundant
community of organisms including copepods, fish eggs, and larvae of both fish
and invertebrates. The eggs of bay anchovy, hogchoker, and the larvae of
blue crab all reside for some time at the water surface.
Samples were collected from six sites in Chesapeake Bay. Analyses
confirmed earlier findings of high surface microlayer concentrations of
aromatic hydrocarbons, saturate hydrocarbons, and metals. In addition, these
analyses indicated the presence of high concentrations of organotin,
pesticides, and several other organic contaminants. Application of a
microlayer toxicity model to the measured contaminant concentrations
suggested that surface contamination results in an average 50 to 65 percent
reduction in the survival of surface organisms (neuston) and floating fish
eggs in Chesapeake Bay, with even higher reductions at some sites. These
results, based on very limited sampling, point to an urgent need for a
detailed and comprehensive study of microlayer contamination in Chesapeake
Bay.
Microlayer sample collection methods were evaluated, both by a
review of the literature and experimentally by measurements of collection
efficiency. The rotating drum sampler is recommended as the method of choice
for collecting samples of anthropogenic contaminants from the aquatic surface
microlayer. The Teflon™ drum collects a surface layer 30- to 60-/*m thick.
Its characteristics are similar to the glass plate, with a collection
efficiency of about 70 to 90 percent over a wide range of surface film
conditions.
To establish the biological significance of microlayer
contamination in Chesapeake Bay, we propose the convening of a workshop
with representatives from the scientific community and state and federal
agencies. The workshop would evaluate existing information on toxic surface
contaminants, identify the biological resources at risk from such
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contaminants and, if needed, formulate a research and/or monitoring plan for
Chesapeake Bay.
A work plan is presented that will provide a comprehensive
evaluation of aquatic surface contamination and toxicity in Chesapeake Bay.
Sampling will provide information on both spatial and temporal trends. The
stratified random sampling plan calls for collection of a total of 252
samples at two seasons throughout the Bay and major tributaries. Microlayer
toxicity will be evaluated using a combination of laboratory and j_n sjtu
toxicity tests with the bay anchovy and blue crab larvae. Based on the
results of the toxicity tests, samples will be selected and analyzed
chemically for contaminants.
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CONTENTS
ACKNOWLEDGEMENTS i i i
EXECUTIVE SUMMARY v
1.0 INTRODUCTION 1.1
2.0 TASK 1--LITERATURE REVIEW, CHESAPEAKE BAY NEUSTON 2.1
2.1 OBJECTIVE 2.1
2.2 METHODS 2.2
2.3 RESULTS 2.3
3.0 TASK 2—RATIONALE AND SAMPLING PLAN FOR STUDIES IN
CHESAPEAKE BAY 3.1
3.1 OBJECTIVE 3.1
3.2 RECOMMENDED SAMPLING DESIGN 3.1
3.3 RECOMMENDED SAMPLE TREATMENT 3.4
3.4 RECOMMENDED APPROACH TO DATA ANALYSIS 3.4
4.0 TASK 3—RATIONALE AND METHODOLOGY FOR MICROLAYER
TOXICITY STUDIES 4.1
4.1 OBJECTIVE 4.1
4.2 RATIONALE 4.1
4.3 RECOMMENDED APPROACH 4.3
5.0 TASK 4—WORKSHOP ON CONTAMINATION AND TOXICITY OF THE
AQUATIC SURFACE LAYER 5.1
5.1 OBJECTIVE 5.1
5.2 RECOMMENDED APPROACH 5.1
5.3 PARTICIPANTS 5.3
6.0 TASK 5—EVALUATION AND SELECTION OF MICROLAYER SAMPLING
PROTOCOL 6.1
6.1 BACKGROUND 6.1
6.2 OBJECTIVE 6.7
VII
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6.3 METHODS 6.7
6.3.1 Experiments with Hydrophobia Particles
(Lycopodium Spores) 6.8
6.3.2 Experiments with Radiolabeled DDT 6.8
6.4 RESULTS 6.9
6.4.1 Hydrophobia Lycopodium Spores 6.9
6.4.2 Labeled DDT in Oleyl Alcohol '.6.9
6.5 DISCUSSION AND CONCLUSIONS 6.10
7.0 TASK 6—COLLECTION AND CHEMICAL ANALYSIS OF CHESAPEAKE
BAY MICROLAYER SAMPLES 7.1
7.1 OBJECTIVE 7.1
7.2 METHODS 7.1
7.3 RESULTS 7.4
7.3.1 September Sampling 7.4
7.3.2 October Sampling 7.4
7.4 DISCUSSION AND CONCLUSIONS 7.9
8.0 BIBLIOGRAPHY 8.1
APPENDIX A - KEY WORDS A.I
APPENDIX B - PERSONS CONTACTED B.I
Vlll
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LIST OF TABLES
TABLE 2.1 TAXA FOUND PRINCIPALLY IN NEUSTON TOWS IN THE
MID-ATLANTIC BIGHT THAT ARE ALSO KNOWN TO OCCUR
IN LOWER CHESAPEAKE BAY (AFTER GRANT,1979;
WASS, 1972; LIPPSON ET AL., 1979) 2.5
TABLE 2.2 NEUSTON CONCENTRATIONS (INDIVIDUALS/METERS) IN
THE UPPER CHESAPEAKE BAY 2.6
TABLE 6.1 COLLECTION EFFICIENCY OF SAMPLING METHODS 6.2
TABLE 6.2 LYCOPODIUM SPORE SAMPLING EFFICIENCY AS A FUNCTION
OF SPREADING PRESSURE 6.9
TABLE 7.1 FIELD SAMPLING OF SURFACE MICROLAYER IN CHESAPEAKE
BAY 7.2
TABLE 7.2 FIELD SAMPLING OF SURFACE MICROLAYER IN CHESAPEAKE
BAY, OCTOBER 1987 7.3
TABLE 7.3 CONCENTRATIONS OF (pg/L) OF PESTICIDES AND ORGANIC
COMPOUNDS IN THE SURFACE MICROLAYER AND BULKWATER
OF CHESAPEAKE BAY, SEPTEMBER 1987 7.5
TABLE 7.4 ORGANOTIN BY AAS (AS INORGANIC TIN) AND TRIBUTYLTIN
AND DIBUTYLTIN BY GC-MS (AS TBT CHLORIDE AND DBT
CHLORIDE) IN CHESAPEAKE BAY MICROLAYER AND BULKWATER
SAMPLES COLLECTED OCTOBER 1987 7.6
TABLE 7.5 CONCENTRATIONS (/tg/L) OF AROMATIC HYDROCARBONS
IN THE SURFACE MICROLAYER OF CHESAPEAKE BAY,
OCTOBER 1987 7.7
TABLE 7.6 CONCENTRATIONS (pg/L) OF SATURATE HYDROCARBONS IN THE
SURFACE MICROLAYER OF CHESAPEAKE BAY, OCTOBER 1987 7.8
LIST OF FIGURES
FIGURE 3.1 ZONES FOR MICROLAYER SAMPLING IN CHESAPEAKE BAY 3.3
IX
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1.0 INTRODUCTION
The boundary between the atmosphere and the aquatic environment
is an important biological habitat and a collection point for pollutants.
The eggs and larvae of many fish and shellfish species float on, or come in
contact with, the water surface throughout their early development. The
aquatic surface microlayer (surface microlayer), approximately 50 fan thick,
serves as a concentration point for metal and organic contaminants that have
low water solubility or are associated with floatable particles. Recent
studies have linked aquatic surface contamination with negative biological
impacts. In Puget Sound [Hardy et al., 1988a (in press)], Southern
California (Cross et al., in press), and the North Sea (Kocan et al., 1982),
fish eggs exposed to contaminated surface microlayer exhibited reduced
viability.
Preliminary evaluation of Chesapeake Bay surface microlayer samples
indicated elevated levels of contaminants in the surface microlayer (Hardy
et al., 1987). Based on these results the U.S. Environmental Protection
Agency (EPA) recognized the need for further assessment of the potential
impact of these contaminants. To conduct the assessment, additional work
including evaluations of microlayer sampler collection efficiencies,
identification of important living resources impacted, and exploratory
chemical analyses to identify specific contaminants is needed. Additionally,
a work plan for conducting a comprehensive investigation of the Chesapeake
Bay surface microlayer needs to be developed. The work plan should be
designed to determine contaminant concentrations; to evaluate the
significance of surface contamination to important living resources; to
measure chronic toxicity properties of the surface microlayer; to address the
transport, enrichment and removal of contaminants, and to identify discussion
topics that need to be comprehensively explored in an interdisciplinary
workshop.
The objectives of this Work Assignment (listed by Task number) were
to supply the Chesapeake Bay Program with the following:
1.1
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1) A review of knowledge concerning the Chesapeake Bay surface-
dwelling, neuston community, its major components, and a
preliminary field evaluation of its composition.
2 and 3) Recommendations for a comprehensive work plan for future
studies designed to evaluate contaminant concentrations of the
surface microlayer and potential impacts on the living resources of
Chesapeake Bay.
4) A preliminary plan for a workshop on aquatic contamination
problems in Chesapeake Bay.
5) A tested and recommended protocol to collect accurate and
representative samples of the surface microlayer of Chesapeake Bay.
6) Exploratory analytical results, identifying major chemical
contaminants of surface microlayer samples collected from six sites
in Chesapeake Bay.
1.2
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2.0 TASK 1—LITERATURE REVIEW, CHESAPEAKE BAY NEUSTON
2.1 OBJECTIVE
The National Estuary Study reported that Chesapeake Bay and a
number of other estuaries were critical elements in coastal fisheries;
consequently, several government research programs were developed (U.S.
Department of the Interior, 1970). In the National Estuarine Pollution Study
(U.S. Senate, 1970), Chesapeake Bay was selected as an example of an
interstate estuary that demonstrated a complex set of problems originating
from pollution. To maintain the economic productivity of the Bay and the
rich diversity of its biological resources, we must understand the effects of
aquatic surface contamination on the survival and reproduction of the
neustonic organisms as well as the benthic and planktonic ones.
