leroymoore

Marco Kaltofen’s Technical Report on Sept. 2011 Sampling for Plutonium at Rocky Flats

In Environment, Nuclear Guardianship, Plutonium, Public Health, Rocky Flats, Wildlife Refuge on February 20, 2012 at 6:18 am

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Field investigation and
laboratory report for:

LeRoy Moore, Ph.D.
Rocky Mountain Peace & Justice Center
P. O. Box 1156
Boulder, CO
80306

Prepared by:

Marco Kaltofen, MS, PE, (Civil, Mass.)
Boston Chemical Data Corp.
January 23, 2012

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Summary of Key Findings

This revised report includes additional plutonium data by PACE Analytical.  Six of
nine soil samples tested by a commercial laboratory found plutonium at 30, 36, 37,
126, 270, and 1,579 pCi/Kg.  The soils contained Pu-238 or Pu-239/Pu-240 or
both.  In a 1992 to 1994 study, offsite soil levels were found at 30 pCi/Kg, (Ref. 3,
p. 177).  The Litaor (1999) study as cited in reference 3 found 5.9 to 400 pCi/Kg in
42 soil samples adjacent to the site.

A 2005 USDOE study found that soil background total plutonium concentrations
at a community distant from Hanford, WA averaged between 3 and 4 pCi/Kg, and
that further study found that contaminated Columbia River sediments at the
Hanford Nuclear Reservation had between 1.6 and 10 pCi/Kg of plutonium, (Ref.
3, p. 178).  Two New Mexico studies found 4.3 to 8.0 pCi/Kg of background
plutonium in soils, (Holliman, 1987, 36 samples, cited by Rocky Flats RAC Report
No. 1-RSALOP-2000-Final, and WIPP Report, 2000, 40 samples, url:
http://www.cemrc.org/reports/00rept/pdf/7-soil.pdf).

In addition to the nine soil samples commercially tested for plutonium, a sample
of tree bark from opposite the site on Indiana Street was found to contain 32
pCi/Kg plutonium as Pu-238.  Soil from that same location had 37 pCi/Kg of Pu-
238, which was above the uncertainty level, but below the MDC.  A study of trees
in France, (Garrec, 1995, Applied Radiation and Isotopes, ref. 1), found a
maximum of 0.25 pCi/Kg of plutonium in tree rings.

All of the locations with positive detections of plutonium were to the east of the
Rocky Flats site, and were on the right of way paralleling Indiana Street.

Reference samples taken at greater distances from the site than any of the
remaining study samples showed high levels of thorium and uranium.  In fact, the
highest levels, (6.56 pCi/g Th and 2.13 pCi/g U), were found in the buried near
subsurface soils of an eroding bank at Eldorado Canyon State Park.  The data does
not show that the presence of these isotopes is caused by activities at Rocky Flats.
In fact, the Jamestown district of Boulder County, Colorado has been known since
1945 as a region that contains thorium and uranium bearing rare earth
mineralizations. Total uranium and total thorium were therefore not usable as
indicators of contamination from the Rocky Flats site.

This left plutonium as the sole radioactive element used as an indicator of
contamination from the Rocky Flats site.  However any individual uranium and
thorium bearing particles that are found to be definitively anthropogenic in origin
by SEM/EDS remain candidate indicators of contamination from the Rocky Flats
site.  The study samples with high total counts were found to contain thorium as
the primary radioactive isotope, based on sodium iodide gamma spectrometry.

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Trace levels of cesium-134 and cesium-137 were found in two offsite soil samples.
Given the two-year half life of cesium-134, it is unlikely that the material related to
this low level detection originated at Rocky Flats.  While other sources, (USEPA
Radnet data, 2011, and U. Calif. Berkeley, Dept. of Nuclear Engineering, 2011),
have detected these isotopes in the US, presumably as a result of the Fukushima
releases, this is beyond the scope of this study.

The SEM/EDS analyses by Microvision Laboratories were completed on January
17, 2012.  This analysis determines the elemental composition and size of
individual microscopic particles.  The particles are identified for analysis by the
presence of high z nuclei that are viewed in real time on the instrument’s video
monitoring system.  These analyses confirmed that monazites containing thorium,
uranium, and rare earths were present in the samples.  Silicates containing
uranium and thorium were also detected.  Many, but not all, of these particles
were in the respirable size fraction of 0.5 to 5.0 microns.

Microvision also detected particles containing plutonium and lead in its analysis
of dust samples collected due East of the Rocky Flats site during 2010.  A subset of
these particles from the 2010 series also contained traces of americium.

