relative small number of areas in ERF where the
concentrations was first developed during this
greatest levels of mortality were observed. The
phase and has since been adopted by the USEPA as
results of this sampling have demonstrated that
elevated levels of WP exist in most ponds where
and review of these data have led to the following
the highest mortality levels occur; however, in
conclusions:
some ponds where high mortality has been
WP is the primary cause of waterfowl mortality.
observed, WP has not been extensively detected in
Symptoms exhibited by exposed ducks in
the sediment. This finding suggests that some
ERF are similar to those observed in ducks
birds may ingest WP in a contaminated area but
dosed with WP in the laboratory. WP also was
fly away from the point of exposure before suc-
detected in tissue samples collected from
cumbing. The potential for birds to move follow-
duck carcasses found in ERF.
ing exposure, coupled with limitations on sam-
WP was deposited in the sediment primarily dur-
pling efforts because of the hazard posed to site
ing range firing activities. WP smoke munitions
workers by the unexploded ordnance (UXO), has
were used during training activities in ERF for
complicated delineation of the lateral and vertical
several decades. Rounds were fired onto the
flats and detonated, dispersing WP particles
Previous sampling results and detailed obser-
over large areas. Further distribution of the
vation of various populations within ERF have
particles likely occurred when high-explosive
identified waterfowl as the primary receptors of
rounds exploded in WP-contaminated soil
and sediment.
have been found in plants, macroinvertebrates,
Craters in ERF potentially indicate the level of
and fish, existing data do not show that these pop-
range firing activity. Detonation of HE muni-
ulations have been significantly affected by the
tions generally creates a crater at the point of
presence of WP in ERF. There is some evidence
impact. Although WP munitions do not form
indicating that scavengers that feed on waterfowl
craters upon detonation, they typically have
carcasses in ERF, particularly bald eagles, may
been used in conjunction with HE training ac-
have been affected by WP. It is believed, however,
tivities. By applying a cause-and-effect
that reducing the acute effect in dabbling water-
approach, it can be deduced that the more cra-
fowl (mortality) to acceptable levels also will
ters in an area, the more munitions that have
reduce potential effects (acute or chronic) in the
likely been fired there, and thus the higher
predators and scavengers that have been identi-
fied as secondary receptors because of the reduc-
WP particles are not homogeneous throughout
tion in their exposure concentrations. Therefore,
ERF. WP particles are dispersed after muni-
the primary preliminary remediation goal for ERF
tions containing WP are detonated. Particle
is the reduction of mortality in dabbling ducks
sizes vary because of the nature of an explo-
and swans.
sive release. Particle size, dispersion pattern,
Observations of carcass locations, areas pre-
and ultimate resting location also depend on
ferred by waterfowl, and crater densities were
whether the munitions were detonated on
used by researchers to define areas most likely to
land or over water. Even within small areas,
contain WP. The sediments in these areas were
the particle density can vary substantially.
extensively sampled for WP, with the use of radial
The detection frequencies and concentrations for
transects in open ponds. The distribution of ponds,
WP in sediment are highest Area C, Bread Truck,
and analytical results of WP in sediment, were com-
and Racine Island. Of the overall ERF sampling
piled and used in conjunction with landcovers
locations, 63% had no detectable concentra-
(combination of landform and vegetation) and bird
tions, but at least 45% of the locations in each
usage data to identify hot ponds that are likely the
of these three areas had detectable concentra-
area presenting the highest risk. The UXO hazard in
tions. The highest concentration, 3071 mg/g,
ERF, in combination with the high sampling fre-
was found on Racine Island.
quency, makes extensive future sampling efforts
WP particles can break down (sublime) when
infeasible.
exposed to air, but are long lasting in water-
The findings documented in this report are
saturated media. WP particles are readily oxi-
based primarily on data collected before imple-
dized when exposed to air at temperatures
exceeding 20C. Because they dissolve so
menting the CERCLA process at OUC. However,
the analytical process for the identification of WP
slowly, particles have an indefinite life when
15
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