2.
CHROMIUM CONCENTRATIONS IN TUNICATES (UROCHORDATA: ASCIDIACEA)
TAKEN NEAR MONTEREY, CALIFORNIA; RELATION TO LOCAL SEWAGE
OUTFALLS
HENRY HOWARD STIBBS
Hopkins Marine Station of Stanford University, California
Ascidians are known to concentrate such heavy metals as
titanium, vanadium, niobium, and chromium in levels that tremen-
dously exceed the concentrations of these elements in the surround-
ing seawater (Webb, 1939; Bertrand, 1950; Carlisle, 1958; Le-
vine, 1962). Chromium is a common constituent of industrial
sewage, and it may at times constitute part of domestic sewage.
Monterey, Bay, California, has a number of both industrial and
domestic sewage outfalls. Using atomic absorption spectropho-
tometry, a study was made of the chromium content of ascidians
living in the Monterey area to determine the chromium levels
present in different species and to see whether intraspecific
variations in chromium content might be correlated with the lo-
cations of selected sewage outfalls.
MATERIALS and METHODS
Eighteen species of ascidians were taken from the follow-
ing four locations near Monterey: the floats at the marina in
Monterey harbor; the rocky shore by the Hopkins Marine Station
in Pacific Grove; the rocky shore at Point Pinos, Pacific
Grove, 50 to 100 feet from the opening of the city sewage outfall;
and the rocky shore south of the mouth of the Carmel River,
2
500 to 1000 feet from the opening of the city of Carmel
sewage outfall. No ascidians were found living less than 50 feet
from the Pacific Grove outfall and 500 feet from the Carmel
outfall, although the rocks nearer to the outfalls appeared,
but for the sewage, very suitable for ascidian habitation.
Living solitary and colonial ascidians were picked clean
of gross extraneous material and placed in finger bowls
filled with millipore-filtered seawater to allow the gut to
clear. The water was changed 2-3 times daily and the bowls
maintained at about 14°0. The intestines of the ascidians were
usually empty of feces within 48 hours, but some of the smaller
ascidians (e.g., Clavelina huntsmani) closed their siphons in
filtered seawater and never thoroughly evacuated. The large
solitary ascidians (e.g., Styela, Ciona, and Ascidia) gener-
ally proved much hardier than the smaller colonial species.
After the ascidians were removed from the filtered seawater,
all external adhering material was picked and scraped from
the tunics as thoroughly as possible. An approximate wet
weight was obtained, then the ascidians were either chopped up
by hand or ground for several minutes in a Waring blendor. The
chopped or ground samples were placed in 50 ml beakers and
dried for 12-18 hr at 110°C to constant weight. A dry weight
(to the nearest mg) was obtained for each sample. Samples were
then ashed in a muffle furnace at 450°C for 8-12 hrs (24 hrs
at 475°C for some samples, see Table 1) and weighed again.
Aliquots of the ashed samples (usually O.5 g) were taken,
weighed (to the nearest mg) in 15 ml beakers, and 3 ml of aqua
261
regia were added to each beaker. Samples were heated to
dryness over a steam bath. Next, 2-3 ml of cold, concen-
trated (30%) hydrogen peroxide were added to each beaker, and
the samples were again completely evaporated over a steam bath.
Finally, 3 ml of aqua regia were added to each sample and this
evaporated as before. All samples contained distinct crystals
of digested material at this time.
Samples were redissolved in 10 ml of O.1 N HCl (prepared
with deionized distilled water). This solution was poured
into a 50 ml beaker. An additional 10 ml of the O.1 N HCI
was used to rinse the 15 ml beaker, and this was also added
to the 50 ml beaker. This 20 ml of solution, which often
contained considerable undigested material, was filtered through
5 Whatman filter paper to remove macroscopic suspended mater-
ial and larger pieces of sand and unidentified micaceous grit.
An additional 5 ml of O.1 N HCl was used to rinse the 50 ml
beaker and was filtered with the rest of the sample.
