Pochop, P.A., J.L. Cummings, and C.A. Yoder
the detection limit to 0.02 mg/kg (mean = 0.01
(1995) Evaluation of AquaBlokTM on contamin-
ated sediment to reduce mortality of foraging
from the sediment below the barrier. No mortal-
waterfowl. In Interagency expanded site investiga-
ity of waterfowl was observed during a second
tion: Evaluation of white phosphorus contamination
year of AquaBlokTM exposure to weather and tide
and potential treatability at Eagle River Flats, Alaska
events. AquaBlokTM thickness was reduced by
(C.H. Racine and D. Cate, Ed.). CRREL Contract
05 cm from values in 1994. However, this was
Report to U.S. Army, Alaska, Directorate of Public
largely influenced by heavy traffic (animal and
Works, FY94 Final Report, p. 429444.
human) and limitations in the sampling method.
The results of a 1993 pilot study indicated that
Tide plots indicated that erosion and movement
the AquaBlokTM barrier system could reduce
of AquaBlokTM were lowest on Racine Island,
mortality of foraging waterfowl on Eagle River
where vegetation was important in stabilizing the
Flats, Alaska. Therefore, a definitive study was
barrier.
conducted in 1994. Our objectives were to evalu-
ate the longevity of AquaBlokTM when applied to
Racine, C.H. (1994) Habitat and vegetation. In
an isolated pond up to 0.5 ha in size and to mea-
Interagency expanded site investigation: Evaluation of
sure its effects on waterfowl foraging behavior
white phosphorus contamination and potential treat-
and mortality on Eagle River Flats. During pre-
ability at Eagle River Flats, Alaska (C.H. Racine and
treatment, 23 mallards (Anas platyrhynchos) died
D. Cate, Ed.). CRREL Contract Report to U.S.
in the control pen and 15 died in the treated pen
Army Garrison, Alaska, Directorate of Public
over 10 days; during post-treatment, 24 mallards
Works, FY93 Final Report, p. 523.
died in the control pen and 3 mallards died in the
Five zones and 18 habitat-vegetation types
treated pen. During pre-treatment, the mallards
occur on the 865-ha Eagle River Flats, an estua-
in the treated pen were observed feeding more
rine salt marsh on upper Cook Inlet. These zones
than those in the control pen. However, control
are arranged both longitudinally from the coastal
ducks were observed feeding more frequently
inlet inland and laterally from the river toward
post-treatment. Data collected to date indicates
the upland. The mudflat/distributary zone, located
that AquaBlokTM shows promise for reducing
nearest the river and coastal inlet, occupies 30%
waterfowl mortality from white phosphorus poi-
of ERF and is influenced by actively eroding dis-
soning on Eagle River Flats, Alaska.
tributary channels cutting across the mudflats.
Vegetation cover varies from bare sediment areas
Pochop, P.A., J.L. Cummings, and C.A. Yoder
to sparse cover by annual plants and alkali grass
(1996) Evaluation of AquaBlokTM on contamin-
to well-vegetated stands of arrowgrass, beach
ated sediment to reduce mortality of foraging
rye, and goose tongue. Geese graze in this habitat
waterfowl. In Interagency expanded site investiga-
during early spring, and sandhill cranes use the
tion: Evaluation of white phosphorus contamination
area throughout the summer. Just inside the
and potential treatability at Eagle River Flats, Alaska
mudflat/distributary zone is a continuous or
(C.H. Racine and D. Cate, Ed.). CRREL Contract
fragmented sedge meadow zone dominated by
Report to U.S. Army, Alaska, Directorate of Public
Ramenski's sedge and covering about 8% of ERF.
Works, FY95 Final Report, p. 205230.
A pond/marsh zone (17% of ERF) is located inside
The results of a study conducted in 1994 by
this sedge meadow zone and includes bulrush
covering the bottom of a pond indicated that
and Lyngbyaei's sedge ponds up to 50 cm deep
AquaBlokTM, a physical barrier to foraging
with well-developed submerged aquatic vegeta-
waterfowl, could reduce mortality of waterfowl
tion. This area is important feeding habitat for
when applied to a WP-contaminated pond up to
dabbling ducks and swans. A sedge marsh zone
0.5 ha in size. The objective in 1995 was to con-
occupies the inland end of ERF (30% of the Flats)
tinue to evaluate the effectiveness of this barrier.
where the glacial Eagle River enters and accounts
Emergent vegetation growing through or on the
for any flooding and sediment deposition.
AquaBlokTM recovered from 45% in 1994 to 76%
Finally, a border zone (5% of ERF) with various for-
in 1995. In 1991 (before application), vegetation
est, shrub, and sedge bog communities occurs in
cover in the pond was only 52%, indicating that
two embayments along the upland edge. The
there was no adverse impact of the AquaBlokTM
channel of Eagle River occupies about 8% of ERF.
on the vegetation. Analysis of AquaBlokTM indi-
cated that WP concentration varied from below
Racine, C.H. (1994) A preliminary literature list
51
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