and recovered in 1997, loss was approximately
15). Confirming previous discrete sampling, we
50% in Area C. In 1998, loss was approximately
did not find white phosphorus in this pond.
78%. Although drying conditions in 1998 were not
Pond 258 is located on the west side of ERF in
as favorable as in 1997, the consolidation of the
Area A. It is a large pond (1.72 ha [4.25 acres])
sediments over the course of the 1997 season
where over 50 discrete samples were collected be-
boosted the effectiveness of the 1998 season.
tween 1991 and 1994. Sampling was prompted by
the large number of waterfowl carcasses that have
Composite sampling
been found in this pond (e.g., 70 carcasses in Aug-
The objectives of composite sampling are to pro-
ust 1992). Only four of these discrete samples were
vide a measure of mean concentration over a large
positive; the highest concentration found was 0.04
g/g. Several positive samples were collected just
area and to detect the presence of hot spots con-
taining white phosphorus particles large enough
north of Pond 258, but again concentrations and
to present a lethal dose to a duck. In June 1997, a 200-
frequency of detection were much lower than in
m-long transect was established through Area C,
Ponds 183, 109, and Racine Island. In August 1998,
extending from the intermittent pond in the west
we established three west to east transects labeled
through the permanent pond in the east. Compos-
258 south, 258 middle, and 258 north. The lengths
ite samples collected at 50-m intervals along the
of these transects were 90, 80, and 75 m. Compos-
transect showed that the highest concentrations
ite samples were collected from the nodes of grids
were in the middle (100 m) of the transect, at the
extending south and north of the east-west
western end of the permanent pond, where previ-
transects. We also collected several composite
ous discrete sampling showed high concentrations
samples by combining subsamples taken at 2-m
of white phosphorus. We sieved each of the com-
intervals along lines. Five composites were
posite samples through a 0.5-mm sieve and found
formed from sediment collected along a drainage
macroscopic white phosphorus particles only in
ditch along the southwest side of the pond. One
the 100-m grid sample. Water was pumped from
composite was formed from samples taken in a
the pond and the sediments allowed to consolidate
circle around the only target in this pond. Two
and dry. Resampling of the 100-m grid in Septem-
composites were formed from samples taken
ber 1997 showed an 89% reduction in the mean
along lines running through datalogger stations in
concentration found in the grid. Samples collected
Ponds 258 and 256 (labeled A1 and A2). Addition-
from the grid in 1998 showed low concentrations
al samples were taken between line A1 and the
persisting, despite drying of the sediment. We did
sump hole in Pond 258 and around the rim of the
not find white phosphorus particles when we
sump hole after a sandpiper died while feeding
sieved the September 1997 and the 1998 samples.
In 1998, transects were established
in Area A, Ponds 290 and 258, with the
objective to find hotspots. Previous
N
sampling in Area A showed some
contamination, but no hotspots. Pond
290 was identified as a "hot pond"
North
North
due to the presence of craters, perma-
Miidddle
M dle
nent water, and waterfowl. While pre-
Southh
So ut
vious sampling did not indicate wide-
Pond 256
ond 256
P
spread contamination with white
Pond 258
Pond 258
phosphorus, the pond was sufficiently
similar to other contaminated areas to
warrant further sampling. In June
160 m
160 m
1200 m
12 m
1998, we set up a 160-m transect
80 mm
80
through the long axis of Pond 290,
400m
4 m
based on the design we used in Area
0m
0m
C. At 40-m intervals, we collected grid
Pond 290
composite samples. Additional sam-
0
200 m
0
200 m
ples were collected north and south of
the transect, and along a line perpen-
Figure 15. Composite sampling transects in Area A.
dicular to the transect at 140 m (Fig.
19
Previous Page