The 25 ml of filtrate representing each sample was col-
lected in a 50 ml Erlenmeyer flask and tested for chromium
using a Perkin-Elmer Model 303 atomic absorption spectropho-
tometer equipped with a three-slot burner head and an air-
acetylene flame. The detection limit of this instrument is
about 0.004 ppm chromium and the sensitivity (concentration
needed to produce 1% absorption) was sometimes as great as
0.0713 ppm chromium. Standard solutions, containing 1, 5, 10,
15, and 20 ppm chromium, were made up using a Beckman stock
solution of 1000 ppm chromium (prepared especially for atom-
ic absorption procedures), diluted with the same O.1 N HCI
solution that was used in making up the samples. Working
curves, showing absorbance (derived from per cent absorp
tion) plotted against ppm chromium, were used in determining
concentrations of chromium in the samples. Appendix 1 shows
one of the working curves obtained from the chromium standards.
Fresh standard solutions were made up and tested prior to ana-
lysing each group of ascidian samples. Since each 0.5 g ashed
aliquot was dissolved in 25 ml of solution, the sample concen-
trations read off the working curves were multiplied by 50 in
order to obtain values in parts per million per gram of ash.
Since glassware at the Hopkins Marine Station is cleaned
with a solution of potassium dichromate and sulfuric acid,
all of the beakers, flasks, and pipets used in these experi-
ments were submerged in a solution of concentrated nitric and
sulfuric acids for 15 minutes, then rinsed 6 times with tap-
water, in order to prevent any chromium contamination.
Control samples were prepared and tested for chromium to
ascertain that no contamination was occurring at any stage of
sample preparation. Tapwater, deionized water,aand the O.1 N
HCl (the "blank") were all tested with the spectrophotometer
and found to lack chromium. A 50 ml beaker was spared the usual
washing with concentrated acid and filled with 25 ml of the
0.1 N HCl; this control, which might have shown contamination
resulting from the washing procedure at the Hopkins Marine
Station, also exhibited no chromium content when tested. One
beaker was run through the gamut of sample preparation proce-
dures and found to contain no chromium. Finally, the aqua re-
2d
gia was tested and it, too, showed a lack of chromium.
Neither the acid solution used in washing the glassware
nor the concentrated hydrogen peroxide were run through
the spectrophotometer, however.
Samples of sewage effluent were obtained from local
sewage treatment plants (Monterey, Pacific Grove, and Car-
mel) and analysed for chromium using the method of additions.
In this procedure, matrix interference is obviated by adding
increasing amounts of chromium to a series of sewage samples;
the atomic absorption readings are plotted against the
chromium additions (Figures 1-4), and the line connecting
the points extrapolated to the abscissa. The distance of
this intersection to the left of the zero point of additions
on the abscissa represents the chromium concentration in the
unadulterated sample.
RESULTS and DISCUSSION
Monterey sewage sampled on May 29, 1970, contained
approximately 0.008 ppm of chromium (Figure 1). No chromium
was detected in the sewage effluents of Pacific Grove and
Carmel (Figures 2 and 3). Seawater taken from the east shore
of the Hopkins Marine Station in Pacific Grove contained
0.095 ppm of chromium (Figure 4). The open ocean contains
about 0.00005 ppm of chromium (Goldberg, 1963).
Chromium levels found in the eighteen species of ascidians
tested are tabulated in Appendix 2 and summarized in Table 1.
