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Pacific Northwest Laboratories
Battelle Boulevard
Richland, Washington 99352 * ~
409805
Telephone (509) 946-2378
Telex 32-6345
October 19, 1976
REPOSITORY
COLLECTION Marsha ]) lslands
Mr. E. M. Bramlitt
Defense Nuclear Agency
Field Command
Kirttand Air Force Base, NM
PN NMA.
"BOX No.
871715
FOLDER
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Dear Ed:
239-240
Enclosed are the
Pu in soil contours Dr. Pam Doctor and I obtained
using the data you sent us that were collected at random soil locations on
the istand of Enjebi (Janet) Enewetak Atoll] in 1972.
The enclosure labeled "A" gives estimated contours in units of pCi/gram;
in addition, the location of data points are indicated by a cross. Three
contour levels in log, scale are indicated; 2.08, 2.7] and 3.56. These are
rounded from actual contour levels of 2.079442, 2.70805, and 3.555348, which
when antilogs are taken, correspond to 8, 15, and 35 pCi/gram, respectively.
The contours on the plot are in log, units since the contours were obtained
on the logarithms of the data. The coordinates around the plot correspond
to the North and East coordinate system you supplied with the data.
Enclosure "B" qivss the same contour lines as "A" and in addition plots the
value of the 259-240py soil concentrations (pCi/gram) at collection locations.
These are the
to "B" except
four bands of
contour lines
data used to estimate the contours. Enclosure "C" is identical
that Pam has roughed in the shoreline of Enjebi and colored the
estimated concentrations (<8, 8-15, 15-35, >35 pCi/gram). The
extending off the island should be ignored.
The estimated contours were obtained using a nearest-neighbor estimation
routine on the SURFACE II Graphics System developed by the Kansas Geological
Survey. This system is described in “The SURFACE II Graphics System” by R.
J. Sampson, pp. 244-266 in Display and Analysis of Spatial Data (J. C. Davis
and M. J. McCullogh, eds.), John Wiley and Sons, 1975.
routines used were GRID and NEAR.
The specific sub-
The basic idea is to estimate 239-240py
concentrations at equally spaced grid points over the island. The grid size
used here was 100 feet. The estimate at each grid point was obtained as a
weighted average of the eight nearest data points, where the data nearest