Neuston are an important biological component of the Chesapeake Bay
ecosystem. The term neuston was proposed by the Swedish hydrobiologist
E. Naumann in 1917 to describe the "surface film community," as distinct from
the pleuston or floating plants, such as duckweed. Zaitsev (1971) defines
the concept as a "zone of the surface film" including not only the
microorganisms of the surface, but also the pelagic fish eggs of high
buoyancy and the larvae that use the surface film. The surface layer is a
vital zone of incubation for the early life stages of numerous fish and
shellfish species. The density of bacterioneuston, the first link in the
neustonic food chain, is often hundreds or thousands of times more dense than
that of the bacterioplankton (Zaitsev, 1971). Bacterioneuston provide a food
source for larger zooneuston (copepods, fish larvae, etc.) (Hardy, 1982).
While a wealth of information exists on the fisheries,
shellfisheries, wildlife, agriculture, pollution, biology, and geology of the
Chesapeake Bay, earlier studies dealt only with "surface waters" or "surface
plankton" with little reference to the precise definition of the word. The
concept of the neuston as a separate community is relatively new and is not
well defined in older work. Part of this lack of definition has to do with
the sampling methods used; older collections were often surface tows of
conical nets in the upper meter of the water. Some researchers used single
nets, sampling only the surface; others used double nets sampling both a
2.1
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surface layer and a deeper layer below the surface. Some sampled only the
upper 1 to 4 cm, others the upper 10 cm, and still others, the upper meter.
Even modern neuston nets, supported by floats, differ greatly from one
another, making comparison of different data difficult.
It is the purpose of this task, then, to undertake a review of the
readily available literature and document current knowledge of Chesapeake
Bay's neuston community and its species composition. Additionally, a limited
field survey was conducted to provide a qualitative comparison to species
identified in prior literature.
2.2 METHODS
Four methods were used to review the literature. A computer search
was done on DIALOG (DIALOG Information Services, Inc., 3460 Hillview Avenue,
Palo Alto, California 94304), using standard methods and a selection of key
words appropriate to the neuston. A list of key words is found in
Appendix A. Similarly, the EPA's CHESSEE database was searched to examine
other aspects of the Chesapeake Bay literature found in project reports and
other documents that were not referenced in the open literature. Secondly,
literature commonly used to report Chesapeake Bay work was examined in more
detail. This included the older issues of Chesapeake Science and the more
recent issues of Estuaries, as well as a number of other commonly referenced
journals. Thirdly, interviews and discussions were held with members of the
research community around Chesapeake Bay to discuss other published or
unpublished work and research in progress. Finally, we reviewed relevant
articles for research done in adjacent regions with similar fauna, such as
Delaware Bay and North Carolina estuaries. Research from these areas has
direct relevance to the species being reviewed for this study.
The present literature summary reports a number of general works
that have proven useful in defining the surface fauna of the Bay as well as a
number of specific works that report on "neuston" in the modern definition of
the word.
In addition to a review of the literature, we conducted neuston
tows in Chesapeake Bay. The neuston collections were made on a "ship of
opportunity" basis and are meant to serve as a qualitative corroboration of
2.2
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information gleaned from the literature. Thus, collections were limited to
waters of the upper Chesapeake Bay (entirely within the state of Maryland)
and, unfortunately, did not include nighttime tows. Because of the
opportunistic basis of sampling, total volumes sampled were not always well
characterized. The net was a rectangular mouth (0.46 x 0.3 m) zooplankton
net, with a mesh size of 100 /tm. In the Choptank River, Loran-C was used to
insure tow lengths of 0.2 nautical miles. Hence, the 0.46-m wide net,
immersed to an average depth of 0.05 m, sampled a surface-water volume of
9 m3. In a few cases, the distance towed was estimated from the elapsed time
of a tow at a known speed (dead reckoning). In several others, the towing
was done very slowly during surface-microlayer chemical sampling. In these
instances, the volume sampled was about 4 m3, although the slow speed makes
the precise volume determination uncertain. Samples were preserved in
buffered 5 percent formalin for later analysis.
Identification was made by counting aliquots of the sample in a
Durrel trough. Initial aliquot volumes of 5 to 10 ml were increased until
consistent concentrations for identified species were obtained. Dissecting
scopes and low power (X40) inverting microscopes were used as required. The
major literature sources for taxonomic identification are included in the
references (Ward and Whipple, 1966; Lippson and Moran, 1974).
2.3 RESULTS
Our literature search failed to locate any previous studies
specifically intended to characterize the neuston community of Chesapeake
Bay. Many studies on plankton, in general, included some information
pertaining to the biology of the surface layer, but for the most part, these
studies did not use neuston sampling techniques. However, several studies
were found that are relevant to the question of the biological importance of
the surface layer of Chesapeake Bay or potential toxic effects of surface
contamination (Birdsong et al., 1983; Burrell, 1972; McConaugha et al., 1983;
Mansueti, 1954; Mansueti and Hardy, 1967; Morgan et al., 1973; Olney, 1978;
Olney, 1983; Paul, 1983; Provenzano et al., 1982; 1983).
2.3
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Table 2.1 is a list of species that are found in neuston tows in
the mid-Atlantic Bight and are also likely to occur as neuston in lower
Chesapeake Bay. This list was constructed by comparing a species list
generated for mid-Atlantic neuston by Grant et al. (1979) with publications
by Wass (1972) and Lippson et al. (1979) listing species of plankton (without
specific reference to neuston) occurring in Chesapeake Bay. The species
listed in Table 2.1 are assumed to be neustonic, however, there are
exceptions. For example, zoea of blue crab (Callinectes sapidus) are
neustonic offshore, but once transported into Bay waters, the zoea and
megalopae become pelagic (Provenzano et al., 1982; 1983). It should be noted
that this approach to identifying the neuston of Chesapeake Bay may apply
only to species likely to occur in the more saline lower Bay and may not
accurately characterize the neuston of freshwater zones in the upper Bay.
The limited collections we undertook as part of this effort were
solely an attempt to provide a qualitative comparison to species identified
as neustonic in prior literature. Our analysis of neuston tows collected
this summer and fall from four sites in Chesapeake Bay indicates the presence
of at least 20 abundant taxa dominated by the copepod Acartia tonsa
(Table 2.2). All tows were conducted in daytime and only zooplankton were
collected. The limited scope of the study (no replicate sampling) and late
season of the sampling could not comprehensively represent overall neuston
abundance and diversity. The freshwater organisms found in the Susquehanna
River station (dominated by Cladocera), of course, represent species not
reported in our literature comparison. However, our results indicate that
surface-dwelling organisms occur at very high densities in the areas sampled,
with a mean density > 7000 individuals/meter3. For comparison, densities of
total zooneuston in Puget Sound collected with a similar net were about
100 to 400 individuals/meter3, with copepods dominating the community. In
Chesapeake Bay, the copepod Acartia tonsa could represent an important prey
item for surface feeding fish or other organisms.
Phytoneuston and their predators colonize the surface and form an
increasingly complex web. The mechanisms that bring them to this
environment need not be those used by neustonic holoplankters. Certainly
buoyancy, phototropism, negative geotropism, turbulence, and random swimming
motions all contribute to surface entrapment and surface residence.
2.4
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TABLE 2.1
TAXA FOUND PRINCIPALLY IN NEUSTON TOWS IN THE MID-ATLANTIC BIGHT
THAT ARE ALSO KNOWN TO OCCUR IN LOWER CHESAPEAKE BAY (AFTER GRANT
ET AL., 1979; WASS, 1972; LIPPSON ET AL., 1979)
CNIDARIA (comb jellies)
Li nope sp.
COPEPODA (zooplankton)
Acartia sp.
Acartia tonsa
Calanus finmarchicus
Candacia armata
Centropages furcatus
Centropages hamatus
Centropaqes typicus
Corycaeus sp.
Eucalanus sp.
Eucalanus pileatus
Labidocera
Labidocera
sp.
aestiva
Qithona spp.
Qncaea venusta
Paracalanus parvus
Paracalanus quasimodo
Pontena
Pontella
sp.
meadii
Pseudocalanus sp.
Temora lonqicornis
Temora stylifera
Temora turbinata
ECHINODERMATA (including starfish,
etc.)
unidentified ophiuroids
CHAETOGNATHA (arrow worms)
Sagitta elegans
Sagitta inflata
Saqitta
Sagitta
hispida
tenuTS
unidentified chaetognaths
MOLLUSCA (mussels & clams)
Dosim'a discus
Melampus bidentatus
Spisula solidisima
MYSIDACEA (mysid shrimp)
Heteromysis formosa
Mysidopsis bigelowi
Neomysi s americana
CUMACEA
Oxyurostylis sp.
ISOPODA
Edotea
triloba
Idotea metallica
AMPHIPODA
Corophium sp.
Stenothoe sp.
DECAPODA (principally crabs)
Callianassa sp.
Callinectes sp.
Crangon septemspinosa
Homarus americanus
Homola barbata
Latreutes fucorum
LeptocheTa sp.
Libinia sp.
Munida sp.
Pinnixa cylindrica
Portunus sp.
PISCES (fish, eggs, and/or larvae)
Astroscopus guttatus
Cynoscion regal is
Hippocampus sp.
Menidia menidia
Scomberesox saurus
Scophthalmus aquosus
Sphoeroides sp.
Syngnathus sp.
Synqnathus fuscus
Urophycis sp.
Urophycis regius
2.5
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TABLE 2.2
NEUSTON CONCENTRATIONS (INDIVIDUALS/METERS) IN THE
UPPER CHESAPEAKE BAY
Station
Choptank
River
Taxa
Acartia tonsa
copepod naupl i i
barnacle naupl i i
Bosnina
longirostris
Camptocercus
rectirostris
Insecta
shrimp larvae
Moina licrura
Podon
polyphemoides
Chydorus sp.
Cyclops vernal is
anphtpod?
Polychaete larva
Cyclops
bicuspidatus
DiaphanosoBi
crab zoeae
unident'd, damaged
No.
per.
.3
9362
942
626
312
208
184
184
184
92
92
10
10
0
0
0
0
0
Percent
Total
76.7
7.7
5.1
2.6
1.7
l.S
l.S
1.5
0.8
0.8
0.1
0.1
0.0
0.0
0.0 .