The ascidians tested contained chromium levels (ppm dry weight)
2
015
.010
.005
O.00
FIGURE
Chromium Content of Monterey Sewage
.008
CI
Added

ppm
20
01
.010
9
005
0.00
FIGURE 2
Chromium Content of Pacific Grove Sewage
CI
Added ppm
6
.015
o.010
.005
0.(
FIGURE
Chromium Content of Carmel Sewage
CI
Added ppm
20
2
.01
o.010
005
0.00
095
FIGURE 4
Chromium Content of Mussel Point Seawater
C I
Added
p p m
.20
70
at least 31,800 times, and in some species as much as
3,050,000 times, that in seawater in the open ocean. Species
of Synoicum, Ritterella, and Eudistoma were found to contain
the highest levels of chromium. These genera are all members
of the Order Aplousobranchia; this fact is of particular
interest, since the ascidians showing high levels of vanadium
fall mainly in the Order Phlebobranchia (Webb, 1939; Bertrand,
1950). Within Orders and Families of ascidians there is consid-
erable variation in the tendency to concentrate chromium. How-
ever, all samples of Eudistoma species contained relatively
high concentrations of chromium, whereas samples of Amaroucium
species were consistently lower. The levels found in Eudistoma
ritteri (zooids plus tunic) are somewhat lower than those ob-
tained by Levine (1961), who found 72-144 ppm (dry weight) for
whole zooids, and 100 ppm for zooid abdomens only.
It is apparent (Table 1) that chromium levels in ascidians
taken near sewage outfalls were generally lower than those in
ascidians collected in an area considered unpolluted (Mussel
Point, Hopkins Marine Station). In the case of the ascidians
taken from the region of the Carmel outfall (indicated by an
asterisk in Table 1), it is possible that the low levels reflect
a difference in procedure. These animals were prepared in the
same general way as the others, but were ashed for 24 hours
at 475°C instead of the usual 8-12 hours at 450°0, and the
low chromium values here may be due to vaporization of some
chromium-containing component of the ash. Since these values
appear abnormally low, they are not considered further here.
Ascidians living near the Pacific Grove sewage outfall at
7
TABLE 1
Chromium content of Ascidians;
Mean and Range, ppm in Ash
Sampling
Monterey
Point
Hopkins
Location
Marina
Marine
Pinos
Station
Species
Order APLOUSOBRANCHIA
Family SYNOICIDAE
4.0*
Amaroucium californicum
14
12.75
Amaroucium solidum
(11.5-14)
12
8
Polyclinum planum
105
98.7
Synoicum par-fustus
(97.4-100)
10*
85
Ritterella pulchra
61
Ritterella rubra
Family POLYCITORIDAE
6.75
21.5
Clavelina huntsmani
(6.5-7.0)
Cystodytes lobatus
9.
8.5
Distaplia occidentalis
(9.0-10.5
Distaplia smithii
18.66
Eudistoma molle
(17-19.5)
110
162.5
Eudistoma psammion
(150-170)
25.75
30.25
Eudistoma ritteri
3-32.5) (24.5-27)
Carmel
Sewage
Outfall
10.75
(10.5-11)
6*
5.5*
10*
7.25*
7.5*
11.5
6.75*
88.75
(86.5-91)
14.25*
27
TABLE 1
(continued)
Hopkins
Sampling
Monterey
Point
Location
Marine
Pinos
Marina
Station
Species
Order PHLEBOBRANCHIA
Family ASCIDIIDAE
Ascidia ceratodes
9.5-12.5
Family CIONIDAE
6.75
Ciona intestinalis
(6.5-7.0
Family PEROPHORIDAE
Perophora annectens
Order STOLIDOBRANCHIA
Family BOTRYLLIDAE
12.8
Botrylloides sp.
9.5-17.0
Family STYELIDAE
4.
Styela montereyensis
(4-5)
* Denotes samples that were ashed for 24 hours at 475°C inst
the usual 8-12 hours at 450°C.

Carmel
Sewage
Outfall
12.58*
6.1*
ad o
7
7
Point Pinos generally tend to contain less chromium than do those
on Mussel Point by the Hopkins Marine Station. It is possible
that this tendency is due to the higher concentration of chromium
in the seawater off Mussel Point. Water here, however, was not
compared to seawater in other localities. It is also possible
that Pacific Grove sewage effluent has some influence on the
ability of Point Pinos ascidians to concentrate chromium. Al-
though it has been shown to lack detectable amounts of this
heavy metal, Pacific Grove sewage effluent flows into the ocean
as fresh water 1-2°C warmer than the seawater at Point Pinos.
