ture grass was irrigated almost continuously, while the vegetables were irrigated
freely in the sea water and in a position
to exploit a new food supply. Whether
las fir, elm, hemlock, redwood, western
red cedar, and western yellow pine, were
exposed to healthy Limnoria. Each of
these wood species was attacked within
24 hours at Friday Harbor, and within
2 to 3 hours at Naples. If “conditioned”
wood is unnecessary in laboratory cultures, it is unlikely to be essential in the
sea.
Finally, with reference to observation
(iii), it was reported that Limnoria is
unable to attack sterilized wood (3) and
that animals living in sterilized wood
survive no longer than controls kept without a food source (2). We find that
healthy animals are quite capable of attacking and living in woodsterilized by
autoclaving. In these tests the samesix
species of wood were used and the ani-
mals attacked them all within the same
period of time (24 hours at Friday Harbor; about 2 hours at Naples). In all of
these cases, growing populations were es-
tablished in the absence of marine fungi
(7).
D. L. Ray
D. E. Stuntz
Departments of Zoology and Botany,
University of Washington, Seattle
References and Notes
1. S. P. Meyers and E. §. Reynolds, Sctence 126,
969 (1957).
G. Becker, W.-D. Kampf, J. Kohlmeyer, Nafurwissenschaften 17, 473 (1957).
3. E. 8. Reynolds and S. P. Meyers, Office Naval
2.
Research, Research Revs. (Dec. 1957), pp.
sd
6-11.
4. R. D. Schafer and C. E. Lane, Buil. Marine
Set. Gulf and Caribbean 7, 289 (1957).
5. These studies were aided by a contract (NR
104-142) between the Office of Naval Research,
Department of the Navy, and the University
of Washington.
6. “Marine Boring and Fouling Organisms,” Proc.
Friday Harbor Symposia in Marine Biology
(Univ. of Washington Press, 1958).
A full report on this whole problem, including
consideration of marine wood-inhabiting bacteria and a discussion of the suggestion made
by Becker and by Schafer and Lane that fungi
might contribute to the nutrition of Limnoria,
is in preparation.
8 September 1958
Zinc-65 in Foods and People
Abstract. Disposal of trace amounts of
Zn™ is made in the Columbia River via
Hanford reactor effluent water. The subsequent utilization of river water for irri-
gation permits the concentration of this
radioisotope in farm produce and its
eventual deposition in man. The Zn® in
irrigation water, in farm produce, and in
individuals utilizing these materials has
been measured.
Water from the Columbia River is
used as a coolant for the Hanford reac94
only a few times during their growing
season. In addition, the Zn®> may enter
the grass by foliate absorption during irrigation as well as through the soil.
The relatively high Zn®> concentra-
260
COUNTS / MINUTE / 50 Kev CHANNEL
attack on fresh wood is possible can be
tested under controlled laboratory conditions. Accordingly, dry ‘“unconditioned” blocks of lumber, including Doug-
200F-
tion in milk as compared with thatin the
pasture grass indicated that a large
amount of Zn®5 is taken from the feed
into the blood stream of the cow and
translocated into the milk. The low Zn®
concentration found in the beef samples
(Table {) may be explained by the fact
aor
°
10
20
30
a0
CHANNEL NUMBER
so
690
Fig. 1. Gamma-ray spectrum of an individual containing Zn”.
tors. The subsequent disposal of this
water in the river introduces trace
amounts of several induced radioisotopes,
most of which have half-lives of the order
that the animal wasslaughtered in late
winter and had been fed on essentially
Zn*5-free foodstuffs for 3 to 4 months
prior to that time. Measurements of Zn**
in the same milk supply during January
and February of 1958 showed about 10
percent of the value listed in Table 1.
This again can be explained by the animals’ relatively Zn®*-free diet during the
winter months.
A second animal which had spent its
entire life in the same location was
slaughtered in March of 1958 and was
of minutes to a few hours; however, the
half-lives of some of these isotopes are
sufficiently long to permit tracing the distribution of the isotopes inte the food
chains of the aquaticlife in the river (2).
Zinc-65 is the major long-lived radicisotope introduced into the river, and although it is present at a concentration
far below the most conservative permissible limits, it exists in sufficient amounts
to serve as a tracer; it is thus possible to
follow its path from irrigation water
through plants and animals to man.
Only a small fraction of the Columbia
Table 1, Concentrations of Zn“ in farm
produce.
5
\
ample
Pasture grass
Beef, flesh
Beef, fat
Beef, bone
ConcentraConcentra tion factor
,
_
(muc/g)
(Pros
82.9
5.23
1.48
440
28
7.9
4.88
0.55
26
2.9
5.80
River water used for irrigation is ob-
Milk (cow)
Black-eyed peas
samples considered here were obtained
Okra
String beans
0.39
0.29
Grapes
Irrigation water
0.089
0.188
tained downstream from the Hanford
project. The farm-produce and animal
from an irrigation project about 30 miles
downstream from the Hanford reactors.
By means of gamma-ray spectrometric
Tomatoes
Gorn
31
0.46
2.4
2.1
1.5
0.16
0.83
0.47
techniques, measurable amounts of Zn®*
were found in all the farm produce sampled from this location. The Zn®> concentrations found in milk, beef, and the
various types of vegetables from this land
are shown in Table 1. The concentration
factor (Zn®> concentration in the sample/Zn®> concentration in the irrigation
water) for each sample is also included.
With the exception of the beef, all of
these samples were obtained during July
and August 1957. The beef was obtained
from an animal slaughtered in January
1957 after it had lived 1 year on the irrigation project. The fact that the pasture grass contained a relatively high
Zn® concentration as compared with the
vegetables is probably related to both the
manner and amountofirrigation as well
as to the fact that some difference in up-
take between the leaf and fruit portion
of plants would be expected. The pas-
Table 2. Concentrations of Zn® observed
in the various organs of a beef animal.
Concentration
Sample
(wutc/g)
Flesh
Fat
Bone
Ovaries
Hide
10.7
2.22
13.4
4.07
3.91
Kidney
Lung
5.98
3.11
Brain
Pancreas
Blood
2.74
7.27
0.86
Hair
28.6
Thymus
Liver
Horn
Hoof
.
.
3.79
11.5.
3.59:
" 9159
44
SCIENCE, VOL. 129