AquaBlok 42 days after application indicated that
waterfowl deaths since 1980. Unoxidized white
phosphorus (P4) particles are found in the marsh
algae had begun to grow on it. A large scale field
sediments. Ingestion of P4 is the primary cause of
test is warranted to determine the feasibility of
using AquaBlok as an interim remediation action
the waterfowl deaths. In poisoned ducks, the giz-
zards contained mg amounts of P4; the tissues had
on Eagle River Flats to reduce waterfowl mortality
microgram amounts of P4. Studies were under-
caused by white phosphorus.
taken to determine if predators of ducks were
exposed to P4. Field observations were made to
Pochop, P.A., J.L. Cummings, C.A. Yoder, and
determine predators and frequency of predation.
W .A. Gossweiler (in press) A physical barrier to
Tissue P4 was extracted into isooctane and quanti-
reduce white phosphorus mortalities of foraging
fied by gas chromatography. Numerous predation
waterfowl. In Journal of Environmental Engineering.
events were directly observed. All ducks found
White phosphorus has been identified as the
sick or dead at the site contained P4. Predators of
cause of mortality to certain species of waterfowl
waterfowl included bald eagles, herring gulls, and
using Eagle River Flats, a tidal marsh in Alaska
ravens. Tissues from a dead immature female bald
that is an ordnance impact area belonging to the
eagle contained P4: 0.060 g/g of tissue in the fat
U.S. Army. A blend of calcium bentonite/organo-
and 0.010 g/g tissue in the skin. Two collected
clays, gravel, and binding polymers was tested for
herring gull eggs contained traces of P4. Biotrans-
effectiveness as a barrier to reduce duck foraging
fer of P4 from meat to predator has been confirmed
and mortality. Following the application of the
and quantified in the laboratory using kestrels.
barrier to one of two contaminated ponds, we
Based upon the frequently observed events of
observed greater duck foraging and higher mor-
predation and the lipophilic nature of P4, the prob-
tality in the untreated pond and no mortality in the
ability of P4 poisoning to predators of ducks con-
treated pond after a year of tidal inundations and
taining P4 is great.
ice effects. Emergent vegetation recovered within
a year of treatment. White phosphorus levels in
the barrier were less than the method limit of
Pochop, P.A., and J.L. Cummings (1994) Labora-
tory and field evaluation of AquaBlok to reduce
detection, indicating no migration of white phos-
phorus into the material. Barrier thickness remained
mortality of foraging waterfowl at Eagle River
relatively stable over a period of 4 years, while vege-
Flats, Fort Richardson, Alaska. In Proceedings,
tation was found to be important in stabilizing the
SETAC 15th Annual Meeting, 30 October3 Novem-
barrier material.
ber, Denver, Colorado, p. 3.
Eagle River Flats is an artillery impact area and
Racine, C.H., and L.E. Hunter (1997) Ecology of
is also an important spring and fall waterfowl
staging area. However, white phosphorus, depos-
salt marsh ponds at Eagle River Flats, Upper Cook
ited in the sediment by certain types of explosives,
Inlet, Alaska. In Proceedings, Cook Inlet Symposium,
has been found to cause mortality of large numbers
Anchorage, Alaska, p. 23.
of foraging waterfowl on Eagle River Flats. This
White phosphorus contamination of several
study evaluated the effectiveness of AquaBlok
shallow ponds at Eagle River Flats initiated an
barrier system as a physical barrier to foraging
evaluation of their physical, chemical, and bio-
waterfowl. A laboratory trial was conducted to
logic characteristics. Biological attributes (water-
evaluate the physical characteristics, application
birds, seeds, invertebrates, and vegetation) were
rate, and longevity of AquaBlok when applied to
measured along with physical characteristics
bottom sediment in a simulated pond setting. The
(morphology and distribution, flooding dynam-
laboratory trial indicated that the AquaBlok
ics, water quality). Three types of ponds were rec-
appeared to maintain its structure under mallard
ognized (wet swales, permanent ponds, and inter-
(Anas platyrhynchos) use. The field trial was con-
mittent ponds), each with different species and
ducted at Eagle River Flats, Fort Richardson,
physical characteristics. Intermittent ponds and
Alaska. Six mallards each were placed in a control
wet swales fill when tidal flooding is above a criti-
(7 20 m) and treated (7 7 m) pen for a pre- and
cal threshold. The same ponds dry out during pro-
post-treatment period. During a 6-day pre-treat-
longed intervals between flooding events. Perma-
ment period, all of the ducks died in the control
nent ponds receive fresh water from upland
and half of the ducks died in the AquaBlok pen.
springs, nearby rivers and creeks, and precipi-
After treatment, all of the control ducks and none of
tation, while brackish water is introduced during
the AquaBlok ducks died. Inspections of the
tidal flooding. Shorebirds use intermittent ponds
28
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