environmental problems related to chemicals are
Walsh, M.E., C.M. Collins, and C.H. Racine
(1996) Persistence of white phosphorus (P4) parti-
surfacing. White phosphorus, commonly used as
cles in salt marsh sediments. Environmental Toxicol-
an obscurant, is a chemical previously thought to
ogy and Chemistry, 15(6): 846855.
be innocuous after use. In 1990, however, it was
Remediation of sediments at Eagle River Flats,
linked to the deaths of thousands of waterfowl at
Alaska, a salt marsh contaminated with solid par-
the Eagle River Flats impact area on Ft. Richard-
ticles of white phosphorus (P4), may require
son near Anchorage, Alaska, U.S.A., and shortly
severe alterations of the wetland by dredging,
after, a series of remedial investigations was initi-
draining, or covering. However, some sediments
ated. This paper describes three of the remedial
may undergo decontamination naturally in areas
methods currently under investigation, namely
that are seasonally subaerially exposed. The per-
enhanced in-situ remediation, pond draining
sistence of millimeter-size P4 particles was studied
through ditching or pumping, or dredging. These
in laboratory and field experiments. White phos-
three approaches are best applied in different
phorus particles were found to be persistent in sat-
environments, but they can be used together or in
urated sediments. In unsaturated sediments, loss
conjuntion with other strategies. Their impacts
was rapid (within 24 hours) at 20C, and was re-
on the environment will vary as well.
tarded by low temperatures.
Experience with these remediation strategies
has proven very useful in determining the direc-
Walsh, M.E., and S. Taylor (1993) Analytical meth-
tion that the cleanup effort at Eagle River Flats
od for white phosphorus residues in munitions-
(ERF) should take. Dredging, an effective means
contaminated sediments. Analytica Chimica Acta.,
of removing contaminated sediments for off-site
282(1): 5561.
remediation, has been shown to be too slow and
An analytical method is described to determine
expensive at ERF because unexploded ordnance
white phosphorus (P4) in sediments contaminated
is present. Enhanced natural remediation is effec-
by smoke munitions. Experiments were per-
tive under favorable climatological conditions in
formed to promote the extraction of P4 from satu-
areas that experience intermittent flooding, but
rated sediment with a nonpolar solvent. P4 extrac-
desaturation of the sediments is critical to its
tion was enhanced by adding water to form a sed-
effectiveness. Pond draining by blasting a ditch
iment-water slurry prior to shaking with isooctane
effectively removes waterfowl feeding habitat,
for up to 24 hours. P4 was determined with a por-
but attenuation of the contaminant is inhibited
table capillary gas chromatograph equipped with
a nitrogen-phosphorus detector. A certified report-
and the habitat alteration is permanent. Pond
ing limit of 0.88 g kg1 was estimated.
pumping, where feasible, has shown great poten-
tial for the desaturating of wide areas of ERF,
Walsh, M.R., M.E. Walsh, and C.M. Collins (1999)
enabling the natural attenuation mechanism to
Remediation methods for white phosphorus con-
progress. Further investigation will be necessary
tamination in a coastal salt marsh. Environmental
to confirm these initial conclusions and deter-
Conservation, 26(2): 112124.
mine the overall effectiveness of all three method-
With the closure of many military bases world-
ologies. Methods developed over the course of
wide and a closer scrutiny of practices on remain-
this work may be applied to other remediation
ing bases, the environmental impact of the mili-
projects where in-situ volatilation can occur and
tary is now an important consideration in the
limited disturbance of wetlands is critical.
operation of bases. Many previously unknown
MAGAZINE ARTICLES
Clark, K. (1991) Researchers unravel duck death
Alaska (1991) The jury's in. Alaska, 57(8): 50.
mystery. VOX of Dartmouth, IX(28): 1.
Alaska Geographic (1991) Scientists solve mys-
Darling, M. (1999) U.S. Army, Army Corps, and
tery of duck deaths. Alaska Geographic, 18(2 (sup-
DPW work together to save ducks. Public Works,
plement)): S11.
IX(4): 1011.
Canterbury, C. (1991) Military munitions blamed
Engineer Update (1991) Solving the mystery.
for waterfowl deaths at Eagle River. Arctic Star,
Engineer Update, 15(6): 9.
4(8): 1.
79
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