0.0
Q.Q
Uatapeake
No.
per
•3
2167
557
0
1052
0
0
0
0
62
0
62
0
0
371
62
0
0
Percent
Total
50.0
12.9
0.0
24.3
Q.Q
0.0
0.0
0.0
1.4
0.0
1.4
0.0
0.0
8.6
1.4
0.0
0.0
Elk
River
No.
per
.3
495
0
0
0
0
0
0
0
0
0
0
0
0
0
21
3
0
Percent
Total
95.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
4.0
0.6
0.0
Susquehanna
River
No.
per
1.3
4800
0
0
0
0
1280
0
0
0
320
2880
0
0
0
0
0
3200
Percent
Total
38.5
0.0
0.0
0.0
0.0
10.3
0.0
0.0
0.0
2.6
23.1
0.0
0.0
0.0
0.0
0.0
25.6
TotaI Neuston
12204
4333
519
12480
2.6
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Few studies were available that discuss the phytoneuston of
Chesapeake Bay. Microlayer samples collected with the Garrett screen
indicated that microalgae densities are greater in the microlayer in
Chesapeake Bay than in subsurface water from the same area (Gibson, 1971).
Enrichment of chlorophyll and other pigments have also been observed for
other waters (Hartwig and Herr, 1984). Our own measurements of chlorophyll a
in the microlayer and the enrichment that it represents are presented
elsewhere (Hardy and Apts, 1984; Gucinski, 1986). Many species of
phytoneuston (microalgae) concentrate at the surface by phototropism. Light
intensity, including ultraviolet radiation, is frequently high near the
surface and the activity of organisms photoinhibited (Worrest, 1983).
Nevertheless, because of the presence of abundant phytoneuston populations,
primary productivity is often 2 to 30 times greater in the microlayer than
the bulkwater (Hardy and Apts, submitted)^9'.
Although we did not find eggs and larvae of fish in our neuston
collections, various species (bay anchovy, Atlantic silverside and hogchoker)
are thought to have egg, larval, or adult stages that contact the surface
microlayer. Again, however, no studies were found that specifically
described neustonic fish eggs and larvae of Chesapeake Bay.
The presence of surfactant materials (organic surface-active
agents) in the microlayer serves as a precursor to other biological events
(Baier, 1987). This enriched interface is capable of trapping other
molecules, both dissolved and particulate, and forms a substrate leading to
the growth of bacterial numbers 1 to 4 orders of magnitude greater in the
microlayer than the subsurface water. However, as with other taxonomic
groups, studies relevant to the bacterial species occurring within the
neuston of Chesapeake Bay were unavailable. In estuarine waters the time
scale for such initial enrichment is likely to be very short. Studies in
estuaries of water-solid interface colonization to the level of algae (almost
certainly a more lengthy process than colonization by bacteria alone) suggest
a time frame of hours or tens of hours (Gucinski, 1985; Olson, 1983; Crow
et al., 1975; Sieburth, 1982; Hartwig and Herr, 1984).
(a) Hardy, J.T. and C.W. Apts. Photosynthetic carbon reduction: high rates
in the sea-surface microlayer. (Submitted to Marine Biology in 1988.)
2.7
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In summary, very little specific information exists on the neuston
of Chesapeake Bay, but studies from other areas, as well as our preliminary
sampling, suggest that this community forms an important part of the
Chesapeake Bay ecosystem. Additional sampling and analysis covering the
spawning season of important fish and invertebrates is needed.
2.8
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3.0 TASK 2--RATIONALE AND SAMPLING PUN FOR STUDIES IN CHESAPEAKE BAY
3.1 OBJECTIVE
To assess the overall importance and biological impact of aquatic
surface contamination in Chesapeake Bay, a comprehensive study is needed on
the spatial and temporal distribution of surface contamination and toxicity.
Initial studies of surface microlayer contamination in Chesapeake Bay were
conducted in 1986 (Hardy et al., 1987). However, that study did not include
analysis of pesticides, PCBs, or an evaluation of toxicity. The following
proposed sampling plan will provide the first comprehensive assessment of
this potential problem in Chesapeake Bay. The objective is to provide a
cost-effective assessment of the temporal and spatial distribution of
surface- microlayer contamination and toxicity in Chesapeake Bay and its
impact on biological resources.
3.2 RECOMMENDED SAMPLING DESIGN
Studies conducted in 1986 (Hardy et al., 1987) provide some useful
a priori information on aquatic surface contamination in upper Chesapeake Bay
to aid in designing a representative field program. This previous study
suggested that serious surface microlayer contamination, consisting of
complex mixtures of chemicals, occurs in Chesapeake Bay. Contamination was
divided into three major zones (based on cluster analysis of aromatic
hydrocarbon contamination)--the upper Bay, with high levels of contamination;
the Potomac River, with moderate to high levels; and the southern and eastern
shore, with a different chemical mixture and generally low levels of
contamination. Samples were collected only three times in May 1986.
Considerable differences in contamination occurred over a 3-week period
within the same sites, but differences between sites were generally greater
than temporal differences.
The pattern of surface contamination found to exist in 1986 (Hardy
et al., 1987) points toward selection of a stratified sampling design,
allowing us to divide the entire area into less variable strata and to sample
these strata at different rates depending on our requirements. Economic
3.1
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limitations, which are reflected in the total number of samples that can be
analyzed and the travel time required to collect those samples, generate
further rationale for the stratified design. Unlike the more traditional
transect sampling method, for an equal number of samples sites, the
stratified design can provide greater total coverage for estimating spatial
variation, as well as differential coverage in areas of greater or lesser
interest. The stratified sampling design also provides the greatest detail
in areas of suspected contamination and less detail in cleaner areas.
Intuitively, the biological communities are likely to be most variable in
areas of suspected higher contamination.
Chesapeake Bay will be divided into four zones (Figure 3.1), the
first three of which were studied previously (Hardy et al., 1987): Zone 1—
the northern Bay including Baltimore Harbor, lower Susquehanna River and
other areas as far south as the Annapolis Bay Bridge; Zone 2--the western
Bay proper, Potomac and Patuxent Rivers; Zone 3—the eastern and southern
Bay and tributaries; and Zone 4--the southern areas including the Elizabeth
River, Newport News/Norfolk and James River and Hampton Roads. Zone 1
will be subdivided into three subzones--A) Baltimore Harbor, B) lower
Susquehanna River, and C) northern Bay proper. Zone 2 will be divided into
two subzones--A) the Potomac River and B) the Patuxent River. Zones 3 and 4
will consist of only one subzone, i.e., remain undivided. Thus, there will
be a total of seven subzones.
To determine long-term variability in microlayer contamination,
samples will be collected two times per year: once when precipitation and
runoff are high, and once when these conditions are low. During each of
these seasonal samplings, samples will be collected on 3 consecutive days
within each subzone to determine the short-term variability. On each of the
3 days, microlayer samples will be collected at two fixed stations at the
same time each day in order to estimate temporal variation. To estimate
spatial variation, microlayer samples will be collected from three newly
selected stations randomly chosen without replacement from a square grid
covering each subzone. For comparison, a bulkwater sample will be taken from
one of the three newly selected microlayer sampling stations. Thus, a total
of 15 microlayer and 3 bulkwater samples will be collected in each subzone
each season. The sequence of sampling subzones will be determined randomly.
3.2
-------
WASHINGTON, D.C.
FIGURE 3.1
ZONES FOR MICROLAYER SAMPLING IN CHESAPEAKE BAY
3.3
-------
For each season, then, the number of samples collected will be 45, 30, 15 and
15 far microlayer and 9, 6, 3 and 3 for bulkwater in Zones 1, 2, 3 and 4,
respectively. A total of 252 samples will be collected over a period of
1 year (126 samples from all zones x 2 seasonal samplings).
3.3 RECOMMENDED SAMPLE TREATMENT
Toxicity tests of bay anchovy and blue crab larvae will be
conducted on all microlayer samples (see Section 4.0). All samples will be
extracted and archived for possible chemical analysis. However, because of
the high cost of chemical analysis, only 21 samples will be chemically
analyzed. Samples for analysis will be selected, based on the results of the
toxicity tests, to span a range from nontoxic to very toxic. Within
subzones, if samples are consistently either high or low in toxicity, they
may be pooled prior to analysis (aliquots of the unpooled samples will be
maintained). Samples will be analyzed for metals (Pb, Cu, Zn and Cd) by
atomic absorption spectrophotometry and for organics (polyaromatic
hydrocarbons, pesticides, polychlorinated biphenyls) by capillary gas
chromatography, and also for organotin by hydride generation and gas
chromatography-mass spectrometry.
3.4 RECOMMENDED APPROACH TO DATA ANALYSIS
Discriminant analysis will be used to examine the relationship
between toxicity and classes of chemical contaminants (e.g., pesticides or
polychlorinated biphenyls). Spatial and-temporal categories will be ranked
in terms of toxicity and contamination. Estimates of short-term (day-to-day)
and long-term (seasonal) variability will be presented. In Zone 1, where
greater sampling effort is expended and more synoptic detail is available,
data on the toxicity of surface microlayer samples will be presented as
synoptic contour maps of toxicity. These contour maps will be prepared using
kriging techniques (Thomas et al., 1986). Kriging is a weighted, moving-
average technique for calculating point estimates or block averages over a
specified grid. The contour maps will be prepared as overlays on point
3.4
-------
sources of contamination that have been previously identified within the
sampling area.
Temporal trends will be examined using multinomial logic analysis.
The proportion of time that the mean toxicity values within the subzones are
greater than a certain value (e.g., 20 percent reduction in normal live
larvae) will be compared over time within each subzone and between subzones.
3.5
-------
4.0 TASK 3—RATIONALE AND METHODOLOGY FOR MICROLAYER TOXICITY STUDIES
4.1 OBJECTIVE
A research program is needed to assess the current state of surface
microlayer contamination in Chesapeake Bay and its impacts on valued aquatic
biota. A sampling plan for such a .program is outlined in Section 3.0.
Section 4.0 addresses the need to develop specific protocols to assess the
toxicity of surface microlayer contaminants to important aquatic species.
Section 4.0 also outlines a general approach to be followed in screening
(i.e., identifying "hot spots") of surface contamination, for relating
measured chemical concentrations to biological effects and for monitoring
short- and long-term trends in surface contamination.