The presence of hot particles, (see note below), containing plutonium is consistent
with the gross analytical findings of plutonium in fine sediments particles at the
ground surface around the eastern border of the former Rocky Flats facility.

Note:

Hot particles are particles that contain substantially more
activity than surrounding inert materials.  When these
particles are in the 0.5 to 5.0 micron size range, they can
present a significant inhalation hazard, which is
substantially different from that imposed by purely
external electromagnetic radiation such as X-rays and
gamma rays.

(References: See Kaltofen, 2011, Tracking radiological
plumes from the Fukushima Daiichi accident,  Oct. 31, 2011
presentation at 139th annual meeting of the APHA,
Washington, DC, Kaltofen, 2010, Microanalysis of
Workplace Dusts from the Mixed Waste Tank Farm of the
Hanford Nuclear Reservation, J. Environmental
Engineering Science, and Kaltofen, 2009, Master’s
Research Report, Worcester Polytechnic Institute,
Microanalysis of Heterogeneous Radiation in Particulate
Matter.)
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Methods

2010 study: In 2010 a total of four samples, two dusts and two soils, were
received for testing via microanalytical suite for radionuclides.  Samples
were prepped, screened by standard gross radiochemical analyses, and
autoradiographed to determine the degree of total activity and the potential
number of radioactively-hot particles.

Samples were tested via scanning electron microscopy with energy
dispersive X-ray analysis, SEM/EDS, for individual microparticles.  This
method detects both stable and radioactive isotopes.  The presence of
definitively radioactive elements including U, Pu, and Th are noted in the
individual results sections.  Antimony and lead were also reported.

Based on the detected heavy element particles in sample RFCO001D, many
of the heavier elements in this dust were fused or melted aerosol spherical
shot particles. Many of the large particles showed signs of having multiple
phases, fused together like cement or heat-fused grains.  The ! to ” um
thickness of lead screening on many of these shot particles will obscure the
photon returns on any transuranic elements (TRUs) if they are present
inside an aggregate.  Epoxy-fixing and polishing would expose any obscured
TRUs, but this procedure was beyond the scope of this project.

2011 follow up study: Based on these results a field investigation was
undertaken from September 13, 2011 to September 15, 2011.  Forty-five
samples were collected, including seven biological specimens and thirty-
eight surface and shallow buried soils.  Three of the soils were from
reference locations presumed to be subject to reduced influence from the
study site at Rocky Flats, yet still close enough to share similar soil parent
material.  One additional sample was collected of sediment from a
watercourse west of Indiana on March 16, 2011.  This sample was collected
prior to recent ground disturbance by construction at this location.

At the close of the investigation, a total of fifty samples, including the four
2010 samples, had been collected to date.  The 2011 samples included soils
and plant materials.  Soil samples were collected from the top 1 inch, or
from 0.5 or 1.0 feet below the ground surface.  Plant materials included
lichens and bark from mature trees.

All 2011 samples were collected with full chain of custody protocols.
Mapping is via Google Earth Pro, 2011 edition.  Samples were air dried prior
to analysis.  Reference samples were collected from three sites, two east and
one west of the Rocky Flats site.

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Samples were air dried prior to any analyses to reduce self-absorption of any
radiation.  All samples were measured for total surface alpha, beta, and
gamma activity using a Victoreen counter and a pancake probe.  All samples
were scanned using a Ludlum model 702 sodium iodide gamma
spectrometer, with follow-up analyses using either an Ortech 3 inch sodium
iodide gamma spectrometer or a liquid nitrogen cooled germanium lithium
detector.  All gamma detectors used lead/copper multi element shields of
various sizes to reduce background gamma levels.  Gamma emission lines at
46, 73 and 234 keV were used to monitor thorium and uranium
concentrations.

The concentrations of plutonium were presumed to be at levels below those
of the naturally occurring nuclides of thorium and uranium.  Plutonium
analyses were therefore performed commercially at PACE Analytical of
Pennsylvania.

Samples were prepared for SEM/EDS analyses by sieving to pass a standard
ASTM 150 micron brass screen, and mounted using double sided mounting
tape onto aluminum stubs.

Figure 1a: Area map, 2011 Rocky Flats sample study

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Analytical methods and instruments

Preparation:  Air-dried whole samples, except for SEM/EDS which is
prepared by drying then sieving to pass a 150 um screen prior to mounting
and analysis

Counting:  Two channel Ludlum model 3030 alpha/beta counter

Counting:  Victoreen rate meter with pancake detector.