Furthermore, in the period of the present study this sewage
at the outfall itself was found to contain residual chlorine
levels up to 45 ppm. Perhaps one or more of the components of this
sewage lowers the chromium-concentrating capacity of the Point
Pinos ascidians. Another possibility is that the plankton con-
sumed by the ascidians is being affected by the sewage. While
the exact mechanism by which ascidians concentrate heavy metals
is still debatable, it has been suggested that since chromium
exists in such low concentrations in the open ocean, ascidians
may acquire this metal in a preconcentrated form in their
plankton meals (Levine, 1962).
SUMMARY
1. Eighteen species of ascidians taken near Monterey, Cal-
ifornia, were analysed for chromium content using atomic absorp-
tion spectrophotmetry.
2. The highest values (ppm dry weight) were found in the
genera Eudistoma (E. psammion, 152.5; E. ritteri, 25.6; E.
molle, 15.0), Synoicum, (Synoicum par-fustus, 83.6), and
Ritterella (R. pulchra, 69.6; R. rubra, 45.2). All are mem-
bers of the Order Aplousobranchia. The lowest value was ob-
tained in Styela montereyensis (1.59 ppm dry weight). Seawater
taken by the Hopkins Marine Station yielded a value of 0.095
ppm.
3. The chromium content of ascidians found near local
domestic sewage outfalls was often lower than that of ascidians
found in less polluted areas. The chromium concentration in
three different samples of domestic sewage effluent (ranging
from 0.000 to 0.008 ppm) was much lower than that in seawater
from Monterey Bay.(0.095 ppm).
LITERATURE CITED
Bertrand, D., 1950. Survey of Contemporary Knowledge of
Biochemistry, 12: The Biochemistry of Vanadium. Bul-
letin of the American Museum of Natural History. Vol.
29: Article 7, New York.
Carlisle, D. B., 1958. "Niobium in Ascidians," Nature,
181:933.
Goldberg, E. D., 1963. "The Oceans as a Chemical System,
p. 3-25. In M. N. Hill (ed.), The Sea, Vol. 2. Inter-
science.
Levine, E. P., 1962. "Studies on the Structure, Reproduc-
tion, Development, and Accumulation of Metals in the
Colonial Ascidian Eudistoma ritteri Van Name, 1945,
Journal of Morphology, Vol. 111, No. 2.
D. A., 1939. "Observations on the blood of certain
Webb,
ascidians, with special reference to the biochemistry
of vanadium," Journal of Experimental Biology, 16:499-
523.
FOOTNOTES
1. This work was supported in part by the National
Science Foundation Undergraduate Research Program, Grant
+GY-7288. The author wishes to express his gratitude to
Dr. Donald P. Abbott, under whose guidance this work was
carried out; and to acknowledge with appreciation his gen-
erous help with identification of species and arrangement
and discussion of data.