4.2 RATIONALE
The biota of Chesapeake Bay is diverse and considerable applicable
literature exists including that on the developmental stages of numerous fish
in east coast estuaries (Mansueti, 1954). Many of these studies began with
Alexander Agassiz and his anatomical studies on fish, fish eggs, and larvae
(Agassiz and Whitman, 1885) and the early studies of the U. S. Fish
Commission, particularly those of John Ryder (Ryder, 1881).
Pollutant and toxicity tests have also formed an important part of
the environmental studies on Chesapeake Bay (McErlean et al., 1972; Swartz,
1972; McErlean and Kerby, 1972). There are in excess of 2,000 species of
plants and animals that could serve as candidates for toxicity and
environmental work in the Chesapeake Bay region (Swartz, 1972; McErlean
et al., 1972). But, as stated earlier, few candidates are strictly
neustonic organisms or suitable for toxicity tests of surface microlayer
contaminants. Recently Hall et al. (1987b) reported elevated levels of
butyltin compounds in Chesapeake Bay. Previous toxicity tests on butyltin
compounds examined effects on sheepshead minnows (Cyprinodon variegatus),
unicellular marine algae (Skeletonema costatum and Thallasiosira
pseudonana), copepods (Acartia tonsa), and mussel larvae (Mytilus edulis).
Most of these species could be used for determining the toxicity of surface
4.1
-------
microlayer contaminants in Chesapeake Bay, but other species are more
representative of the Bay neuston.
Pelagic (floating) fish eggs are particularly suitable for studies
of aquatic surface toxicity. For example, eggs of anchovy (Hunter, 1981),
sole (Hardy et al., 1987), and mackerel (Longwell, 1976; Longwell and Hughes,
1980) have been used successfully as sensitive indicators of toxicity. The
eggs of such pelagic spawners are often distributed in extremely patchy but
dense concentrations. Eggs are frequently present in only 5 percent of the
neuston net trawls, but when found, are often in densities of 17 to 31
eggs/L. This is the equivalent of up to 46,000 eggs per 10 square meters of
water surface. These patches originate from intensive-spawning activity and
gradually disperse (Hunter, 1981).
Thus, neustonic species and nocturnal spawners typically have a
general distribution of patchy, but dense, numbers of eggs which are
dispersed by the tides over the first few days. Nocturnal spawning, when egg
release is highest at night, makes collection difficult. In terms of
toxicity test procedures, an effective approach is to collect microlayer
samples at the same sites over several days (short-term temporal differences)
and at several times of year (long-term seasonal differences), and then do
toxicity tests in the laboratory at the time of year when appropriate
toxicity test organisms are available.
In recent years, toxicity tests for sediment contamination have
involved the development of an environmental quality triad to determine
environmental impact (Long and Chapman, 1985). Chapman and Long (1983)
argued that for accurate evaluation of sediment quality, at least three
categories of measurement must be evaluated. These are 1) concentrations of
toxic chemicals, 2) toxicity of the environmental samples (bioassay), and 3)
evidence of modified resident biota, particularly the infauna.
The same approach can be used for determining the effects of
surface microlayer contamination on neustonic eggs and larvae. Thus,
accurate evaluation of surface waters may involve at least four categories of
sampling, testing, and evaluation. These are 1) determination of
concentrations of toxic chemicals, 2) collection and enumeration of
representative resident neuston species populations, 3) conduct of toxicity
tests in the laboratory, and 4) conduct of toxicity tests on representative
4.2
-------
neustonic organisms in the field. Certainly all four measures are necessary
to obtain an accurate picture of the physical, biological and chemical
parameters that contribute to aquatic surface quality. At this stage, the
toxicity evaluation should involve both laboratory tests with standard
organisms, such as the sea urchin, and selected field tests with important
resident organisms, such as the bay anchovy or crab larvae.
To determine the toxicity of surface microlayer in Chesapeake Bay a
dual approach, consisting of both vn situ and laboratory tests, may be
useful. ]_n situ studies simulate natural conditions, but are often unable to
determine controlling variables (e.g., temperature and salinity). Organisms
for field tests are not always available. That field studies are subject to
the availability of spawning organisms is often a source of unproductive time
in the field. If it can be demonstrated that no difference exists in the
results of toxicity tests using fresh versus frozen surface microlayer
samples, the samples could be collected throughout the year and tested on
seasonal spawning species when eggs are available. Laboratory studies can be
controlled more carefully, and provide a basis for accurate hypothesis
testing, but they are not necessarily representative of the natural
environment. Both types of test are necessary.
4.3 RECOMMENDED APPROACH
Review of relevant literature and discussions with a number of
researchers (see Appendix B list) suggests several species that would serve
as suitable organisms for surface microlayer toxicity studies. Two fish, in
particular, are important ecosystem components and produce floating eggs in
large numbers. Neuston net tows at the South Island of the Chesapeake Bay
Bridge-Tunnel indicated maximum egg densities in mid-June and mid-July for
the hogchoker (Trinectes maculatus) and the bay anchovy (Anchoa mitchilli),
(personal communication, R. S. Birdsong, Old Dominion University, Norfolk,
Virginia). Blue crab (Callinectes sapidus) occurred in high densities near
the surface in mid-July to mid-August. Also, the zoeal larvae of the blue
crab concentrate at the surface and can be cultured in the laboratory.
We recommend the bay anchovy and the blue crab larva as appropriate
species for assessing surface microlayer toxicity in Chesapeake Bay. The
4.3
-------
anchovy egg is a representative pelagic fish egg that contacts the surface
during an approximately four-day period during development, is widespread and
euryhaline, and can be collected in large numbers during the summer using
neuston net tows. Blue crab larvae represent the reproductive stage of an
important commercial shellfish resource. They are typical of crustacean
neuston that probably feed on the high densities of microorganisms at the
water surface (Zaitsev, 1971). Also, they can be cultured and used for
toxicity tests in the laboratory.
We propose the following general approach using the sampling plan
outlined in Section 3.0 above. Surface microlayer samples will be collected
from all stations and split into separate fractions for chemical analysis and
toxicity testing. The samples for chemical analysis will be extracted,
frozen, or otherwise prepared according to sample type for long term storage.
For toxicity tests, freshly collected surface microlayer samples will be
transported on ice to the laboratory. Where necessary, salinity of samples
will be adjusted using artificial sea salts. Blue crab larvae will be
exposed to the collected surface microlayer samples in static or partial
replacement bioassays according to standard procedures (APHA, 1976, pp. 794-
826). A fraction of the surface microlayer samples will also be frozen for
conducting toxicity tests on eggs of bay anchovy at a later time (summer).
During summer, bay anchovy eggs will be collected using a neuston
net. Anchovy eggs will be used for 1) examination of J_n situ cytotoxic
effects, 2) jin situ tests, and 3) laboratory tests. To determine if harmful
effects of surface microlayer contamination are occurring in the field,
anchovy eggs collected at a variety of sites (from sites believed to be clean
to more contaminated sites) will be examined in the laboratory for mitotic
anaphase aberrations. The incidence of abnormalities in mitotically active
embryos exposed to surface microlayer samples will be determined according to
Longwell and Hughes (1980) as modified by Liguori and Landolt (1985). As an
additional test of in situ effects, eggs collected from a clean area will be
placed in screened cages and incubated j_n situ in areas of suspected
contamination until hatching. Hatching success in clean versus contaminated
areas will be compared. Eggs will also be brought into the laboratory and
exposed to thawed surface microlayer samples collected earlier in the year.
4.4
-------
At the same time, a percentage of the thawed samples will be used
to expose blue crab larvae. Comparison of the blue crab larval bioassays
performed earlier on the fresh samples and later on the frozen/thawed samples
will be used to test the hypothesis that sample freezing has no effect on the
toxicity of the samples. _Iri situ toxicity tests will also be conducted at
selected sites.
As described in Section 3.0, the results of the toxicity tests will
be used to decide which selected samples will be chemically analyzed for
contaminants. Results of the chemical analysis will then be used to relate
(using discriminant analysis statistics) contaminant levels to toxicity.
4.5
-------
5.0 TASK 4—WORKSHOP ON CONTAMINATION AND TOXICITY
OF THE AQUATIC SURFACE LAYER
5.1 OBJECTIVE
Establishing the biological significance of the enrichment of toxic
substances in the sea-surface micro!ayer represents a largely new,
interdisciplinary initiative. Unlike previous efforts, it requires analysis
of phenomena, the consequences of which are often counter-intuitive and not
easily fit to a preconceived framework. Required are understanding of the
sources and pathways of toxic substances into the microlayer, establishment
of their residence times and removal fluxes, and delineation of the biota
that is exposed. The obvious question that must be addressed is: Can a
layer typically defined in terms of millimeter or even micrometer thickness
have important biological impacts?
It will be the objective of this task to outline a workshop
approach that addresses these fundamental questions. It will also be our
objective to insure that the workshop serves an educational role and provides
new perspectives which will increase our basic understanding of basic
processes occurring at.the air-sea interface. The workshop should also
facilitate prioritization of research needs and approaches to fill them, and
describe scientifically defensible monitoring techniques for the sea-surface
microlayer. Finally, the workshop should outline an approach leading to the
application of conceptual models by regulators in determining the fate and
potential effects of residuals in the microlayer from ocean waste disposal.
5.2 RECOMMENDED APPROACH
We have assembled the outline of a programmatic approach that
addresses many of the fundamental questions.. Yet it is clear that the
inputs of specialists in several disciplines will be required to develop
collection and analysis techniques, provide guidelines in the delineation of
processes, allow for the creation of theoretical underpinnings, and establish
the framework to ask the most cogent questions concerning potential impacts.
A workshop is needed that will bring together scientists and managers from
5.1
-------
the core areas that deal with effects of microlayer processes. This group
would develop an agenda that will bring maximum progress toward establishing
the programmatic requirements of managing microlayer toxics enrichment and
delimit the effort and resources required in view of competing needs. We
recommend the following outline for a workshop.
Goal: Establish the biological significance of enriched toxic
substances in the surface microlayer.
Topics:
1. Biological resources:
a. Identify ecologically important populations that
experience microlayer exposure.
b. Hypothesize the exposure risk in terms of
measurable variables, such as life stages,
exposure duration, relative hardiness, survival
to reproduction, etc.
c. Develop strategies for obtaining necessary
information in a cost-effective manner.
