A Trophic Transfer Factor equals the concentration in an organism expressed
as a percent of the mean sediment concentration. This was related to
gut loading of sediments and/or surface contamination (Table 3). [n
general, snails exhibited highest concentrations in shells and lost 50%
of their plutonium burden when held for 48 hours. The importance of the
gut contribution is best shown in the goldfish data. Plutonium concen-
trations are nearly an order of magnitude less when the gut is isolated.
The uptake by rooted macrophytes not exposed to surface contamination
was quite small:
< 0.03 to 0.1%.
The comparison between emergent plants
sampled above the waterline, and submerged plants was very instructive in
this regard. Concentrations were many orders of magnitude higher in
submerged piants; sorption to surfaces is strongly indicated.
CONCLUSIONS
ili
We believe
our results have shown the utility
of ??7Pu as a laboratory
i
tool to shed light on some of the fundamental
processes occurring in
:
natural aquatic systems.
It is equally obvious that it cannot be used
to answer questions relative to long-term time-dependent phenomena.
Specific plutonium-contaminated aquatic ecosystems must be preserved as
research sites to answer those important questions. Environmenta?
:
be required
studies carried out in a natural ecosystem will ultimately
to validate results of laboratory studies.
Our results suggest that surface phenomena at plant surfaces, on gut
walls, and on exoskeletons appear to dominate in submerged components of
aquatic systems. This is a partial explanation for the higher plutonium
levels found in biota from aquatic versus terrestrial environments as
reported in reviews on the subject.
We also note that trophic transfer
factors for sediment-associated animals in the microcosm study are
comparable to the percentage uptake of plutonium in our gavage work with
channel catfish.
Conmon
name
i
|
Emergent plants
|
Gi
{
1
!
!
{
|
mes
Panicum
a
Spikes
Stem and leaves
nN
3]
«0.11
«0,045
Cateail
°
aes
Typha
Stem and leaves
Stem and leaves
1
1
<0.029
Watercress
Nasturtium
Stem and leaves
?
<0.089
Algae
Oedogeonium
Clumps
Moss
Hygrohypnum
Branches
Stonewort
Pondweed
Chara
,
Potamogeton
Branches
a1
Stem and teaves
gnats
Physa
whole body
|
i
|
|
«0,040
Submerged plants
Gyraulus
Gonfobas{s
terrestrial systems where significant surface contamination occurs
either by atmospheric processes or as a result of periodic inmersion of
floodplains, for example. A major question not addressed by our studies
tim
longer time
biologically available form of plutonium could occur over a longer
nphipod
ayatela
ACKNOWLEDGMENTS
Goldfish
carasstus
We would like to thank J. W. Gooch and C. P. Allen for technical support
Whole body
60
75
0
27.0
.
0.19 + 0.078"
05
.
30
2.42 0.46
63
6421.4
1.52 0.28
13 0-3
30
%
whole body”
Shell
;
9,1
7
Invertebrates
ae
Our results also suqgest that surface phenomena also may predominate in
to date would appear to be whether biochemical transformation to a more
Trophic transfer
factors
Sample
size
Body Part
Genus
b
14
;
Wele body,
;
99
16
75
Whole body
snore poe
:
ie
note body
130
carcasses?
Vertebrate
Carcass-gut
4
Gut
Whole body
4
5.0
sb
36°09)
0.47 (0.16, 0.54
30 (18-91)
2.3 (1.2-8.1
}
‘
4
in gavage studies. We would particularly like to single out M. L. Frank
for work involving plasma protein separation and identification. Finally,
:
of blood-transport proteins and assistance in tissue preparation for
banimals held for 48 hr {n uncontaminated spring water before sacrifice.
H. L. Bergman provided significant input regarding physiological behavior
raeionssey-
500
| if les
95% C.1. (counting error). Not shown f
“geometric means and ranges.
Significant values only.
Table 3.
Tess
than
than
10% of mean.
9
Mean for carcasses based on statistically
Trophic Transfer Factors for Plutonium-237 in Biota of an
Aquatic Microcosm.
50]