1.0
0.9
0.8
0.7
Ouos
0.5
8
o
0.4


0.3
0.2
0.1
0.0
20
CHROMLUM
A PPEN
WORKING
URN
15
RO MI UM
7
Species
Location
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Amaroucium
califor¬
nicum
Hopkins
11.9g
1.083g
1.083
.551g
.5g
4
2.03
.184
APPE NDIX 2
ASCIDIAN SAMPLES
Amaroucium
Amaroucium
califor¬
califor¬
nicum
nicum
Carmel
Point
Outfall
Pinos
18g
25.2g
2.158g
1.648g
2.Og
1.648g
1.464g
.775g
5g
5g
10.5
14
7.7
6.6
.66
.605
Amaroucium
califor¬
nicum
Carmel
Outfall
24.7g
2.159g
2.Og
1.445g
.5g
11
7.95
.695
Amaroucium
solidum
Hopkins
43.3g
3.75g
2.Og
1.591g
.5g
14
7.96
6.87
279
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Synoicum
par-fustus
Hopkins
42.9g
2.740g
2.Og
1.674g
.5g
100
83.6
5.35
SAMPLES
Synoicum
Synoicum
par-fustus
par-fustus
Point
Hopkins
Pinos
43.5g
6.1g
2.762g
1.086g
2.Og
1.086g
1.691g
.847g
.5g
.5g
97.4
105
82.3
82
5.23
14.6
Synoicum
par-fustus
Carmel
Outfall
40.8g
7.207g
7.207g
5.768g
5g
5.5
4.4
.78
Ritterella
pulchra
Hopkins
2.8g
.311g
.311g
.206g
.201g
10
6.62
.735
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Ritterella
pulchra
Point
Pinos
36.2g
4.038g
4.038g
3.306g
.5g
85
69.6
7.8
SAMPLES
Ritterella
Ritterella
rubra
rubra
Carmel
Point
Outfall
Pinos
15.7g
12.1g
2.127g
1.635g
1.635g
2.127g
1.574g
1.081g
.5g
.5g
10
61
45.2
6.62
6.14
.895
Clavelina
huntsmani
Hopkins
25.8g
1.274g
1.274g
.840g
5
21.5
14.2
.703
Clavelina
huntsmani
Hopkins
42.6g
2.105g
2.105g
1.617g
5g
21.5
16.5
1.3
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Amaroucium
solidum
Hopkins
43.2g
3.143g
2.Og
1.55g
.5g
11.5
8.91
6.49
SAMPLES
Amaroucium
Amaroucium
solidum
solidum
Carmel
Point
Outfall
Pinos
23.9g
59.6g
1.531g
3.835g
1.531g
3.835g
1.103g
.862g
.5g
.5g
77
6
2.05
3.37
.216
.132
Polyclinum
planum
Hopkins
107.7g
3.437g
2.Og
1.176g
5g
12
7.05
.137
Polyclinum
planum
Point
Pinos
———
1.340g
1.340g
.683g
.5g
8
4.07g
————
Species
Location
Weight
Dry
Weight
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Eudistoma
molle
Hopkins
51.6g
5.601g
2.Og
1.473g
.5g
17
12.5
1.36
SAMPLES
Eudistoma
Eudistoma
molle
molle
Hopkins
Hopkins
53.1g
55.8g
5.806g
5.118g
2.Og
2.Og
1.491g
1.545g
5g
.5g
19.5
19.5
14.5
15
1.58
1.37
Eudistoma
ritteri
Hopkins
53.0g
3.917g
2.Og
1.408g
.5g
32.5
25.6
1.88
Eudistoma
ritteri
Hopkins
55.7g
4.007g
2.Og
1.462g
5g
28.0
20.5
1.48
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Or per
gm. Wet Wt.