2. Toxic substances:
a. Rank order substances entering microlayer by their
toxicity and likelihood of occurrence.
b. Assess major modes of spatial and temporal
variation in build-up of toxic substances in the
microlayer.
c. Establish protocols to monitor representative
"indicator" molecules.
d. Integrate the knowledge of biological hazards with
quantification of chemical concentrations.
e. Develop a bioassay monitoring approach that reduces
both the frequency and density of sampling, as well
as the need for extensive chemical analysis.
3. Microlayer processes:
a. Define the enrichment pathways, removal processes,
and residence times for toxic substances.
5.2
-------
b. Explore the expected trends of impacts in view of
present management efforts directed at containment
of toxic material release.
c. Examine the potential to use microlayer information
as an early warning tool for the presence of
environmental hazards.
d. Review current remote sensing technology as a tool
for assessment of microlayer dynamics, and
establish the limits of this tool in aiding the
monitoring effort.
The workshop should lead to a report that addresses the level of success in
meeting these objectives and should seek to establish an informed consensus
on what the short-range objectives of highest priority should be. It should
also define an orderly pathway for long-range efforts, both those that can
meet the needs of environmental management and those that can deepen our
understanding of the overall significance of microlayer processes from a
biological perspective.
5.3 PARTICIPANTS
We recommend that invitations be extended to a variety of
scientists and managers and that the scientists invited be true specialists
in microlayer work involving various disciplines. The following list is
intended to be indicative rather than exhaustive; approval of the workshop
concept would clearly involve an effort to further identify and select
relevant investigators. On the other hand, we recommend that total
participation be limited so that working groups can be small enough to
formulate goals in a timely way and work dynamically and efficiently.
Examples of potential invitees include the following:
Scientists
Robert Baier, surface science, State University of New York, Buffalo, NY
James Blake, benthic ecology, Battelle Ocean Sciences, Duxbury, MA
Duncan Blanchard, microlayer dynamics, State University of New York,
Albany, NY
David Carlson, organic chemistry, Oregon State University, Corvallis, OR
5.3
-------
Mike Castagna, biology, Virginia Institute of Marine Science, Wachapreague,
VA
Eric Crecelius, chemistry, Battelle Marine Research Laboratory,
Sequim, WA
Jeff Cross, microlayer toxicity, Southern California Coastal Water Research
Project, Long Beach, CA
Earl Davey, microcosm studies, U.S. Environmental Protection Agency,
Narragansett, RI
Robert Gagosian, chemistry, Woods Hole Oceanographic Institution, Woods Hole,
MA
Lenwood Hall, environmental biology/toxicology, Johns Hopkins University-
Applied Physics Laboratory, Shady Side, MD
Jack Hardy, biological oceanography, Battelle/Marine Research Laboratory,
Sequim, WA
Robert Huggett, environmental chemistry, Virginia Institute of Marine
Science, Gloucester Point, VA
Carlton Hunt, marine chemistry, Battelle Ocean Sciences, Duxbury, MA
Richard Kocan, fisheries biology, University of Washington, Seattle, WA
John Lehman, biology, University of Michigan, Ann Arbor, MI
Peter Liss, air-sea interface chemistry, University of East Anglia,
Norwich, UK
Kent Price, fisheries biology, University of Delaware, Lewes, DE
Jon Schenker, zooneuston, University of California, Davis, Bodega Marine
Laboratory, Bodega Bay, CA
John Scott, surface chemistry, University of Essex, UK
Randall Smith, microlayer bioassays, Portland State University, Portland, OR
William Steinhauer, chemistry, Battelle Ocean Sciences, Duxbury, MA
John Strand, fisheries biology, Battelle/Marine Research Laboratory, Sequim,
WA
Mary Tyler, remote sensing, VERSAR Inc., Columbia, MD
Allen Uhler, organic analytical chemistry, Battelle Ocean Sciences, Duxbury,
MA
Robert Weller, physical oceanography, Woods Hole Oceanographic Institution,
Woods Hole, MA
Christine Werme, marine ecology , Battelle Ocean Sciences, Duxbury, MA
Peter Williams, surface chemistry/biology, Scripps Institution of
Oceanography, La Jolla, CA
5.4
-------
Agency Representatives
Bert Brun, U.S. Fish and Wildlife Service, Annapolis, MD
Tudor Davies, U.S. Environmental Protection Agency, Washington, DC
Chris D'Elia, National Science Foundation, Washington, DC
Edward Long, National Oceanic and Atmospheric Administration, Seattle, WA
Ira Skurnick, Defense Advanced Research Projects Agency, Arlington, VA
Virginia Tippie, National Oceanic and Atmospheric Administration,
Washington, D.C.
Other Agencies (Representatives not Determined)
Maryland, Department of the Environment, Baltimore, MD
Maryland, Department of Natural Resources, Annapolis, MD
Pennsylvania Department of Environmental Resources, Harrisburg, PA
Pennsylvania Fish Commission, Harrisburg, PA
Potomac Fish Commission, Colonial Beach, VA
Potomac- River Basin Commission, Rockville, MD
Susquehanna River Basin Commission, Harrisburg, PA
Virginia Water Control Board, Richmond, VA
Virginia Marine Control Board, Richmond, VA
5.5
-------
-------
6.0 TASK 5—EVALUATION AND SELECTION OF MICROLAYER SAMPLING PROTOCOL
*
6.1 BACKGROUND
More than 20 different techniques have been used to sample the
surface microlayer. Each has certain advantages and disadvantages (Hardy,
1982). The rotating Teflon®-coated drum and the glass plate [Hardy et al.,
1985; Hardy et al., 1987; Hardy et al., 1988c (in press)] have proven quite
useful, but additional information on the characteristics and collection
efficiency of these techniques is needed. In chemical studies, steps that
involve separation, extraction, and conversion as part of the analysis
sequence suffer from uncertainty due to incomplete recovery at one or more
of these steps. In principle, this can be overcome by testing a standard
solution and/or by adding known quantities of the standard to the sample as a
"spike" (APHA, 1976; U.S. EPA, 1983).
The problem is more difficult because the collection efficiency of
any of the several methods of recovery of surface material is generally not
known or is poorly defined. The most widely used technique, the horizontally
dipped screen, initiated by Garrett (1965; 1967), recovers water and its
constituents and contaminants from both the immediate surface layer and the
bulk water below. Although a nominal sampling depth can be calculated from
the known surface area contacted and the volume of entrained water thus
collected, the ratio of surface to bulk water is not known; in fact, the
definition of what is properly considered as surface adsorbed material is
itself still somewhat unclear (Gucinski, 1986; Herr and Williams, 1986).
Attempts at quantification generally involve adding a surfactant
or, as has been done in a very few cases, a mixture of tagged surfactants to
a laboratory tank and measuring the recovery efficiency by assuming this
surfactant remains surface adsorbed (see Hatcher & Parker, 1974; van Vleet
and Williams, 1980; Hardy et al., 1985). Field evaluations have also been
carried out by Carlson (1982). There is at least one case where surface
water was removed to a specific depth using a razor edge mounted on a sled,
® Registered trademark of the DuPont de Nemours Co., Inc., Welmington,
Delaware.
6.1
-------
in order to verify a surface depletion of salts predicted from Gibb's Free
Energy considerations (see McBain's experiments in Adamson, 1974). Table 6.1
summarizes the data available on collection efficiencies and variations of
sample performance for different microlayer samples and chemical components.
The data are presented by sampling device, such as the Garrett screen, the
vertically dipped glass plate, etc. Even casual inspection of the table
shows that a number of investigators restricted themselves to comparative
tests, i.e., relative efficiencies of material recovery, while the data show
enough variation to create the impression of poor predictive performance. A
step-by-step description of the sampling principles shows that some optimism
is, nevertheless, warranted. Several factors need to be considered when
contemplating microlayer sampling. These include sampling depth,
partitioning of enriched molecular species or particulates, and the presence
of other likely groups of molecules that can affect the enrichment process.
We advance the following concept of the microlayer to aid
visualization of the role of dominant variables. The creation of surface
area at the air-water interface requires work because of cohesive forces
among the water molecules (if pure water is considered) and adhesive forces
among water and its contaminants, whether they are salts, as in seawater,
dissolved organic matter, or both. The work required is reflected by
the surface tension, a force per unit length, typically measured in
millinewtons/meter (mN/m). Thus pure water, a highly polar liquid having
strong cohesive forces, has a surface tension value of 72.4 mN/m at 20°C.
The units are equivalent dimensionally to millijoules/square meter, i.e.,
work per unit area. Any substance that reduces the water's surface tension
will reduce the Gibb-'s Free Energy (Moore, 1962) and, therefore, lead to
thermodynamically favored, stable adsorption at the interface. Amphiphillic
molecules, having polar, hydrophobic and non-polar, hydrophobic moieties can
reduce water surface tension markedly and thus lower the Gibb's Free Energy.
For example, oleic acid, spread on water in the form of a monolayer, will
reduce the surface tension from 72.4 mN/m to about 40 mN/m. Salts and acids
increase the surface tension by virtue of their strong affinity for water
molecules, thus sea water has a surface tension of 75.4 mN/m and salts will
be rejected from the interface (Adamson, 1974; Gucinski, 1986b). Organic
6.2
-------
TABLE 6.1
COLLECTION EFFICIENCY OF SAMPLING METHODS
Th i ckness
Type of Sampler u«
30-55
20-80
i
Glass Plate '
1
i
1
22
22
22
22
nd
nd
nd
nd
nd
Screen nd
200-300
400-550
nd
nd
nd
nd
nd
nd
nd
nd
nd
150
150
Compound or
Pa rt i c 1 e
lycopod
NBS partic
DOC
UVabs «at
chloroph
ATP
POC
PON
octadecanol
hexadecanol
talc
kerosene
oleic acid
1
i
•
i
i
nd
nd
protein
carbohyd
POC
PON
Seston
fatty (P).
fatty (D)
alka.(P)
alka(D)
oleic acid
i
Surface
Pressure
0-22
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
5
5
5
5
5
5
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
Abso 1 ute
Efficiency X
60-61
i
nd
nd
nd
nd
nd
nd
83
84
74
12.6
99.6
74.2
95.0
42.6
87.0
28.8
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
Coiments
= garr scr
= garr scr
< garr sc
depletion
too sparse
no dips
1
2-10
1
2-5
1
2-5
ENRCH FAC:
poll /clean
1.6/1.4
3.1/1.3
5.0 /I. 5
3.0/1.5
2.8/1.4
nd/1.9
1.7/4.2
169/5.7
6.3/1.0
51--16
51*-16
Reference
Hardy et »!.,
1985
Carlson, 1982
i
i
1
i
•
Hatcher and
Parker, 1974
i
i
Garrett, 1965
•
i
•
i
i
Carlson, 1982
i
Douias et al . ,
1976
i
i
i
i
i
i
i
i
i
6.3
-------
TABLE 6.1
COLLECTION EFFICIENCY OF SAMPLING METHODS (Cont.)