Gamma Spectrometry: Ludlum 1 inch portable sodium iodide detector with
single wall lead shield

Gamma Spectrometry: Ortech 3 inch sodium iodide gamma detector with
Canberra multiwall shield

Gamma Spectrometry: LN2 cooled germanium lithium gamma detector.

Gamma Spectrometry, commercial:  PACE Analytical, Walter Miltz
Laboratory, Pennsylvania, for uranium, thorium, and plutonium isotopic
analysis.

SEM/EDS:  Scanning electron microscopy / energy dispersive X-ray analysis
at Microvision Laboratories of Chelmsford, Mass., using a LEO/Brucher
system lithium-drifted silicon detector and high-z Robinson detector at 0.60
nAmperes and 0 to 60 keV acceleration voltage.

Calibration:  Single element 5 nCi Am-241 metallic certified standard and
multinuclide Eckert & Ziegler evaporated metallic salt 0.584 nCi standard
source received on September 12, 2011 for Cd-109, Co-57, Ce-139, Hg-203,
Sn-113, Sr-85, Cs-137, Y-88, and Co-60.

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Figure 1b: Area map, location of reference samples

Results:

The total activity, measured as sodium iodide gamma counts per second,
was measured for the set of three reference samples and randomly selected
site fence line soil and biota samples.  The mean and standard deviation of
these results are below.  Given that the offsite samples collected at a
significant distance from Rocky Flats have higher gamma counts per second
than the fence line samples, it’s clear from the blank-corrected data below
that total activity is not a reliable indicator of contamination from the Rocky
Flats site.

Reference samples: 3.9 gCPS with SD = 3.7

Biological samples:  0.2 gCPS with SD = 0.6

Fence line soils: 2.1 gCPS with SD = 1.6

Both the reference and fence line samples had gamma spectral lines, (73 keV
and 234 keV), consistent with thorium.  (See appendix) Some of the fence
line samples also had a gamma spectral line at 46 keV, consistent with lead-
210, a daughter isotope of nonfissile uranium-238.  (See appendix)
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Figure 2: Total activity in soil and plant
material samples, 2011 Rocky Flats sample set

Seven samples of biological material, (lichen and bark from mature trees
more than 6 inches ABH), were collected and analyzed along with the soils.
Total activity in the biological samples was relatively low compared to both
the reference soils and the fence line soils.

Gamma spectral peaks associated with uranium and thorium, (see previous
page), were found in the soil samples.  These were absent in the biological
samples.  This is confirmed in the data from PACE Analytical, which found
an average of 4.36 pCi/g of thorium and 1.59 pCi/g of uranium in the soils,
compared to 0.63 pCi/g of thorium and 0.08 pCi/g of uranium in the
biological samples.

A sample of tree bark collected opposite the site on Indiana, (sample
RFCO044B), contained a quantifiable amount of plutonium 238, at a
concentration of 30. pCi/Kg.  (Note units change.)

Notably, plutonium was not detected in the reference sample taken from
Eldorado Canyon State Park.  In fact, plutonium was only detected in
samples that were along a line on the eastern edge of the Rocky Flats site.
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Figure 3a:  Locations of plutonium detections

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Figure 3b:  Locations of plutonium nondetects

Figure 3c: Pu-239 distribution adapted from 1970 Krey-Hardy report

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The plutonium concentrations faithfully follow the contours shown in the
Krey- Hardy report, with positive detections along Indiana Street directly
east of the site, but nondetects west and south of the site.

The following discussion of the plutonium test results is based on (a),
Toxicological Profile For Plutonium, U.S. Department Of Health And
Human Services Public Health Service Agency For Toxic Substances And
Disease Registry, November 2010, (b), Argonne National Laboratory, EVS
Human Health Fact Sheet, Plutonium, August 2005,
http://www.evs.anl.gov/pub/doc/Plutonium.pdf, and (c), LaVelle et al,
(2002), A Comparative Study of 239,240Pu in Soil Near the Former Rocky
Flats Nuclear Weapons Facility, Golden, CO.

The dust inhalation vs. soil ingestion risk factors for plutonium are:

Lifetime Cancer Mortality Risk

Isotope   Inhalation   Ingestion
(pCi-1)  (pCi-1)

Plutonium-236  2.1 X 10-8  6.9 X 10-11
Plutonium-238  3.0 X 10-8  1.3 X 10-10
Plutonium-239  2.9 X 10-8  1.3 X 10-10
Plutonium-240  2.9 X 10-8  1.3 X 10-10
Plutonium-241  2.8 X 10-10  1.9 X 10-12
Plutonium-242  2.8 X 10-8  1.3 X 10-10
Plutonium-244  2.0 X 10-8  1.3 X 10-10

Based on these lifetime cancer mortality risk factors, inhalation of particles
containing Plutonium is a more significant risk than contact with or
ingestion of soils.

