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DUES IN I
PCB and DDT
ISHES OF ELKHORN SLOUGH
AND THE PAJARO RIVER, CALIFORNIA
By W. D. Koenig
Hopkins Marine Station of Stanford University
Pacific Grove, California
Since 1967, when polychlorinated biphenyls (POB's
were first identified in animal residues (1,2), there
increasing concern about PCB concentrations in
has bee
the environment. Efforts to measure these concentrations
have been considerably complicated by the complex nature
of POB's, which are not a single group of analogs but a
series of isomers with varying degrees of chlorination
Until recently, quantification of POB's using gas
liquid chromatography has been made by assuming identical
response of the electron-capture detector for all isomers
and using either p,p'-DDE (3) or commercial PCB mixtures
(Aroclors) as standards (4,5). Rote and Murphy (6),
showed that the detector response varies according to
the degree of chlorination of the individual isomer. By
semi-logarithmically plotting the total ine/ng from the
chromatograms of six different Aroclors against their
average chlorine content they formulated a response
curve from which the absolute values of specific POB
isomers can be estimated. Using this technique, POB
214
levels were determined in fishes from Elkhorn Slough and
the Pajaro River, California. DDE, DDD, and DDT residues
were also quantified and their combined values compared
to the total POB content.
METHODS
Elkhorn Slough and the Pajaro River both drain
agricultural lands in the Monterey Bay area. They
empty into Monterey Bay near Moss Landing (Fig. 1) and
are both susceptable to considerable salt water intrusion
from the bay. Staghorn sculpin (Leptocottus armatus),
shiner perch (Cymatogaster aggregata), and leopard sharks
(Tr
akis semifasciata) were seined and gill netted in
Elkhorn Slough at Kirby Park (A). A starry flounder
(Platichthys stellatus) was obtained from near the Moss
Landing marina (B). All fishes from the Pajaro River
including top smelt (Atherinop:
finis), and striped bass
(Roccus saxatilis) were gill netted about one mile from
the mough (C).
Samples were either dissected soon after capture or
frozen and stored until ready for analysis. Three liver
and two flesh samples were analyzed from the leopard
sharks; all other samples were single preparations of
flesh or whole fish. Tissues were digested in a
perchloric-glacial acetic acid mixture, extracted with
hexane, and evaporated to dryness. The fat residue was
weighed and then cleaned by acetonitrile partitioning
followed by elution with 6% diethyl ether through a
florisil column (7). The resulting mixture of pesticides
and PCB's was evaluated by gas liquid chromatography
for the approximate DDE content and an aliquot containing
no more than 20 ug was concentrated down to 5 ml. for
separation. This involved elution by petroleum ether
through a column packed with specially treated silicic
acid following the method of Armour and Burke (8). POB
residues are eluted with the first 250 ml. of runoff
DDE and other pesticide residues remain in the column and
can later be recovered using a methylene chloride-hexane¬
acetonitrile mixture (80-19-1). As some difficulty in
separation was frequently encountered, the last 30 ml.
of petroleum ether eluate was collected in 10 ml. fractions
and tested for early DDE runoff before it was added back
to the original 220 ml. All eluates were concentrated to
appropriate levels for analysis by gas liquid chromatography
employing identical equipment and operating conditions
used by Rote and Murphy (6). Peak area was measured by an
automatic disc integrator and quantitated according to
detector response.
In order to adjust for variations in machine sensitivity,
standards of Aroclor 1232 and 1260 were injected soon before
or after the samples. The total peak area in in/ng from
these two standards was plotted semi-logarithmically against
2/6
O
the average number of chlorine atoms per molecule in the
mixture. This average is known from the Aroclor number:
1232 contains 32% chlorine by weight or an average of two
chlorines per molecule; 1260 contains 60% chlorine by weight
or an average of six chlorines per molecule. A straight
line was drawn through these two points from which
detector response levels for any given isomer with a known
number of chlorine atoms could be determined. Chlorine
content of specific isomers was determined whenever
possible by comparison with the mass spectometry work
of other investigators (4,9,10). Peaks not previously
identified were assumed to contain the same number of
chlorines as peaks having approximately the same retention
time. Each isomer found in a chromatogram was quantified
individually and summed to obtain a value for total PCB
content.
RESULTS
A total of thirty-nine different peaks were resolved
in
ifteen samples. Thirty-two of these correspond to
those identified by Rote and Murphy in their analysis of
Aroclor standards and were numbered identically 1 to 32 (6).