Type of Sampler
Screen
Gerianiui
Prisi
Teflon Slab
Teflon Sheet
Teflon Plate
Glass SI ide
Hydrophi lie SI ide
Luc i te
Fff.LUC.
Nucleopore
Ft Iter
Mi 1 1 ipore Fi Iter
Th i ckness
Ul
150
150
150
369—154
369—154
369—154
369-154
150
150
6.5
6.5
6.5
< 6.5
6.5
6.5
36
36
36
36
36
36
150
150
150
150
150
0.8
0.8
0.8
Q.8
0.8
Q.8
150
Coipound or
Particle
,
i
i
octadecanol
hexadecanol
talc
kerosene
oleic acid
i
oleic acid
i
ol ive oil
i
tri-glycer.
i
oleic acid
i
ol ive oil
i
tri-glycer.
i
i
i
i
i
i
oleic acid
1
ol ive oil
i
tri-glycer.
i
i
Surface
Pressure
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
Abso i ute
Efficiency >
nd
nd
nd
2.9
5.7
2.3
2.6
nd
nd
80
99
72
62
45
87
99
83
83
124
52
nd
nd
nd
nd
nd
nd
nd
93
59
94
45
31
nd
Comments
73-23
73-23
0
see Garrett,
1974
i
*
37
18
12
4
2
1
106
•ono layer
deca layer
•ono layer
tri layer
gaseous
•ono layer
128
Reference
Douias et at.,
1976
i
Hatcher and
Parker, 1974
1
i
van Vleet and
lilliais, 1980
Kjallebarg
et al., 1979
1
i
i
1
Kjallebarg
et al., 1979
•
i
i
i
van Vleet and
filliais, 1980
i
i
i
Kjallebarg
et al., 1979
i
i
i
i
van Vleet and
Willia*s, 1980
6.4
-------
TABLE 6.1
COLLECTION EFFICIENCY OF SAMPLING METHODS (Cont.)
Type of Sampler
Roller
Tray
Freezing
PVC Fill
Thickness
im
nd
nd
nd
nd
nd
nd
nd
nd
nd
52
52
52
52
634*- 134
634—134
634—134
634.- 134
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
16
Compound or
Particle
protein
carbohyd
POC
PON
Seston
fatty (P).
fatty (D)
alka.(P)
alka(D)
octadecanol
hexadecanol
talc
kerosene
octadecano 1
hexadecanol
talc
kerosene
sed i lent
shel I/sand
pol 1 en/spores
p rot. powder
arteiia
p 1 ankton
clay
oleic acid
stearic a.
hexadecane
DDT
oleic acid
partic.
L-atino a.
Surface
Pressure
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
Abso I ute
Efficiency X
nd
nd
nd
nd
nd
nd
nd
nd
nd
26
49
65
3.2
28
18
10
13
100
100
100
100
100
100
>SO
69
81
92
>95
98
>90
nd
Cements Reference
11/3.3 DOOMS et al . ,
13/2.3 1976
11/2.7 '
14/2. S '
9.0/1.6 '
12/3.5 '
2.2/2.4 f
682/11 '
nd/1.0 '
see Hatcher and
Garrett Parker, 1974
1974 '
i i
see Garrett Hatcher and
1974 Parker, 1974
i i
1 '
Ha«i Iton and
Clifton, 1979
1
i
i
i
i
i
i
•
i
i
i
t
6.5
-------
alcohols, fatty acids, lipids, and low molecular weight detergents all lower
water's surface tension, adsorb stably at the interface, and have been called
"dry" surfactants because a significant portion of the individual molecule
extends into the gaseous phase. High molecular weight molecules, even if
largely polar, can be surface active (surfactants) by virtue of their
tertiary structure. Proteins, polysaccharides, and humic acids are
surfactants, but remain essentially in the aqueous phase and, hence, are
called "wet" surfactants (Maclntyre, 1974). Recovery of a dry surfactant
monolayer is achieved by providing a substratum to which the molecule readily
adheres. It may be counter-intuitive, but both highly polar, high energy
surfaces (such as glass, ceramics, and germanium) and nonpolar, low energy
surfaces (such as Teflon® or silicon) do this quite well. Hence, vertically
lowered and retrieved plates or horizontally touched sheets work well as
adsorbing surfaces, and screens collect surface microlayer in their
interstitial spaces. However, the apparent depth of the layer varies, as do
the means of releasing the materials thus collected into a suitable vessel
for subsequent chemical analysis. For example, the germanium prism, dipped
vertically, allows infrared analysis by attenuated total reflection (ATR)
spectroscopy of material retained on the prism, and has excellent collection
efficiencies under controlled conditions (Baier et al., 1974; Gucinski
et al., 1981), yet efficiency deteriorates markedly when the sample is
removed for subsequent analysis (van Vleet and Williams, 1980). Moreover,
retrieval of surfactants is influenced by the density of material present, as
reflected by surface pressure measurements; this phenomenon is observable by
the changes in volume of sample retrieved per unit area sampled, which in
turn changes the nominal sampling depth. These changes are often noted in
the literature, but their significance is rarely taken into account.
Materials other than surfactants accumulate at the interface and may be of
biological significance. Enrichment may result from buoyancy, as is the case
with some fish eggs, from hydrophobicity of aerially deposited
particles--urban air particulate matter and many spores are highly
hydrophobic, or from dissolution of substances in the surfactants present.
Bubble scavenging is another enrichment process (Syzdek, 1982).
6.6
-------
6.2 OBJECTIVE
It was the objective of this task to establish the collection
efficiency of two types of sampler and report the results for two classes of
materials. The Teflon®-coated drum sampler (Hardy, 1987) was chosen because
it is a device that allows collection of the relatively large volumes of
microlayer required for extensive chemical analysis and for bioassays. Its
utility is enhanced because large volumes can be amassed quickly. Like all
samplers, its use is limited to wind speeds of 15 to 20 knots (sea-states of
about Beaufort 3) or less. The glass plate is the other choice, because it
is used frequently and its hydrophilic surface presents a recognized and
accepted alternative. When properly cleaned, the recovery characteristics of
the glass plate are similar to those of other high surface energy materials
such as ceramic or germanium.
6.3 METHODS
Two sampling efficiency determinations were made. The first
determination used Lycopodium spores, a hydrophobic particulate
representative of aerially deposited materials such as pollen, organically
coated clays or dusts, and some sands. The second determination used
radiolabeled 14C DDT dissolved in oleyl alcohol to represent a dry
surfactant that forms monolayers. Three mini-drum samplers were constructed
to about 1/6 of the scale used in actual field sampling devices. The mini-
drums were made by applying adhesive-backed Teflon® (polytetrafluoroethylene)
to PVC pipe sections. The drums had surface areas of 132 to 137 cm2 The
rectangular glass plate sampler was marked to give a sampling area of 121
cm2.
The Teflon® samplers were detergent washed, following the procedure
used in field sampling, and the glass plate was acid-washed in a acid mixture
of sulfuric and nitric acids.
6.7
-------
6.3.1 Experiments with Hydrophobia Particles (Lycopodium Spores)
Tapwater and natural seawater were used to fill a Pyrex® dish
measuring 642 cm2 and allowed to equilibrate. A pre-weighed quantity of
Lycopodium spores was dropped onto the surface. Although a homogeneous
distribution of spores was impossible to achieve, the scale of irregularities
could be made much smaller than the area sampled, so that uniformity on the
scale of sampling could be maintained.
6.3.2 Experiments with Radiolabeled DQT
Experiments were conducted at three surface pressures. Three
solutions were prepared with concentrations of oleyl alcohol dissolved in
hexane of 0.5, 1.0 and 1.5 mg/L. One hundred microliters of a l^ODDT was
added separately to 12 ml of each of the above solutions. A 1-mL sample of
this solution (3.456 x 10& dpm) was added to the surface of each of three
Pyrex® glass trays (surface area 704 cm2) containing 2960 to 3020 ml of
deionized water and allowed to spread. Thus, Trays 1, 2 and 3 had increasing
quantities of oleyl alcohol on the water surface. Following evaporation of
the hexane (10 min) the surface film was sampled by one rotation of the
mini-drum, i.e., 19.43 percent of the surface area of the tray. Following
collection, the drum surface was rinsed with a measured volume (23 to 41 ml)
of methylene chloride and the rinse collected in a beaker. Half of a
milliliter of the rinse was added to each of three replicate scintillation
vials and counted in a scintillation counter. The external standards for
ratio technique was used to correct the counts for background and for
quenching.
® Registered trademark of Dow Corning Corporation, Midland, Michigan.
6.8
-------
6.4 RESULTS
6.4.1 Hydrophobic Particles (Lycopodium Spores)
In trials with Lycopodium spores, both the drum and plate samplers
were affected by the surface spreading pressure of surfactants present. This
was consistent with other reports in the literature, and with field
observations that show a greater amount of water recovered per unit sampler
area when surface pressure is high, i.e., when surface tension of water is
reduced by the presence of surfactants.
Table 6.2 summarizes the results of these experiments, which were
done on seawater, except for a single run on tapwater at 0 mN/m spreading
pressure. As can be seen, sample variability is common and results
nonuniform for the glass plate sampler. Nevertheless, the trend toward
higher collection efficiencies at higher spreading pressures is evident.
TABLE 6.2
LYCOPODIUM SPORE SAMPLING EFFICIENCY AS A
FUNCTION OF SPREADING PRESSURE
Sampler
Drum
Glass plate
0
64.4
31.1
Surface
<0.82
18.4*
55.2
Spreading Pressure, mN/m
4.4
74.3
37.6
18.8
89.8
99
*Visual observation showed spores pushed away from sampler, suggesting
some surfactant contamination that produced its own spreading pressure.