Eudistoma
psammion
Hopkins
45.3g
10.533g
2.0g
1.783g
.5g
167.5
149.5
34.8
SAMPLES
Eudistoma
psammion
Hopkins
44.4g
12.066g
2.Og
1.808g
.5g
150
135.5
36.8
Eudistoma
psammion
Hopkins
40.8g
8.500g
2.Og
1.791g
.5g
170
152.5
31.7
Eudistoma
psammion
Point
Pinos
25.Og
3.684g
3.684g
3.ooog
5g
110
74
10.9
Eudistoma
psammion
Carmel
Outfall
39.6g
7.739g
2.Og
1.794g
.5g
91
81.7
15.9
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Distaplia
occident¬
alis
Hopkins
48.9g
3.4833
2.Og
.699g
.5g
9
3.14
.224
SAMPLES
Distaplia
Distaplia
occident¬
ocident
alis
alis
Point
Hopkins
Pinos
49.6g
62.2g
3.769g
5.427g
2.Og
5.427g
.669g
3.761g
.5g
.5g
9
8.5
3.01
5.9
.514
.229
Distaplia
occident¬
alis
Carmel
Outfall
39.6g
3.443g
2.Og
.939g
.5g
11.5
5.39
.468
Distaplia
smithii
Carmel
Outfall
29.5g
2.072g
2.072g
.858g
.5g
6.75
2.8
.197
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Clavelina
huntsmani
Point
Pinos
49.2g
2.426g
2.426g
1.802g
.5g
6.5
4.83
.238
SAMPLES
Clavelina
Clavelina
huntsmani
huntsmani
Carmel
Point
Outfall
Pinos
11.6g
52.2g
.573g
2.575g
.573g
2.575g
1.975g
.314g
.310g
.5g
7.25
5.37
3.97
.196
.265
Cystodytes
lobatus
Carmel
Outfall
25.7g
1.604g
1.604g
.759g
.5g
7.5
3.55
.222
Distaplia
occident¬
alis
Hopkins
49.5g
3.367g
2.Og
.682g
5g
10.5
3.58
.243
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
eight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Eudistoma
ritteri
Point
Pinos
41.5g
3.Og
2.Og
1.184g
.5g
27
16
1.15
SAMPLES
Eudistoma
Eudistoma
ritteri
ritteri
Point
Carmel
Pinos
Outfall
23.6g
45.1g
2.635g
3.5g
2.635g
2.Og
1.206g
1.723g
.5g
.5g
24.5
14.25
14.8
9.33
1.13
1.04
Ascidia
ceratodes
Monterey
Marina
36.7g
———
2.Og
.871g
.5g
12.5
5.94
————
Ascidia
ceratodes
Monterey
Marina
35.9g
———
1.Og
.469g
.469g
9.5
4.46
———
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
SAMPLES
Ciona
Ciona
Ciona
Ciona
Perophora
intestinalisintestinalis
intestinalisintestinalis annectens
(tunics
(w/o tunics
Monterey
Monterey
Monterey
Monterey
Carmel
Marina
Marina
Marina
Marina
Outfall
20.3g
8.1g
53.9g
37.7g
47.2g
0.950g
2.032g
1.273g
1.675g
0.768g
2.0g
1.Og
1.Og
0.579g
0.871g
0.467g
0.270g
0.485g
0.5g
0.5g
0.267g
0.467g
0.485g
6.5
7.0
44.9
12.58
5.61
3.96
3.04
12.1
2.72
7.65
0.284
0.185
0.41
0.124
0.097
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Botryl¬
loides
sp.
Monterey
Marina
7.8g
.547g
.547g
.210g
.206g
17
6.55
.218
SAMPLES
Botryl-
Botryl-
loides
loides
sp.
sp.
Monterey
Monterey
Marina
Marina
53.3g
53.3g
4.020g
4.020g
1.Og
2.Og
1.184g
706g
5g
.482g
9.5
11.9
8.4
5.62
.632
.423
Styela
monterey-
ensis
Monterey
Marina
42.9g
2.146g
2.Og
.808g
5g
1.62
.81
Styela
monterey-
ensis
Monterey
Marina
48.1g
2.370g
2.Og
.794g
.5g
1.59
.0785
Species
Location
Wet
Weight
Dry
Weight
Dry
Aliquot
Ashed
Weight of
Dry Aliquot
Ashed
Aliquot
Ppm Cr per
gm. Ash
Ppm Cr per
gm. Dry Wt.
Ppm Cr per
gm. Wet Wt.
Styela
monterey-
ensis
Monterey
Marina
48.5g
2.443g
2.Og
.783g
.5g
5
1.96
.095
SAMPLES
Styela
Styela
monterey-
monterey.
ensis
ensis
Monterey
Carmel
Marina
Outfall
17.3g
51.6g
1.978g
2.650g
1.978g
2.Og
.514g
.791g
.5g
.492g
5
6.1
1.98
1.59
.11
.182
29