Seven additional peaks were detected and designated by the
number of the peak preceding it plus a letter. Five of these
peaks (7A, 9A, 19A, 27A, 27B) had retention times between
two POB compounds with equal numbers of chlorine atoms and
were evaluated by using the response curve value appropriate
for the two surrounding isomers. Peak 31A was located
2/
between a nonachlorobiphenyl and a decachlorobiphenyl.
Since only one decachlorobiphenyl isomer is possible it
was evaluated as having nine chlorine atoms. The degree
of chlorination of the compound corresponding to peak 32A
could not be inferred from its retention time and was
not included in total POB content. Retention times
relative to p,p'-DDE and the known or approximate degree
of chlorination for each isomer are given in Table I.
Results calculated in total PCB and total DDT residue
content in both fat and whole tissue are listed in Table II.
Fig. 2 compares the residue levels (ppm whole tissue weight)
found in the three species of fish that were sampled from
both rivers. Both POB and DDT levels strongly suggest
that fishes in the Pajaro are concentrating more
polychlorinated residues than the same fishes in Elkhorn
Slough, though this data become somewhat confused depending
on whether values referring to ppm of lipid or total tissue
weight are examined.
A rough correlation of residues in whole tissue weight
to the approximate trophic level on which the fishes from
the Pajaro River feed (11) is shown in Fig. 3. Except for
the high values found in the top smelt, a primary carnivore
the total PCB content shows a distinct upward trend while
the DDT values exhibit only minimal correlation.
After individual quantification, the POB isomers were
divided into ten groups according to their degree of
/8
chlorination. In order to judge the relative amounts of
each group accounting for the total POB's, each is listed
in Table III in percentage of total POB content. Further
analysis, made by adding up the percentages of mono, di,
and trichlorobiphenyls present in the sample fishes from
the Pajaro River show the slight inverse relationship to
the idealized trophic levels of the fishes shown in Fig. 4.
Samples run on shiner perch roe from Elkhorn Slough
and on top smelt eggs from the Pajaro River show opposite
trends for the initial residue levels passed on by these
species to their young. Both POB's and DDT were concentrated
over 2-fold in the shiner perch roe compared to the levels
found in the adult flesh while both were present in only
one-half the concentration of the adult flesh in top smelt
eggs.
Particularly interesting are the results on the three
leopard shark livers and two flesh samples. All livers
show higher levels of DDT than POB's with a ratio averaging
2.91. In contrast, flesh samples from the same sharks
show DDT/POB ratios approximating those values found in all
other samples where either whole fish or flesh was analyzed,
Absolute values for DDT and POB residues (ppm in lipid) in
the shark livers, shark flesh, and the average of the three
other flesh samples from Elkhorn Slough are shown in Fig. 5.
The breakdown of the total DDT residue levels into DDE,
DDD, and DDT percentages is found in Table IV.
219
DISCUSSION
Holmes (2), Risebrough ét al (12), Koeman et al (4),
and Rote and Murphy (6) all found the higher chlorinated
POB's to be predominant in organisms high up in food
chains such as fish, sea birds, and a sea otter. Jensen et al
(13) and Koeman et al (4) both present evidence which
indicates that there is significant breakdown of the lower
chlorinated PCB's as they pass through biological systems.
Though lower chlorinated POB's were found in all samples
the trend shown in Fig. 4 indicates breakdown among these
compounds relative to the total POB content as one goes
from the primary carnivore (top smelt) to the tertiary
carnivores (striped bass and starry flounder). This
finding substantiates the evidence of Jensen and of Koeman.
DDT/POB ratios have been studied extensively by
Risebrough et al (14). Their findings showed a regional

fallout pattern in the DDT/PCB ratios with low values
between one and two being found in birds around San Francisco
Bay and increasingly higher ratios being found in birds
ogressively further from industrialization. DDT/POB
living pr
ratios from.4 to .8 have been recorded by Presst and
Jeffries in great crested grebes from the British Isles
(15). In marine animals along the west coast of Sweden
the DDT/POB ratios were found to be as low as .15 (13).
From these data Peakall and Lincer (16) suggest that POB's
206
C
are not as easily transported to remote areas as are DDI
residues and thus the DDT/PCB ratio tends to be lower the
closer one comes to industrial centers. Findings reported
here do not contirm this hypothesis. Both the Pajaro
River and Elkhorn Slough are near relatively little
yet DDT/POB ratios were is general found to be
industr
as low or lower than values reported from industrialized
areas.