Overall the results of this sampling and analysis campaign are consistent with
previous reported findings on the site, including the following excerpts:

Another source of soil contamination at Rocky Flats was the leakage
of stored plutonium-contaminated oil. Plutonium was present as the
dioxide when it was released. The dioxide was then adsorbed to the
soil. Fugitive dust emissions caused plutonium-contaminated soil to
be distributed away from the spill. Most of the plutonium remained
on the surface, although some was released and migrated downward
through the soil column (citing Little and Whicker 1978, P. 166).

Plutonium has been identified in 6 soil and 9 sediment samples
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collected from 1,689 NPL hazardous waste sites, where it was
detected in some environmental media (HazDat 2007).  P. 166

The particle size expected to be released from either of the above
mentioned sources, (nuclear testing, NPPs, fuel reprocessing), ranges
from 0.3 to 1.1 µm p. 166

Soil samples collected at the RFETS during 1992–1994 were reported
to range from 1.1 Bq/kg (30 pCi/kg) offsite to 57 Bq/kg (1,500
pCi/kg) onsite. P.177  (Note by M. Kaltofen, 0.03 pCi/g is not the
background level, it is the average offsite level.)

Average Pu concentrations in the Hanford 100N, 200/600, and
300/400 areas were 0.004, 0.350, and 0.030 pCi/g
respectively.  The average Pu concentration was 0.0033 pCi/g in a
community distant from Hanford, P.178

Pu in pCi/g was 0.0008 to 0.011 for Columbia River sediment,
median Pu in pCi/g was 0.002 to 0.010 p. 178.

Liao 2008 as cited on P. 182 found an average of 0.008 pCi/g
Pu239/240 from global fallout in the top 11 cm.

The median offsite soil plutonium concentration found in 2002 by LaVelle et al
was 0.265 pCi/g.  The mean offsite soil plutonium concentration found in this
2011 sample set was 0.226 pCi/g.   These central values are within 1 standard
deviation of each other, meaning that there is no statistically significant
difference between these data sets.  This result does not necessarily imply a
static plutonium distribution, rather, it is likely that losses from the fence line
area are offset by added inputs of plutonium from the former Rocky Flats site.

Subsurface results

Four subsurface samples taken at 12 inches below ground surface were
collected along with surface soil samples at these same locations.  There was
no significant difference in total activity or in gamma spectrometry results
for thorium and uranium between surface and subsurface samples.  The
original intent was to determine whether total activity or uranium and
thorium concentration were related to depth.  Due to the high natural
background levels of uranium and thorium, analysis of these two nuclides is
not a sufficient method for investigating surface contamination related to
activity at the Rocky Flats site.

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Below: Ratio of surface to subsurface gamma activity showing mean (0.93)
and 95 percent confidence limits, (2 times the standard deviation).  The two
sets are not significantly different.

Americium

Americium isotopes were not detected in the Rocky Flats soils, except for
trace amounts in a handful of particles found by SEM/EDS.  The sodium
iodide and germanium lithium gamma detectors were standardized against
a calibrated Am-241 source using the sensitive 59.54 keV gamma line.
There were no detections of americium among the soils or biological
samples.

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Summation:

All 50 samples from the 2010 and 2011 sampling campaigns were tested for
total activity and by gamma isotopic analysis.  A subset of the samples was
tested commercially for plutonium, radioactively-hot particles, along with
confirmation testing for uranium and thorium.

Plutonium exceeded reported background levels by two orders of magnitude
at locations that match those noted in the Krey Hardy report.  (P. W. Krey
and E. P. Hardy, 1970, “Plutonium in Soil Around the Rocky Flats Plant”)

Naturally-occurring total activity, uranium, and thorium levels are elevated
in this area, and were not used as indicators of contamination.

There was no statistically significant difference between this data set and the
1970 data set.  Plutonium losses appear to be approximately equal in
magnitude to plutonium inputs in the Indiana St. area.

The portion of the study area surrounding Indiana St. was contaminated
with plutonium isotopes and traces of americium.  This zone also contained
uranium and thorium bearing monazite particles.  Although monazites are
naturally occurring, these particles nevertheless represent an inhalation
hazard, as they were in the respirable size range of 0.5 to 5.0 microns.
Particles of silicates containing uranium and thorium were also detected.