6.4.2 Labeled DDT in Oleyl Alcohol
Assuming all of the DDT remained in the film of oleyl alcohol and
spread throughout the surface of the tray, samples collected with the
Teflon®-coated mini-drum should have recovered 19.43 percent of all the added
DDT. Counts of 14c DDT indicated a recovery 78 to 88 percent of this
6.9
-------
amount. Recovery increased with increasing film pressure and was 78.7, 80.3
-and 88.2 percent, for mean surface pressures of 4.6, 19.6 and >23 mN/m,
respectively. This represents the minimum collection efficiency of the drum
because any loss to the subsurface water or walls of the tray would decrease
the expected quantity of DDT recovered by the drum.
6.5 DISCUSSION AND CONCLUSIONS
Collection efficiencies of the two microlayer samplers tested are
less than 100 percent, and vary both with the substance recovered and with
the presence of slick-forming surfactant molecules, as determined by surface
pressure or surface tension measurement. In general, efficiencies are higher
when surfactant molecules form a coherent film, whether these molecules are
themselves the target of analysis, or when they serve as a trap for
particulates or materials soluble within this film, such as DDT in the dry
surfactant, oleyl alcohol. Within slicks, such efficiencies exceed
85 percent, and are much less, from 60 percent to nearly 80 percent, when
surface waters are "free" of organized, coherent films. It appears therefore
that surface film pressure measurements or equivalent indicators of the
presence of surfactants should routinely accompany sample collection. The -
Adam spreading oils lend themselves to field applications, but surface
tensions, surface viscosity, surface potential and other methods can be
better indicators in highly controlled laboratory situations. A readily
available technique is to note changes of nominal sampling depth for
differing environmental conditions. Variation in efficiencies reported in
the literature or inferred from comparative sampling data suggest that
whatever method is used, a determination of collection efficiency is
desirable for the target molecule(s) or target particle(s) selected for
study. In general, the rotating Teflon®-coated drum appears to be an
effective and useful device for rapidly collecting large volumes of aquatic
surface microlayer for chemical and toxicological analysis. The collection
efficiency of the drum for particles and hydrophobic organic films is similar
to the glass plate (about 70 to 90 percent) over a range of surface pressures
from 4 to >23 mN/m.
6.10
-------
7,0 TASK 6—COLLECTION AND CHEMICAL ANALYSIS OF
CHESAPEAKE BAY MICROLAYER SAMPLES
7.1 OBJECTIVE
Preliminary evaluation of Chesapeake Bay microlayer samples
indicated that concentrations of metals, alkanes, and aromatic hydrocarbons
were high compared to associated bulkwater samples (Hardy et al., 1987).
Based on these results, the U.S. EPA asked Battelle to undertake an
additional survey of Chesapeake Bay microlayers, with particular interest on
the urban-industrialized areas of Havre de Grace, Baltimore, Cambridge,
Washington, and Norfolk. The purpose of this effort was exploratory with the
limited objective of detecting only major contaminants. It should be
understood that our results represent a reconnaissance of the problem and are
not rigorously quantitative.
7.2 METHODS
Samples of the sea-surface microlayer were collected from six sites
in Chesapeake Bay between September 10 and 12, 1987, using the rotating
Teflon® drum microlayer sampler (Table 7.1). The 6 sampling sites were
selected from 12 sites sampled in a previous study (Hardy et al., 1987).
Subsamples of these collected samples were delivered to EPA for chemical
analysis. Samples shipped to Battelle/Marine Research Laboratory in Sequim,
Washington, were lost in shipment; therefore, sampling was repeated during
October 1987 (Table 7.2). Methods of sample handling, extraction and organic
chemical analysis followed, in general, those described previously for
similar samples [Hardy et al., 1986; Hardy et al., 1987; Hardy et al.,
1988a,b (in press)]. In addition, samples were analyzed for concentrations
of organotin by hydride generation with atomic absorption detection. Two
other samples were analyzed for tributyltin and dibutyltin by gas
chromatography/mass spectrometry.
7.1
-------
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7.3 RESULTS
7.3.1. September Sampling
Samples were collected during October 1987 (Table 7.2) and analyzed
by a separate EPA contractor. High concentrations of metals were found in
the micro!ayer. Of particular interest, in terms of potential toxicity, were
the concentrations and/or enrichments (microlayer/bulkwater concentrations)
of silver (indicative of sewage inputs) at Stations 7, 8, and 12; copper at
all stations; and arsenic, lead and zinc at Station 8. Concentrations of
total metals (Ag, Cu, Cd, Pb, Zn) in the microlayer ranged from 59 to
642 ;tg/L. Such high total metals concentrations have been found in
microlayer samples elsewhere (Hardy, 1982; Hardy et al., 1985). However,
the analytical method used in this study, inductively coupled plasma (ICP),
has low sensitivity for seawater analysis and most of the results were below
the calibrated range of the instrument. Some of the data were not consistent
with previous measurements of metals by more sensitive methods. Therefore,
we have not included a detailed data table here.
Pesticides and other organic compounds were frequently highly
enriched in the microlayer compared to the bulkwater samples. Total
microlayer concentrations ranged from 3.5 to 11.8 /ig/L (Table 7.3).
Relatively high microlayer concentrations or enrichments occurred at two or
more stations for the following: carbophenothion, demeton, diazinon, di-
butyl phthalate, EPN, ethion, famphur, fensulfothion, and kepone. In
general, Stations 7 and 8 were most contaminated; e.g. the microlayer at
Station 8 was enriched in almost 50 percent of the compounds analyzed.
7.3.2. October Sampling
Samples were collected during October 1987 (Table 7.2) and analyzed
by Battelle. High concentrations of organic contaminants were found in the
aquatic surface microlayer at most stations sampled. Concentrations of
organotin ranged from 95 to 1,076 ng/L in the microlayer and 190 to 285 ng/L
in the two bulkwater samples analyzed (Table 7.4).
7.4
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TABLE 7.4
ORGANOTIN BY AAS (AS INORGANIC TIN) AND TRIBUTYLTIN
AND DIBUTYLTIN BY GC-MS (AS TBT CHLORIDE AND DBT
CHLORIDE) IN CHESAPEAKE BAY MICROLAYER AND BULKWATER
SAMPLES COLLECTED OCTOBER 1987
Station
Number
Location
Organotin
(nq/L)
Microlayer Bulkwater
TBT DBT
(nq/L)
Microlayer
2
3
7
8
Point Lookout
Upper Potomac
Hedge Neck
Inner Baltimore Harbor
Susquehanna River
95
1,076
253
997
_
130 180
_
110 90
Havre de Grace
11
12
Choptank River
Cambridge
Mid-Chesapeake Bay
Bay Bridge
222
617
190
285
Concentrations of total aromatic hydrocarbons in the surface
microlayer of Chesapeake Bay ranged from 0 to 20 /*g/L (Table 7.5). Spike
recovery measurements using surrogate aromatic hydrocarbons suggested that
only 35 to 100 percent (mean 69 percent) of the aromatic hydrocarbons were
recovered, i.e., our reported values (Table 7.5) represent roughly 69 percent
of the actual concentrations present in the sample. Aromatic hydrocarbon
concentrations were low or below detection at Stations 2 and 3, significant
(potentially toxic) at Stations 7, 11, and 12, and very high at Station 8
(Susquehanna River). Concentrations of total saturate hydrocarbons ranged
from 3.8 to 66.5 (mean 21.3) /ig/L (Table 7.6). Highest concentrations
occurred at Stations 3, 7 and 8.
High concentrations of the plasticizer bis(2 ethylhexyl)phthalate
were found in all the samples. However, high concentrations also occurred in
the blank, raising the possibility that concentrations represent sample
contamination.
7.6
-------
TABLE 7.5
CONCENTRATIONS (M9/L) OF AROMATIC HYDROCARBONS IN
THE SURFACE MICROLAYER OF CHESAPEAKE BAY, OCTOBER 1987
Station f
Compound
1 Naphthalene
2 Cl-Naphthalene
3 C2-Naphthalene
4 CS-Naphthalene
5 C4-Naphthalene
6 Acenaphthylene
7 Biphenyl
8 Acenaphthene
9 Fluorene
10 Cl-Fluorene
11 C2-Fluorene
12 C3-Fluorene
13 C4-Fluorene
14 Phenanthrene
15 Anthracene
16 C1-P/C1-A
17 C2-P/C2-A
18 C3-P/C3-A
19 C4-P/C4-A
20 Dibenzothiophene
21 Cl-D
22 C2-0
23 C3-0
24 C4-D
25 Fluoranthene
26 Pyrene
27 B«ni (a) anthracene
28 Chrysen*
29 Benzo(b)f luoranthene
30 Benzo(k)f luoranthene
31 Benzo(e)pyrene
32 Benzo(a)pyrene
33 Perylene
34 Bis (2 ethylhexyl)phthalate
35 Indeno(l,2,3-CD)pyrene
36 Benzo(g,h, i,)perylene
37 Dibenz(a,h)anthracene
Total
Total iinus |34
X = Present, but below detection
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
48.5
D
0
0
48.5
0
lii it of
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4.4
0
0
0
4.4
0
7
0
0
0
0
0
0
0
0
0
0
0
0
0
0.1
0
0
0
0
0
0
0
0
0
0
0.2
0.1
0
0
0
0
0
0
0
11
0
0
0
12.