In contrast to these findings are the DDT/PCB ratios
found in the liver samples of the leopard sharks. All
three samples have ratios over 1.0 with a mean of 2.91.
T/POB ratios in the flesh of the same specimens, however,
were comparable to those found in the other tissue samples.
As an explanation for this phenomenon, perhaps the
exceptionally high levels of DDT residues concentrated in
the liver tissue affect POB storage such that the DDT/PCB
ratio becomes considerably higher than would otherwise
be expected. This view is substantiated by the absolute
residue concentrations found in the lipid of these samples
which, because of the high fat content of liver tissue,
gives a better relative measure of the residue levels.
Using these values, both PCB and DDT levels in the shark
flesh are seen to be similar to the levels found in the
flesh samples from the other fishes taken from Elkhorn
Slough (Fig. 5). In the liver tissue, however, DDT is far
more concentrated than in any of the other fish samples
O
while POB content is slightly below those levels found
in either the tissue samples from the same sharks or any
of the other tissue samples from the Elkhorn Slough
fishes. A similar effect on dieldrin storage in fish and
rats has been shown to be caused by the presence of DDT
(17,18).
SUMMAR
Samples of fishes from the Pajaro River and Elkhorn
Slough were analyzed for chlorinated hydrocarbon residues.
All DDT/POB ratios for flesh and whole fish samples were
less than 1.2 ; ratios were substantially greater than 1
in leopard shark liver samples. The possibility that the
high concentration of DDT stored in the liver tissue is
ic to POB storage is discussed. The percentage
antagonist:
of total POB content present in combined mono, di, and
trichlorobiphenyls for the five species taken from the
Pajaro River was found to exhibit a slight inverse
relationship to the idealized trophic levels on which these
fishes feed in accordance with findings by Jensen et al (13)
and Koeman et al (4) that breakdown occurs in the lower
chlorinated PCB's as they pass through biological system
POB's more than DDT levels tended to increase in these same
five fishes as one moved up this simplified fraction of a
food chain. Samples from the Pajaro River were compared
to the same species captured in Elkhorn Slough and found
to have significantly greater PCB and DDT concentrations.
23
C

10
ACKNOWLEDGEMENTS
I would like to thank James Rote and Philip Murphy
for providing invaluable aid throughout all phases of
this project.
REFERENCE
1. Widmark, G. 1967. Possible interference by chlorinated
fic. Anal. Chem. 50: 1069.
biphenyls. J. Assoc. C
2. Holmes, D. C., J. H. Simmons, and J. 0. Tatton. 1967.
Chlorinated hydrocarbons in British wildlife. Nature
216: 227-229.
Risebrough, R. W. 1969. Chlorinated hydrocarbons in the
3.
lout, G. G. Berg and
global ecosystem. In: Chemical E
M. W. Miller (Eds.), Charles C. Thomas, Springfield, Ill.,
p. 5-23.
4. Koeman, J. H., M. C. Ten Noever de Brauw, and R. H. de
Vos, 1969. Chlorinated biphenyls in fish, mussels and
birds from the River Rhine and the Netherlands coastal
: 1126-1128.
area. Nature2
71. Pesticide residue analysis in the
5. Reynolds, L. M. 1
presence of Polychlorobiphenyls (POB's). Residue Reviews
34: 27-5
6. Rote, James W. and Philip G. Murphy. A Method for the
quantitation of polychlorinated biphenyl (POB) isomers.
In press.
7. Pesticide Analytical Manual Vol. III, Food and Drug
Administration, Washington, D. C. 1970.
223
10.
and J. A.
Arm
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from DDT
Bipheny
Separat
Polyc
61-
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Anal.
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rom
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bery
Wall
ios,
ancis J.
C
enyls in human adipose tissue.
aed
Poly
hlor
201. 5: 317-3
. Cont
ishes of Califor.
Baxter, John
L. 1966. In
De
t. of Fish and
State of
H.
lott.
e, and
brou
Reid
O
ati
p.
i
the dete
Tox
91. 4
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m. T
nviron. Con
Ott
Jensen, S., A. G. Johnels, S.
om Swedi
ine animal
1969.
T and P
: 247.
Watu
. Peakall,
Reiche,
iseb
lorinated biphen;
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