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Sample Record

ID  Depth (in.) Description (soil unless noted)

RFCO001D NA  (2010 collection) duct dust
RFCO002D NA  (2010 collection) vac bag dust
RFCO002S 0  (2010 collection) open space soil
RFCO003S 0  (2010 collection) 96th St. & Indiana

RFCO005S -6  Watercourse on Indiana
RFCO006S 0  Rte. 93S hiking trail
RFCO007S 0  McCaskin Hwy & Rte. 128
RFCO008S 0  McCaskin Hwy & Rte. 128
RFCO009S 0  Indiana and C.C. Canyon Rd.
RFCO010S -12  Indiana and C.C. Canyon Rd.
RFCO011S 0  Reference: N. Garrison & 100th St.
RFCO012S 0  Reference: 100th & N. Simms
RFCO013S 0  Rte. 93 N and Rte. 128
RFCO014S 0  Rte. 128 @ creek bed
RFCO015S -12  Rte. 128 @ creek bed
RFCO016S 0  Indiana southward 0.4 miles
RFCO017S 0  Indiana southward 0.8 miles
RFCO018S 0  Indiana southward 1.2 miles
RFCO019S 0  Indiana southward 1.6 miles
RFCO020S -12  Indiana southward 1.6 miles
RFCO021S 0  Indiana southward 2.0 miles
RFCO022S 0  Indiana southward 2.4 miles
RFCO023S 0  Indiana southward 2.4 miles
RFCO024S 0  Indiana southward 2.8 miles
RFCO025S -12  Indiana southward 2.8 miles

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Sample Record (continued)

ID  Depth (in.) Description (soil unless noted)

RFCO026S 0  Indiana southward 3.2 miles
RFCO027S 0  Indiana southward 3.6 miles
RFCO028S -6  Reference: Eldorado Canyon State Park
RFCO029S 0  93N near plant gate
RFCO030S 0  93N near plant gate
RFCO031S 0  93N at RF entrance sign
RFCO032S 0  93N & Rte. 72
RFCO033B NA  Lichen south side Rte. 72
RFCO034S 0  At south side Rte. 72
RFCO035S 0  At RR bridge south on Indiana
RFCO036Z 0  At RR bridge south on Indiana (stone)
RFCO037S 0  At RR bridge south on Indiana
RFCO038S 0  At RR bridge south on Indiana
RFCO039B NA  Lichen Rte. 27, Gate 17
RFCO040S 0  Rte. 27, Gate 17
RFCO041B NA  Bark, Rte. 128 near McCaslin
RFCO042S 0  Rte. 128 near McCaslin
RFCO043S 0  Indiana near culvert
RFCO044B NA  Bark, large tree, Ind. @ culvert
RFCO045B NA  Bark, Indiana near culvert
RFCO046B NA  Bark, Indiana near culvert
RFCO047S 0  Indiana near culvert
RFCO048B NA  Lichen – on tree W. of Indiana
RFCO049S 0  NE gate area soil on Indiana
RFCO050S 0  NE gate area soil on Indiana

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Total activity record

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Appendix:  Example gamma spectra

top – thorium present,
bottom – uranium and thorium present

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Copy of isotopic Pu, Th, and U laboratory report pages (1 of 3)
(See PACE reports for full results)

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Copy of isotopic Pu, Th, and U laboratory report pages (2 of 3)
(See PACE reports for full results)

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Copy of isotopic Pu, Th, and U laboratory report pages (3 of 3)
(See PACE reports for full results)

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References:

1) Applied Radiation and Isotopes
Volume 46, Issue 11, November 1995, Pages 1271-1278
Proceedings of Plutonium in the Environment
doi:10.1016/0969-8043(95)00170-I

Plutonium in tree rings from France and Japan
J.-P. Garrec, T. Suzuki, Y. Mahara, D.C. Santry, S. Miyahara, M. Sugahara, J. Zheng, A.
Kudo