D.
approximately
8
0
0
0
0
0
0
0
0.1
0.4
0
0
0
0
3.4
0.9
0.8
0
0
0
0.1
0
0
0
0
5.3
3.5
1.4
2.8
0.8
0.1
0.1
0.1
0
.7 6.9
0
0
0
.1 28.7
4 20.2
0.05 ug/L
11
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
X
X
X
0
X
X
0
0
8.3
0
0
0
8.3
0.1
12A
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
8.1
0
0
0
6.1
0
12B
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
6.1
0
0
0
6.1
1
Blank
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
30.6
0
0
0
30.6
0
7.7
-------
TABLE 7.6
CONCENTRATIONS (nq/L) OF SATURATE HYDROCARBONS IN THE
SURFACE MICROLAYER OF CHESAPEAKE BAY, OCTOBER 1987
Station f
Conpound
1 Decane
2 Undecane
3 Dodecane
4 Tridecane
5 Tetradecane
6 Pentadecane
7 Hexadecane
8 Heptadecane
9 Pristane
10 Dctadecane
11 Phytane
12 Nonadecane
13 Eicosane
14 Henicosane
15 Docosane
16 Tricosane
17 Tetracosane
IB Pentacosane
19 Hexacosane
20 Heptacosane
21 Octacosane
22 Nonacosane
23 Triacontane
24 Hentriacontane
25 Dotriacontan*
26 Tritriacontana
27 Tetratriacontane
28 DTP
29 Isopronoid 1360
30 Farnesane 1470
31 Isopronoid 1650
Total
Mean for Al 1 Stations
2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.9
0.1
2.1
0.0
0.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
3.9
3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.3
0.2
0.7
0.3
1.9
0.2
4.5
0.3
2.4
0.0
0.2
0.0
0.0
0.0
0.0
0.0
11.0
23.7
7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.4
0.5
0.0
1.2
1.1
2.3
5.5
9.8
11.8
10.7
7.8
4.8
3.2
3.4
1.2
1.8
0.2
0.7
0.0
0.0
0.0
0.0
0.0
66.6
8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.3
0.6
1.9
2.0
4.2
2.1
6.3
1.6
18.3
1.5
10.5
0.4
1.7
0.0
0.0
0.0
0.0
0.0
51.4
11
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.3
0.4
0.4
0.2
0.0
0.0
0.3
0.5
0.2
1.1
0.5
Q.9
0.0
0.2
0.6
0.0
0.0
0.0
0.0
5.7
12A
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.8
0.0
0.9
0.0
0.0
0.0
2.9
0.0
0.0
0.0
0.1
0.3
0.2
0.8
7.0
12B
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.0
0.4
0.4
1.0
0.0
1.1
0.0
0.7
0.0
0.0
0.0
O.D
0.0
0.0
0.0
3.7
Blank
0.0
0.0
0.0
O.D
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
7.8
-------
Pesticide and chlorinated organic compounds analyzed for in the
October samples were largely undetected in surface micro!ayer samples, with
the exception of dieldrin. Dieldrin occurred in all microlayer samples at
concentrations of 1 to 18 ng/L except at Station 2, where it was absent.
7.4 DISCUSSION AND CONCLUSIONS
What is the significance of the surface microlayer contamination
found in Chesapeake Bay and its potential toxicity to fish eggs or other
surface organisms? These results confirm those of the previous study (Hardy
et al., 1987) and indicate that a complex mixture of contaminants (metals,
pesticides, aromatic hydrocarbons) occurs, frequently in high concentrations,
at widely separated sites in Chesapeake Bay. Concentrations are potentially
toxic to surface dwelling organisms (neuston) and floating fish eggs of
species such as the bay anchovy, hogchoaker and others. For example, despite
recent legislation limiting its use, the concentrations of organotin found
in the microlayer of Chesapeake Bay (about 1000 ng/L at Stations 3 and 8) are
very high. For comparison, previous data (Batiuk, 1987) indicates that TBT
levels in the bulkwater of Chesapeake Bay are highest near Annapolis, where
mean concentrations are 99 to 121 ng/L. TBT concentrates in the microlayer
where it may be transported laterally. Similarly high concentrations of TBT
(24 to 3,620 ng/L) occur in the microlayer near Devon and Cornwall, England
(Cleary and Stebbing, 1987). Floating fish eggs, larvae, or other neuston
are likely to be negatively impacted by the complex mixture of contaminants
found at many sites in Chesapeake Bay.
Our research in Puget Sound suggested that toxicity to pelagic fish
eggs and other organisms resulted from a complex mixture of contaminants,
with no single compound or group of compounds responsible for the overall
toxicity [Hardy et al., 1988a (in press)]. We do not yet have toxicity
measurements for Chesapeake Bay microlayer. To obtain a relative measure of
toxicity we entered data from this study into our microlayer toxicity model
[Hardy et al., 1988b (in press)]. We used the mean concentrations for all
stations measured (i.e., total of five metals = 235 /*g/L, pesticides and
other organics = 15.9 /tg/L, aromatic hydrocarbons = 3.5 /*g/L, and saturate
hydrocarbons = 24.0 M9/U- The results of the modeling exercise suggest
7.9
-------
surface contamination in Chesapeake Bay may be responsible for an average
reduction in the survival of neuston, including the hatching success of
pelagic fish eggs, by an average of 50 to 65 percent Predicted toxicity
would be considerably higher at Stations 3, 7 and 8, where few if any
organisms would survive contact with the microlayer for more than a few
hours. This estimate, based on a limited data set, is uncertain, but is
probably conservative because it does not take into account the possible
effects of PCBs or the high concentrations of toxic organotin found in our
samples. A comprehensive study (see Sections 3.0 and 4.0), including
simultaneous measurements of toxicity and concentrations of contaminants,
should be conducted in Chesapeake Bay.
7.10
-------
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Zaitsev, Y.P. 1971. Marine neustonology. Acad. Sci. Ukr. SSR. (Trans.
from Russian). National Marine Fisheries Service and the National
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8.7
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APPENDIX A—KEY WORDS
A.I
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APPENDIX A—KEY WORDS
A review of two major databases was considered for this study. The larger
review was undertaken using the DIALOG database. BIOSIS provided the
greatest number of responses, and was used for the search. The key words
were: Surface Layer, Chesapeake, Neuston, Pleuston, Ichthyoplankton,
Microlayer.
The combined number of references evaluated were 851 for Chesapeake, and 144
for Ichthyoplankton. Neuston returned 171 references for cross checking.
Combinations were evaluated for review, and abstracts were requested on
appropriate documents. A typical citation is given in the following
example:
11/4/4
FN-DIALOG BIOSIS Previews File 5
AN- 0014184733
AN- 77017717
TI-VERTICAL DISTRIBUTION OF 1ST STAGE LARVAE OF THE BLUE
CRAB CALLINECTES-SAPIDUS AT- THE MOUTH OF CHESPAEAKE BAY USA.
AU- PROVENZANO A 0 JR; MCCONAUGHA J R; PHILIPS K B; JOHNSON D F; CLARK J.
CS- DEP. OCEANOGRAPHY, OLD DOMINION UNIV., NORFOLK, VA 23508, USA.
JN- ESTUARINE COASTAL SHELF SCI
VO-16 (5). 1983. 489-500
CO- ECSSD
LA- ENGLISH
SF- BA
AB- The vertical distribution of stage I blue crab larvae, near the mouth of
Chesapeake Bay, was examined over 4 diurnal cycles. Each of 2 stations was
occupied for 30 h twice during the summer of 1979. On each of the 4 cruises,
peak larval abundance occurred after a nighttime high slack tide, suggesting
a synchronized hatch of blue crab larvae. Of all larvae collected, 90-99%
A.2
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were taken in the neuston layer. The apparent timing of the hatches to
coincide with the beginning of an ebb tide and the concentration of larvae
in the neuston layer strongly suggests seaward transport of these early stage
larvae and the probability of offshore development.
DE- NEUSTON LAYER SEAWARD TRANSPORT EBB TIDE HATCHING OFFSHORE DEVELOPMENT
CC- *07508 Ecology; Environmental Biology-Animal *07510 Ecology;
Environmental Biology-Oceanogr. & Limnol. *07512 Ecology; Environmental
Biology-Oceanography *16504 Reproductive System-Physiology and Biochemistry
*64054 Invertebrata, Comparative and Experimental Morphology, Physiology and
Pathology-Arthropoda-Crustacea
CC- 07200 Circadian Rhythms and Other Periodic Cycles 07517 Ecology;
Environmental Biology-Water Research and Fishery Biology (1969-1984) 12100
Movement (1971- )
BC- 75112 Malacostraca
BC- Animals; Invertebrates; Arthropods; Crustaceans
As shown in the above example, the BIOSIS abstract proved to be the most
complete for our purposes. In addition a search was done on the CHESSEE
database located in the EPA computer. Similar key words were used to search,
and this was checked against the larger and apparently more complete database
provided by BIOSIS. Pleuston was not used in the CHESSEE search, but the
key word "slick" was. There were not significant differences in the results
of the search procedure.
A.3
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APPENDIX B—PERSONS CONTACTED
B.I
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APPENDIX B--PERSONS CONTACTED
Discussions were held with the following individuals concerning the neuston
of Chesapeake Bay and the potential utility of different organisms for
toxicity tests.
Birdsong, Ray. Department of Biological Sciences, Old Dominion University,
Norfolk, Virginia.
Brun, Bert. U. S. Fish and Wildlife Service, Annapolis, Maryland.
Castagna, Michael. Virginia Institute of Marine Science, Wachapreague,
Virginia.
Cronin, Tom. Department of Biology, Univ. of Maryland, Keatonville,
Maryland.
Corps of Engineers, Baltimore District, Baltimore Maryland.
Corps of Engineers, Phildelphia District, Philadelphia, Pennsylvania.
Grant, George. Virginia Institute of Marine Science, Gloucester Point,
'Virginia.
Houde, Edward. University of Maryland, Chesapeake Biological Laboratories,
Solomons, Maryland.
Ingebritson, W. G. S. Natural Resources Research, Portland, Oregon.
Lippson, Robert. National Marine Fisheries Service, Biological Laboratory,
Oxford, Maryland.
Long, Edward. National Oceanic and Atmospheric Administration, Ocean
Assessment Division, Seattle, Washington.
Mihursky, Joseph. Chesapeake Biological Laboratory, Solomons, Maryland.
Miller, Paul. Power Plant Reseearch Program, Department of Natural
Resources, Annapolis, Maryland.
Mountford, Kent. Chesapeake Bay Program, Annapolis, Maryland.
Olney, John. Virginia Institute of Marine Science, Gloucester Point,
Virginia, and the University of Maryland, Solomons, Maryland.
Sawyer, Tom. National Marine Fisheries Service, Biological Laboratory,
Oxford, Maryland.
Sulkin, Steve. Western Washington State University, Shannon Point Marine
Laboratory, Anacortes, Washington.
Watson, Jay. U. S. Fish and Wildlife Service, Portland, Oregon.
B.2
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