Abstract
Plutonium, along with other radionuclide concentrations, was measured in evergreen tree
rings from two different locations. This was used as an information source for the past two
centuries. Tree rings are a product of annual layers and thus chronological information is
clearly visible. Three trees were harvested in 1988–1990: a French white fir (137 years old)
and a spruce tree (177 years old) from the France-Germany border near Nancy, France and
a sugi (78 years old) from Nagasaki, Japan. The uniform branchless part of the trunks from
the harvested trees were immediately separated into a set of tree ring samples each of which
contained 3–20 years of growth. The separated samples were mechanically powdered, dried
at 105°C to obtain the dry weight, ashed at 350°C to measure 40K, 134Cs and 137Cs and
ashed again at 600°C to determine 239+240Pu. The highest 239+240 Pu concentration of
30.0 mBq/kg of dry wood was obtained from the tree rings from Nagasaki, located at the
centre of the local fallout of the Pu A-bomb detonated in 1945. This concentration peak was,
however, observed in tree rings of 1965–1967. The concentration was only 2.9 mBq/kg for
the tree rings of 1944–1946. The contribution of the local fallout on the surface soils from
the A-bomb was 181 mBq/cm2 at the harvested area of the tree, while the contribution of
global fallout by many weapons testing was 5.9 mBq/cm2 (or 3.3% total fallout in the
region). The reason for the over 20 year time lag of 239+240Pu uptake by the tree rings is
unknown because many factors influence the routes of Pu into the tree rings. Also the
chemical form of Pu in surface soils may have been changed by the surrounding
environment. The highest concentration in the tree rings from France was 9.4 mBq/kg
which is about 31% of Nagasaki 239 + 240Pu concentration. The harvested area did not
have any recorded Pu sources other than global fallout. An interesting result was that that
distribution of 134Cs and 137Cs concentrations in the French white fir was different from
Nagasaki. Data suggested that these new radionuclide inputs were from the Chernobyl
accident. The mobility (or diffusion coefficient) of cesium is 2–8 cm2/yr. in the portion of
heart-wood tree rings (1870–1955). Although tree rings can record chronological inputs of
various trace elements, some elements cannot be used. These exceptions would be elements
that: (1) are mobile within tree rings; (2) have little understood entry routes to the tree
rings (via roots, leaves or barks); and (3) have unknown biogeochemical behaviour in the
surrounding environment. Further investigation is warranted to use tree rings as a tool to
record past environmental history.

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2) Journal of Environmental Radioactivity
Volume 21, Issue 1, 1993, Pages 55-63

Effectiveness of tree rings for recording Pu history at Nagasaki, Japan, A. Kudo,
T. Suzuki, D.C. Santry, Y. Mahara, S. Miyahara, J.P. Garrec

Abstract
A 78-year-old tree was harvested in 1988 at 2.8 km east of the Nagasaki Pu bomb
hypocentre, where the local fallout of the 1945 blast was highest. The surface soil
concentration of 239 + 240Pu was 64.5 mBq g
!
1
and that of 137Cs was 87.4 mBq g
!
1
. The tree
rings were analyzed for their concentrations of 239 + 240Pu, 137Cs and 40K. Interestingly, the
concentration profiles over seven decades showed that the Pu was immobile, while Cs and K
were mobile in the tree rings. In other words, the Pu concentration profile revealed a
history of Pu in the surrounding environment of Nagasaki. However, the combined routes,
via leaves from the atmospheric deposition and roots from surface soils to tree rings, made
the record less clear. Surprisingly, the Pu from the Nagasaki Pu-bomb in the tree rings of
1946–44 played a minor role in the concentration profile compared to that from global
fallout. This meant that the Pu in the local fallout was less bio-available compared to that of
the global fallout.

3) Toxicological Profile for Plutonium, ATSDR,
(http://www.atsdr.cdc.gov/toxprofiles/tp143-c6.pdf, accessed 11/29/11)

“A fire on May 11, 1969, occurred at the plutonium processing facility at Rocky Flats,
which caused concerns about possible contamination of the surrounding areas (Agency
for Toxic Substances and Disease Registry 2005). Studies showed that while trace
amounts of plutonium were present in soil, the distribution was not consistent with the
wind direction at the time of the fire. It was determined that the major source of
plutonium contamination was leakage from drums of machine oil containing plutonium
that were being stored in an outdoor area (Eisenbud and Gesell 1997). Another source of
soil contamination at Rocky Flats was the leakage of plutonium-contaminated oil.
Plutonium was present as the dioxide when it was released. The dioxide was then
adsorbed to the soil. Fugitive dust emissions caused plutonium-contaminated soil to be
distributed away from the spill. Most of the plutonium remained on the surface, although
some was released and migrated downward through the soil column (Little and Whicker
1978). ”

January 23, 2012
Marco Kaltofen, PE, (Civil, Mass.)
For Boston Chemical Data Corp.

End of field investigation and laboratory report

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